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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Parts 56, 57, 60, 70, 71, 72, 75,
and 90
[Docket No. MSHA–2023–0001]
RIN 1219–AB36
Lowering Miners’ Exposure to
Respirable Crystalline Silica and
Improving Respiratory Protection
Mine Safety and Health
Administration (MSHA), Department of
Labor.
ACTION: Final rule.
AGENCY:
SUMMARY: The Mine Safety and Health
Administration (MSHA) is amending its
existing standards to better protect
miners against occupational exposure to
respirable crystalline silica, a significant
health hazard, and to improve
respiratory protection for miners from
exposure to airborne contaminants.
MSHA’s final rule also includes other
requirements to protect miner health,
such as exposure sampling, corrective
actions to be taken when a miner’s
exposure exceeds the permissible
exposure limit, and medical
surveillance for metal and nonmetal
mines.
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DATES:
Effective date: The final rule is
effective June 17, 2024, except for
amendments 21, 22, 25, 26, 27, 30, 31,
34, 35, 36, 38, 39, 42, 43, 46, 47, 50, 51,
54, 55, 59, 60, 63, 64, 68, 69, 73, 74, 77,
78, 81, 82, 83, 86, 87, 90, 91, 94, 95, 98,
99, 102, 103, 106, 107, 110, and 111,
which are effective April 14, 2025, and
amendments 4, 5, 8, 9, 13, 14, 17, and
18, which are effective April 8, 2026.
Incorporation by reference date: The
incorporation by reference of certain
materials listed in the rule is approved
by the Director of the Federal Register
beginning June 17, 2024, except for the
material in amendment 60, which is
approved beginning April 14, 2025, and
the material in amendments 9 and 18,
which is approved beginning April 8,
2026. The incorporation by reference of
certain other material listed in the rule
was approved by the Director of the
Federal Register as of July 10, 1995.
Compliance dates: Compliance with
this final rule is required April 14, 2025
for coal mine operators and April 8,
2026 for metal and nonmetal mine
operators.
S.
Aromie Noe, Director, Office of
Standards, Regulations, and Variances,
MSHA, at: silicaquestions@dol.gov
FOR FURTHER INFORMATION CONTACT:
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(email); 202–693–9440 (voice); or 202–
693–9441 (facsimile). These are not tollfree numbers.
SUPPLEMENTARY INFORMATION:
The preamble to the final standard
follows this outline:
I. Executive Summary
II. Pertinent Legal Authority
III. Regulatory History
IV. Background
V. Health Effects Summary
VI. Final Risk Analysis Summary
VII. Feasibility
VIII. Summary and Explanation of the Final
Rule
IX. Summary of Final Regulatory Impact
Analysis and Regulatory Alternatives
X. Final Regulatory Flexibility Analysis
XI. Paperwork Reduction Act
XII. Other Regulatory Considerations
XIII. References
XIV. Appendix
Acronyms and Abbreviations
COPD chronic obstructive pulmonary
disease
ESRD end-stage renal disease
FEV forced expiratory volume
FRA final risk analysis
FRIA final regulatory impact analysis
FVC forced vital capacity
L/min liters per minute
mg milligram
mg/m3 milligrams per cubic meter
mL milliliter
mg/m3 micrograms per cubic meter
MNM metal and nonmetal
MRE Mining Research Establishment
NMRD nonmalignant respiratory disease
PEL permissible exposure limit
PMF progressive massive fibrosis
PRA preliminary risk analysis
RCMD respirable coal mine dust
REL recommended exposure limit
SiO2 silica
TB tuberculosis
TLV® Threshold Limit Value
TWA time-weighted average
I. Executive Summary
A. Purpose of the Regulatory Action
The purpose of this final rule is to
reduce occupational disease in miners
and to improve respiratory protection
against airborne contaminants. The rule
sets the permissible exposure limit
(PEL) of respirable crystalline silica at
50 micrograms per cubic meter of air
(mg/m3) for a full-shift exposure,
calculated as an 8-hour time weighted
average (TWA) for all mines. This rule
also establishes an action level for
respirable crystalline silica of 25 mg/m3
for a full-shift exposure, calculated as an
8-hour TWA for all mines. In addition
to the PEL and action level, the rule
includes provisions for methods of
compliance, exposure monitoring,
corrective actions, respiratory
protection, medical surveillance for
metal and nonmetal (MNM) mines, and
recordkeeping.
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The statutory authority for this rule is
provided by the Mine Act under
sections 101(a), 103(h), and 508. 30
U.S.C. 811(a), 813(h), and 957. A full
discussion of Mine Act legal
requirements can be found in Section II.
Pertinent Legal Authority. MSHA
implements and administers the
provisions of the Mine Act to prevent
death, illness, and injury from mining
and promote safe and healthful
workplaces for miners.
Respirable crystalline silica is
classified by the International Agency
for Research on Cancer (IARC) as a
human carcinogen. Occupational
exposure to respirable crystalline silica
results in adverse health effects and
increases risk of death. The adverse
health effects include silicosis (i.e.,
acute silicosis, accelerated silicosis,
chronic silicosis, and progressive
massive fibrosis), nonmalignant
respiratory diseases (e.g., emphysema
and chronic bronchitis), lung cancer,
and kidney disease. Each of these effects
is chronic, irreversible, and potentially
disabling or fatal. Occupational
exposure to respirable crystalline silica
at mines occurs most commonly from
respirable dust generated during mining
activities, such as cutting, sanding,
drilling, crushing, grinding, sawing,
scraping, jackhammering, excavating,
and hauling of materials that contain
silica.
Existing standards pertaining to
respirable crystalline silica for both
MNM and coal mines have been in
place since the early 1970s. For MNM
mines, the existing standards,
established by the Department of
Interior, Bureau of Mines, in 1974,
helped protect miners from the most
dangerous levels of exposure to
respirable crystalline silica. The existing
MNM PELs for the three polymorphs of
respirable crystalline silica are: 0.1 mg/
m3 or 100 micrograms per cubic meter
of air (mg/m3) for quartz; 0.05 mg/m3 or
50 mg/m3 for cristobalite; and 0.05 mg/
m3 or 50 mg/m3 for tridymite. Existing
standards for coal mines, first
established by the Federal Coal Mine
Health and Safety Act of 1969 as interim
standards in 1970, control miners’
exposures to respirable crystalline silica
indirectly by reducing the respirable
coal mine dust standard when quartz is
present. The exposure limit for
respirable crystalline silica during a coal
miner’s shift is 100 mg/m3, reported as
an equivalent concentration as
measured by the Mining Research
Establishment (MRE) instrument.
However, since the promulgation of
these existing standards, the National
Institute for Occupational Safety and
Health (NIOSH) has recommended a
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lower respirable crystalline silica
exposure level of 50 mg/m3 for all
workers, including miners. In 2016, the
Occupational Safety and Health
Administration (OSHA) established a
PEL of 50 and an action level of 25 mg/
m3 as an 8-hour TWA in the general and
construction industries and maritime
sector that it regulates. In the mining
industry, however, the higher PELs have
remained in place for miners in both the
MNM sector and the coal sector.
To better protect miners’ health,
therefore, with this final rule MSHA is
lowering its existing exposure limits for
quartz or respirable crystalline silica to
50 mg/m3 and setting an action level of
25 mg/m3 for all miners. As discussed in
Section V. Health Effects Summary and
Section VI. Final Risk Analysis
Summary, lowering the PEL will
substantially reduce health risks to
miners. This final rule also provides a
uniform, streamlined regulatory
framework to ensure consistent
protection across mining sectors and
make compliance more straightforward.
As discussed in Section VII. Feasibility
and Section IX. Summary of Final
Regulatory Impact Analysis and
Regulatory Alternatives, compliance
with the final rule is technologically
and economically feasible, and the final
rule has quantified benefits in terms of
avoided deaths and illnesses that greatly
outweigh the costs, as well as other
important unquantified benefits.
B. Summary of Major Provisions
MSHA amends its existing standards
on respirable crystalline silica or quartz,
after considering all the testimonies and
written comments the Agency received
from a variety of stakeholders, including
miners, mine operators, labor unions,
industry trade associations, government
officials, and public health
professionals, in response to its notice
of proposed rulemaking. Below is a
summary of major provisions in the
final rule. Section VIII. Summary and
Explanation of the Final Rule discusses
each provision in the final rule.
This final rule:
1. Establishes a uniform permissible
exposure limit (PEL) and action level for
all mines. The rule sets a PEL for
respirable crystalline silica at 50
micrograms per cubic meter of air (mg/
m3) over a full shift, calculated as an 8hour TWA and an action level at 25 mg/
m3 over a full shift, calculated as an 8hour TWA for all mines.
2. Requires exposure monitoring for
respirable crystalline silica. Mine
operators are required to conduct
sampling to assess miners’ exposures to
respirable crystalline silica. Mine
operators are also required to evaluate
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the impact of mining production,
processes, equipment, engineering
controls, and geological condition
changes on respirable crystalline silica
exposures.
3. Updates the standard for respirable
crystalline silica sampling. ISO
7708:1995(E), Air quality—Particle size
fraction definitions for health-related
sampling, First Edition, 1995–04–01
(ISO 7708:1995), is incorporated by
reference. The final rule requires mine
operators to conduct sampling for
respirable crystalline silica using
respirable particle size-selective
samplers that conform to ISO
7708:1995, which is the international
consensus standard that defines
sampling conventions for particle size
fractions used in assessing possible
health effects of airborne particles in the
workplace and ambient environment.
4. Requires immediate reporting and
corrective action to remedy
overexposures. Whenever an
overexposure is identified, mine
operators must immediately report to
MSHA and take corrective action to
lower the concentration of respirable
crystalline silica to at or below the PEL,
resample to determine the efficacy of
the corrective action taken, and make a
record of all sampling and corrective
actions that were taken.
5. Specifies methods of controlling
respirable crystalline silica. All mines
are required to install, use, and maintain
feasible engineering controls as the
primary means of controlling respirable
crystalline silica; administrative
controls may be used, when necessary,
as a supplementary control.
6. Requires temporary use of
respirators at metal and nonmetal
mines when miners must work in
concentrations above the PEL. When
MNM miners must work in
concentrations of respirable crystalline
silica above the PEL while engineering
controls are being developed and
implemented or it is necessary by nature
of the work involved, the mine operator
shall use respiratory protection as a
temporary measure.
7. Updates the respiratory protection
standard. ASTM F3387–19, Standard
Practice for Respiratory Protection,
approved August 1, 2019 (ASTM
F3387–19), is incorporated by reference.
When approved respirators are used, the
mine operator must have a written
respiratory protection program to
protect miners from airborne
contaminants, including respirable
crystalline silica, in accordance with
ASTM requirements.
8. Requires medical surveillance at
MNM mines. Metal and nonmetal mine
operators are required to provide to all
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miners, including those who are new to
the mining industry, periodic medical
examinations performed by a physician
or other licensed health care
professional (PLHCP) or specialist, at no
cost to the miner. Like coal miners,
MNM miners will be able to monitor
their health and detect early signs of
respiratory illness.
The requirements in the new part 60
will take effect on June 17, 2024. For
coal mine operators, compliance with
part 60 is required by 12 months after
the publication date; for MNM
operators, compliance is required by 24
months after the publication date. The
delayed compliance is to strike a
balance between meeting the urgent
need to protect miners from this health
hazard and giving mining operators
adequate preparation time to allow them
to comply effectively with the new
requirements.
In addition, conforming amendments
to parts 56, 57, 70, 71, 72, 75, and 90
will take effect on June 17, 2024.
Compliance with conforming
amendments to parts 56 and 57 is
required by 24 months after the
publication date; and compliance with
conforming amendments to parts 70, 71,
72, 75, and 90 is required by 12 months
after the publication date.
C. Summary of Final Regulatory Impact
Analysis
MSHA’s economic analysis estimates
that the final rule would cost
approximately an average of $89 million
per year in 2022 dollars at an
undiscounted rate, $90 million at a 3
percent discount rate, and $92 million
at a 7 percent discount rate. Based on
the results of the Final Regulatory
Impact Analysis (FRIA), MSHA
estimates that this final rule’s monetized
benefits would exceed its costs, with or
without discount rates. Monetized
benefits are estimated from avoidance of
531 deaths related to NMRD, silicosis,
ESRD, and lung cancer and 1,836 cases
of silicosis associated with silica
exposure over the first 60-year period
after the promulgation of the final rule.
The estimated annualized net benefit is
approximately $294 million at an
undiscounted rate, $157 million at a 3
percent discount rate, and $40 million
at a 7 percent discount rate.
A rule is significant under Executive
Order 12866 Section 3(f)(1), as amended
by E.O. 14094, if it is likely to result in
‘‘an annual effect on the economy of
$200 million or more.’’ The Office of
Management and Budget has
determined that the final rule is
significant under E.O. 12866 Section
3(f)(1).
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In summary, this final rule will
strengthen MSHA’s existing regulatory
framework and improve health
protections for the nation’s miners. It
establishes a uniform PEL that aligns
respirable crystalline silica exposure
limits for MNM and coal miners with
workers in other industries. Moreover,
the final rule updates the existing
respiratory protection standard to
require mine operators to provide
miners with NIOSH-approved
respiratory equipment that has been
fitted, selected, maintained, and used in
accordance with recent consensus
standards. It also requires all MNM
operators to provide medical
surveillance in the form of a medical
examination regime similar to the one
that already covers coal miners.
Cumulatively, the final rule will lower
miners’ risks of developing chronic,
irreversible, disabling, and potentially
fatal health conditions, consistent with
MSHA’s mission and statutory mandate
to prevent occupational diseases and
protect U.S. miners from suffering
material health impairments.
II. Pertinent Legal Authority
The statutory authority for this final
rule is provided by the Mine Act under
sections 101(a), 103(h), and 508. 30
U.S.C. 811(a), 813(h), and 957. MSHA
implements the provisions of the Mine
Act to prevent death, illness, and injury
from mining and promote safe and
healthful workplaces for miners. The
Mine Act requires the Secretary of Labor
(Secretary) to develop and promulgate
improved mandatory health or safety
standards to prevent hazardous and
unhealthy conditions and protect the
health and safety of the nation’s miners.
30 U.S.C. 811(a).
Congress passed the Mine Act to
address these dangers, finding ‘‘an
urgent need to provide more effective
means and measures for improving the
working conditions and practices in the
Nation’s coal or other mines in order to
prevent death and serious physical
harm, and in order to prevent
occupational diseases originating in
such mines.’’ 30 U.S.C. 801(c). Congress
concluded that ‘‘the existence of unsafe
and unhealthful conditions and
practices in the Nation’s coal or other
mines is a serious impediment to the
future growth of the coal or other
mining industry and cannot be
tolerated.’’ 30 U.S.C. 801(d).
Accordingly, ‘‘the Mine Act evinces a
clear bias in favor of miner health and
safety.’’ Nat’l Mining Ass’n v. Sec’y, U.S.
Dep’t of Lab., 812 F.3d 843, 866 (11th
Cir. 2016).
Section 101(a) of the Mine Act gives
the Secretary the authority to develop,
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promulgate, and revise mandatory
health standards to address toxic
materials or harmful physical agents.
Under Section 101(a), a standard must
protect lives and prevent injuries in
mines and be ‘‘improved’’ over any
standard that it replaces or revises.
The Secretary must set standards to
assure, based on the best available
evidence, that no miner will suffer
material impairment of health or
functional capacity from exposure to
toxic materials or harmful physical
agents over their working lives. 30
U.S.C. 811(a)(6)(A). In developing
standards that attain the ‘‘highest degree
of health and safety protection for the
miner,’’ the Mine Act requires that the
Secretary consider the latest available
scientific data in the field, the feasibility
of the standards, and experience gained
under the Mine Act and other health
and safety laws. Id. As a result, courts
have found it ‘‘appropriate to ‘give an
extreme degree of deference’ ’’ to MSHA
‘‘ ‘when it is evaluating scientific data
within its technical expertise.’ ’’ Nat’l
Mining Ass’n, 812 F.3d at 866 (quoting
Kennecott Greens Creek Mining Co. v.
MSHA, 476 F.3d 946, 954 (D.C. Cir.
2007)). Consequently, MSHA’s ‘‘duty to
use the best evidence and to consider
feasibility . . . cannot be wielded as
counterweight to MSHA’s overarching
role to protect the life and health of
workers in the mining industry.’’ Nat’l
Mining Ass’n, 812 F.3d at 866. Thus,
‘‘when MSHA itself weighs the evidence
before it, it does so in light of its
congressional mandate’’ in favor of
protecting miners’ health. Id. Moreover,
‘‘the Mine Act does not contain the
‘significant risk’ threshold requirement’’
from the OSH Act. Nat’l Mining Ass’n v.
United Steel Workers, 985 F.3d 1309,
1319 (11th Cir. 2021); see also Nat’l
Min. Ass’n v. Mine Safety & Health
Admin., 116 F.3d 520, 527–28 (D.C. Cir.
1997) (contrasting the Mine Act at 30
U.S.C. 811(a) with the OSH Act at 29
U.S.C. 652 and noting that ‘‘[a]rguably,
this language does not mandate the
same risk-finding requirement as
OSHA’’ and holding that ‘‘[a]t most,
. . . [MSHA] was required to identify a
significant risk associated with having
no oxygen standard at all’’).
Section 103(h) of the Mine Act gives
the Secretary the authority to
promulgate standards involving
recordkeeping and reporting. 30 U.S.C.
813(h). Additionally, section 103(h)
requires that every mine operator
establish and maintain records, make
reports, and provide this information as
required by the Secretary. Id. Section
508 of the Mine Act gives the Secretary
the authority to issue regulations to
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carry out any provision of the Mine Act.
30 U.S.C. 957.
MSHA’s final rule to lower the
exposure limits for respirable crystalline
silica adopts an integrated monitoring
approach across all mining sectors and
updates the existing respiratory
protection requirements. The final rule
fulfills Congress’ direction to protect
miners from material impairments of
health or functional capacity caused by
exposure to respirable crystalline silica
and other airborne contaminants.
III. Regulatory History
On August 29, 2019, MSHA published
a Request for Information (RFI) in the
Federal Register to solicit information
and data on a variety of topics
concerning silica (quartz) in respirable
dust (84 FR 45452). In the RFI, MSHA
requested data and information on
technologically and economically
feasible best practices to protect MNM
and coal miners’ health from exposure
to quartz, including a lowered
permissible exposure limit (PEL), new
or developing protective technologies,
and/or effective technical and
educational assistance (84 FR 45456).
Specifically, MSHA requested input
from industry, labor, and other
interested parties on the following four
topics: (1) new or developing
technologies and best practices that can
be used to protect miners from exposure
to quartz dust; (2) how engineering
controls, administrative controls, and
personal protective equipment can be
used, either alone or concurrently, to
protect miners from exposure to quartz
dust; (3) additional feasible dust-control
methods that could be used by mining
operations to reduce miners’ exposures
to respirable quartz during high-silica
cutting situations, such as on
development sections, shaft and slope
work, and cutting overcasts; and (4) any
other experience, data, or information
that may be useful to MSHA in
evaluating miners’ exposures to quartz
(84 FR 45456).
The Agency received 57 comments
from citizens, labor, industry, and
public health stakeholders in response
to the RFI. Stakeholders expressed
various and differing opinions on how
and to what extent MSHA should
address the protection of miners’ health
from exposure to silica. Many of these
stakeholders also commented on
MSHA’s proposed rulemaking,
summarized below.
On June 30, 2023, MSHA made an
informal copy of the proposed rule
available on the Agency’s website, prior
to publication in the Federal Register,
so the public and stakeholders could
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review it in advance of the comment
period.
On July 13, 2023, MSHA published
the proposed rule, Lowering Miners’
Exposure to Respirable Crystalline
Silica and Improving Respiratory
Protection, in the Federal Register (88
FR 44852). The standalone documents
‘‘Health Effects of Respirable Crystalline
Silica,’’ ‘‘Preliminary Risk Analysis,’’
and ‘‘Preliminary Regulatory Impact
Analysis’’ were also made publicly
available at that time. MSHA proposed
to set the PEL of respirable crystalline
silica at 50 micrograms1 per cubic meter
of air (mg/m3) for a full-shift exposure,
calculated as an 8-hour time-weighted
average. MSHA’s proposal included
other requirements for sampling,
qualitative evaluations, corrective
actions, and medical surveillance for
MNM mines. Finally, the proposal
included requirements for respiratory
protection, including the incorporation
by reference of ASTM F3387–19
Standard Practice for Respiratory
Protection.
On July 26, 2023, MSHA published a
notice in the Federal Register
scheduling three public hearings on the
proposed rule (88 FR 48146). Hearings
were held on: (1) August 3, 2023, in
Arlington, Virginia; (2) August 10, 2023,
in Beckley, West Virginia; and (3)
August 21, 2023, in Denver, Colorado.
Speakers and attendees could
participate in-person or online. There
were 14 speakers and over 150 attendees
at the Arlington hearing; 24 speakers
and over 200 attendees at the Beckley
hearing; and 10 speakers and over 175
attendees at the Denver hearing.
Speakers included active and retired
miners and representatives from the
mining industry, unions, the health care
profession, advocacy groups, industry
groups, trade associations, and law
firms. Transcripts from the public
hearings are available at
www.regulations.gov and on the MSHA
website.
On August 14, 2023, in response to
requests from the public, MSHA
published a notice in the Federal
Register extending the comment period
by changing the closing date from
August 28, 2023, to September 11, 2023
(88 FR 54961).
During the comment period, MSHA
received 157 written comments on the
proposed rule from miners, mine
operators, individuals, government
officials, labor organizations, advocacy
groups, industry groups, trade
associations, and health organizations.
Some commenters supported various
1 One microgram is equal to one-thousandth of a
milligram (1 milligram = 1000 micrograms).
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aspects of the proposal. Other
commenters opposed aspects of the
proposal and offered recommendations
for suggested changes to the proposed
rule. All public comments and
supporting documentation are available
at www.regulations.gov and on the
MSHA website. MSHA carefully
reviewed and considered the written
comments on the proposed rule and the
speakers’ testimonies from the hearings
and addresses them in the relevant
sections below.
IV. Background
A. Respirable Crystalline Silica Hazard
and Mining
Silica is a common component of rock
composed of silicon and oxygen
(chemical formula SiO2), existing in
amorphous and crystalline states. Silica
in the crystalline state is the focus of
this rulemaking. Respirable crystalline
silica consists of small particles of
crystalline silica that can be inhaled and
reach the alveolar region of the lungs,
where they can accumulate and cause
disease. In crystalline silica, the silicon
and oxygen atoms are arranged in a
three-dimensional repeating pattern.
The crystallization pattern varies
depending on the circumstances of
crystallization, resulting in a
polymorphic state, meaning several
different structures with the same
chemical composition. The most
common form of crystalline silica found
in nature is quartz, but cristobalite and
tridymite also occur in limited
circumstances. Quartz accounts for the
overwhelming majority of naturally
occurring crystalline silica. In fact,
quartz accounts for almost 12 percent of
the earth’s crust by volume. All soils
contain at least trace amounts of quartz,
and it is present in varying amounts in
almost every type of mineral. Quartz is
also abundant in most rock types,
including granites, sandstones, and
shale. Moreover, quartz bands and veins
are commonly found in limestone
formations, although limestone itself
does not contain quartz. Because of its
abundance, crystalline silica in the form
of quartz is present in nearly all mining
operations.
Cristobalite and tridymite are formed
at very high temperatures and are
associated with volcanic activity.
Naturally occurring cristobalite and
tridymite are rare, but they can be found
in volcanic ash and in a relatively small
number of rock types limited to specific
geographic regions. Although rare,
exposure to cristobalite can occur when
volcanic deposits are mined. In
addition, when other materials are
mined, miners can potentially be
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exposed to cristobalite during certain
processing steps (e.g., heating silicacontaining materials) and contact with
refractory materials (e.g., replacing fire
bricks in mine processing facility
furnaces). Tridymite is rarely found in
nature and miner exposure to tridymite
is much more infrequent.
Most mining activities generate silica
dust because silica is often contained in
the ore being mined or in the
overburden (i.e., the soil and surface
material surrounding the commodity
being mined). Such activities include,
but are not limited to, cutting, sanding,
drilling, crushing, grinding, sawing,
scraping, jackhammering, excavating,
and hauling materials that contain
silica. These activities can generate
respirable crystalline silica and
therefore may lead to miner exposure.
Inhaled small particles of silica dust
can be deposited throughout the lungs.
Because of their small size, many of
these particles can reach and remain in
the deep lung (i.e., alveolar region),
although some can be cleared from the
lungs. Because respirable crystalline
silica particles are not water-soluble and
do not undergo metabolism into less
toxic compounds, those particles
remaining in the lungs result in a
variety of cellular responses that may
lead to pulmonary diseases, such as
silicosis and lung cancer. The respirable
crystalline silica particles that are
cleared from the lungs can be
distributed to lymph nodes, blood, liver,
spleen, and kidneys, potentially
accumulating in those other organ
systems and causing renal disease and
other adverse health effects.
In the U.S. in 2021, a total of 12,162
mines produced a variety of
commodities. As shown in Table IV–1,
of those 12,162 total mines, 11,231
mines were MNM mines and 931 mines
were coal mines. MNM mines can be
broadly divided into five commodity
groups: metal, nonmetal, stone, crushed
limestone, and sand and gravel. These
broad categories encompass
approximately 98 different
commodities.2 Table IV–1 shows that a
majority of MNM mines produce sand
and gravel, while the largest number of
MNM miners work at metal mines, not
including MNM contract workers (i.e.,
2 Commodities such as sand, gravel, silica, and/
or stone are used in road building, concrete
construction, the manufacture of glass and
ceramics, molds for metal castings in foundries,
abrasive blasting operations, plastics, rubber, paint,
soaps, scouring cleansers, filters, hydraulic
fracturing, and various architectural applications.
Some commodities naturally contain high levels of
crystalline silica, such as high-quartz industrial and
construction sands and granite dimension stone and
gravel (both produced for the construction
industry).
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independent contractors and employees
of independent contractors who are
engaged in mining operations).
of independent contractors who are
engaged in mining operations).
Table IV-1: Number of Mines and Miners by Commodity in 2021
Number of Mines
Number of Miners
264
549
2,320
1,866
6,232
35,864
15,736
33,031
23,691
33,296
57,426
199,044
MNMMines
Metal
Nonmetal
Stone
Crushed Limestone
Sand and Gravel
MNM Contract Workers 1
MNM Subtotal
Coal Mines
Underground
Surface
Coal Contract Workers 1
Coal Subtotal
-
11,231
211
720
931
21,108
17,571
16,151
54,830
12,162
253,874
-
Grand Total
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The 931 coal mines—underground
and surface—produce bituminous,
subbituminous, anthracite, and lignite
coal. Coal mining activities generate
mixed coal mine dust that contains
respirable silicates such as kaolinite,
oxides such as quartz, and other
components (IARC, 1997). These
activities include the general mining
activities previously mentioned (e.g.,
cutting, sanding, drilling, crushing,
hauling, etc.), as well as roof bolter
operations, continuous mining machine
operations, longwall mining, and other
activities. Table IV–1 shows that there
are more surface coal mines than
underground coal mines, but more
miners are working in underground coal
mines than surface coal mines (not
including coal contract workers).
B. Existing Standards
Since the early 1970s, MSHA has
maintained health standards to protect
MNM and coal miners from excessive
exposure to airborne contaminants,
including respirable crystalline silica.
These standards require mine operators
to use engineering controls as the
primary means of suppressing, diluting,
or diverting dust generated by mining
activities. They also require mine
operators to provide miners with
respiratory protection in limited
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situations for a short period. The
existing standards for MNM and coal
mines differ in some respects, including
exposure limits and monitoring
requirements. This section describes
MSHA’s existing standards for
respirable crystalline silica and presents
respirable crystalline silica sampling
data to show how MNM and coal mine
operators have complied with the
standards in recent years.
1. Existing Standards—Metal and
Nonmetal Mines
MSHA’s existing standards for
exposure to airborne contaminants in
MNM mines, including respirable
crystalline silica, are found in 30 CFR
56 subpart D (Air Quality and Physical
Agents) and 30 CFR 57 subpart D (Air
Quality, Radiation, Physical Agents, and
Diesel Particulate Matter). These
standards include PELs for airborne
contaminants (§§ 56.5001 and 57.5001),
exposure monitoring (§§ 56.5002 and
57.5002), and control of exposure to
airborne contaminants (§§ 56.5005 and
57.5005).
Permissible Exposure Limits. The
existing PELs for the three polymorphs
of respirable crystalline silica are based
on the TLVs® Threshold Limit Values
for Chemical Substances in Workroom
Air Adopted by the American
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Conference of Governmental Industrial
Hygienists (ACGIH) for 1973,
incorporated by reference in 30 CFR
56.5001 and 57.5001 (ACGIH, 1974).
The 1973 TLV® establishes limits for
respirable dust containing 1 percent
quartz or greater and is calculated in
milligrams per cubic meter of air (mg/
m3) for each respirable dust sample. The
resulting TLVs® for respirable dust
containing 1 percent respirable
crystalline silica or greater are designed
to limit exposures to less than 0.1 mg/
m3 or 100 micrograms per cubic meter
of air (mg/m3) for quartz, to less than
0.05 mg/m3 or 50 mg/m3 for cristobalite,
and to less than 0.05 mg/m3 or 50 mg/
m3 for tridymite. Throughout the
remainder of this preamble, the
concentrations of respirable dust and
respirable crystalline silica are
expressed in mg/m3.
Exposure Monitoring. Under 30 CFR
56.5002 and 57.5002, MNM mine
operators must conduct respirable dust
‘‘surveys . . . as frequently as necessary
to determine the adequacy of control
measures.’’ Mine operators can satisfy
the survey requirement through various
activities, such as respirable dust
sampling and analysis, walk-through
inspections, wipe sampling,
examination of dust control system and
ventilation system maintenance, and
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1. The number of MNM and coal contract workers is presented in aggregate because commodity data
for contract workers is unavailable.
Source: MSHA MSIS Data (reported on MSHA Form 7000-2).
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review of information obtained from
injury, illness, and accident reports.
MSHA encourages MNM mine
operators to conduct sampling for
airborne contaminants to ensure a
healthy and safe work environment for
miners, because sampling provides
more accurate information about
miners’ exposures and the effectiveness
of existing controls in reducing
exposures. When a mine operator’s
respirable dust survey indicates that
miners have been overexposed to any
airborne contaminant, including
respirable crystalline silica, the operator
is expected to adjust its control
measures (e.g., exhaust ventilation) to
reduce or eliminate the identified
hazard. After doing so, the mine
operator is expected to conduct
additional surveys to determine whether
its adjustments to control measures
were successful. Re-surveying should be
done as frequently as necessary to
ensure that the sampling results comply
with the PEL and the implemented
control measures remain adequate.
Exposure Controls. MSHA’s existing
standards for controlling a miner’s
exposure to harmful airborne
contaminants in §§ 56.5005 and 57.5005
require, if feasible, prevention of
contamination, removal by exhaust
ventilation, or dilution with
uncontaminated air. These requirements
to use feasible engineering controls,
supplemented by administrative
controls, are consistent with widely
accepted industrial hygiene principles
and NIOSH’s recommendations (NIOSH,
1974). Engineering controls designed to
remove or reduce the hazard at the
source are the most effective. Although
administrative controls are considered a
supplementary or secondary measure to
engineering controls, mine operators
may use administrative controls to
further reduce miners’ exposures to
respirable crystalline silica and other
airborne contaminants.
The use of respiratory protective
equipment is also allowed under
specified circumstances, such as where
engineering controls are not yet
developed or when it is necessary due
to the nature of the work—for example,
while establishing controls or during
occasional entry into hazardous
atmospheres to perform maintenance or
investigation. Respirators approved by
NIOSH and suitable for their intended
purpose must be provided by mine
operators at no cost to the miner and
must be used by miners to protect
themselves against the health and safety
hazards of respirable crystalline silica
and other airborne contaminants. When
respiratory protective equipment is
used, MNM mine operators must
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implement a respiratory protection
program consistent with the
requirements of American National
Standards Practices for Respiratory
Protection ANSI Z88.2–1969 (ANSI
Z88.2–1969).
2. Existing Standards—Coal Mines
Under the existing coal mine
standards, there is no separate standard
for respirable crystalline silica. MSHA’s
existing standards for exposure to
respirable quartz in coal mines, found in
30 CFR 70.101 and 71.101, establish a
respirable dust standard when quartz is
present for underground and surface
coal mines, respectively. Under 30 CFR
part 90 (Mandatory Health Standards—
Coal Miners Who Have Evidence of the
Development of Pneumoconiosis),
§ 90.101 also sets the respirable dust
standard when quartz is present for Part
90 miners.3 Coal miners’ exposures to
respirable quartz are indirectly
regulated through reductions in the
overall respirable dust standards.
Under its existing respirable coal
mine dust standards, MSHA defines
quartz as crystalline silicon dioxide
(SiO2), which includes not only quartz
but also two other polymorphs,
cristobalite and tridymite.4 Therefore,
the terms quartz and respirable
crystalline silica are used
interchangeably in the discussions of
MSHA’s existing standards for
controlling exposures to respirable
crystalline silica in coal mines.
Exposure Limits. The exposure limit
for respirable crystalline silica during a
coal miner’s shift is 100 mg/m3, reported
as an equivalent concentration as
measured by the Mining Research
Establishment (MRE) instrument.5 The
equivalent concentration of respirable
3 A ‘‘Part 90 miner’’ is defined in 30 CFR 90.3 as
a miner employed at a coal mine who shows
evidence of having contracted pneumoconiosis
based on a chest X-ray or based on other medical
examinations, and who is afforded the option to
work in an area of a mine where the average
concentration of respirable dust in the mine
atmosphere during each shift to which that miner
is exposed is continuously maintained at or below
the applicable standard.
4 Quartz is defined in 30 CFR 70.2, 71.2, and 90.2
as crystalline silicon dioxide (SiO2) not chemically
combined with other substances and having a
distinctive physical structure. Crystalline silicon
dioxide is most commonly found in nature as
quartz but sometimes occurs as cristobalite or,
rarely, as tridymite. Quartz accounts for the
overwhelming majority of naturally occurring
crystalline silica and is present in varying amounts
in almost every type of mineral.
5 As defined in 30 CFR 70.2, an MRE instrument
is a gravimetric dust sampler with a four channel
horizontal elutriator developed by the Mining
Research Establishment of the National Coal Board,
London, England. MSHA inspectors use Dorr-Oliver
10-mm nylon cyclones operated at a 2.0 L/min flow
rate (reported as MRE-equivalent concentrations)
for coal mine sampling.
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crystalline silica must not be exceeded
during the miner’s entire shift,
regardless of duration. When the
equivalent concentration of respirable
quartz exceeds 100 mg/m3, under
§§ 70.101, 71.101, and 90.101, MSHA
imposes a reduced respirable dust
standard designed to ensure that
respirable quartz will not exceed 100
mg/m3. Various sections within a mine
may have different reduced respirable
coal mine dust (RCMD) exposure limits.
Therefore, when a respirable dust
sample collected by MSHA indicates
that the average concentration of
respirable quartz dust exceeds the
exposure limit, the mine operator is
required to comply with the applicable
dust standard. Because respirable
crystalline silica is a percentage of
RCMD, by reducing the amount of
respirable dust to which miners are
exposed during their shifts, the miners’
exposures to respirable crystalline silica
are reduced to a level at or below the
exposure limit of 100 mg/m3.
Exposure Monitoring. Under
§§ 70.208, 70.209, 71.206, and 90.207,
coal mine operators are required to
sample for respirable dust on a quarterly
basis for specified occupations and
work areas. The occupations and work
areas specified in the existing coal dust
standards are the occupations and work
areas at a coal mine that are expected to
have the highest concentrations of
respirable dust—typically in locations
where respirable dust is generated.
Respirable dust sampling must be
representative of respirable dust
exposures during a normal production
shift and must occur while miners are
performing routine, day-to-day
activities. Part 90 miners must be
sampled for the air they breathe while
performing their normal work duties, in
their normal work locations, from the
start of their work day to the end of their
work day.
Exposure Controls. Under §§ 70.208,
70.209, 71.206, and 90.207, coal mine
operators are required to use
engineering or environmental controls
as the primary means of complying with
the respirable dust standards. For many
underground coal mines, providing
adequate ventilation is the primary
engineering control for respirable dust,
ensuring that dust concentrations are
continuously diluted with fresh air and
exhausted away from miners.
When a respirable dust sample
exceeds the exposure limit of 100 mg/m3
for respirable quartz, the operator must
reduce the average concentration of
RCMD to a level designed to maintain
the quartz level at or below 100 mg/m3.
If operators exceed the RCMD standard,
they are required to take corrective
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samples to the MSHA Laboratory for
analysis.
minutes) are calculated as if they had
been collected over 480 minutes.
D. Respirable Crystalline Silica
Sampling Results—Metal and Nonmetal
Mines
Under the existing standards, MSHA
inspectors arrive at mines, determine
which miners and which areas of the
mine to select for respirable dust
sampling, and place gravimetric
samplers on the selected miners and at
the selected locations. The gravimetric
samplers capture air from the breathing
zone of each selected miner and from
each selected work area for the entire
duration of the work shift. Full-shift
sampling is used to minimize errors
associated with fluctuations in airborne
contaminant concentrations during the
miners’ work shifts and to avoid any
speculation about the miners’ exposures
during unsampled periods of the work
shift. Once sampling is completed,
MSHA inspectors send cassettes
containing the full-shift respirable dust
2. Respirable Dust Sample Analysis
The MSHA Laboratory analyzes
respirable dust samples following the
standard operating procedures
summarized below.6 Any samples that
are broken, torn, or visibly wet are
voided and removed before analysis.
Samples are weighed and then
examined for validity based on mass
gain. All valid samples that meet the
minimum mass gain criteria per the
associated MSHA analytical method are
then analyzed for respirable crystalline
silica and for the compliance
determination.7
The MSHA Laboratory uses two
analytical methods to determine the
concentration of quartz (and cristobalite
and tridymite, if requested) in respirable
dust samples: X-ray diffraction (XRD)
for samples from MNM mines and
Fourier transform infrared spectroscopy
(FTIR) for samples from coal mines.8
The percentage of silica in the MNM
mine dust sample is calculated using
the mass of quartz or cristobalite
determined from the XRD analysis and
the measured mass of respirable dust.
Similarly, in the respirable coal mine
dust sample, the percentage of quartz is
calculated using the quartz mass
determined from the FTIR analysis and
the sample’s mass of dust. Current FTIR
methods, however, cannot quantify
quartz and cristobalite, and/or
tridymite, in the same sample.
MSHA calculates full-shift exposures
to respirable crystalline silica (and other
airborne contaminants) in the same way
for MNM and coal miners when the
miner works an 8-hour shift, but the
calculated exposures differ for longer
shifts. For work shifts that last longer
than 8 hours, a coal miner’s full-shift
exposure is calculated using the entire
duration of the coal miner’s shift. For
the MNM miner, by contrast, MSHA
calculates extended full-shift exposure
for respirable dust samples using 480
minutes (8 hours) as the sampling time,
meaning that contaminants collected
over extended shifts (e.g., 600–720
6 The MSHA Laboratory has fulfilled the
requirements of the AIHA Laboratory Accreditation
Programs (AIHA–LAP), LLC accreditation to the
ISO/IEC 17025:2017 international standard for
industrial hygiene.
7 The minimum mass gain criteria used by the
MSHA Laboratory for the different samples are:
• MNM mine respirable dust samples: greater
than or equal to 0.100 mg;
• Underground coal mine respirable dust
samples: greater than or equal to 0.100 mg; and
• Surface coal mine respirable dust samples:
greater than or equal to 0.200 mg.
Exception: For six surface occupations that have
been deemed ‘‘high risk,’’ the laboratory uses a
minimum mass gain criterion of greater than or
equal to 0.100 mg.
If cristobalite analysis is requested for MNM mine
respirable dust samples, filters having a mass gain
of 0.05 mg or more are analyzed. In the rare
instance when tridymite analysis is requested, a
qualitative analysis for the presence of the
polymorph is conducted concurrently with the
cristobalite analysis.
8 Details on MSHA’s analytical procedures for
respirable crystalline silica analysis can be found in
‘‘MSHA P–2: X-Ray Diffraction Determination of
Quartz and Cristobalite in Respirable Metal/
Nonmetal Mine Dust’’ and ‘‘MSHA P–7:
Determination of Quartz in Respirable Coal Mine
Dust by Fourier Transform Infrared Spectroscopy.’’
action to reduce exposure and comply
with the reduced standard. Corrective
actions that lower respirable coal mine
dust, thus lowering respirable quartz
exposures, are selected after evaluating
the cause or causes of the overexposure.
When taking corrective actions to
reduce the exposure to respirable dust,
coal mine operators must make
approved respiratory equipment
available to miners under §§ 70.208,
70.209, and 71.206. Whenever
respiratory protection is used, § 72.700
requires coal mine operators to comply
with requirements specified in ANSI
Z88.2–1969.
C. MSHA Inspection and Respirable
Dust Sampling
Under the existing standards, MSHA
collects respirable dust samples at
mines and analyzes them for respirable
crystalline silica to determine whether
the respirable crystalline silica exposure
limits are exceeded and whether
exposure controls are adequate. MSHA’s
inspection and respirable dust sampling
were discussed in detail in the proposal
(88 FR 44862). This section, for ease of
reference, briefly summarizes the
process for MSHA’s inspection and
respirable dust sampling.
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1. Respirable Dust Sample Collection
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MSHA’s respirable crystalline silica
sampling results for MNM mines were
discussed in detail in the proposal (88
FR 44863). This section, for ease of
reference, summarizes the results of
respirable dust samples that were
collected by MSHA inspectors at MNM
mines from 2005 to 2019. From January
1, 2005, to December 31, 2019, a total
of 104,354 valid samples were collected.
Of this total, 57,769 samples met the
minimum mass gain criteria and were
analyzed for respirable crystalline silica.
The vast majority of the 46,585 valid
samples that were excluded from the
analysis did not meet the mass gain
criteria. Further information on the
valid respirable dust samples that were
excluded from the analysis can be found
in Appendix A of the preamble.
1. Annual Results of MNM Respirable
Crystalline Silica Samples
Table IV–2 below shows the variation
between 2005 and 2019 in: (1) the
number of MNM respirable dust
samples analyzed for respirable
crystalline silica; and (2) the number
and percentage of samples that had
concentrations of respirable crystalline
silica greater than 100 mg/m3. Of the
57,769 MNM respirable dust samples
analyzed for respirable crystalline silica
over the 15-year period, about 6 percent
(3,539 samples) had respirable
crystalline silica concentrations
exceeding the existing PEL of 100 mg/
m3. The average annual rates of
overexposure ranged from a maximum
of approximately 10 percent in 2006
(the second year) to a minimum of
approximately 4 percent in 2019 (the
last year of the time series). Compared
with the rates in 2005–2008,
overexposure rates were substantially
lower in 2009–2017, with a further drop
in 2018–19.
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Department of Labor, Mine Safety and Health
Administration, Pittsburgh Safety and Health
Technology Center, X-Ray Diffraction
Determination of Quartz and Cristobalite in
Respirable Metal/Nonmetal Mine Dust. https://
arlweb.msha.gov/Techsupp/pshtcweb/
MSHA%20P2.pdf (last accessed Jan. 10, 2024).
Department of Labor, Mine Safety and Health
Administration, Pittsburgh Safety and Health
Technology Center, MSHA P–7: Determination of
Quartz in Respirable Coal Mine Dust By Fourier
Transform Infrared Spectroscopy. https://
arlweb.msha.gov/Techsupp/pshtcweb/
MSHA%20P7.pdf (last accessed Jan. 10, 2024).
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Table IV-2: MNM Respirable Dust Samples, 2005-2019
Year
Number of
Samples
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
6,982
3,385
3,879
2,806
5,937
4,992
3,938
3,422
3,150
3,067
3,015
2,958
3,526
3,227
3,485
Number of
Samples with
Respirable
Crystalline Silica
Concentration
Greater than
100 11e/m3
503
338
297
269
320
259
234
205
140
153
169
150
205
152
145
57,769
3,539
Total
Percent of
Samples with
Respirable
Crystalline Silica
Concentration
Greater than
100 11e/m3
7.2%
10.0%
7.7%
9.6%
5.4%
5.2%
5.9%
6.0%
4.4%
5.0%
5.6%
5.1%
5.8%
4.7%
4.2%
6.1%
Source: MSHA MSIS respirable crystalline silica data for the MNM industry,
January 1, 2005, through December 31, 2019 (version 20220812).
2. Analysis of MNM Respirable
Crystalline Silica Samples by
Commodity
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Because the MNM mining industry
produces commodities that contain
varying degrees of respirable crystalline
silica, it is important to examine each
commodity separately. MNM mines can
be grouped by five commodities: metal,
sand and gravel, stone, crushed
limestone, and nonmetal (where
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nonmetal includes all other materials
that are not metals, besides sand, gravel,
stone, and limestone). This grouping is
based on the mine operator-reported
mining products and the North
American Industry Classification
System (NAICS) codes. (Appendix B of
the preamble provides a list of the
NAICS codes relevant for MNM mining
and how each code is assigned to one
of the five commodities.)
Table IV–3 shows the distribution of
the respirable dust samples analyzed for
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respirable crystalline silica by mine
commodity. The percentage of samples
with respirable crystalline silica
concentrations greater than the existing
exposure limit of 100 mg/m3 varies
across the different commodities. It is
highest for the metal, sand and gravel,
and stone commodities (at
approximately 11, 7, and 7 percent,
respectively), and lowest for the
nonmetal and crushed limestone
commodities (at approximately 4 and 3
percent, respectively).
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Table IV-3: MNM Respirable Dust Samples by Commodity, 2005-2019
Commodity
Number of
Samples
Metal Mines
Nonmetal Mines
Stone Mines
Crushed Limestone Mines
Sand and Gravel Mines
3,499
5,165
15,415
15,184
18,506
Number of Samples
with Respirable
Crystalline Silica
Concentration
Greater than
100 U!!/m 3
376
232
1,134
434
1,363
57,769
3,569
Total
Percent of Samples
with Respirable
Crystalline Silica
Concentration
Greater than
100 u!!lm3
10.8%
4.5%
7.4%
2.9%
7.4%
6.1%
3. Analysis of MNM Respirable
Crystalline Silica Samples by
Occupation
To examine how miners who perform
different tasks differ in occupational
exposure to respirable crystalline silica,
MSHA grouped MNM mining jobs into
11 occupational categories. These
categories include jobs that are similar
in terms of tasks performed, equipment
used, and engineering or administrative
controls used to control miners’
exposure. For example, backhoe
operators, bulldozer operators, and
tractor operators were grouped into
‘‘operators of large powered haulage
equipment,’’ whereas belt crew, belt
cleaners, and belt vulcanizers were
grouped into ‘‘conveyer operators.’’ The
121 MNM job codes used by MSHA
inspectors were grouped into the
following occupational categories: 9
(1) Drillers (e.g., Diamond Drill
Operator, Wagon Drill Operator, and
Drill Helper),
(2) Stone Cutting Operators (e.g.,
Jackhammer Operator, Cutting Machine
Operator, and Cutting Machine Helper),
(3) Kiln, Mill, and Concentrator
Workers (e.g., Ball Mill Operator,
Leaching Operator, and Pelletizer
Operator),
(4) Crushing Equipment and Plant
Operators (e.g., Crusher Operator/
Worker, Scalper Screen Operator, and
Dry Screen Plant Operator),
(5) Packaging Equipment Operators
(e.g., Bagging Operator and Packaging
Operations Worker),
(6) Conveyor Operators (e.g., Belt
Cleaner, Belt Crew, and Belt
Vulcanizer),
(7) Truck Loading Station Tenders
(e.g., Dump Operator and Truck Loader),
(8) Operators of Large Powered
Haulage Equipment (e.g., Tractor
Operators, Bulldozer Operator, and
Backhoe Operators),
(9) Operators of Small Powered
Haulage Equipment (e.g., Bobcat
Operator, Scoop-Tram Operator, and
Forklift Operator),
(10) Mobile Workers (e.g., Laborers,
Electricians, Mechanics, and
Supervisors), and
(11) Miners in Other Occupations
(e.g., Welder, Dragline Operator,
Ventilation Crew and Dredge/Barge
Operator).
Table IV–4 shows sample numbers
and overexposure rates by MNM
occupation. Operators of large powered
haulage equipment accounted for the
largest number of samples analyzed for
silica (17,016 samples), whereas
conveyor operators accounted for the
fewest (215 samples). Table IV–4 also
shows the number and percentage of the
samples exceeding the existing
respirable crystalline silica PEL of 100
mg/m3. In every occupational category,
some MNM miners were exposed to
respirable crystalline silica levels above
the existing PEL. In 9 out of the 11
occupational categories, the percentage
of samples exceeding the existing PEL is
less than 10 percent, although two have
higher rates, ranging up to more than 19
percent (in the case of stone cutting
operators).
9 For a full crosswalk of job codes included in
each of these 11 Occupational Categories, please see
Appendix C of the preamble. Also, note that the
order of the presentation of the 11 Occupational
Categories here follows the general sequence of
mining activities: first development and
production, then ore/mineral processing, then
loading, hauling, and dumping, and finally all
others.
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Source: MSHA MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through December
31, 2019 (version 20220812).
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Table IV-4: MNM Respirable Dust Samples by Occupation, 2005-2019
2,092
2,446
1,802
Number of
Samples with
Respirable
Crystalline
Silica
Concentration
Greater than
100 U!!/m 3
107
474
125
Percent of
Samples with
Respirable
Crystalline
Silica
Concentration
Greater than
100 u!!lm3
5.1%
19.4%
6.9%
11,565
816
7.1%
2,980
215
453
278
24
32
9.3%
11.2%
7.1%
17,016
378
2.2%
1,110
77
6.9%
15,216
2,874
1,108
120
7.3%
4.2%
57,769
3,539
6.1%
Number of
Samples
Occupation
Drillers
Stone Cutting Operators
Kiln, Mill, and Concentrator Workers
Crushing Equipment Operators and Plant
Operators
Packing Equipment Operators
Conveyor Operators
Truck Loading Station Tenders
Operators of Large Powered Haulage
Equipment
Operators of Small Powered Haulage
Equipment
Mobile Workers
Miners in Other Occupations
Total
Source: MSHA MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through
December 31, 2019 (version 20220812).
4. Conclusion
This analysis of MSHA inspector
sampling data shows that MNM
operators have generally met the
existing standard. Of the 57,769
respirable dust samples from MNM
mines, approximately 6 percent
exceeded the existing respirable
crystalline silica PEL of 100 mg/m3,
although there are several outliers with
much higher overexposures. For 9 of the
11 occupational categories, less than 10
percent of the respirable dust samples
had concentrations over the existing
PEL of 100 mg/m3 for respirable
crystalline silica. While stone-cutting
operators have historically had high
exposures to respirable dust and
respirable crystalline silica 10 and
continue to experience the highest
overexposures of any MNM occupation,
10 Analysis of MSHA respirable dust samples
from 2005 to 2010 showed that stone and rock saw
operators had approximately 20 percent of the
sampled exposures exceeding the PEL. Watts et al.
(2012).
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about 80 percent of samples taken from
stone cutting operators did not exceed
the existing PEL. For the categories of
drillers, miners in other occupations,
and operators of large powered haulage
equipment, approximately 5 percent or
less of the respirable dust samples
showed concentrations over the existing
exposure limit.
In summary, the analysis of MSHA
inspector sampling data indicates that
the controls that MNM mine operators
are using, together with MSHA’s
enforcement, have generally been
effective in keeping miners’ exposures
at or below the existing limit of 100 mg/
m3.
E. Respirable Crystalline Silica
Sampling Results—Coal Mines
MSHA’s respirable crystalline silica
sampling results for coal mines were
discussed in detail in the proposal (88
FR 44866). This section, for ease of
reference, summarizes the results of
RCMD samples collected by MSHA
inspectors from 2016 to 2021. (The data
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analyses for this rulemaking do not
include any respirable dust samples
collected by coal mine operators.) The
analysis below is based on the samples
collected by MSHA inspectors starting
on August 1, 2016, when Phase III of
MSHA’s 2014 Lowering Miners’
Exposure to Respirable Coal Mine Dust,
Including Continuous Personal Dust
Monitors (referred to throughout the
preamble as the 2014 RCMD Standard)
(79 FR 24813) went into effect. At that
time, the exposure limits for RCMD
were lowered from 2.0 mg/m3 to 1.5 mg/
m3 (MRE equivalent) at underground
and surface coal mines, and from 1.0
mg/m3 to 0.5 mg/m3 (MRE equivalent)
for intake air at underground coal mines
and for Part 90 miners. From August 1,
2016, to July 31, 2021, MSHA inspectors
collected a total of 113,607 valid RCMD
samples. Of the valid samples, only
those collected from the breathing zones
of miners were used in the analysis for
this rulemaking; no environmental dust
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samples were included.11 Of the valid
breathing zone samples, there were
63,127 samples that met the minimum
mass gain criteria and were analyzed for
respirable quartz. The majority of the
non-environmental valid samples
excluded from this rulemaking analysis
were excluded due to insufficient mass.
Further information on the valid
respirable dust samples that are not
included in the rulemaking analysis can
be found in Appendix A of the
preamble.
Of the 63,127 valid samples analyzed
for respirable crystalline silica and used
for this analysis, about 1 percent (777
samples) were over the existing quartz
exposure limit of 100 mg/m3 (MRE
equivalent) for a full shift, calculated as
a TWA.12 Overexposure rates decreased
by nearly a quarter between the first half
and the second half of the 2016–2021
period. As in MNM mines, different
miner occupations had different
overexposure rates. Using broader
groupings, surface mines experienced
higher rates of overexposure than
underground mines (2.4 percent versus
1.0 percent, respectively).
1. Annual Results of Coal Respirable
Crystalline Silica Samples
In examining trends from one year to
the next, the discussion below focuses
on the samples collected in the 6
calendar years from 2016 to 2021. The
number of samples per year was stable
from 2017 to 2019 before decreasing in
2020.13 The overexposure rate
decreased across the entire 2016 to 2021
period, from 1.41 percent in 2016 to
0.95 percent in 2021. As shown in Table
IV–5, a review of the 6 calendar years
reveals that the overexposure rate
decreased by nearly a quarter from
2016–2018 (1.38 percent) to 2019–2021
(1.07 percent).
Table IV-5: Respirable Coal Mine Dust Samples, 2016-2021
Year
Number of
Samples
2016 1
2017
2018
2019
2020
2021 1
4,879
13,787
14,054
13,745
10,267
6,395
Number of
Samples with
Respirable
Crystalline Silica
Concentration
Greater than
100 u!!lm3 MRE
69
190
194
153
110
61
63,127
777
Total
Percent of
Samples with
Respirable
Crystalline Silica
Concentration
Greater than
100 u!!lm3 MRE
1.4%
1.4%
1.4%
1.1%
1.1%
1.0%
1.2%
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2. Analysis of Coal Respirable
Crystalline Silica Samples by Location
Coal mining activities differ
depending on the characteristics and
locations of coal seams. When coal
seams are several hundred feet below
the surface, miners tunnel into the earth
and use underground mining equipment
to extract coal, whereas miners at
surface coal mines remove topsoil and
11 Environmental samples were not included in
the analysis to be consistent with the proposed
sampling requirements to determine individual
miner exposure.
12 The conversion between ISO values and MRE
values uses the NIOSH conversion factor of 0.857.
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layers of rock to expose coal seams. Due
to these differences, it is important to
examine the respirable crystalline silica
data by location to determine how
underground and surface coal miners
differ in occupational exposure to
respirable crystalline silica.
Table IV–6, which presents the
overexposure rate by type of mine
where respirable coal mine dust
samples were collected, shows that
samples from surface coal mines
reflected higher rates of overexposure
than samples from underground mines.
Out of the 53,095 respirable coal mine
dust samples from underground mines,
1 percent (537 samples) were over the
existing exposure limit. By contrast,
there were 10,032 samples from surface
coal mines, and approximately 2.4
percent (240 samples) of those samples
were over the existing exposure limit.
In the 1995b Criteria Document, NIOSH presented
an empirically derived conversion factor of 0.857
for comparing current (MRE) and recommended
(ISO) respirable dust sampling criteria using the 10
mm Dorr-Oliver nylon cyclone operated at 2.0 and
1.7 L/min, respectively (i.e., 1.5 mg/m3 BMRC–MRE
= 1.29 mg/m3 ISO).
13 The coal samples for 2016 begin in August of
that year and the coal samples for 2021 end in July
of that year.
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1. The 2016 data represents respirable crystalline silica samples from August 1 to December 31,
2016, and the 2021 data represents respirable crystalline silica samples from January 1 to July 31,
2021.
Source: MSHA MSIS respirable crystalline silica data for the Coal Industry, August 1, 2016,
through July 31, 2021 (version 20220617).
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
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Table IV-6: Respirable Coal Mine Dust Samples by Location, 2016 - 2021
Location
Number of
Samples
Number of
Samples with
Respirable
Crystalline Silica
Concentration
Greater than
100 µ,g/m 3 MRE
53,095
10,032
537
240
Percent of
Samples with
Respirable
Crystalline
Silica
Concentration
Greater than
100 u!!lm3 MRE
1.0%
2.4%
63,127
777
1.2%
Underground Mines
Surface Mines
Total
Source: MSHA MSIS respirable crystalline silica data for the Coal Industry, August 1, 2016, through July
31, 2021 (version 20220617).
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To assess the exposure to respirable
crystalline silica of miners in different
occupations, MSHA has consolidated
the 220 job codes for coal mines into 9
occupational categories (using a similar
process to the one it used for the MNM
mines, but with different job codes and
categories). For the coal mine
occupational categories,14 a distinction
is made between occupations based on
whether the job tasks are being
performed at the surface of a mine or
underground. For example, bulldozer
operators are assigned to the job
category of operators of large powered
haulage equipment grouping and then
sorted into separate occupational
categories based on whether they are
working at the surface of a mine or
underground.
Of the nine occupational categories
used for coal miners, the five
underground categories are:
(1) Continuous Mining Machine
Operators (e.g., Coal Drill Helper and
Coal Drill Operator),
(2) Longwall Workers (e.g., Headgate
Operator and Jack Setter (Longwall)),
(3) Roof Bolters (e.g., Roof Bolter and
Roof Bolter Helper),
(4) Operators of Large Powered
Haulage Equipment (e.g., Shuttle Car
Operator, Tractor Operator/Motorman,
Scoop Car Operator), and
(5) All Other Underground Miners
(e.g., Electrician, Mechanic, Belt Cleaner
and Laborer, etc.).
The four surface occupational
categories are:
(1) Drillers (e.g., Coal Drill Operator,
Coal Drill Helper, and Auger Operator),
(2) Crusher Operators (e.g., Crusher
Attendant, Washer Operator, and
Scalper-Screen Operator),
(3) Operators of Large Powered
Haulage Equipment (e.g., Backhoe
Operator, Forklift Operator, and
Bulldozer Operator), and
(4) Mobile Workers (e.g., Electrician,
Mechanic, Blaster, Laborer, etc.).
The most sampled occupational
category was operators of large powered
haulage equipment (underground),
representing approximately 34 percent
of the samples taken. The least sampled
occupational category was crusher
operators (surface), consisting of 1
percent of the samples taken. Table IV–
7 displays the number and percent of
respirable coal mine dust samples with
quartz greater than the existing exposure
limit for each occupational category.
14 For a full crosswalk of which job codes were
included in each of these nine Occupational
Categories, please see Appendix C of the preamble.
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3. Analysis of Coal Respirable
Crystalline Silica Samples by
Occupation
28230
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Table IV-7: Respirable Coal Mine Dust Samples by Occupation, 2016-2021
Occupation
Continuous Mining Machine
Operators (UG)
Longwall Workers (UG)
RoofBolters (UG)
Operators of Large Powered
Haulage Equipment (UG)
All Other Underground Miners
(UG)
Drillers (Surface)
Crusher Operators (Surface)
Operators of Large Powered
Haulage Equipment (Surface)
Mobile Workers (Surface)
Total
Number of
Samples
Number of
Samples with
Respirable
Crystalline Silica
Concentration
Greater than
100 l12i'm 3 MRE
Percent of
Samples with
Respirable
Crystalline Silica
Concentration
Greater than
100 l12i'm 3 MRE
9,910
154
1.6%
3,176
14,306
115
145
3.6%
1.0%
21,777
99
0.5%
3,926
24
0.6%
1,762
631
98
1
5.6%
0.2%
5,313
132
2.5%
2,326
9
0.4%
63,127
777
1.2%
Source: MSHA MSIS respirable crystalline silica data for the Coal Industry, August 1, 2016, through July 31, 2021
(version 20220617).
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2021 period than in the 2016–2018
period.
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Figure IV–1: Percent of RCMD Samples
With Respirable Crystalline Silica
Concentration Greater Than 100 MRE
mg/m3 (MRE) by Occupational
Category *
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Looking at trends, every occupational
category shows a decrease in
overexposure rates over time. See Figure
IV–1. Most of the nine categories had
lower rates of overexposure in the 2019–
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28231
7.0%
~
la 2016
2017 Ill 2018
m2019 t3 2020 ~ 2021
6.0%
5.0%
4.0%
3.0%
2.0%
1.0%
0.0%
Roof Bolters
(UG)
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* For Crusher Operators (Surface), only one
sample with a quartz concentration greater
than 100 mg/m3 MRE occurred (in 2018); and
for Mobile Workers (Surface), only nine
samples with a quartz concentration greater
than 100 mg/m3 MRE occurred (three in 2017,
five in 2018 and one in 2021). Source: MSHA
MSIS respirable crystalline silica data for the
Coal Industry, August 1, 2016, through July
31, 2021 (version 20220617).
In all occupational categories, coal
miners were sometimes exposed to
respirable crystalline silica levels above
the existing exposure limit. But the
sampling data showed that coal mine
operators can generally comply with the
existing exposure limit. For example,
although mining tasks performed by the
occupational category of roof bolters
(underground) historically resulted in
high levels of overexposure to quartz,
the low levels of overexposure for that
occupation in 2016–2021 (i.e., 1
percent) suggest that roof bolters now
benefit from the improved respirable
dust standard, improved technology,
and better training.15 Over the 2016–
2021 period, coal miners in the
occupational category drillers (surface)
were the most frequently overexposed,
with approximately 6 percent of
samples over the existing quartz limit;
they were followed by longwall workers
15 The drilling operation in the roof bolting
process, especially in hard rock, generates excessive
respirable coal and quartz dusts, which could
expose the roof bolting operator to continued health
risks (Jiang and Luo, 2021).
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Operators of
All Other
Dn11ers (Surface)
Large Powered Underground
Haulage
Miners (UG)
Equipment (UG)
(underground) (about 4 percent),
operators of large powered haulage
equipment (surface) (about 3 percent),
and continuous mining machine
operators (underground) (about 2
percent). For all other occupational
categories, the overexposure rate was
less than 1 percent.
4. Conclusion
This analysis of MSHA inspector
sampling data shows that coal mine
operators generally comply with the
existing standards related to quartz. Of
the 63,127 valid respirable dust samples
from coal mines over the most recent 5year period, 1.2 percent had respirable
quartz over the existing exposure limit
of 100 mg/m3 (MRE equivalent) for a
full-shift exposure, calculated as a
TWA. Seven of the nine occupational
categories had overexposure rates of 2.5
percent or less. Roof bolters
(underground), which historically have
had high exposures to respirable dust
and respirable crystalline silica, had
overexposure rates of 1 percent over this
recent period. The data demonstrates
that the controls that coal mine
operators are using, together with
MSHA’s enforcement, have generally
been effective in keeping miners’
exposure to respirable crystalline silica
at or below the existing exposure limit.
V. Health Effects Summary
This section summarizes the health
effects from occupational exposure to
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Crusher
Operators
(surface}
Operators of Mobile Workers
Large Powered
(Surface)
Haulage
Equipment
{Surface)
respirable crystalline silica. MSHA’s full
analysis of the health effects literature is
contained in the standalone document,
entitled ‘‘Effects of Occupational
Exposure to Respirable Crystalline
Silica on the Health of Miners’’ (referred
to as the standalone Health Effects
document throughout the preamble),
which is placed in the rulemaking
docket for the MSHA silica rulemaking
(RIN 1219–AB36, Docket No. MSHA–
2023–0001). MSHA reviewed a wide
range of health effects literature that
included more than 600 studies
exploring the relationship between
respirable crystalline silica exposure
and resultant health effects in miners
and other workers across various
industries. The purpose of this summary
is to briefly present MSHA’s findings on
the nature of the hazards of exposure to
respirable crystalline silica. Based on its
review of the health effects literature
and the weight-of-evidence approach,
MSHA makes the following
conclusions:
1. Miners in MNM and coal mines
exposed to respirable crystalline silica
at MSHA’s existing exposure limits are
subject to material impairment of health
or functional capacity. The illnesses
associated with exposure to respirable
crystalline silica develop independent
of other exposures.
2. Occupational exposure to
respirable crystalline silica (as quartz
and/or cristobalite) causes silicosis,
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Longwall
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Operators (UG)
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nonmalignant respiratory disease
(NMRD) (e.g., emphysema and chronic
bronchitis), lung cancer, and renal
disease. Each of these health effects
outcomes is exposure-dependent,
potentially chronic, irreversible,
potentially disabling, and can be fatal.
3. Exposure to respirable crystalline
silica contributes to the development of
autoimmune disorders through
inflammatory pathways.
4. The development of silicosis,
NMRD, lung cancer, renal disease, and
autoimmune disorders is largely
dependent upon cumulative respirable
crystalline silica exposure.
These conclusions are the basis of
MSHA’s Final Risk Analysis (FRA) on
miners’ exposure to respirable
crystalline silica. In the FRA, MSHA
quantifies risks associated with the five
specific health outcomes mentioned
above. The FRA summary is presented
in Section VI. Final Risk Analysis
Summary and a standalone document,
entitled ‘‘Final Risk Analysis’’ (referred
to as the standalone FRA document
throughout the preamble), has been
placed in the rulemaking docket for the
MSHA silica rulemaking (RIN 1219–
AB36, Docket No. MSHA–2023–0001).
From its health effects literature
review and FRA, MSHA determines that
miners exposed to respirable crystalline
silica continue to face a risk of material
impairment of health or functional
capacity under MSHA’s existing
exposure limits. Thus, MSHA also
makes the following conclusions:
(1) The rate of silicosis and other
diseases caused by respirable crystalline
silica exposure would decrease with
reduction in occupational exposures,
which is the most effective way to
prevent these types of diseases.
(2) Regulatory action is necessary to
reduce these occupational exposures
and protect miners’ health. Section
101(a)(6)(A) of the Federal Mine Safety
and Health Act of 1977, as amended
(Mine Act), requires MSHA to ‘‘set
standards which most adequately assure
on the basis of the best available
evidence that no miner will suffer
material impairment of health or
functional capacity even if such miner
has regular exposure to the hazards
dealt with by such standard for the
period of his working life.’’ 30 U.S.C.
811(a)(6)(A).
Regulatory action to protect miners’
health is required by section
101(a)(6)(A) of the Mine Act, and
MSHA’s statutory authority and mission
has been recognized and upheld by
reviewing courts. ‘‘[T]he Mine Act
evinces a clear bias in favor of miner
health and safety.’’ Nat’l Min. Ass’n v.
Sec’y, U.S. Dep’t of Lab., 812 F.3d 843,
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866 (11th Cir. 2016). Courts interpret
MSHA’s obligation to promulgate
standards to protect the health of the
nation’s miners to include
‘‘ ‘prevent[ing],’ not merely reduc[ing]
the incidence of, ‘occupational diseases
originating in . . . mines.’ ’’ Id. at 883
(quoting 30 U.S.C. 801(c)). Where
occupational disease ‘‘incidence has not
been reduced to zero . . . MSHA has
not completely fulfilled its mission to
‘protect the health . . . of the Nation’s
coal or other miners.’ ’’ Id. (quoting 30
U.S.C. 801(g)). Case law instructs that
MSHA must demonstrate risk before
regulating: ‘‘[B]efore promulgating a
health or safety standard under the
Mine Act, MSHA must show that the
substance being regulated presents a
risk of ‘material impairment of health or
functional capacity’ for miners who are
regularly exposed to the substance.’’
Kennecott Greens Creek Min. Co. v.
Mine Safety & Health Admin., 476 F.3d
946, 952 (D.C. Cir. 2007) (quoting 30
U.S.C. 811(a)(6)(A)). Although the Mine
Act requires MSHA to consider the best
available evidence, the ‘‘duty to use the
best available evidence . . . cannot be
wielded as a counterweight to MSHA’s
overarching role to protect the life and
health of workers in the mining
industry.’’ Nat’l Min. Ass’n, 812 F.3d at
866. With this regulatory action, MSHA
is addressing this urgent need. See 30
U.S.C. 801(c).
On July 13, 2023, MSHA published a
notice of proposed rulemaking, entitled
‘‘Lowering Miners’ Exposure to
Respirable Crystalline Silica and
Improving Respiratory Protection’’,
along with supplemental documents.
The Agency specifically sought
comments on its preliminary
determination from the literature review
that miners’ exposure to respirable
crystalline silica presents a risk of
material health impairment or
functional capacity. MSHA also
requested input on any additional
adverse health effects that should be
included or more recent literature that
offers a different perspective. MSHA
received numerous comments in
response to this request and considered
them in preparing the final standalone
Health Effects document and the final
rule.
This section will describe how MSHA
conducted its review of the health
effects literature on respirable
crystalline silica and what the Agency
has found about the toxicity of
respirable crystalline silica. This section
will also present the findings on the
following health effects: (1) Silicosis; (2)
Non-malignant respiratory disease
(NMRD), excluding silicosis; (3) Lung
cancer and cancer at other sites; (4)
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Renal disease; and (5) Autoimmune
diseases. Public comments received are
reflected throughout this section.
A. General Approach to Health Effects
Literature Review
MSHA reviewed a wide range of
health effects literature totaling over 600
studies that explore the relationship
between respirable crystalline silica
exposure and resultant adverse health
effects in miners and other workers
across various industries. The health
effects literature reviewed by MSHA
included both studies reviewed by
OSHA for its 2016 respirable crystalline
silica standard and many other newer
studies and studies that focused
specifically on the mining industry.
OSHA’s ‘‘Health Effects Analysis and
Preliminary Quantitative Risk
Assessment’’ (2013b) included studies
that were identified from previously
published scientific reviews, such as the
IARC (1997) and NIOSH (2002), and
from newer evaluations of scientific
literature, literature searches, and
contact with experts and stakeholders.
That document underwent extensive
peer review by a panel of nationally
recognized experts in occupational
epidemiology, biostatistics and risk
assessment, animal and cellular
toxicology, and occupational medicine
who had no conflict of interest (COI) or
apparent bias in performing the review.
These experts were asked to consider
the strengths, weaknesses,
interpretations, and inclusion of studies
used to support the findings, and OSHA
revised the document based on their
feedback.
To ensure that its literature review
was thorough and up to date, MSHA
reviewed a large body of additional
evidence beyond the studies considered
by OSHA. It added many studies
focused on miners’ exposures to
respirable crystalline silica, as well as
newer studies published over the past
decade. MSHA drew upon numerous
studies conducted by NIOSH, the
International Agency for Research on
Cancer (IARC), the National Toxicology
Program (NTP), and other researchers.
These studies provided epidemiological
data, analyses of morbidity (having a
disease or a symptom of disease) and
mortality (disease resulting in death),
progression and pathology evaluations,
death certificate and autopsy reviews,
medical surveillance data, health hazard
assessments, in vivo (animal) and in
vitro (cell-based) toxicity data, and other
toxicological reviews. These studies are
cited throughout this summary and are
listed in the References section of
MSHA’s standalone Health Effects
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document. Additionally, these studies
appear in the rulemaking docket.
MSHA received some comments from
industry stakeholders who disagreed
with MSHA’s selection of studies for its
literature review and therefore with its
findings. The Nevada Mining
Association (NVMA) and the Sorptive
Minerals Institute (SMI) stated that not
all relevant studies were discussed in
the Health Effects literature review
(Document ID 1441; 1446). NVMA also
stated that the studies referenced are
outdated. The National Stone, Sand, &
Gravel Association (NSSGA) stated that
MSHA’s review is overly reliant on
OSHA’s review (2013b) (Document ID
1448, Attachment 3). The state mining
association stated that the studies
MSHA considered do not recognize that
the likelihood of prolonged exposure to
respirable crystalline silica has been
dramatically reduced over the years,
noting improvements to respirators,
equipment, and engineering controls
(Document ID 1441).
However, commenters from health
and labor organizations stated that
MSHA’s review was thorough, was
consistent with the scientific consensus,
and addressed the primary health effects
of concern. These commenters agreed
with MSHA’s findings and conclusions
related to health risks from exposure to
respirable crystalline silica (Document
ID 1398; 1405; 1410; 1416). The
American Public Health Association
(APHA) also noted the inclusion of
several recent peer-reviewed
publications included in MSHA’s
review (Document ID 1416). The
American College of Occupational and
Environmental Medicine (ACOEM)
commented that there has been an
explosion of new information about the
molecular basis for silica’s adverse
effects since OSHA’s comprehensive
summary of the medical literature in its
preamble to the 2016 revisions to the
silica standard (Document ID 1405).
This commenter stressed that this new
information only adds to the urgency of
establishing and enforcing MSHA’s
proposed standard and applauded the
Agency’s review of the medical and
epidemiologic literature on the health
effects of silica exposure.
MSHA has taken several steps to
ensure that its review of health effects
literature represents the current
understanding of health risks related to
exposures to respirable crystalline
silica. In its initial standalone Health
Effects document, which was published
alongside the proposed rule, MSHA
included several recent publications
(published as late as 2022), and since
then, it has added more recent
publications (through 2023) in its final
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standalone Health Effects document.
Examples of recent literature included
in the standalone Health Effects
document are: Carrington and
Hershberger (2022), Cohen et al. (2022),
Descatha et al. (2022), Hall et al. (2022),
and Keles et al. (2022). Furthermore,
many of the more recent studies
included miners regulated under the
existing MSHA PEL of 100 mg/m3 (e.g.,
Almberg et al., 2017, 2018a; Graber et
al., 2017; Blackley et al., 2018a; Cohen
et al., 2022). In response to the comment
that the initial standalone Health Effects
document did not take into account
improved mining conditions or
contemporary engineering controls, the
Agency notes that it considered several
studies featuring miners in a larger
range of exposure groups, including
some that had lower exposure levels
(e.g., Mannetje et al., 2002b; Park et al.,
2002; Buchanan et al., 2003; Attfield
and Costello, 2004; Chen et al., 2012).
Two commenters (an industry trade
association and a training consulting
company) stated that MSHA presented a
significant amount of data showing the
consequences of the various chronic
health effects that silica can and does
have on the human body but no viable
data on mortality and morbidity among
MNM miners (Document ID 1442; 1392).
As discussed elsewhere, MSHA is not
required to prove a risk of death due to
silica exposure to justify regulating to
reduce a silica health risk. But the
evidence shows that respirable silica
exposure causes death as well as
chronic disease. MSHA reviewed and
discussed multiple studies that reported
an increase in mortality rates
throughout the standalone Health
Effects document (e.g., Bang et al., 2005;
Mazurek and Wood, 2008a; Liu et al.,
2017a; Wang et al., 2020a). Examples of
MNM morbidity studies included are
Mamuya et al. (2007), Tse et al. (2007a),
Rego et al. (2008), Reynolds et al.
(2016), and Wang et al. (2020b); while
MNM specific mortality studies include
Attfield and Costello (2004), Chen et al.
(2005, 2012), Schubauer-Berigan et al.
(2009), and Vacek et al. (2011), among
others. MSHA considered the best
available evidence for MNM and
concludes that MNM miners have an
increased mortality and morbidity due
to exposure to respirable crystalline
silica.
Commenters from health and labor
organizations suggested additional
studies for MSHA to include in the final
standalone Health Effects document
(Document ID 1405; 1373; 1449). These
studies included topics such as new
information regarding the molecular
basis for silica’s adverse health effects or
related to engineered stone workers.
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One commenter stated that MSHA
should include studies from outside of
the mining industry (Document ID 1448,
Attachment 3).
MSHA thoroughly reviewed these
studies and did not find sufficient
evidence to alter MSHA’s overall
conclusions of health risk, as discussed
in detail in the sections that follow.
However, MSHA did add many of the
recommended studies to its final
standalone Health Effects document
(e.g., Chilosi et al., 2003; Chen et al.,
2018; Cao et al., 2020). MSHA also
reviewed other suggested literature,
including promising animal studies
exploring novel drug treatments for
diseases caused by exposure to
respirable crystalline silica; however, it
determined that these studies are not
sufficiently developed for inclusion at
this time (e.g., Guo et al., 2019; Huang
et al., 2019; Jia et al., 2022). MSHA has
already included several studies related
to non-mining occupations throughout
its standalone Health Effects document.
Examples of other occupational studies
include studies of health effects on
granite workers (e.g., Davis et al., 1983;
Attfield and Costello, 2004), brick
workers (e.g., Merlo et al., 1991), agate
stone grinders (Rastogi et al., 1991),
pottery workers (e.g., McDonald et al.,
1995; Cherry et al., 1998), industrial
sand workers (e.g., McDonald et al.,
2001; Rando et al., 2001), concrete
workers (e.g., Meijers et al., 2001),
ceramic workers (e.g., Forastiere et al.,
2002), and foundry workers (e.g.,
Hertzberg et al., 2002; Vihlborg et al.,
2017), among others. Occupations such
as granite, industrial sand, or concrete
workers, represent similar job tasks and
exposures which may overlap with
mining occupations. Others such as
brick, pottery, and ceramic workers
involve processing of mined materials
into a commercial product.
To analyze the extensive literature
that it considered, MSHA used the
widely accepted weight-of-evidence
(WoE) approach. Under this approach,
studies with varied methodologies and
conclusions are evaluated for their
overall quality. Causal inferences are
drawn based on a determination of
whether there is substantial evidence
that exposure increases the risk of a
particular adverse health effect. This
approach is a well-accepted method of
conducting health hazard assessments
(NRC, 2009; NIOSH, 2019a).
Additionally, it was used by OSHA in
its review of health effects literature
(2013b) for its 2016 respirable
crystalline silica standard. Factors that
MSHA considered in its WoE analysis
include: (1) size of the cohort studied
and power of the study to detect a
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sufficiently low level of disease risk; (2)
duration of follow-up of the study
population; (3) potential for study bias,
such as selection bias or healthy worker
effects, and (4) adequacy of underlying
exposure information for examining
exposure-response relationships. Of the
studies examined in the standalone
Health Effects document, studies were
deemed suitable for inclusion in the
FRA if they provided adequate
quantitative information on exposure
and disease risks and were judged to be
of sufficiently high quality according to
the above criteria. MSHA’s literature
review expanded upon OSHA’s (2013b)
review of the health effects literature to
support its final respirable crystalline
silica rule (81 FR 16286), reviewing
pertinent new research. MSHA’s
assessment of the literature is consistent
with OSHA’s conclusion from its silica
literature review.
MSHA received one comment from
the NSSGA challenging the validity of
MSHA’s literature review methodology
(Document ID 1448, Attachment 3). This
commenter submitted a report analyzing
MSHA’s health effects literature review,
arguing that MSHA’s review cannot be
replicated or fully evaluated for its
scientific validity and claiming that it is
unclear whether MSHA’s interpretations
are sufficiently reliable as a basis for
decision-making. The commenter
asserted the need for literature reviews
to be done pursuant to Lynch et al.’s
(2022) framework of a ‘‘systematic
review,’’ a review method that seeks to
eliminate bias by adhering to a
transparent, a priori protocol. The
commenter also expressed concerns that
MSHA’s methodology is inadequately
explained and possibly dated. The
commenter suggested further studies to
be included in MSHA’s review and
provided specific responses to some of
MSHA’s statements in its literature
review.
On the other hand, the APHA
provided a different perspective on the
methodology (Document ID 1416). This
commenter stated that MSHA
thoroughly describes the health risks,
which include developing chronic
silicosis, accelerated silicosis,
progressive massive fibrosis, chronic
obstructive pulmonary disease, lung
cancer and kidney disease. Further, the
commenter noted that MSHA’s review
of the health effects literature included
more than three dozen peer-reviewed
papers published in just the last few
years. This commenter concurred with
MSHA’s determination that miners’
exposure to respirable crystalline silica
presents a risk of material impairment of
health or functional capacity.
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MSHA disagrees with the comment
challenging MSHA’s methodology.
Although the ‘‘systematic review’’
framework outlined in Lynch et al.
(2022) is increasingly used in review
publications, it is not the only valid
method of conducting a literature
review of the current science. As
explained in the standalone Health
Effects document, MSHA’s review of the
scientific literature on respirable
crystalline silica used a widely accepted
WoE approach.
The term, ‘‘weight-of-evidence’’ was
coined as early as 40 years ago by the
NRC (1983) in their seminal publication
‘‘Risk Assessment in the Federal
Government: Managing the Process’’. It
has become a fundamental element of
the risk assessment process (NRC, 2009;
EPA, 1986; Martin et al., 2018; Lee et
al., 2023). MSHA selected this approach
for use in its respirable crystalline silica
risk analysis for a variety of reasons.
First, it has withstood the scrutiny of
scientists throughout the world (Suter et
al., 2020). Second, it has been used
successfully throughout the world for
conducting a wide variety of risk
assessments and analyses involving a
wide range of exposures in both
occupational and environmental
settings (e.g., drugs, pesticides,
industrial chemicals) (EPA, 1986, 2016;
National Research Council (NRC), 2009;
Suter et al., 2020; Government of
Canada, 2022). Third, it continues to be
a solid and accepted approach that is
still used today (EPA, 1986, 2016;
National Research Council (NRC), 2009;
Martin et al., 2018; Suter et al., 2020;
Government of Canada, 2022; Lee et al.,
2023). Current searches of the scientific
literature (e.g., using search engines
such as PubMed or Google Scholar)
continue to identify studies in which
the WoE approach has been employed.
Finally, numerous courts have approved
of federal agencies relying on this
methodology in rulemaking for over 40
years. See Mississippi v. E.P.A., 744
F.3d 1334, 1344–45 (D.C. Cir. 2013)
(upholding the ‘‘weight of evidence
approach’’ because ‘‘one type of study
might be useful for interpreting
ambivalent results from another type
. . . and though a new study does little
besides confirm or quantify a previous
finding, such incremental (and arguably
duplicative) studies are valuable
precisely because they confirm or
quantify previous findings or otherwise
decrease uncertainty’’) (citing Ethyl
Corp. v. EPA, 541 F.2d 1, 26 (D.C. Cir.
1976) (en banc)); N. Am.’s Bldg. Trades
Unions v. OSHA, 878 F.3d 271, 284
(D.C. Cir. 2017) (rejecting challenges to
OSHA’s ‘‘weight of evidence’’ approach
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supporting its silica rulemaking). Thus,
MSHA finds that the WoE approach is
appropriate for use in its respirable
crystalline silica rulemaking.
In summary, MSHA’s weight-ofevidence analysis is based on OSHA’s
extensive literature review and peer
review process; includes a substantial
number of studies and data published
after the OSHA rulemaking; and has
received support from NIOSH experts.16
As described in greater detail in
MSHA’s standalone Health Effects
document, the scientific understanding
of how respirable crystalline silica
causes adverse health effects has
evolved greatly in the more than 45
years since the Mine Act was passed in
1977. MSHA’s review of the literature
indicates that under the existing
standards found in 30 CFR parts 56, 57,
70, 71, and 90, miners are still
developing preventable diseases that are
material impairments of health or
functional capacity. Regulatory action to
reduce occupational exposures that
cause these diseases is necessary to
ensure no miner suffers material
impairment of health or functional
capacity, as required by section
101(a)(6)(A) of the Mine Act.
Based on an extensive review of
health effects literature, MSHA
determines that occupational exposure
to respirable crystalline silica causes
silicosis (acute silicosis, accelerated
silicosis, chronic silicosis, and
progressive massive fibrosis (PMF)),
NMRD (including COPD), lung cancer,
and end-stage renal disease (ESRD).
Each of these effects is exposuredependent, potentially chronic,
irreversible, potentially disabling, and
can be fatal. In addition, MSHA’s review
of the health effects literature has shown
that respirable crystalline silica
exposure is causally related to the
development of some autoimmune
disorders through inflammatory
pathways. Current health information
cited in the final standalone Health
Effects document indicates that miners
are suffering material impairment of
health or functional capacity due to
their occupational exposures to
respirable crystalline silica. MSHA’s
review of respirable crystalline silica
health effects concludes that the final
rule, which lowers the exposure limits
in MNM and coal mining to 50 mg/m3
and establishes an action level of 25 mg/
m3 for a full-shift exposure, calculated
as an 8-hour TWA, will reduce the risk
16 MSHA’s review benefitted from feedback and
review from experts at NIOSH, both informally and
through the interagency review process organized
by OMB, during the literature review process and
preparation of the standalone Health Effects
document.
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of miners developing silicosis, NMRD,
lung cancer, and renal disease.
B. Toxicity of Respirable Crystalline
Silica
Respirable crystalline silica is
released into the environment during
mining or milling processes, thus
creating an airborne hazard. The
particles may be freshly generated or resuspended from surfaces on which they
are deposited in mines or mills.
Respirable crystalline silica particles
may be irregularly shaped and variable
in size. These particles may be inhaled
by miners and can be deposited
throughout the lungs. Some pulmonary
clearance of particles deposited in the
alveolar region (deep lung) may occur,
but many particles can be retained and
initiate or advance the disease process.
The toxicity of these retained particles
is amplified because the particles are
not water-soluble and are not
metabolized into less toxic compounds.
This is important because insoluble
dusts may remain in the lungs for
prolonged periods, resulting in a variety
of cellular responses that can lead to
pulmonary disease (ATSDR, 2019).
Respirable crystalline silica particles
that are cleared from the lungs by the
lymphatic system are distributed to the
lymph nodes, blood, liver, spleen, and
kidneys, potentially accumulating in
these other organ systems and causing
renal disease and other adverse health
effects (ATSDR, 2019).
Physical characteristics relevant to the
toxicity of respirable crystalline silica
primarily relate to its size and surface
characteristics, both of which play
important roles in how respirable
crystalline silica causes tissue damage.
Any factor that influences or modifies
these physical characteristics may alter
the toxicity of respirable crystalline
silica by affecting the mechanistic
processes (ATSDR, 2019).
Inflammatory pathways affect disease
development in various systems and
tissues in the human body. For instance,
it has been proposed that lung fibrosis
caused by exposure to respirable
crystalline silica results from a cycle of
cell damage, oxidant generation,
inflammation, scarring, and ultimately
fibrosis. This has been reported by:
Nolan et al. (1981), Shi et al. (1989,
1998), Lapp and Castranova (1993),
Brown and Donaldson (1996), Parker
and Banks (1998), Castranova and
Vallyathan (2000), Castranova (2004),
Fubini et al. (2004), Hu et al. (2017),
Benmerzoug et al. (2018), and Yu et al.
(2020).
Respirable crystalline silica entering
the lungs could cause damage by a
variety of mechanisms, including direct
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damage to lung cells. In addition,
activation or stimulation by respirable
crystalline silica of alveolar
macrophages (after phagocytosis) and/or
alveolar epithelial cells may lead to: (1)
release of cytotoxic enzymes, reactive
oxygen species (ROS), reactive nitrogen
species (RNS), inflammatory cytokines
and chemokines; (2) eventual cell death
with the release of respirable crystalline
silica; and (3) recruitment and
activation of polymorphonuclear
leukocytes (PMNs) and additional
alveolar macrophages (Castranova and
Vallyathan, 2000; Castranova, 2004;
Hamilton et al., 2008). The elevated
production of ROS/RNS could result in
oxidative stress and lung injury that
stimulate alveolar macrophages,
ultimately resulting in fibroblast
activation and pulmonary fibrosis (Li et
al., 2018; Feng et al., 2020). The
prolonged recruitment of macrophages
and PMN causes persistent
inflammation, regarded as a primary
step in the development of silicosis.
The strong immune response in the
lung following exposure to respirable
crystalline silica may also be linked to
a variety of extra-pulmonary adverse
effects such as
hypergammaglobulinemia
(overproduction of more than one class
of immunoglobulins by plasma cells),
production of rheumatoid factor, antinuclear antibodies, and release of other
immune complexes (Haustein and
Anderegg, 1998; Green and Vallyathan,
1996; Parks et al., 1999). Respirable
crystalline silica exposure has also been
associated with ESRD through the
initiation of immunological injury to the
glomerulus of the kidney (Calvert et al.,
1997).
Proposed mechanisms involved in
respirable crystalline silica-induced
carcinogenesis have included: direct
DNA damage, inhibition of the p53
tumor suppressor gene, loss of cell cycle
regulation; stimulation of growth
factors, and production on oncogenes
(Nolan et al., 1981; Shi et al., 1989,
1998; Brown and Donaldson, 1996;
Castranova, 2004; Fubini et al., 2004).
Three commenters expressed
concerns about the findings of the
health effects literature review and their
relevance to the sorptive minerals
industry (Document ID 1446,
Attachment 1; 1442; 1419). The SMI and
Essential Minerals Association (EMA)
stated that MSHA has an incomplete
understanding of the latest available
scientific research (Document ID 1446,
Attachment 1; 1442). Asserting that
occluded quartz in sorptive clays is not
fractured (either in the clay formation in
which it exists or during the mining and
processing of the material to form
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sorptive mineral-based products), the
SMI concluded that occluded quartz in
sorptive clays does not pose the health
risk posed by fractured quartz
(Document ID 1446, Attachment 1).
Discussing at length studies it
recommended MSHA include in its
health effects literature review, SMI and
EMA said that much of this research
was previously considered by OSHA
(2013b) and that it had led to OSHA’s
decision to exempt sorptive clays from
coverage under OSHA’s silica standard.
SMI also noted that additional research
since OSHA’s revised silica standard
was promulgated has advanced the
question of how quartz causes disease
and the difference in risk potential
between fractured and unfractured and
occluded quartz. Asserting that, without
consideration of the additional research
provided, the proposed standard would
not be based on the best available
evidence and would not reflect the
latest available scientific data in the
field, this commenter discussed Mine
Act statutory provisions and case law
that it asserted demonstrate the high
level of scientific evidence and scrutiny
required of MSHA when setting health
and safety standards.
A more detailed response to SMI’s
overall comment can be found in
Section VIII.A. General Issues of this
preamble. In response to the suggestion
to consider additional studies, MSHA
reviewed the suggested references and
added some to the final standalone
Health Effects document (Creutzenberg
et al., 2008; Borm et al., 2018; Pavan et
al., 2019). MSHA also notes that some
of these studies were already cited in
the version of the standalone Health
Effects document published alongside
the proposed rule (e.g., Donaldson and
Borm, 1998; Fubini, 1998; Bruch et al.,
2004; Fubini et al., 2004). Overall, many
of the studies suggested by the
commenter have argued that occluded
or aged quartz is less toxic but have not
suggested that occluded or aged quartz
is not toxic or carries no risk of disease.
MSHA agrees that there is some
evidence to suggest that occluded silica
is less toxic than unoccluded silica
(Wallace et al., 1996), but there is no
evidence that occlusion and the initial
reduced toxicity persist following
deposition and retention of the
crystalline silica particles in the lungs.
Similarly, animal studies involving
respirable crystalline silica suggest that
the aged form has lower toxicity than
the freshly fractured form; however, the
aged form still retains toxicity
(Shoemaker et al., 1995; Vallyathan et
al., 1995; Porter et al., 2002c). From
these studies, MSHA concludes that
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exposure to the crystalline silica present
in sorptive minerals poses a risk of
material impairment of health or
functional capacity to miners.
Others appeared to be irrelevant to the
scope of the rule, such as those focused
on amorphous silica, microscopy
techniques, or workshop discussions
(e.g., Mercer et al., 2018; Weber et al.,
2018; Driscoll and Borm, 2020). MSHA
notes that none of the suggested animal
studies included acute or chronic
inhalation exposures to aged or
occluded respirable crystalline silica.
One suggested review, Poland et al.
(2023) described a 2020 animal
inhalation study (nose-only) which did
not include exposures to aged or
occluded respirable crystalline silica;
the 2020 study was conducted using
amorphous silica and the data were
compared to a 1988 animal study that
included whole-body (as opposed to
nose-only) exposures to respirable
crystalline silica.17 Since this 2020
surface area comparison study described
by Poland et al. (2023) focused on
amorphous silica, which is not a part of
this rulemaking, it was deemed
unsuitable for inclusion in MSHA’s
final standalone Health Effects
document. Other animal studies
discussing aged or occluded respirable
crystalline silica suggested used either
intratracheal instillation or
oropharyngeal aspiration, which do not
reflect the behavior of particles that
enter the lungs via inhalation, including
lung clearance (Foster et al., 2001;
Wong, 2007; Driscoll and Borm, 2020).
Section VIII.A. General Issues of this
preamble responds more fully to these
comments. In its response, MSHA notes
that several studies of occluded or
fractured quartz discussed their
methods, including careful handling of
occluded samples, but did not include
analysis of occluded quartz that was
analyzed with less than careful
handling. This is not applicable to realworld conditions; MSHA’s experience
with mining and processing of sorptive
minerals includes the use of grinding
and milling processes.
After reviewing the available
literature, MSHA concludes that miners
working in the sorptive minerals
industry are exposed to respirable
crystalline silica. OSHA (2013b)
concluded that while there was
considerable evidence that several
environmental influences can modify
surface activity to either enhance or
17 These two studies (1988 and 2020) described
by Poland et al. (2023) had limited comparability
for a variety of reasons; they differ in: (1) rat strains
(types of rats), (2) exposure durations, (3) recovery
periods, as well as (4) types of inhalation exposure,
among others.
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diminish the toxicity of silica, the
available information was insufficient to
determine in any quantitative way how
these influences may affect disease risk
to workers in any particular workplace
setting (81 FR at 16311). MSHA agrees
with OSHA (2013b) that there is
evidence to support that surface activity
of respirable crystalline silica may play
a role in producing disease. However,
mining is significantly different from
other industries regulated by OSHA, for
instance, in that it involves milling,
grinding and removal of overburden.
While the available information is
insufficient to determine how these
influences may affect disease risk to
miners in any quantitative way and in
any mining sector. MSHA is permitted
‘‘ ‘to err on the side of overprotection by
setting a fully adequate margin of
safety.’ ’’ Kennecott Greens Creek Min.
Co. v. Mine Safety & Health Admin., 476
F.3d 946, 952 (D.C. Cir. 2007) (quoting
Nat’l Min. Ass’n v. Mine Safety & Health
Admin., 116 F.3d 520, 528 (D.C. Cir.
1997)).
C. Diseases
1. Silicosis
Silicosis is a material impairment of
health or functional capacity, as defined
by the Mine Act, and refers to a group
of lung diseases caused by the
inhalation of respirable crystalline
silica. See 30 U.S.C. 811(a)(6)(A).
Silicosis is a progressive, occupational
disease, in which accumulation of
respirable crystalline silica particles
causes an inflammatory reaction in the
lung. This reaction leads to lung damage
and scarring and, in some cases,
progresses to disability and death.
Respirable crystalline silica has long
been identified as a cause of lung
diseases in miners, and adverse health
effects were noted and described as
early as 1550 by Georgius Agricola
(Agricola, as translated by Banner in
1950). Based on the review of the
literature, MSHA has determined that
exposure to respirable crystalline silica
causes silicosis in MNM and coal
miners and that it is a significant cause
of premature morbidity and mortality
(Mazurek and Attfield, 2008; Mazurek
and Wood, 2008a,b; Mazurek et al.,
2015, 2018).
When respirable crystalline silica
accumulates in the lungs, it causes an
inflammatory reaction, leading to lung
damage and scarring. Silicosis can
continue to develop even after silica
exposure has ceased (Hughes et al.,
1982; Ng et al., 1987a; Hessel et al.,
1988; Kreiss and Zhen, 1996; Miller et
al., 1998; Yang et al., 2006). It is not
reversible, and there is only
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symptomatic treatment, including
bronchodilators to maintain open
airways, oxygen therapy, and lung
transplants in the most severe cases
(Cochrane et al., 1956; Ng et al., 1987a;
Lee et al., 2001; Mohebbi and Zubeyri,
2007; Kimura et al., 2010; Laney et al.,
2017; Almberg et al., 2020; Hall et al.,
2022). Respirable crystalline silica
exposure in miners can lead to all three
forms of silicosis (acute, accelerated,
and chronic). These forms differ in the
rate of exposure, pathology (structural
and functional changes produced by the
disease), and latency period from
exposure to disease onset.
Acute silicosis is an aggressive
inflammatory process following intense
exposure to respirable crystalline silica
for ‘‘periods measured in months rather
than years’’ (Cowie and Becklake, 2016).
It causes alveolar proteinosis, an
accumulation of lipoproteins in the
alveoli of the lungs. This restructuring
of the lungs leads to symptoms such as
coughing and difficult or labored
breathing, and often progresses to
profound disability and death due to
respiratory failure or infectious
complications. In addition, symptoms
often advance even after exposure has
stopped, primarily due to the massive
amount of protein debris and fluid that
collects in the alveoli, which leads to
the impairment of gas exchange
(oxygen) in the lungs and respiratory
distress of the patient. The X-ray
appearance and results of microscopic
examination of acute silicosis are like
those of idiopathic (having an unknown
cause) pulmonary alveolar proteinosis.
Accelerated silicosis includes both
inflammation and fibrosis and is
associated with intense respirable
crystalline silica exposure. Accelerated
silicosis usually manifests over a period
of three to ten years (Cowie and
Becklake, 2016), but it can develop in as
little as two to five years if exposure is
sufficiently intense (Davis, 1996).
Accelerated silicosis may have features
of both chronic and acute silicosis, with
alveolar proteinosis in addition to X-ray
evidence of fibrosis, seen as small
opacities or the large opacities of PMF.
Although the symptoms are like those of
chronic silicosis, the clinical and
radiographic progression of accelerated
silicosis evolves more rapidly, and often
leads to PMF, severe respiratory
impairment, and respiratory failure.
Accelerated silicosis can progress with
associated morbidity and mortality,
even if exposure ceases. Accelerated
silicosis is frequently fatal.
Chronic silicosis is the most
frequently observed form of silicosis in
the United States today (Banks, 2005;
OSHA, 2013b; Cowie and Becklake,
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2016). It is also the most common form
of silicosis diagnosed in miners.
Chronic silicosis is a fibrotic process
that typically follows less intense
respirable crystalline silica exposure of
ten or more years (Becklake, 1994;
Balaan and Banks, 1998; NIOSH, 2002b;
Kambouchner and Bernaudin, 2015;
Cowie and Becklake, 2016; Rosental,
2017; ATSDR, 2019; Barnes et al., 2019;
Hoy and Chambers, 2020). It is
identified histopathologically by the
presence of the silicotic islet or nodule
that is an agent-specific fibrotic lesion
and is recognized by its pathology
(Balaan and Banks, 1998). Chronic
silicosis develops slowly and creates
rounded whorls of scar tissue that
progressively destroy the normal
structure and function of the lungs. In
addition, the scar tissue opacities
become visible by chest X-ray or
computerized tomography (CT) only
after the disease is well-established and
the lesions become large enough to
view. As a result, surveys based on
identification of small and large opacity
disease on chest X-ray films usually
underestimate the true prevalence of
silicosis (Craighead and Vallyathan,
1980; Hnizdo et al., 1993; Rosenman et
al., 1997; Cohen and Velho, 2002). The
lesions eventually advance and result in
lung restriction, reduced lung volumes,
decreased pulmonary compliance, and
reduction in the gas exchange
capabilities of the lungs (Balaan and
Banks, 1998). As the disease progresses,
affected miners may have chronic
cough, sputum production, shortness of
breath, and reduced pulmonary
function.
Among coal miners, silicosis is
usually found in conjunction with
simple coal workers’ pneumoconiosis
(CWP) because of the miners’ exposures
to RCMD that also contains respirable
crystalline silica (Castranova and
Vallyathan, 2000). Coal miners also face
an added risk of developing mixed-dust
pneumoconiosis (MDP) (includes the
presence of coal dust macules), mixeddust fibrosis (MDF), and/or silicotic
nodules (Honma et al., 2004; Green,
2019). The autopsy studies on coal
miners that MSHA reviewed support a
pathological relationship between
mixed-RCMD or respirable crystalline
silica exposures and PMF, silicosis, and
CWP (Davis et al., 1979; Ruckley et al.,
1981, 1984; Douglas et al., 1986; Fernie
and Ruckley, 1987; Green et al., 1989,
1998b; Attfield et al., 1994; Vallyathan
et al., 2011; Cohen et al., 2016, 2019,
2022). Autopsy studies in British coal
miners indicated that the more
advanced the disease, the more mixedRCMD components were retained in the
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lung tissue (Ruckley et al., 1984;
Douglas et al., 1986). Green et al.
(1998b) determined that of 4,115 coal
miners with pneumoconiosis autopsied
as part of the National Coal Workers’
Autopsy Study (NCWAS), 39 percent
had mixed dust nodules and 23 percent
had silicotic nodules.
PMF or ‘‘complicated silicosis’’ has
been diagnosed in both coal and MNM
miners exposed to dusts containing
respirable crystalline silica. Recent
literature on the pathophysiology of
PMF supports the importance of
crystalline silica as a cause of PMF in
silica-exposed workers such as coal
miners (Cohen et al., 2016, 2022),
sandblasters (Hughes et al., 1982;
Abraham and Wiesenfeld, 1997),
industrial sand workers (Vacek et al.,
2019), hard rock miners (Verma et al.,
1982, 2008), and gold miners (Carneiro
et al., 2006a; Tse et al., 2007b).
a. Classifying Radiographic Findings of
Silicosis
The studies reviewed by MSHA used
one of two established methods for
identifying findings of pneumoconiosis:
the International Labour Office (ILO)
Classification System or the Chinese
categorization system, each of which is
described below. In addition, the
NIOSH case definition of silicosis used
in surveillance systems relies on the ILO
system.
The ILO developed a standardized
system to classify the radiographic
appearances of pneumoconiosis
identified in chest X-rays films or digital
chest radiographic images (ILO, 1980,
2002, 2011, 2022). One aspect of the ILO
system involves grading the size, shape,
and profusion (density) of opacities in
the lungs. The density of opacities is
classified on a four-point major category
scale (category 0, 1, 2, or 3), with each
major category divided into three
subcategories, giving a 12-point scale
between 0/¥ and 3/+. Differences
between ILO categories are subtle. For
each subcategory, the top number
indicates the major category that the
profusion most closely resembles, and
the bottom number indicates the major
category that was given secondary
consideration. For example, film readers
may assign classifications such as 1/0,
which means the reader classified it as
category 1, but category 0 (normal) was
also considered (ILO, 2022). Major
category 0 indicates the absence of
visible opacities consistent with
pneumoconiosis and categories 1 to 3
reflect increasing profusion of opacities
and a concomitant increase in severity
of disease.
However, some studies in MSHA’s
literature review used the Chinese
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system of X-ray classification based on
the ‘‘Radiological Diagnostic Criteria of
Pneumoconiosis and Principles for
Management of Pneumoconiosis’’
(GB5906–86). This includes four
categories of pneumoconiosis findings: a
suspected case (0+), stage I, stage II, or
stage III. Under this scheme, a panel of
three radiologists determines the
presence and severity of radiographic
changes consistent with
pneumoconiosis. The four categories
correspond to ILO profusion category 0/
1, category 1, category 2, and category
3, respectively. A suspected case of
silicosis (0+) in a dust-exposed worker
refers to a dust response in the lung and
its corresponding lymph nodes, or a
scale and severity of small opacities that
fall short of the level observed in a stage
I case of silicosis (Chen et al., 2001;
Yang et al., 2006).
MSHA’s analysis of silicosis studies
uses NIOSH’s surveillance case
definition to determine the presence of
silicosis. As described further in the
final standalone Health Effects
document, NIOSH defines the presence
of silicosis in terms of the ILO system
and considers a small opacity profusion
score of 1/0 or greater to indicate
pneumoconiosis (NIOSH, 2014b). This
definition originated from testimony
before Congress regarding the 1969 Coal
Act in which the Public Health Service
recommended that miners be removed
from dusty environments as soon as
they showed ‘‘minimal effects’’ of dust
exposure on a chest X-ray (i.e., pinpoint,
dispersed micro-nodular lesions).
MSHA interprets ‘‘minimal effects’’ to
mean an X-ray ILO profusion score of
category 1/0 or greater. This is also
consistent with Hnizdo et al. (1993),
which recommended that, due to the
low sensitivity of chest x-rays for
detecting silicosis, radiographs
consistent with an ILO category of 0/1
or greater be considered indictive of
silicosis among workers exposed to a
high concentration of silica-containing
dust.
b. Progression and Associated
Impairment
MSHA reviewed studies referenced by
OSHA (2013b) that examined the
relationship between exposure and
progression, as well as between X-ray
findings and pulmonary function.
Additionally, MSHA considered
literature not previously reviewed by
OSHA (2013b) (Mohebbi and Zubeyri,
2007; Wade et al., 2011; Dumavibhat et
al., 2013).
Progression of silicosis is recognized
when there are changes or worsening of
the opacities in the lungs, and
sequential chest radiographs are
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classified higher by one or more
subcategories (e.g., from 1/0 to 1/1)
because of changes in the location,
thickness, or extent of lung
abnormalities and/or the presence of
calcifications. The higher the category
number, the more severe the disease.
Due to the variability in film technique
and classification of films, some
investigators count progression as
advancing two or more subcategories,
such as 1/0 to 1/2.
Overall, the studies indicate that
progression is more likely with
continued exposure, especially high
average levels of exposure. Progression
is also more likely for miners with
higher ILO profusion classifications. As
discussed previously, progression of
disease may continue after miners are
no longer exposed to respirable
crystalline silica (Cochrane et al., 1956;
Maclaren and Soutar, 1985; Hurley et
al., 1987; Kimura et al., 2010; Almberg
et al., 2020; Hall et al., 2020b). In
addition, although lung function
impairment is highly correlated with
chest X-ray films indicating silicosis,
researchers caution that respirable
crystalline silica exposure could impair
lung function before it is detected by Xray.
Of the studies in which silicosis
progression was documented in
populations of workers, four included
quantitative exposure data that were
based on either existing exposure levels
or historical measurements of respirable
crystalline silica (Ng et al., 1987a study
of granite miners; Hessel et al., 1988
study of gold miners; Miller et al., 1998
study of coal miners; Miller and
MacCalman, 2010 study of coal miners).
In some studies, episodic exposures to
high average concentrations were
documented and considered in the
analysis. These exposures were strong
predictors of more rapid progression
beyond that predicted by cumulative
exposure alone. Otherwise, the variable
most strongly associated in these studies
with progression of silicosis was
cumulative respirable crystalline silica
exposure (the product of the
concentration times duration of
exposure, which is summed over time)
(Ng et al., 1987a; Hessel et al., 1988;
Miller et al., 1998; Miller and
MacCalman, 2010). In the absence of
concentration measurements, duration
of employment in specific occupations
known to involve exposure to high
levels of respirable dust has been used
as a surrogate for cumulative exposure
to respirable crystalline silica. Duration
of employment has also been found to
be associated with the progression of
silicosis (Ogawa et al., 2003a).
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Miller et al. (1998) examined the
impact of high quartz exposures on
silicosis disease progression in 547
British coal miners from 1990 to 1991
and evaluated chest X-ray changes after
the mines closed in 1981. The study
reviewed chest X-rays taken during
health surveys conducted between 1954
and 1978 and data from extensive
exposure monitoring conducted
between 1964 and 1978. For some
occupations, exposure was high because
miners had to dig through a sandstone
stratum to reach the coal. For example,
quarterly mean respirable crystalline
silica (quartz) concentrations ranged
from 1,000 to 3,000 mg/m3 and for a brief
period, concentrations exceeded 10,000
mg/m3 for one job. Some of these high
exposures were associated with
accelerated disease progression in these
miners.
Buchanan et al. (2003) reviewed the
exposure history and chest X-ray
progression of 371 retired miners and
found that short-term exposures (i.e., ‘‘a
few months’’) to high concentrations of
respirable crystalline silica (e.g., >2,000
mg/m3) increased the silicosis risk by
three-fold (compared to the risk of
cumulative exposure alone) (see the
standalone FRA document).
The risks of increased rate of
progression predicted by Buchanan et
al. (2003) have been seen in coal miners
(Miller et al., 1998; Laney et al., 2010,
2017; Cohen et al., 2016), metal (Hessel
et al., 1988; Hnizdo and Sluis-Cremer,
1993; Nelson, 2013), and nonmetal
miners such as silica plant and ground
silica mill workers, whetstone cutters,
and silica flour packers (NIOSH,
2000a,b; Ogawa et al., 2003a; Mohebbi
and Zubeyri, 2007). Accordingly, it is
important to limit higher exposures to
respirable crystalline silica to minimize
the risk of rapid progressive
pneumoconiosis (RPP) in miners. RPP is
the development of progressive massive
fibrosis (PMF) and/or an increase in
small opacity profusion greater than one
subcategory over five years or less
(Anta˜o et al., 2005).
The results of many surveillance
studies conducted by NIOSH as part of
the Coal Workers’ Health Surveillance
Program indicate that the pathology of
pneumoconiosis in coal miners has
changed over time, in part due to
increased exposure to respirable
crystalline silica. The studies of Cohen
et al. (2016, 2022) indicate that RPP
develops due to increased exposure to
respirable crystalline silica among
contemporary coal miners as compared
to historical coal miners. Through the
examination of pathologic materials
from 23 contemporary (born in or after
1930) and 62 historical coal miners
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(born between 1910 and 1930) with
severe pneumoconiosis, who were
autopsied as part of NCWAS, Cohen et
al. (2022) found a significantly higher
proportion of silica-type PMF among
contemporary miners (57 percent vs. 18
percent, p <0.001). They also found that
mineral dust alveolar proteinosis
(MDAP) was more common in the
current generation of miners and that
the lung tissues of contemporary coal
miners contained a significantly greater
percentage and concentration of silica
particles than those of past generations
of miners.
Many studies found an association
between pulmonary function
decrements and ILO profusion category
2 or 3. Additionally, the review of the
literature indicated a decreased lung
function among workers who were
exposed to respirable crystalline silica.
MSHA therefore concludes that
respirable crystalline silica exposure
may impair lung function in some
instances before silicosis can be
detected by chest X-rays.
c. Occupation-Based Epidemiological
Studies
MSHA reviewed the occupation-based
epidemiological literature, which
examines health outcomes among
workers and their potential association
with conditions in the workplace. In
addition, MSHA reviewed additional
occupation-based literature specific to
respirable crystalline silica exposure in
MNM and coal miners and concludes
that respirable crystalline silica
exposure increases the risk of silicosis
morbidity and early mortality.
One study examined the acute and
accelerated silicosis outbreak that
occurred during and after construction
of Hawk’s Nest Tunnel in West Virginia
from 1930 to 1931. There, an estimated
2,500 men worked in a tunnel drilling
rock consisting of 90 percent silica or
more. The study later estimated that at
least 764 of the 2,500 workers (30.6
percent) died from acute or accelerated
silicosis (Cherniack, 1986). There was
also high turnover among the tunnel
workers, with an average length of
employment underground of only about
two months.
MSHA’s review included the
occupation-based literature cited by
OSHA (2013b) in developing its
respirable crystalline silica standard
(OSHA, 2016a). Overall, MSHA found
substantial evidence suggesting that
occupational exposure to respirable
crystalline silica increases the risk of
silicosis. This conclusion is consistent
with OSHA’s conclusion.
In a population of granite quarry
workers (mean length of employment:
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23.4 years) exposed to an average
respirable crystalline silica
concentration of 480 mg/m3, 45 percent
of those diagnosed with simple silicosis
showed radiological progression of
disease two to ten years after diagnosis
(Ng et al., 1987a). Among a population
of gold miners, 92 percent showed
progression after 14 years (Hessel et al.,
1988). Chinese factory workers and
miners who were categorized under the
Chinese system of X-ray classification as
‘‘suspected’’ silicosis cases (analogous
to ILO 0/1) had a progression rate to
stage I (analogous to ILO major category
1) of 48.7 percent, with an average
interval of about 5.1 years (Yang et al.,
2006).
The risk of silicosis, and particularly
its progression, carries with it an
increased risk of reduced lung function.
Strong evidence has shown that lung
function deteriorates more rapidly in
miners exposed to respirable crystalline
silica, especially in those with silicosis
(Hughes et al., 1982; Ng and Chan, 1992;
Malmberg et al., 1993; Cowie, 1998).
The rates of decline in lung function are
greater where disease shows evidence of
radiologic progression (Be´gin et al.,
1987; Ng et al., 1987a; Ng and Chan,
1992; Cowie, 1998). Additionally, the
average deterioration of lung function
exceeds that in smokers (Hughes et al.,
1982).
Blackley et al. (2015) found
progressive lung function impairment
across the range of radiographic
profusion of simple CWP in a cohort of
8,230 coal miners that participated in
the Enhanced Coal Workers’ Health
Surveillance Program from 2005 to
2013. There, 269 coal miners had
category 1 or 2 chronic CWP. This study
also found that each increase in
profusion score was associated with
decreases in various lung function
parameters: 1.5 percent (95 percent CI,
1.0 percent–1.9 percent) in forced
expiratory volume in one second (FEV1)
percent predicted, 1.0 percent (95
percent CI, 0.6 percent–1.3 percent)
forced vital capacity (FVC) percent
predicted, and 0.6 percent (95 percent
CI, 0.4 percent–0.8 FEV1/FVC).
Accordingly, MSHA concludes that
respirable crystalline silica exposure
increases the risk of silicosis morbidity
and mortality among miners. This
conclusion is consistent with OSHA’s
conclusion that there is substantial
evidence that occupational exposure to
respirable crystalline silica increases the
risk of silicosis.
d. Surveillance Data
In addition to occupation-based
epidemiological studies, MSHA
reviewed surveillance studies, including
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those submitted by commenters, which
provide and interpret data to facilitate
the prevention and control of disease,
and ultimately MSHA finds that the
prevalence of silicosis generally
increases with duration of exposure
(work tenure). This is evident from the
statistically significant proportional
mortality ratios (PMRs) reported in the
National Occupational Mortality System
(NORMS) data previously reviewed by
OSHA and reported by MSHA in its
standalone Health Effects document.
Several small and ad hoc surveillance
reports reported in the standalone
Health Effects document also found a
prevalence of silicosis of up to 50
percent among working and retired
miners (Hnizdo and Sluis-Cremer, 1993;
Ng and Chan, 1994; Kreiss and Zhen,
1996; Finkelstein, 2000).
However, the available statistics may
underestimate silicosis-related
morbidity and mortality in miners. It
has been widely reported that statistics
underestimate silicosis cases due to: (1)
misclassification of causes of death (as
TB, chronic bronchitis, emphysema, or
cor pulmonale); (2) errors in recording
occupation on death certificates; and (3)
misdiagnosis of disease (Windau et al.,
1991; Goodwin et al., 2003; Rosenman
et al., 2003; Blackley et al., 2017).
Furthermore, reliance on chest X-ray
findings may lead to missed silicosis
cases when fibrotic changes in the lung
are not yet visible on chest X-rays. In
other words, silicosis may be present
but not yet detectable by chest X-ray, or
it may be more severe than indicated by
the assigned profusion score (Craighead
and Vallyathan, 1980; Hnizdo et al.,
1993; Rosenman et al., 1997).
e. Pulmonary Tuberculosis
In addition to the relationship
between silica exposure and silicosis,
studies indicate a relationship between
silica exposure, silicosis, and
pulmonary TB. MSHA reviewed these
studies and concluded that silica
exposure and silicosis increase the risk
of pulmonary TB (Cowie, 1994; Hnizdo
and Murray, 1998; teWaterNaude et al.,
2006), concurring with the conclusion
reached by OSHA in its review.
Although early descriptions of dust
diseases of the lung did not distinguish
between TB and silicosis and most fatal
cases described in the first half of the
20th century were likely a combination
of silicosis and TB (Castranova et al.,
1996), more recent findings have
demonstrated that respirable crystalline
silica exposure, even without silicosis,
increases the risk of infectious (active)
pulmonary TB (Sherson and Lander,
1990; Cowie, 1994; Hnizdo and Murray,
1998; teWaterNaude et al., 2006). These
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co-morbid conditions hasten the
development of respiratory impairment
and increased mortality risk even
beyond the risk in unexposed persons
with active TB (Banks, 2005).
Ng and Chan (1991) hypothesized that
silicosis and TB ‘‘act synergistically’’
(are more than additive) to increase
fibrotic scar tissue (leading to massive
fibrosis) or to enhance susceptibility to
active mycobacterial infection. The
authors found that lung fibrosis is
common to both diseases, and that both
diseases decrease the ability of alveolar
macrophages to aid in the clearance of
dust or infectious particles.
These findings are also supported by
studies published since OSHA’s (2013b)
review (Oni and Ehrlich, 2015; Ndlovu
et al., 2019). Oni and Ehrlich (2015)
reviewed a case of silico-TB in a former
gold miner with ILO category 2/2
silicosis. Ndlovu et al. (2019) found that
in a study sample of South African gold
miners who had died from causes other
than silicosis between 2005 and 2015,
33 percent of men (n=254) and 43
percent of women (n=29) at autopsy
were found to have TB, whereas seven
percent of men (n=54) and three percent
of women (n=4) were found to have
pulmonary silicosis.
Overall, MSHA finds, consistent with
OSHA’s conclusion, that silica exposure
increases the risk of pulmonary TB, and
that pulmonary TB can be a
complication of chronic silicosis.
2. Nonmalignant Respiratory Disease
(Excluding Silicosis)
In addition to causing silicosis,
exposure to respirable crystalline silica
causes other NMRD. NMRD is an
umbrella term that includes chronic
obstructive pulmonary disease (COPD).
Emphysema and chronic bronchitis are
two lung diseases included within
COPD. In patients with COPD, either
chronic bronchitis or emphysema may
be present or both conditions may be
present together (ATS, 2010a).
Based on its review of the literature,
MSHA concludes that exposure to
respirable crystalline silica increases the
risk for mortality from NMRD. The
following summarizes MSHA’s review
of the literature.
a. Emphysema
Emphysema results in the destruction
of lung architecture in the alveolar
region, causing airway obstruction and
impaired gas exchange. Based on its
health effects literature review, MSHA
concludes that exposure to respirable
crystalline silica can increase the risk of
emphysema, regardless of whether
silicosis is present. In addition, MSHA
concludes that this is the case for
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smokers and that smoking amplifies the
effects of respirable crystalline silica
exposure, increasing the risk of
emphysema. MSHA’s conclusions are
consistent with those drawn by OSHA
(2013b). The reviewed studies are
summarized below.
Becklake et al. (1987) determined that
a miner who had worked in a high dust
environment for 20 years had a greater
chance of developing emphysema than
a miner who had never worked in a high
dust environment. In a retrospective
cohort study, Hnizdo et al. (1991a) used
autopsy lung specimens from 1,553 gold
miners to investigate the types of
emphysema caused by respirable
crystalline silica and found that the
occurrence of emphysema was related to
both smoking and dust exposure. This
study also found a significant
association between emphysema, both
panacinar and centriacinar emphysema
types, and length of employment for
miners working in high dust
occupations. A separate study by
Hnizdo et al. (1994) on lifelong nonsmoking South African gold miners
found that the degree of emphysema
was significantly associated with the
degree of hilar gland nodules, which the
authors suggested might serve as a
surrogate for respirable crystalline silica
exposure. While Hnizdo et al. (2000)
conversely found that emphysema
prevalence was decreased in relation to
dust exposure, the authors suggested
that selection bias was responsible for
this finding.
The findings of several cross-sectional
and case-control studies were more
mixed. For example, de Beer et al.
(1992) found an increased risk for
emphysema; however, the reported odds
ratio (OR) was smaller than that
previously reported by Becklake et al.
(1987). A study by Cowie et al. (1993)
found that the presence and grade of
emphysema were statistically significant
in Black underground gold miners.
Be´gin et al. (1995) found that respirable
crystalline silica-exposed smokers
without silicosis had a higher
prevalence of emphysema than a group
of asbestos-exposed workers with a
similar smoking history.
Several of the studies found that
emphysema might occur in respirable
crystalline silica-exposed workers who
did not have silicosis and suggested a
causal relationship between respirable
crystalline silica exposure and
emphysema (Becklake et al., 1987;
Hnizdo et al., 1994; Be´gin et al., 1995).
Experimental (animal) studies found
that emphysema occurred at lower
respirable crystalline silica exposure
concentrations than fibrosis in the
airways or the appearance of early
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silicotic nodules (Wright et al., 1988).
These findings tend to support human
studies that respirable crystalline silicainduced emphysema can occur absent
signs of silicosis.
OSHA (2013b) and others have
concluded that there is a relationship
between respirable crystalline silica
exposure and emphysema. Green and
Vallyathan (1996) reviewed several
studies of emphysema in workers
exposed to silica and found an
association between cumulative dust
exposure and death from emphysema.
The IARC (1997) also reviewed several
studies and concluded that exposure to
respirable crystalline silica increases the
risk of emphysema. Additionally,
NIOSH (2002b) concluded in its Hazard
Review that occupational exposure to
respirable crystalline silica is associated
with emphysema; however, it noted
some epidemiological studies that
suggested that this effect might be less
frequent or absent in non-smokers.
Overall, MSHA concludes that
exposure to respirable crystalline silica
causes emphysema even in the absence
of silicosis. Thus, MSHA concurs with
the conclusions previously reached by
OSHA (2013b).
b. Chronic Bronchitis
MSHA considered many studies that
examined the association between
respirable crystalline silica exposure
and chronic bronchitis and concluded
the following: (1) exposure to respirable
crystalline silica causes chronic
bronchitis regardless of whether
silicosis is present; (2) an exposureresponse relationship may exist; and (3)
smokers may be at an increased risk of
chronic bronchitis compared to nonsmokers. Chronic bronchitis is longterm inflammation of the bronchi,
increasing the risk of lung infections.
This condition develops slowly by small
increments and ‘‘exists’’ when it reaches
a certain stage, specifically the presence
of a productive cough with sputum
production for at least three months of
the year for at least two consecutive
years (ATS, 2010b). MSHA’s
conclusions are supported by OSHA’s
review of the literature.
Miller et al. (1997) reported a 20
percent increased risk of chronic
bronchitis in a British mining cohort
compared to the disease occurrence in
the general population. Using British
pneumoconiosis field research data,
Hurley et al. (2002) calculated estimates
of mixed-RCMD-related disease in
British coal miners at exposure levels
that were common in the late 1980s and
related their lung function and
development of chronic bronchitis with
their cumulative dust exposure. The
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authors estimated that by the age of 58,
5.8 percent of these men would report
breathlessness for every 100 gram-hour/
m3 dust exposure. The authors also
estimated the prevalence of chronic
bronchitis at age 58 would be four
percent per 100 gram-hour/m3 of dust
exposure. These miners averaged over
35 years of tenure in mining and a
cumulative respirable dust exposure of
132 gram-hour/m3 (Hurley et al., 2002).
Cowie and Mabena (1991) found that
chronic bronchitis was present in 742 of
1,197 (62 percent) South African gold
miners, and Ng et al. (1992b) found a
higher prevalence of respiratory
symptoms, independent of smoking and
age, in Singaporean granite quarry
workers exposed to high levels of dust
(rock drilling and crushing) compared to
those exposed to low levels of dust
(maintenance and transport workers).
However, Irwig and Rocks (1978)
compared symptoms of chronic
bronchitis in silicotic and non-silicotic
South African gold miners. They did not
find as clear a relationship as did the
above studies and concluded that the
symptoms were not statistically more
prevalent in the silicotic miners,
although prevalence was slightly higher.
Sluis-Cremer et al. (1967) found that
dust-exposed male smokers had a higher
prevalence of chronic bronchitis than
non-dust exposed smokers in a gold
mining town in South Africa. Similarly,
Wiles and Faure (1975) found that the
prevalence of chronic bronchitis rose
significantly with increasing dust
concentration and cumulative dust
exposure in South African gold miners
who were smokers, nonsmokers, and exsmokers. Rastogi et al. (1991) found that
female grinders of agate stones in India
had a significantly higher prevalence of
acute bronchitis, but they had no
increase in the prevalence of chronic
bronchitis compared to controls
matched by socioeconomic status, age,
and smoking. However, the study noted
that the grinders’ respirable crystalline
silica exposure durations were very
short, and control workers may also
have been exposed to respirable
crystalline silica (Rastogi et al., 1991).
Studies examining the effect of years
of mining on chronic bronchitis risk
were mixed. Samet et al. (1984) found
that prevalence of symptoms of chronic
bronchitis was not associated with years
of mining in a population of
underground uranium miners, even
after adjusting for smoking. However,
Holman et al. (1987) studied gold
miners in West Australia and found that
the prevalence of chronic bronchitis, as
indicated by ORs (controlled for age and
smoking), was significantly increased in
those who had worked in the mines for
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over one year, compared to lifetime nonminers. In addition, while other studies
found no effect of years of mining on
chronic bronchitis risk, those studies
often qualified this result with possible
confounding factors. For example,
Kreiss et al. (1989) studied 281 hardrock (molybdenum) miners and 108
non-miner residents of Leadville,
Colorado. They did not find an
association between the prevalence of
chronic bronchitis and work in the
mining industry (Kreiss et al., 1989);
however, it is important to note that the
mine had been temporarily closed for
five months when the study began, so
miners were not exposed at the time of
the study.
Some reviews concluded that
respirable crystalline silica exposure
causes the development of bronchitis.
The American Thoracic Society (ATS)
(1997) published a review that found
chronic bronchitis to be common among
worker groups exposed to dusty
environments contaminated with
respirable crystalline silica. NIOSH
(2002b) also published a review
demonstrating that occupational
exposure to respirable crystalline silica
has been associated with bronchitis;
however, some epidemiological studies
suggested this effect might be less
frequent or absent in non-smokers.
Additionally, Hnizdo et al. (1990) reanalyzed data from an earlier
investigation (Wiles and Faure, 1975)
and found an independent exposureresponse relationship between
respirable crystalline silica exposure
and impaired lung function. For miners
with less severe impairment, the effects
of smoking and dust together were
additive. The authors also found that for
miners with the most severe
impairment, the effects of smoking and
dust were synergistic (more than
additive) (Hnizdo et al., 1990).
Overall, MSHA concludes that
exposure to respirable crystalline silica
causes chronic bronchitis, regardless of
whether silicosis is present, and that an
exposure-response relationship may
exist. This conclusion is consistent with
the findings of OSHA’s Health Effects
document (2013b).
c. Pulmonary Function Impairment
Pulmonary function impairment is a
common feature of NMRD and may be
assessed via spirometry (lung volumes,
flows) and gas diffusion tests. MSHA
has reviewed the studies cited by OSHA
and agrees with their conclusions.
Based on its review of the evidence in
numerous longitudinal and crosssectional studies and reviews, OSHA
concluded that there is an exposureresponse relationship between
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respirable crystalline silica and the
development of impaired lung function.
OSHA also concluded that the effect of
tobacco smoking on this relationship
may be additive or synergistic, and
workers who were exposed to respirable
crystalline silica, but did not show signs
of silicosis, may also have pulmonary
function impairment.
OSHA reviewed several longitudinal
studies regarding the relationship
between respirable crystalline silica
exposure and pulmonary function
impairment. To evaluate whether
exposure to silica affects pulmonary
function in the absence of silicosis, the
studies focused on workers who did not
exhibit progressive silicosis.
Among both active and retired
Vermont granite workers exposed to an
average quartz dust exposure level of 60
mg/m3, researchers found no exposurerelated decreases in pulmonary function
(Graham et al., 1981, 1994). However,
Eisen et al. (1995) found significant
pulmonary decrements among a subset
of granite workers who left work
(termed ‘‘dropouts’’) and consequently
did not voluntarily participate in the
last of a series of annual pulmonary
function tests. This group experienced
steeper declines in lung function
compared to the subset of workers who
remained at work (termed ‘‘survivors’’)
and participated in all tests, and these
declines were significantly related to
dust exposure. Exposure-related
changes in lung function were also
reported in a 12-year study of granite
workers (Malmberg et al., 1993), in two
five-year studies of South African
miners (Hnizdo, 1992; Cowie, 1998),
and in a study of foundry workers
whose lung function was assessed
between 1978 and 1992 (Hertzberg et
al., 2002). Similar reductions in FEV1
(indicating an airway obstruction) were
linked to respirable crystalline silica
exposure.
Each of these studies reported its
findings in terms of rates of decline in
any of several pulmonary function
measures (e.g., FEV1, FVC, FEV1/FVC).
To put these declines in perspective,
Eisen et al. (1995) reported that the rate
of decline in FEV1 seen among the
‘‘dropout’’ subgroup of Vermont granite
workers was 4 ml per 1,000 mg/m3-year
(4 ml per mg/m3-year) of exposure to
respirable granite dust. By comparison,
FEV1 declines at a rate of 10 ml/year
from smoking one pack of cigarettes
daily. From their study of foundry
workers, Hertzberg et al. (2002) reported
a 1.1 ml/year decline in FEV1 and a 1.6
ml/year decline in FVC for each 1,000
mg/m3-year of respirable crystalline
silica exposure after controlling for
ethnicity and smoking. From these rates
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of decline, they estimated that exposure
to 100 mg/m3 of respirable crystalline
silica for 40 years would result in a total
loss of FEV1 and FVC that was less than,
but still comparable to, smoking a pack
of cigarettes daily for 40 years.
Hertzberg et al. (2002) also estimated
that exposure to the existing MSHA
standards (100 mg/m3) for 40 years
would increase the risk of developing
abnormal FEV1 or FVC by factors of 1.68
and 1.42, respectively.
OSHA reviewed cross-sectional
studies that described relationships
between lung function loss and
respirable crystalline silica exposure (or
exposure measurement surrogates such
as tenure). The results of these studies
were like those of the longitudinal
studies previously discussed. In several
studies, respirable crystalline silica
exposure was found to reduce lung
function of:
(1) White South African gold miners
(Hnizdo et al., 1990),
(2) Black South African gold miners
(Irwig and Rocks, 1978; Cowie and
Mabena, 1991),
(3) Respirable crystalline silicaexposed workers in Quebec (Be´gin et
al., 1995),
(4) Rock drilling and crushing
workers in Singapore (Ng et al., 1992b),
(5) Granite shed workers in Vermont
(Theriault et al., 1974a,b),
(6) Aggregate quarry workers and coal
miners in Spain (Montes et al., 2004a,b),
(7) Concrete workers in the
Netherlands (Meijers et al., 2001),
(8) Chinese refractory brick
manufacturing workers in an iron-steel
plant (Wang et al., 1997),
(9) Chinese gemstone workers (Ng et
al., 1987b),
(10) Hard-rock miners in Manitoba,
Canada (Manfreda et al., 1982) and in
Colorado (Kreiss et al., 1989),
(11) Pottery workers in France
(Neukirch et al., 1994),
(12) Potato sorters in the Netherlands
(Jorna et al., 1994),
(13) Slate workers in Norway (Suhr et
al., 2003), and
(14) Men in a Norwegian community
with years of occupational exposure to
respirable crystalline silica (quartz)
(Humerfelt et al., 1998).
OSHA (2013b) recognized that many
of these studies found that pulmonary
function impairment: (1) can occur in
respirable crystalline silica-exposed
workers without silicosis, (2) was still
observable when controlling for silicosis
in the analysis, and (3) was related to
the magnitude and duration of
respirable crystalline silica exposure,
rather than to the presence or severity
of silicosis. Many other studies
described by OSHA (2013b) have also
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found a relationship between respirable
crystalline silica exposure and lung
function impairment, including IARC
(1997), the ATS (1997), and Hnizdo and
Vallyathan (2003).
MSHA reviewed the studies and
concludes that there is an exposureresponse relationship between
respirable crystalline silica and the
impairment of lung function. MSHA
also concludes that that the effect of
tobacco smoking on this relationship
may be additive or synergistic, and that
workers who were exposed to respirable
crystalline silica, but did not show signs
of silicosis, may also have pulmonary
function impairment. MSHA’s
conclusions are consistent with OSHA’s
findings from its literature review.
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3. Lung Cancer
Commenters from United
Steelworkers (USW), American
Industrial Hygiene Association (AIHA),
and Vanderbilt Minerals, agreed with
MSHA’s conclusion that miners
exposed to respirable crystalline silica
have an increased risk of lung cancer
(Document ID 1447; 1351; 1419). The
AIHA also cited research by the
International Agency for Research on
Cancer (IARC) as documenting the
health risks from inhalation of
respirable crystalline silica, specifically
cancers of the lung, stomach, and
esophagus (Document ID 1351). MSHA
agrees with this comment for the
reasons discussed below.
a. Lung Cancer
Lung cancer, an irreversible and
usually fatal disease, is a type of cancer
that forms in lung tissue. MSHA has
found that the scientific literature
supports that respirable crystalline
silica exposure significantly increases
the risk of lung cancer mortality among
miners. This determination is consistent
with the conclusions of other
government and public health
organizations, including the ATS (1997),
the IARC (1997, 2012), the NTP (2000,
2016), NIOSH (2002b), and the ACGIH
(2010), which have classified respirable
crystalline silica as a ‘‘known human
carcinogen.’’ The Agency’s
determination also is supported by
epidemiological literature,
encompassing more than 85 studies of
occupational cohorts from more than a
dozen industrial sectors including:
granite/stone quarrying and processing
(Gue´nel et al., 1989a,b; Costello et al.,
1995; Carta et al., 2001; Attfield and
Costello, 2004), industrial sand
(Sanderson et al., 2000; Hughes et al.,
2001; McDonald et al., 2001, 2005;
Rando et al., 2001; Steenland and
Sanderson, 2001), MNM mining (Hessel
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et al., 1986, 1990; Hnizdo and SluisCremer, 1991; Meijers et al., 1991; Chen
et al., 1992, 2006, 2012; McLaughlin et
al., 1992; Hua et al., 1994; Roscoe et al.,
1995; Steenland and Brown, 1995a; Reid
and Sluis-Cremer, 1996; Hnizdo et al.,
1997; deKlerk and Musk, 1998;
Finkelstein, 1998; Chen and Chen, 2002;
Schubauer-Berigan et al., 2009; Liu et
al., 2017a; Wang et al., 2020a,b, 2021),
coal mining (Meijers et al., 1988;
Miyazaki and Une, 2001; Miller et al.,
2007; Miller and MacCalman, 2010;
Tomaskova et al., 2012, 2017, 2020,
2022; Graber et al., 2014a,b; Kurth et al.,
2020), pottery (Winter et al., 1990;
McLaughlin et al., 1992; McDonald et
al., 1995), ceramic industries
(Starzynski et al., 1996), diatomaceous
earth (Checkoway et al., 1993, 1996,
1997, 1999; Seixas et al., 1997; Rice et
al., 2001), and refractory brick
industries (cristobalite exposures) (Dong
et al., 1995).
One commenter stated that the work
of Steenland and Sanderson should not
be ‘‘discounted’’ and that Miller and
MacCalman ‘‘did not report on
occupational exposure monitoring
concentrations’’ reported by Steenland
and Sanderson (Document ID 1351).
MSHA chose Miller and MacCalman
(2010) rather than the Steenland et al.
(2001a) pooled cohort study for its lung
cancer mortality risk model but has not
discounted the study of Steenland and
Sanderson. MSHA has cited the
Steenland and Sanderson (2001) study
at multiple points in the final
standalone Health Effects document and
has also cited other investigations from
both researchers. The Miller and
MacCalman (2010) study contained
detailed time-exposure measurements of
both respirable crystalline silica (quartz)
and total mine dust, detailed individual
work histories, and individual smoking
histories. Further discussion regarding
the selection of the risk model of Miller
and MacCalman (2001) is located in the
standalone FRA document.
The strongest evidence comes from
the worldwide cohort and case-control
studies reporting excess lung cancer
mortality among workers exposed to
respirable crystalline silica in various
industrial sectors. This evidence is
confirmed by the ten-cohort pooled
case-control analysis by Steenland et al.
(2001a); the more recent pooled casecontrol analysis of seven European
countries by Cassidy et al. (2007); and
two national death certificate registry
studies, Calvert et al. (2003) in the
United States and Pukkala et al. (2005)
in Finland.
Recent studies examined lung cancer
mortality among coal and non-coal
miners (Meijers et al., 1988, 1991;
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Starzynski et al., 1996; Miyazaki and
Une, 2001; Attfield and Kuempel, 2008;
Tomaskova et al., 2012, 2017, 2020,
2022; Graber et al., 2014a,b; NIOSH,
2019a; Kurth et al., 2020). These studies
also discuss the associations between
RCMD and respirable crystalline silica
exposures with lung cancer in coal
mining populations. Furthermore, the
findings of these newer studies are
consistent with the conclusion of
OSHA’s final Quantitative Risk
Assessment (QRA) (2016a) that
respirable crystalline silica is a human
carcinogen. MSHA concludes that
miners, both MNM and coal miners, are
at risk of developing lung cancer due to
their occupational exposure to
respirable crystalline silica.
In addition, based on its review of the
health effects literature, MSHA has
determined that radiographic silicosis is
a marker for lung cancer risk. Reducing
exposure to levels that lower the
silicosis risk would reduce the lung
cancer risk to exposed miners
(Finkelstein, 1995, 2000; Brown, 2009).
MSHA has also found that, based on the
available epidemiological and animal
data, respirable crystalline silica causes
lung cancer (IARC, 2012; RTECS, 2016;
ATSDR, 2019). Miners who inhale
respirable crystalline silica over time are
at increased risk of developing silicosis
and lung cancer (Greaves, 2000; Erren et
al., 2009; Tomaskova et al., 2017, 2020,
2022).
Other toxicity studies (non-animal)
provide additional evidence of the
carcinogenic potential of respirable
crystalline silica. Studies using DNA
exposed directly to freshly fractured
respirable crystalline silica demonstrate
that respirable crystalline silica directly
increases DNA breakage. Cell culture
research has investigated the processes
by which respirable crystalline silica
disrupts normal gene expression and
replication. Studies have demonstrated
that chronic inflammatory and fibrotic
processes resulting in oxidative and
cellular damage may lead to neoplastic
changes in the lung (Goldsmith, 1997).
In addition, the biologically damaging
physical characteristics of respirable
crystalline silica and its direct and
indirect genotoxicity support MSHA’s
determination that respirable crystalline
silica is an occupational carcinogen
(Borm and Driscoll, 1996; Schins et al.,
2002).
b. Cancers of Other Sites
In addition to examining studies on
lung cancer, MSHA has reviewed
studies examining the relationship
between respirable crystalline silica
exposure and cancers at other sites.
MSHA has reviewed the studies
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examined by OSHA, together with
additional studies focusing on miners’
exposure, and has concluded (as OSHA
did) that there is insufficient evidence
to demonstrate a causal relationship
between respirable crystalline silica
exposure and other (non-lung) cancer
mortality. MSHA notes that OSHA
reviewed mortality studies, on cancer of
the larynx and the digestive system,
including the stomach and esophagus,
and found that studies suggesting a
dose-response relationship were too
limited in terms of size, study design, or
potential for confounding variables, to
be conclusive. In addition, NIOSH
(2002b) in their respirable crystalline
silica review concluded that no
association has been established
between respirable crystalline silica
exposure and excess mortality from
cancer at other sites. The following
summarizes the studies reviewed with
inconclusive findings.
(1) Laryngeal Cancer
MSHA reviewed three lung cancer
studies also discussed by OSHA (2013b)
which suggested an association between
respirable crystalline silica exposure
and increased mortality from laryngeal
cancer (Davis et al., 1983; Checkoway et
al., 1997; McDonald et al., 2001).
However, a small number of cases were
reported in those studies, and the
researchers were unable to determine a
statistically significant effect. Therefore,
MSHA found that there was little
evidence of an association based on
these studies. OSHA also reached this
conclusion.
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(2) Gastric (Stomach) Cancer
MSHA reviewed the literature
discussed by OSHA (2013b) to assess a
potential relationship between
respirable crystalline silica exposures
and stomach cancers. OSHA concurred
with observations made previously by
Cocco et al. (1996) and in the NIOSH
(2002b) respirable crystalline silica
hazard review, which found that most
epidemiological studies of respirable
crystalline silica and stomach cancer
did not sufficiently adjust for the effects
of confounding factors. In addition,
some of these studies were not properly
designed to assess a dose-response
relationship (Selikoff, 1978; Stern et al.,
2001; Moshammer and Neuberger, 2004;
Finkelstein and Verma, 2005) or did not
demonstrate a statistically significant
dose-response relationship (Tsuda et al.,
2001; Calvert et al., 2003). For these
reasons, MSHA determined these
studies were inconclusive in the context
of this rulemaking.
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(3) Esophageal Cancer
MSHA has reviewed studies that
focused on miners and concludes that
the literature does not support
attributing increased esophageal cancer
mortality with exposure to respirable
crystalline silica. The studies by Meijers
et al. (1991) and Swaen et al. (1995)
assessed mortality from esophageal
cancer in Dutch underground coal
miners. Meijers et al. (1991) reported an
elevated standardized mortality ratio
(SMR) of 396, which was not
statistically significant. The SMR was
based on two cases out of 334 confirmed
pneumoconiosis cases followed through
the end of 1983 (case selection based on
health screening between 1956–1960).
Swaen et al. (1995) reported a SMR of
62 (95 percent CI: 25–127) based on
seven cases out of 3,790 underground
coal miners who were diagnosed with
pneumoconiosis between 1956 and
1960. This result was not statistically
significant.
MSHA reviewed the studies presented
by OSHA (2013b) and agrees with
OSHA’s conclusion that the literature
does not support attributing increased
esophageal cancer mortality to exposure
to respirable crystalline silica. OSHA
considered several studies that
examined the relationship between
respirable crystalline silica exposures
and esophageal cancer and found that
the studies were limited in terms of size,
study design, or potential for
confounding variables. Three nested
case-control studies of Chinese workers
demonstrated a dose-response
association between increased risk of
esophageal cancer mortality and
respirable crystalline silica exposure
(Pan et al., 1999; Yu et al., 2005; Wernli
et al., 2006). Other studies also
indicated elevated rates of esophageal
cancer mortality with respirable
crystalline silica exposure (Xu et al.,
1996a; Tsuda et al., 2001). However,
OSHA (2013b) identified that in all
studies, confounding due to other
occupational exposures was possible.
Additionally, two large national
mortality studies in Finland and the
United States did not show a positive
association between respirable
crystalline silica exposure and
esophageal cancer mortality (Calvert et
al., 2003; Weiderpass et al., 2003).
(4) Other Sites
MSHA’s review of additional studies
specific to miners further establishes
that respirable crystalline silica
exposure increases the risk of lung
cancer, although there is insufficient
evidence to demonstrate a causal
relationship between respirable
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crystalline silica exposure and other
(non-lung) cancer mortalities.
Specifically, MSHA concludes that the
epidemiological literature is not
sufficient to conclude that there is an
association between respirable
crystalline silica exposures and
increased cancer of the larynx, gastric
cancer mortality, or esophageal cancer
mortality.
MSHA’s conclusion is consistent with
OSHA’s conclusion. Overall, OSHA
concluded that there was insufficient
evidence of an association between
silica exposure and cancer at sites other
than the lungs. OSHA included a health
literature review by NIOSH (2002b) that
examined effects potentially associated
with respirable crystalline silica
exposure; that review identified only
infrequent reports of statistically
significant excesses of deaths for other
cancers. Cancer studies have been
reported on the following organs/
systems: salivary gland, liver, bone,
pancreas, skin, lymphopoietic or
hematopoietic, brain, and bladder (see
NIOSH, 2002b for full bibliographic
references). However, the findings were
not observed consistently among
epidemiological studies, and NIOSH
(2002b) concluded that no association
has been established between these
cancers and respirable crystalline silica
exposure. OSHA concurred with NIOSH
that these isolated reports of excess
cancer mortality were insufficient to
determine the role of respirable
crystalline silica exposure.
MSHA has reviewed the studies cited
by OSHA and agrees with OSHA’s
conclusion. MSHA’s review of
additional studies specific to miners
further establishes that respirable
crystalline silica exposure increases the
risk of lung cancer, though there is
insufficient evidence to demonstrate a
causal relationship between respirable
crystalline silica exposure and other
(non-lung) cancer mortalities.
4. Renal Disease
MSHA received two comments
related to MSHA’s conclusions related
to renal disease. The AIHA agreed that
silica probably causes renal disease,
quoting a paper by Steenland (2005b)
(Document ID 1351). In contrast, the
NSSGA stated that it was unclear
whether renal disease is causally related
to occupational crystalline silica
exposure, citing a 2017 German Federal
Institute for Occupational Safety and
Health systematic review that
conducted a meta-analysis on respirable
crystalline silica and non-malignant
renal disease (Mo¨hner et al., 2017)
(Document ID 1448).
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MSHA acknowledges that some
studies have not found associations
between respirable crystalline silica
exposures and renal disease; however,
those studies are generally statistically
underpowered, meaning that their
sample sizes are too small to detect even
some substantial health effects. In
contrast, as discussed below, studies
with large cohort sizes and welldocumented, validated job-exposure
matrices found statistically significant
effects on renal disease. MSHA
reviewed the study by Mo¨hner et al.
(2017) and found that it was not suitable
for inclusion in the literature review.
The selection terms used by Mo¨hner et
al. (2017) appear to be overly limiting
and did not appear to capture many of
the studies that were included in
MSHA’s previous standalone Health
Effects document published with its
proposed silica rule (e.g., Gregorini et
al., 1993; Hotz et al., 1995; Fenwick and
Main, 2000; Rosenman et al., 2000;
Kurth et al., 2020). MSHA also notes
that several studies included in the
review by Mo¨hner et al. (2017) were
already cited in MSHA’s previous
standalone Health Effects document
published with its proposed silica rule
(e.g., Koskela et al., 1987; Brown et al.,
1997; Checkoway et al., 1997; Calvert et
al., 2003; Brown and Rushton, 2005b).
Renal disease is characterized by the
loss of kidney function and, in the case
of ESRD, a permanent loss of kidney
function leading to the need for a
regular course of long-term dialysis or a
kidney transplant to maintain life.
MSHA reviewed a wide variety of
longitudinal and mortality
epidemiological studies, including case
series, case-control, and cohort studies,
as well as case reports, and concludes
that there is substantial evidence in the
literature suggesting that occupational
exposures to respirable crystalline silica
exposure increases the risk of morbidity
and mortality related to ESRD. However,
MSHA notes that the available literature
on respirable crystalline silica
exposures and renal disease in coal
miners is less conclusive than the
literature related to MNM miners.
Epidemiological studies have found
statistically significant associations
between occupational exposure to
respirable crystalline silica and chronic
renal disease (e.g., Calvert et al., 1997),
sub-clinical renal changes, including
proteinuria and elevated serum
creatinine (e.g., Ng et al., 1992a; Hotz et
al., 1995; Rosenman et al., 2000), ESRD
morbidity (e.g., Steenland et al., 1990),
ESRD mortality (Steenland et al., 2001b,
2002a), and Wegener’s granulomatosis
(now known as granulomatosis with
polyangiitis, GPA), which is severe
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injury to the glomeruli that, if untreated,
rapidly leads to renal failure (Nuyts et
al., 1995). The pooled analysis
conducted by Steenland et al. (2002a) is
particularly convincing because it
involved a large number of workers
from three combined cohorts and had
well-documented, validated job
exposure matrices. Steenland et al.
(2002a) found a positive and monotonic
exposure-response trend for both
multiple-cause mortality and underlying
cause data. MSHA has determined that
the underlying data from Steenland et
al. (2002a) are sufficient to provide
useful estimates of risk.
Possible mechanisms suggested for
respirable crystalline silica-induced
renal disease include: (1) a direct toxic
effect on the kidney, (2) a deposition in
the kidney of immune complexes (e.g.,
Immunoglobulin A (IgA), an antibody
blood protein) in the kidney following
respirable crystalline silica-related
pulmonary inflammation, and (3) an
autoimmune mechanism (Gregorini et
al., 1993; Calvert et al., 1997). Steenland
et al. (2002a) demonstrated a positive
exposure-response relationship between
respirable crystalline silica exposure
and ESRD mortality.
Overall, MSHA determines that
respirable crystalline silica exposure in
mining increases the risk of renal
disease.
5. Autoimmune Disease
Two commenters—AIHA and
National Coalition of Black Lung and
Respiratory Disease Clinics (hereafter
referred to as ‘‘Black Lung Clinics’’)—
agreed with MSHA’s finding that there
is evidence of a relationship between
respirable crystalline silica exposure
and autoimmune diseases (Document ID
1351; 1410). The Black Lung Clinics
also qualified that there is insufficient
data to model the risk of disease
(Document ID 1410). This is consistent
with MSHA’s conclusion that there is a
casual association between occupational
exposure to respirable crystalline silica
and the development of systematic
autoimmune diseases in miners;
however, there are no studies available
to date that can be used to model
respirable crystalline silica-exposure
risk of autoimmune diseases in the
Agency’s risk analysis.
Autoimmune diseases occur when the
immune system mistakenly attacks
healthy tissues within the body, causing
inflammation, swelling, pain, and tissue
damage. Examples of autoimmune
diseases include autoimmune rheumatic
diseases, sarcoidosis and seropositive
rheumatoid arthritis (RA), Crohn’s
disease (CD), ulcerative colitis (UC),
systemic lupus erythematosus (SLE),
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scleroderma, and systemic sclerosis
(SSc). Some studies reviewed by MSHA
suggest a casual association between
occupational exposure to respirable
crystalline silica and the development
of systematic autoimmune diseases,
particularly RA.
Wallden et al. (2020) found that
respirable crystalline silica exposure is
correlated with an increased risk of
developing UC, and that the risk
increases with duration of exposure
(work tenure) and the level of exposure.
This effect was especially significant in
men. Schmajuk et al. (2019) found that
RA was significantly associated with
coal mining and other non-coal
occupations exposed to respirable
crystalline silica. Vihlborg et al. (2017)
found a significant increased risk of
seropositive RA with high exposure
(>48 mg/m3) to respirable crystalline
silica when compared to rates for
individuals with lower or no exposure.
They examined detailed exposureresponse relationships across four
different groups, each of which was
exposed to a different concentration of
respirable crystalline silica (quartiles):
<23 mg/m3, 24 to 35 mg/m3, 36 to 47 mg/
m3, and >48 mg/m3. However, these
researchers did not report the risk of
sarcoidosis (a condition in which
groups of cells in the immune system
form granulomas in various organ
systems) and seropositive RA in relation
to respirable crystalline silica exposure
using models that could be used in
MSHA’s risk analysis. In addition, the
meta-analysis of 19 published casecontrol and cohort studies on
scleroderma by Rubio-Rivas et al. (2017)
found statistically significant risks
among individuals exposed to respirable
crystalline silica, solvents, silicone,
breast implants, epoxy resins,
pesticides, and welding fumes, but did
not provide detailed quantitative
exposure information that could be used
in the risk analysis.
Based on its literature review, MSHA
concludes that there is a causal
association between occupational
exposure to respirable crystalline silica
and the development of systemic
autoimmune diseases in miners, but that
no studies are available to date that can
be used to model respirable crystalline
silica-exposure risk in a risk analysis.
D. Conclusion
MSHA concludes that exposure to
respirable crystalline silica causes
silicosis (acute, accelerated, chronic,
and PMF), NMRD (including COPD),
lung cancer, and renal disease. Each of
these effects is exposure-dependent,
potentially chronic, irreversible,
potentially disabling, and can be fatal.
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Respirable crystalline silica exposure is
also linked to the development of some
autoimmune disorders through
inflammatory pathways.
The health effects literature, including
peer-reviewed medical, toxicological,
public health, and other related
disciplinary publications, is robust and
compelling. It shows that miners
exposed to the existing respirable
crystalline silica exposure limits of 100
mg/m3 still have an unacceptable
amount of excess risk, for developing
and dying from diseases related to their
occupational respirable crystalline silica
exposures.
MSHA is entrusted with ensuring that
‘‘no miner will suffer material
impairment of health or functional
capacity even if such miner has regular
exposure to the hazards dealt with by
such standard for the period of his
working life’’ (30 U.S.C. 811(a)(6)(A)).
The Agency believes that when the final
rule is implemented and enforced
effectively, it will reduce the rate of
silicosis and other diseases caused by
respirable crystalline silica exposure
and will substantially improve miners’
lives.
VI. Final Risk Analysis Summary
MSHA’s FRA quantifies risks
associated with five specific health
outcomes identified in the standalone
Health Effects document: silicosis
morbidity and mortality, and mortality
from NMRD, lung cancer, and ESRD.
This section serves as a summary of the
standalone FRA document, which is
placed into the rulemaking docket for
the MSHA respirable crystalline silica
rulemaking (RIN 1219–AB36, Docket
No. MSHA–2023–0001) and is available
at Regulations.gov.
MSHA developed an FRA to support
its risk determinations and to quantify
the health risk to miners exposed to
respirable crystalline silica under the
existing exposure limits for MNM and
coal miners, at the new PEL of 50 mg/
m3, and at the action level of 25 mg/m3.
This analysis addresses three
questions related to the final rule:
(1) whether potential health effects
associated with existing exposure
conditions constitute material
impairment to any miner’s health or
functional capacity;
(2) whether existing exposure
conditions place miners at risk of
incurring any material impairment if
regularly exposed for the period of their
working life; and
(3) whether the final rule will reduce
those risks.
To answer these questions, MSHA
relied on the large body of research on
the health effects of respirable
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crystalline silica and published, peerreviewed, quantitative risk assessments
that describe the risk of exposed
workers to silicosis mortality and
morbidity, NMRD mortality, lung cancer
mortality, and ESRD mortality. These
quantitative risk assessments are based
on several studies of occupational
cohorts in a variety of industrial sectors.
The underlying studies are described in
the standalone Health Effects document
and are summarized in Section V.
Health Effects Summary.
Based on its analysis, MSHA found
that, once the current mining workforce
is replaced with new entrants to the
mining industry so that all working
miners and retired miners have been
exposed only under the new PEL, the
final rule will decrease lifetime excess
deaths by at least 1,067 and will
decrease lifetime excess cases of nonfatal silicosis by at least 3,746 among
the working and future retired miner
population. In the FRA, MSHA also
increases its estimate of the number of
miners who will benefit from this rule
to include future retired miners. While
the Preliminary Risk Analysis (PRA) did
consider reductions in excess risk
during years of retirement, the PRA did
not account for the fact that future
retired miners are among the population
that will benefit from the rule. Once the
entire mining workforce, including
future retired miners, has worked only
under the new PEL (i.e., 60 years after
the start of implementation of the rule),
both the retired and working miners
will experience fewer deaths and
illnesses. The FRA updates benefit
estimates to account for all lifetime
excess cases that will be avoided among
all working miners and future retired
miners. It is important to note that the
FRA (as well as the FRIA, discussed
below in Section IX) only monetizes
benefits to future retired miners. The
FRA methodology does not attribute any
health benefits to individuals who
retired before the start of
implementation of the final rule.
This summary highlights the main
findings from the FRA, briefly describes
how they were derived, and directs
readers interested in more detailed
information to corresponding sections of
the standalone FRA document.
A. Summary of MSHA’s Final Risk
Analysis Process and Methods
MSHA evaluated the literature and
selected an exposure-response model for
each of the five health endpoints—
silicosis morbidity, silicosis mortality,
NMRD mortality, lung cancer mortality,
and ESRD mortality. The selected
exposure-response models were used to
estimate lifetime excess risks and
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lifetime excess cases among the current
population of working and the future
population of retired MNM and coal
miners based on real exposure
conditions, as indicated by the samples
in the compliance sampling datasets.
MSHA’s FRA is largely based on the
methodology and findings from OSHA’s
2013 preliminary quantitative risk
assessment (PQRA), OSHA’s 2016 final
quantitative risk assessment (QRA), and
the associated analysis of health effects
in connection with OSHA’s
promulgation of a rule setting PELs for
workplace exposure to respirable
crystalline silica. OSHA’s PQRA
presented quantitative relationships
between respirable crystalline silica
exposure and multiple health
endpoints. Following multiple legal
challenges, the U.S. Court of Appeals for
the D.C. Circuit rejected challenges to
OSHA’s risk assessment methodology
and its findings on different health
risks. N. Am.’s Bldg. Trades Unions v.
OSHA, 878 F.3d 271, 283–89 (D.C. Cir.
2017).
MSHA’s FRA presents detailed
quantitative analyses of health risks
over a range of exposure concentrations
that have been observed in MNM and
coal mines. MSHA applied exposureresponse models to estimate the
respirable crystalline silica-related risk
of material impairment of health or
functional capacity of miners exposed to
respirable crystalline silica at three
levels—(1) the existing standards, (2)
the new PEL, and (3) the action level. As
in past MSHA rulemakings, MSHA
estimated and compared lifetime excess
risks associated with exposures at the
existing and new PEL (and at the action
level) over a miner’s full working life of
45 years and 15 years of retirement.
MSHA’s FRA is also based on a
compilation of miner exposure data to
respirable crystalline silica. For the
MNM sector, MSHA evaluated 57,769
valid respirable dust samples collected
between January 2005 and December
2019; and for the coal sector, MSHA
evaluated 63,127 valid respirable dust
samples collected between August 2016
and July 2021. The compiled data set
characterizes miners’ exposures to
respirable crystalline silica in various
locations (i.e., underground, surface),
occupations (e.g., drillers, underground
miners, equipment operators), and
commodities (e.g., metal, nonmetal,
stone, crushed limestone, sand and
gravel, and coal). MSHA enforcement
sampling indicates a wide range of
exposure concentrations. These include
exposures from below the action level
(25 mg/m3) to above the existing
standards (100 mg/m3 in MNM standards
and 100 mg/m3 MRE in coal standards,
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which is approximately 85.7 mg/m3
ISO).18 19
18 As discussed in the FRA, the existing
PEL for coal is 100 mg/m3 MRE, measured as
a full-shift time-weighted average (TWA). To
calculate risks consistently for both coal and
MNM miners, the FRA converts the MRE
full-shift TWA concentrations experienced
by coal miners to ISO 8-hour TWA
concentrations. (See Section 4 of the
standalone FRA document for a full
explanation.) The equation used to convert
MRE full-shift TWA concentrations into ISO
8-hour TWA concentrations is:
(original sampling time)
ISO 8-hour TWA concentration = ( MRE TWA) x
( 80 .
)
x 0.857
4 mmutes
Exposures at TWA 100 mg/m3 MRE and
SWA 85.7 mg/m3 ISO are only equivalent
when the sampling duration is 480 minutes
(eight hours). However, for the sake of
simplicity and for comparison purposes, the
risk analysis approximates exposures at the
existing coal exposure limit of 100 MRE mg/
m3 as 85.7 mg/m3 ISO. Thus, ISO
concentration values (measured as an 8-hour
TWA) were used as the exposure metric
when (a) calculating risk under the
assumption of full compliance with the
existing standards and (b) calculating risk
under the assumption that no exposure
exceeds the new PEL of 50 mg/m3. To
simulate compliance among coal miners at
the existing exposure limit, exposures were
capped at 85.7 mg/m3 measured as an ISO 8hour TWA.
19 A sample-specific exposure limit is
calculated for each sample based on the
polymorphs present. For samples with >1%
quartz by mass, the formula is:
One commenter (a safety compliance
consultant) stated that the 20 2005–2019
MNM respirable dust samples analyzed
for respirable crystalline silica show a
downward trend in average annual rates
of overexposure and requested access to
data for 2020–2022 (Document ID 1383).
In response, MSHA notes that the 2020–
2022 data may be skewed by the
reduction in mining during the COVID–
19 pandemic and would therefore bias
the analysis. Further, 2019 is recent
enough to adequately capture the
current exposure profile of working
miners.
In addition, commenters from the
United Mine Workers of America
(UMWA), the Black Lung Clinics, and
the Appalachian Citizens’ Law Center
(ACLC) expressed concern that MSHA
used coal mine dust data from 2016–
2021, a historically low period for
quartz levels in coal mining, according
to the commenters (Document ID 1398;
1410; 1445). The ACLC asserted that, as
a result, the estimate of avoided
illnesses and deaths in MSHA’s PRA is
low and urged the Agency to include a
longer history of coal dust sampling
data when estimating miners’ future
exposures (Document ID 1445). As
discussed below, MSHA chose this time
period to account for the 2014 RCMD
20
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Standard, which came into full effect in
2016. The ACLC also stated that,
because the 2014 RCMD Standard does
not directly regulate respirable
crystalline silica, there is no
justification for excluding prior
sampling data (Document ID 1445).
MSHA believes the 2014 RCMD
Standard impacted respirable crystalline
silica exposures, in part because (a) the
coal dust exposure limit is based on a
formula that reduces the limit when the
respirable crystalline silica content
exceeds 100 mg/m3, and (b) measures
that coal mine operators may have taken
to reduce exposures to coal dust under
that rule would have also reduced
exposures to other respirable hazards
including crystalline silica. Using more
recent coal exposure data from 2016–
2021 thus avoids possibly attributing
benefits from the 2014 RCMD Standard
to this rule. However, MSHA agrees that
if respirable crystalline silica
concentrations were to rise in the
future—while remaining within the
limits of the 2014 RCMD Standard and
complying with all existing
regulations—there would be additional
unquantified benefits from the final
rule.21 For example, some researchers
have attributed the increase in
pneumoconiosis prevalence among
miners since the 1990s to respirable
crystalline silica (Cohen et al., 2022;
Hall et al., 2020b). Cohen et al. (2022)
states that respirable crystalline silica
21 In the analyzed coal compliance data from 2016
through 2021, only 6 percent of samples are above
the new PEL of 50 mg/m3. Currently regulation
provides protections to keep samples below 85.7
mg/m3, but it is insufficient to prevent increases in
the proportion of concentrations in the range of 50
to 85.7 mg/m3. The possibility of such an increase
further necessitates this rule.
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has become more concentrated due to
improvements in mining equipment and
processing technology, which allow
‘‘recovery of thin coal seams, which
involves the extraction of large
quantities of surrounding rock strata
that can contain crystalline silica.’’ The
possibility that respirable crystalline
silica exposure could increase in the
future in the absence of this rule
underscores the rule’s importance.
The primary results of the FRA are the
calculated number of deaths and
illnesses avoided assuming full
compliance after implementation of
MSHA’s final rule. These calculations
were performed for non-fatal silicosis
illnesses (morbidity) and for deaths
(mortality) due to silicosis, lung cancer,
NMRD, and ESRD. For each health
outcome, the reduced number of
illnesses or deaths is calculated as the
difference between (a) the number of
excess illnesses and deaths currently
occurring in the industry, assuming
mines fully comply with the previous
standards (100 mg/m3 for MNM and 85.7
mg/m3 ISO for coal) and (b) the number
of excess deaths and illnesses expected
to occur following implementation of
the final rule, which includes a new
PEL of 50 mg/m3 for a full-shift
exposure, calculated as an 8-hour TWA.
Excess risks and cases were estimated
under two scenarios: (a) a Baseline
scenario where all exposures were
capped at 100 mg/m3 for MNM miners
and at 85.7 mg/m3 for coal miners, and
(b) a new PEL 50 mg/m3 scenario where
all risks were capped at the new PEL of
50 mg/m3 for both MNM and coal
miners. The difference between the two
scenarios yields the estimated reduction
in lifetime excess risks and in lifetime
excess cases due to the new PEL.
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When quartz is the only respirable
crystalline silica polymorph in the sample,
the existing MNM standard limits respirable
crystalline silica exposures to 100 mg/m3 or
less in MNM operations. Cristobalite
exposures are currently limited to 50 mg/m3
or less when cristobalite is the only
polymorph present, and the same is true for
tridymite 19. When more than one polymorph
is present in the same sample, then a
Threshold Limit Value for mixtures is used.
ER18AP24.078
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Sample respirable dust exposure limit = - - - - - - - - - (% respirable quartz + 2 )
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To calculate excess risks, MSHA
grouped MNM miners into the following
exposure intervals: ≤25, >25 to ≤50, >50
to ≤100, >100 to ≤250, >250 to ≤500, and
>500 mg/m3. MSHA grouped coal miners
into the following exposure intervals:
≤25, >25 to ≤50, >50 to ≤85.7, >85.7 to
≤100, >100 to ≤250, >250 to ≤500, and
>500 mg/m3. MSHA calculated the
median of all exposure samples in each
exposure interval and assumed the
population of miners is distributed
across the exposure intervals in
proportion to the number of exposure
samples from the compliance dataset in
each interval. Then, miners were
assumed to encounter constant exposure
at the median value of their assigned
exposure interval. MSHA adjusted the
annual cumulative exposure by a fulltime equivalency (FTE) factor to account
for the fact that miners may experience
more or less than 2,000 hours of
exposure per year. MSHA calculated the
FTE adjustment factor as the weighted
average of the miner (excluding contract
miner) FTE ratio (0.99 for MNM and
1.14 for coal) and the contract miner
FTE ratio (0.59 for MNM and 0.64 for
coal), where the weights are the number
of miners [150,928 for MNM miners
(excluding contract miners), 60,275 for
MNM contract miners, 51,573 for coal
miners (excluding contract miners), and
22,003 for coal contract miners]. For
example, the weighted average FTE ratio
for MNM is (0.987 × 150,928 + 0.591 ×
60,275)/(150,928 + 60,275) = 0.87 and is
(1.139 × 51,573 + 0.636 × 22,003)/(51,
573 + 22,003) = 0.99 for coal.
MSHA uses weighted average FTE
ratios to account for the fact that
contract miners may experience lower
exposures per year from mining.
However, this underestimates the
cumulative exposures that miners
(excluding contract miners) experience.
The average coal miner (excluding
contract miners), for example, works
approximately 2,280 hours per year,
which equates to an average shift of over
9.1 hours when assuming 250 working
days per year.22 Additionally, the
studies the FRA relied on to model
excess risks define a full working year
as 1,740 hours, in instances where such
a definition is given (Buchanan et al.,
2003; Miller and MacCalman, 2010).
Based on these studies’ definition of a
22 The fact that miners work over 8-hour shifts is
also supported by MSHA’s compliance data, which
show an average shift duration of approximately 9.2
hours for MNM (MSHA, 2022a) and 9.6 hours for
coal (MSHA, 2022b). These values differ from the
average hours per day implied by the FTE ratios
because the compliance data is only a sample of full
shifts, whereas the FTE data is based on
comprehensive reporting of all full-time and parttime shifts.
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year, MNM miners (excluding contract
miners) have an FTE ratio of 1.13 and
coal miners (excluding contract miners)
have an FTE ratio of 1.31. Additionally,
the contract miner FTE ratios likely
have some negative bias since any
individual who works for multiple
contracting companies is counted
multiple times in the data, inflating the
denominator in the FTE ratio
calculation. MSHA also notes that the
contract miner FTE ratios may
underrepresent the true overall
cumulative exposures since contract
miners may have other jobs involving
exposure to respirable crystalline silica
(e.g., in construction or the oil and gas
industry).
MSHA calculated excess risk, which
refers to the additional risk of disease
and death attributable to exposure to
respirable crystalline silica. For silicosis
morbidity, MSHA used an exposureresponse model that directly yields the
accumulated or lifetime excess risk of
silicosis morbidity, assuming there is no
background rate 23 of silicosis in an
unexposed (i.e., non-miner) group. For
the four mortality endpoints (silicosis
mortality, lung cancer mortality, NMRD
mortality, and ESRD mortality), MSHA
used cohort life tables to calculate
excess risks, assuming all miners enter
the workforce at the start of age 21,
retire at the end of age 65, and do not
live past the end of age 80. From the life
tables, MSHA acquired the lifetime
excess risk of mortality by summing the
miner cohort’s excess mortality risks in
each year from age 21 through age 80.
Life tables were also constructed for
unexposed (i.e., non-miner) groups
assumed to die from a given disease at
typical rates for the U.S. male
population. MSHA used 2018 data for
all males in the U.S. (published by the
National Center for Health Statistics,
2020b) to estimate (a) the diseasespecific mortality rates among
unexposed males and (b) the all-cause
mortality rates among both groups
(exposed miners and unexposed nonminers).
For a given scenario (either Baseline
or New PEL 50 mg/m3), MSHA
constructed life tables in the manner
described above, both for a miner cohort
exposed to respirable crystalline silica
and for an unexposed non-miner cohort.
MSHA calculated excess risk of disease
as the difference between the two
23 Here, the ‘‘background’’ risk (or rate) refers to
the risk of disease that the exposed person would
have experienced in the absence of exposure to
respirable crystalline silica. These background
morbidity and mortality rates are measured using
the disease-specific rates among the general
population, which is not exposed to respirable
crystalline silica.
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28247
cohorts’ disease-specific mortality risk
(due to silicosis, lung cancer, NMRD, or
ESRD). MSHA determined the lifetime
excess cases by multiplying the lifetime
excess risk by the number of exposed
miner FTEs (including contract miner
FTEs). Risks and cases were calculated
separately for each exposure interval
listed above. Then, the lifetime excess
cases were aggregated across all
exposure intervals. MSHA calculated
the final lifetime excess risks per 1,000
miners in the full population of working
and future retired miners by dividing
the total number of lifetime excess cases
by the total number of miners in the
population (exposed at any interval).
Finally, to estimate the risk reductions
and avoided cases of illness due to the
new PEL, MSHA compared the lifetime
excess risks and lifetime excess cases
across the two scenarios (Baseline and
New PEL 50 mg/m3).
In the PRA, MSHA underestimated
the number of miners who will benefit
from the proposed rule. Based on the
2019 Quarterly Employment Production
Industry Profile (MSHA, 2019a) and the
2019 Quarterly Contractor Employment
Production Report (MSHA, 2019b), the
current number of working miner FTEs
is estimated to be 184,615 for MNM and
72,768 for coal. In the PRA, MSHA
assumed excess cases of disease would
be reduced only among these working
miners. However, once the current
mining workforce is replaced with new
entrants to the mining industry so that
the entire workforce has worked only
under the new PEL for their 45 years of
working life, the future mining
workforce will experience fewer excess
deaths and illnesses from exposure to
respirable crystalline silica. The PRA’s
methodology did not include the
number of future retired miners who
will experience lower exposure for their
working lives under the final rule and
will continue to benefit during
retirement, and therefore, the PRA
underestimated the number of avoided
lifetime excess cases attributable to the
rule. In the FRA, the estimates are
updated to account for all excess cases
that will be avoided among not only
working miners but also future retired
miners. As discussed in greater detail in
the FRA, the number of future retired
miners who are expected to benefit from
the rule can be calculated from the
survival rates (which are computed in
the life tables) and from the assumption
that the mining workforces in MNM and
coal will remain the same size as they
are today.
On the related question raised by the
ACLC about whether new clinical data
suggests that the PRA underestimated
benefits of the lower PEL, MSHA
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determines that the approach in the
PRA is the appropriate one (Document
ID 1445). The risk models that MSHA
uses are exposure-response models,
originally selected through OSHA’s peer
review process and silica rulemaking,
based on past clinical data on patients
whose exposure history was known.
Newer data from Black Lung Clinics can
provide suggestive evidence of the risks,
but because it is not yet incorporated
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into these peer-reviewed risk models, it
cannot be included in this analysis as
this commenter recommends.
B. Overview of Epidemiologic Studies
MSHA reviewed extensive research
on the health effects of respirable
crystalline silica and quantitative risk
assessments published in the peerreviewed scientific literature regarding
occupational exposure risks of illness
and death from silicosis, NMRD, lung
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cancer, and ESRD. The standalone
Health Effects document describes the
specific studies reviewed by MSHA. Of
the many studies evaluated, MSHA
believes that the 13 studies used by
OSHA (2013b) to estimate risks provide
reliable estimates of the disease risk
posed by miners’ exposure to respirable
crystalline silica. These studies are
summarized in Table VI–1.
BILLING CODE 4520–43–P
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Table VI-1: Epidemiologic Studies of Miner Exposures to Respirable Crystalline Silica
Reviewed in MSHA's FRA
Study
1. Attfield and
Costello (2004)
2. Buchanan et
al. (2003)
Vermont granite
workers
Scottish coal
miners
3. Chen et al.
(2001)
Chinese tin
mmers
4. Chen et al.
(2005)
Chinese tin,
tungsten miners
and pottery
workers
White South
African gold
miners
North American
industrial sand
workers
Cumulative dust
exposure,
job/exposure
matrix
Job/exposure
matrix, tenure
7. Mannetje et al.
(2002b),
ToxaChemica
International Inc.
(2004)
6 cohorts from
U.S., Finnish,
and Australian
mmers
Cumulative dust
exposure, job/
exposure matrices
8. Miller and
MacCalman
(2010)
9. Park et al.
(2002)
British coal
miners
Tenure,
cumulative dust
exposure
Cumulative dust
exposure;
cristobalite
Cumulative dust
exposure;
cristobalite
5. Hnizdo and
Sluis-Cremer
(1993)
6. Hughes et al.
(2001)
10. Rice et al.
(2001)
11. Steenland
and Brown
(1995b)
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Exposure
Measure
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California
diatomaceous
earth workers
California
diatomaceous
earth workers
South Dakota
gold miners
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Job/exposure
matrix
Cumulative dust
and respirable
crystalline silica
exposure
Cumulative dust
exposure,
job/exposure
matrix
Health Risks Modeled
Mortality
Lung
ESRD
RPP 1 Silicosis NMRD
Cancer
Morbidity
Silicosis
X
X
X
X
X
X
Cumulative dust
exposure,
job/exposure
matrix
Median respirable
crystalline silica
exposure,
job/exposure
matrix
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X
X
X
X
X
X
X
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Table VI-1: Epidemiologic Studies of Miner Exposures to Respirable Crystalline Silica
Reviewed in MSHA's FRA
Population
Studied
Study
12. Steenland et
al. (2001a),
ToxaChemica,
International Inc.
(2004)
13. Steenland et
al. (2002a)
10 cohorts: U.S.
Diatomaceous
earth workers,
Finnish and U.S.
granite, U.S.
industrial sand,
Chinese pottery,
tin, and tungsten
miners, South
African, U.S.,
and Australian
gold miners
3 cohorts: U.S.
gold miners,
industrial sand
workers, and
granite workers
Exposure
Measure
Health Risks Modeled
Morbidity
Mortality
Lung
ESRD
Silicosis RPP 1 Silicosis NMRD
Cancer
Cumulative dust
exposure
X
Cumulative dust
exposure,
job/exposure
matrix
X
1.
MSHA used the Buchanan et al study to assess exposure rate effects on the risks of accelerated silicosis
(more common in MNM miners) and rapidly progressive pneumoconiosis (RPP, primarily seen in coal miners, but
also reported in silica flour packers). Miners exposed to respirable crystalline silica at variable intensities (i.e., high
concentrations and low concentrations) may develop rapid progression of disease, referred to as RPP. It is defmed
as the development of progressive massive fibrosis and/or an increase in small opacity profusion greater than one
subcategory over a 5-year period (Antao et al., 2005).
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Of these 13 studies, OSHA selected
one per health endpoint for final
modeling and estimation of lifetime
excess risk and cases. Combining the
five selected studies with the observed
exposure data yields estimates of actual
lifetime excess risks and lifetime excess
cases among working and future retired
miner populations based on real
exposure conditions. Table VI–2
summarizes key characteristics of the
models presented in the 13 studies from
OSHA’s PQRA, including the cohort
that was investigated, the specific health
endpoint (e.g., chest X-ray of category 2/
1+), whether a lag between exposure
and excess risk was included, and key
model parameters. MSHA evaluated the
evidence of OSHA’s analysis of the 13
studies and the accompanying risks
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associated with exposure at 25, 50, 100,
250, and 500 mg/m3. Thorough
evaluation has led MSHA to determine
that the studies OSHA selected still
provide the best available
epidemiological models (with the
exception of lung cancer mortality).
However, MSHA utilized the Miller and
MacCalman (2010) study to estimate
risks for lung cancer mortality. This
study was included in OSHA’s health
effects assessment and PQRA but was
published after OSHA completed much
of its modeling for the PQRA. The
following lists the studies used by
MSHA for each health endpoint:
Silicosis morbidity: Buchanan et al.
(2003);
Silicosis mortality: Mannetje et al.
(2002b);
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NMRD mortality: Park et al. (2002);
Lung cancer mortality: Miller and
MacCalman (2010); and
ESRD mortality: Steenland et al.
(2002a).
As explained in detail in the
standalone FRA document, MSHA
developed its risk estimates based on
recent mortality data and certain
assumptions that differed from those
used by OSHA. Examples of these
MSHA assumptions include a lifetime
that ends at age 80, updated background
mortality data and all-cause mortality,
miner population sizes, and minerspecific full-time equivalents (FTEs).24
24 FTEs were used to adjust the cumulative
exposure over a year based on the average number
of hours that miners work.
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MSHA’s modeling has been done
using life tables, in a manner consistent
with OSHA’s PQRA. In general, the life
table is a technique that allows
estimation of excess risk of diseasespecific mortality while factoring in the
probability of surviving to a particular
age, assuming no exposure to respirable
crystalline silica. This analysis accounts
for competing causes of death,
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background mortality rates of disease,
and the effect of the accumulation of
risk due to elevated mortality rates in
each year of a working life. For each
cause of mortality, the selected study
was used in the life table analysis to
compute the increase in miners’ diseasespecific mortality rates attributable to
respirable crystalline silica exposure.
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MSHA uses cumulative exposure (i.e.,
cumulative dose) to characterize the
total exposure over a 45-year working
life. Cumulative exposure is defined as
the product of exposure duration and
exposure intensity (i.e., exposure level).
Cumulative exposure is the predictor
variable in the selected exposureresponse models.
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Table VI-2: Summary of Exposure Response Models in Studies Considered in MSHA's
FRA, Based on OSHA's 13 QRA Models
Study
Cohort
Exposure
Lag
(years)'
Model Parameter
(Standard Error (SE))
Silicosis Morbidity
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British coal
miners
U.S. gold
miners
No lag
Chest X-ray
category of 1/1
or greater
(Hnizdo and
Sluis-Cremer,
1993)
Chest X-ray
category of 1
or greater
(Chen et al.,
2001)
Chest X-ray
category of 1
or greater
(Chen et al.,
2005)
South African
gold miners
No lag
Chinese tin
miners
No lag
CR= 1-exp(-0.0076*E)223 where
E is cumulative exposure to total
dust. 5
Chinese tin
miners
No lag
Chest X-ray
category of l
or greater
(Chen et al.,
2005)
Chinese
tungsten
miners
No lag
Chest X-ray
category of 1
or greater
(Chen et al.,
2005)
Chinese
pottery
workers
No lag
Estimated from Figure 2B in
Chen et al. (2005) showing
cumulative risk vs. cumulative
exposure to respirable crystalline
silica. Average age at onset was
47.9 years for tin miners.
Estimated from Figure 2B in
Chen et al. (2005) showing
cumulative risk vs. cumulative
exposure to respirable crystalline
silica. Average age at onset was
41. 8 years for tungsten miners.
Estimated from Figure 2B in
Chen et al. (2005) showing
cumulative risk vs. cumulative
exposure to respirable crystalline
silica. Average age at onset was
52.5 years for pottery workers.
Mannetje et
al., 2002b;
ToxaChemica
International,
Inc., 2004
Pooled
analysis for
silicosis
No lag
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No lag
mg/cubicm), 2
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Life table approach to estimate
silicosis risk based on the
silicosis rates that are age- and
calendar-time-adjusted, from
Table 2 (page 1374) of Steenland
and Brown (1995b). Exposure to
crystalline silica is assumed to
begin at age 20 through age 65. 3
Cumulative Risk (CR)= 1 - {1/[1
+
exp(2.439/.2199)*CDE 112199]}. 4
Estimates derived from rate
ratios based on the categorical
model after accounting for
exposure measurement
uncertainty, from Table 7, page
40 ofToxaChemica,
International Inc. (2004).
Absolute risk calculated as l exp(-Ltime*rate), where rate is
the rate ratio for a given
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Mortality
Silicosis
Prob(2/1 +profusions)= 1/
(l+exp-(-4.83 + 0.443*Cum.
Quart2<2 + 01.323 * Cum.Exp>2
Chest X-ray
category of
2/ 1+ or greater
(Buchanan et
al., 2003)
Silicosis
mortality
and/or X-ray
of 1/1 or
greater
(Steenland and
Brown, 1995b)
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Table VI-2: Summary of Exposure Response Models in Studies Considered in MSHA's
FRA, Based on OSHA's 13 QRA Models
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Cohort
Exposure
Lag
(years) 1
Model Parameter
(Standard Error (SE))
cumulative exposure times a base
rate of 4.7E-5. (OSHA, 2013b,
page 352).
Linear relative rate model:
RR=l +(0.5469*E) where Eis
cumulative respirable crystalline
silica exposure in mg/m3 . 6
Range based on three models with
log cumulative exposure (mg/m 3 years; see Table II-2, OSHA,
2013b, page 290):
1) Log-linear model: B= 0.60
(0.015) (Model with log
cumulative exposure (mg/m 3-days
+ l));
2) Linear model: ~ = 0.074950
(0.024121) (Model with log
cumulative exposure (mg/m3days+ l)); and
3) Linear spline model: ~' =
0.16498 (0.0653) and ~2 = 0.1493 (0.0657) Model with
cumulative exposure (mg/m3years) and 95% confidence
interval calculated as follows
(where CE = cumulative
exposure in mg/m 3-years and SE
is standard error of the parameter
estimate in parentheses): For CE
:S 2.19: 1 + [(~1 ± (1.96*SE1))
*CE] For CE> 2.19: 1 + [(~, *
CE)+ (~2 * (CE-2.19))] ± 1.96 *
SQRT[(CE2 * SEi2) + ((CE2.19)2 *SEz2) + (2*CE*(CE3.29)*-0.00429)]. 8
NMRD
Park et al.,
2002
California
diatomaceous
earth workers
No lag
Lung Cancer
Steenland et
al., 2001a;
ToxaChemica
International,
Inc., 2004
10 pooled
cohorts 7
15
Lung Cancer
Rice et al.,
2001
California
diatomaceous
earth workers
10
Linear relative risk model: ~ =
0.1441*E
Model with cumulative respirable
crystalline silica exposure E
=mg/m 3-years (Table II-2,
OSHA, 2013b, page 290). 9
Lung Cancer
Attfield and
Costello, 2004
U.S. granite
workers
15
Log-linear relative risk model: ~
= exp(0.19*E) where Eis
cumulative respirable crystalline
silica exposure in mg/m3-years
Table II-2 (OSHA, 2013b, page
290). 10
Lung Cancer
Hughes et al.,
2001
North
American
industrial sand
workers
15
Log-linear relative risk model: ~
= 0.13 *E, SE= 0.074; where E
is cumulative respirable
crystalline silica exposure in
mg/m 3-years (Table IT-2, OSHA,
2013b, page 290). 11
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table VI-2: Summary of Exposure Response Models in Studies Considered in MSHA's
FRA, Based on OSHA's 13 QRA Models
Cohort
Lung Cancer
Miller and
MacCalman,
2010
British coal
miners
ESRD
Steenland et
al., 2002a
3 cohorts
Exposure
Lag
(years) 1
15
No lag
Model Parameter
(Standard Error (SE))
Log-linear relative risk model: B
= 0.0524 * E, where E is
cumulative respirable crystalline
silica exposure in mg/m3-years,
SE= 0.0188, life table analysis
(Table 11-2, OSHA, 2013b, page
290).
Log-linear model: R =
exp(0.269(lnE)) where Eis
cumulative
respirable crystalline silica
exposure in mg/m 3-days, life
table analysis. 12•13
Notes:
1.
The exposure-response models may include an exposure lag period that accounts for disease latency
(NIOSH, 2019a). Researchers will typically model different lag periods to determine a model's best fit. An
exposure lag could potentially improve the model as there is often a delay in the development of disease, such as
silicosis and lung cancer, following exposure (OSHA, 2013b).
2.
Quartz is cumulative respirable crystalline silica exposure in ghm-3 (i.e., gram-hours/m3), with one year of
work assumed by MSHA to equal 2000 hours (250 days per year x 8 hours per day). Exposure to crystalline silica
is assumed to begin at age 20 through age 65. Age of cohort at follow-up was between 50 and 74 years (OSHA,
2013b, page 335).
3.
Was used by OSHA in its life table approach.
4.
CDE = cumulative respirable dust exposure in mg/m3-years, assumed quartz content ofrespirable dust was
30%. Average age of cohort at onset was 55.9 years (range 38-74 years) (Hnizdo and Sluis-Cremer, 1993).
5.
Respirable crystalline silica reported by Chen et al. (2001) to be 3 .6 % of total dust. Average age at onset
was 48.3 years.
6.
Was used by OSHA in its life table approach.
7.
10 Cohort studies: US diatomaceous earth (Checkoway et al., 1997), South Africa gold (Hnizdo and SluisCremer, 1991; Hnizdo et al., 1997), US gold (Steenland and Brown, 1995b), Australian gold (de Klerk and Musk,
1998), US granite (Costello and Graham, 1988), Finnish granite (Koskela et al., 1994), US industrial sand
(Steenland and Sanderson, 2001), Chinese tungsten (Chen et al., 1992), Chinese pottery (Chen et al., 1992),
Chinese tin (Chen et al., 1992).
8.
Was used by OSHA in its life table approach.
9.
Was used by OSHA in its life table approach. Standard error not reported; upper and lower confidence
limit on beta estimated from confidence interval ofrisk estimate reported in Rice et al., 2001. (OSHA, 2013b, Table
11-2, page 290).
10.
Was used by OSHA in its life table approach. Standard error not reported; upper and lower confidence
limit on beta were estimated from originally reported confidence interval ofrisk estimate (OSHA, 2013b, Table 112, page 290).
11.
Was used by OSHA in its life table approach. Standard error of the coefficient was estimated from the pvalue for trend (OSHA, 2013b, Table 11-2, page 290).
12.
Was used by OSHA in its life table approach.
13.
The model parameter used in Steenland et al. (2002a) was shown in the document containing personal
communications between OSHA and Steenland (Steenland 2010).
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Two commenters (SMI and NVMA)
expressed concern that not all relevant
studies were considered in MSHA’s
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analysis of the health effects literature
on occupational exposure to respirable
crystalline silica (Document ID 1446;
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1441). For example, the NVMA
commented that the studies referenced
in the health effects literature review are
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outdated and do not recognize the
changing conditions in mines that
reduce the likelihood of prolonged
exposure to respirable crystalline silica,
such as the updates made by mines in
response to the diesel particulate matter
standard published in the early 2000s
(Document ID 1441). Similarly, the
Pennsylvania Coal Alliance stated that
the majority of research MSHA relied on
did not account for significant
technological advancements in mining
and dust control technology (Document
ID 1378). This commenter further
asserted that the rule cannot be justified
until the effects of the 2014 RCMD
Standard are better understood
(Document ID 1378).
MSHA reviewed the relevant
literature, including recent publications.
Additionally, in response to comments
on the PRA, MSHA read and reviewed
studies suggested by commenters.
MSHA selected the studies which
provide the best available
epidemiological models to develop the
estimates of lifetime excess risks and
lifetime excess cases. These models
contain information regarding how the
cumulative level of exposure relates to
the risk of adverse health outcomes. The
selected studies were based on analyses
of miners with a range of exposure
histories. Further, MSHA’s modeling of
the avoided cases in the FRA directly
accounts for any relevant changes in
exposure conditions because it includes
exposure data from as recently as 2019
for MNM miners and 2021 for coal
miners. The exposure data captures
actual concentrations of respirable
crystalline silica that miners were
exposed to during their shifts. To the
extent that changing conditions,
technological advancements, or the
2014 RCMD Standard have impacted
miners’ exposures to respirable
crystalline silica, these effects are
accounted for in MSHA’s models, which
use recent exposure data. The final
provisions of the 2014 RCMD Standard
went into effect in 2016, which is the
first year of coal exposure data MSHA
used when modeling coal miners’
exposures to respirable crystalline silica
dust.
For each health endpoint, MSHA
generated two sets of risk estimates—
one representing a scenario of full
compliance with the existing standards
(herein referred to as the ‘‘Baseline’’
scenario) and another representing a
scenario wherein no samples exceed the
new PEL (herein referred to as the ‘‘New
PEL 50 mg/m3’’ scenario). In the Baseline
scenario, MNM miners in the >100–250,
>250–500, and >500 mg/m3 groups were
assigned exposure intensities of 100 mg/
m3 ISO. Coal miners in the 85.7–100,
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>100–250, >250–500, and >500 mg/m3
groups were assigned exposure
intensities of 85.7 mg/m3 ISO, calculated
as an 8-hour TWA. Exposure intensities
were not changed for miners with lower
exposure concentrations, because their
exposures were considered compliant
with the existing standards. A similar
procedure was used for the New PEL 50
mg/m3 scenario, except that each miner
group whose exposure exceeded the
new PEL was assigned a new exposure
of 50 mg/m3 ISO (for both MNM and
coal). This process—of creating an
exposure profile based on actual
exposure data and modifying it based on
the existing standards or the new PEL—
allowed MSHA to estimate real
exposure conditions that miners would
encounter under each scenario, thereby
enabling estimates of the actual excess
risks the current population of miners
would experience under each scenario
(Baseline and New PEL 50 mg/m3).
For purposes of calculating risk in the
FRA, both for MNM and coal miners,
MSHA estimated excess risks by using
the concentration of respirable
crystalline silica collected over the full
shift and calculating it as a full-shift, 8hour TWA expressed in ISO standards.
This metric of exposure intensity—the
8-hour TWA concentration of respirable
crystalline silica in ISO standards—was
used consistently across all sets of
estimates (both MNM and coal sectors,
and both the Baseline and New PEL 50
mg/m3 scenarios), thereby facilitating
meaningful comparison. MSHA
acknowledges that this metric of
exposure intensity does not correspond
to the manner in which coal exposure
concentrations are currently calculated
for purposes of evaluating compliance
under the existing standard. As
discussed in Section 4 of the standalone
FRA document, MSHA believes that a
full-shift, 8-hour TWA concentration
properly represents risks to miners and
thus is the most appropriate cumulative
exposure metric for computing risk
given that FTEs were used to scale
exposure durations relative to the
assumption of 250 8-hour workdays per
year.
Commenters, including MSHA Safety
Services Inc.; Silica Safety Coalition
(SSC); the NSSGA; Jervois Idaho Cobalt
Operations; and the EMA, suggested
that disease data show respirable
crystalline silica exposure and
associated adverse health effects are not
a problem or crisis in MNM mining or
that there is only negligible exposure to
respirable crystalline silica for certain
MNM miners (Document ID 1392; 1432;
1448; 1453; 1442). Similarly, the
Portland Cement Association stated that
silicosis is unknown in the cement
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industry (Document ID 1407). One
miner-related business further stated
that silicosis cases are on the rise in coal
and are decreasing in MNM and,
therefore, MSHA’s standard should
focus only on coal mining, specifically
underground coal mining (Document ID
1392). In addition, MNM mine operators
such as K & E Excavating Inc. and K &
E Alaska, Inc., also commented that
there is little to no evidence of silicosis
or other similar symptoms in MNM
mining, especially in comparison to coal
mining (Document ID 1435; 1436).
Finally, the president of N-Compliance
Safety Services expressed concern
regarding the origin of the mortality
reduction data included in the FRA and
stated that they could not find deaths
reported by MSHA for MNM miners or
the associated 7000–1 forms (Document
ID 1383).
On the other hand, several
commenters from labor unions and
health organizations agreed with
MSHA’s finding that MNM miners are at
risk of respirable crystalline silicarelated disease from occupational
exposures (Document ID 1447; 1449;
1418; 1373). USW asserted that rock
crushing in iron and other surface mines
can release silica-laden dust and that
silica is also a hazard in cement plants
(Document ID 1447). The same
commenter stated that silica control in
MNM mines is becoming increasingly
important because of new technologies
that are likely to lead to higher dust
exposures (Document ID 1447). Further,
Miners Clinic of Colorado commented
that its data support the need for better
control of exposure to respirable
crystalline silica in MNM mines, and
said that, of the 400 MNM miners the
clinic provided medical surveillance for
in the past 20 years, 62 percent reported
having spent over half of their mining
tenure in MNM or at least 10 years as
a MNM miner and, of those 62 percent,
26 percent had pneumoconiosis (based
on a positive chest radiograph B
reading) (Document ID 1418). This
commenter concluded that MNM
miners are at risk for progressive and
potentially disabling work-related lung
disease, although information on
silicosis disease rates among MNM
miners are less readily available than
those for coal miners (Document ID
1418). Finally, citing several studies
(Kramer et al., 2012; Friedman et al.,
2015; Leso et al., 2019; Rose et al., 2019;
Wu et al., 2020; LACDHS, 2022; Fazio
et al., 2023), the Association of
Occupational and Environmental
Clinics (AOEC) said that severe silicosis
in the engineered stone manufacturing
industry has been reported around the
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world, including in the United States
(Document ID 1373).
MSHA disagree with the assertion
that silicosis or other diseases linked to
respirable crystalline silica are not risks
for MNM miners. MSHA reviewed a
wide range of studies that demonstrated
disease risks amongst miners
occupationally exposed to respirable
crystalline silica. These studies were not
limited to underground coal miners and
show that respirable crystalline
exposure produces excess risk for coal
and MNM miners as well as
underground and surface miners. The
studies MSHA evaluated covered
occupations relevant to MNM mining
such as sandblasters (Abraham and
Wiesenfeld, 1997; Hughes et al., 1982),
industrial sand workers (Vacek et al.,
2019), hard rock miners (Verma et al.,
1982, 2008), and gold miners (Carneiro
et al., 2006a; Tse et al., 2007b), metal
miners (Hessel et al., 1988; Hnizdo and
Sluis-Cremer, 1993; Nelson, 2013), and
nonmetal miners such as silica plant
and ground silica mill workers,
whetstone cutters, and silica flour
packers (Mohebbi and Zubeyri, 2007;
NIOSH, 2000a,b; Ogawa et al., 2003a).
Of the MNM exposure samples MSHA
collected over the 2016–2021 period,
18.2 percent exceed the new PEL of 50
mg/m3 and 6.4 percent exceed the
existing PEL of 100 mg/m3. Based on the
analysis presented in the FRA, MNM
miners are exposed to concentrations of
respirable crystalline silica that are
associated with elevated risks of
morbidity and mortality from a variety
of diseases.
Further, the ACOEM commented that
new information about the molecular
basis for silica’s adverse health effects
since OSHA’s 2016 summary of the
medical literature highlights the need
for establishing and enforcing the 50 mg/
m3 PEL (Wang et al., 2018; Chanda et
al., 2019; Feng et al., 2020; Wu et al.,
2021) (Document ID 1405). MSHA’s
review of the more recent health effects
literature also supports a causal
association between respirable
crystalline silica exposure and increased
risk of silicosis morbidity and mortality.
Thus, MSHA believes that silicosis and
other diseases are a risk to any miner
exposed to high levels of silica dust
concentrations, regardless of mining
commodity.
Regarding the comment about
reported deaths, selected surveillance
data for both silicosis cases and silicosis
deaths are reported in the standalone
Health Effects document. Nonetheless,
MSHA’s estimated risk and case
reductions are based on samples MSHA
collected from MNM mines and peerreviewed models of the relationship
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between exposure to respirable
crystalline silica and related diseases.
The FRA does not rely on reported
mortality data. MSHA previously has
not required operators to conduct
medical surveillance for MNM miners
and becomes aware of cases only when
miners inform their employer of their
illness. Thus, these case data are not
complete enough to serve as a basis for
estimating applicable exposure-response
models needed for a comprehensive risk
analysis. However, MSHA believes that
the final rule’s MNM medical
surveillance provisions, which are
discussed in further detail in the FRIA
and in the final rule text, will likely
help to improve this gap in the data.
Commenters from the SMI, EMA, and
Vanderbilt Minerals, argued that the
aged and occluded crystalline silica
(quartz) encountered in sorptive
minerals, does not pose the same health
risk of other forms of crystalline silica
(Document ID 1446; 1442; 1419). The
SMI commented that their mining and
processing operations do not pose a risk
to miners’ health (Document ID 1446). A
more comprehensive discussion of these
commenters’ concerns is addressed in
the preamble under Section VIII.A.3.
Sorptive Minerals.
The Agency notes that, unlike OSHA,
MSHA has no requirement to identify a
‘‘significant risk’’ before regulating to
protect miners’ health and safety. Nat’l
Mining Ass’n v. United Steel Workers,
985 F.3d 1309, 1319 (11th Cir. 2021)
(‘‘[T]he Mine Act does not contain the
‘significant risk’ threshold requirement
. . . from the OSH Act.’’). Moreover,
unlike OSHA-regulated industries, the
mining of sorptive minerals involves the
removal of overburden, which can
disturb sedimentary and other silicarich rock that could contain unoccluded
respirable crystalline silica. The mining
and milling processes generate and
expose miners to hazardous dust
surrounding the mined deposits. Also,
during mineral processing, sorptive
minerals may be crushed, heated, dried
to remove moisture, re-crushed, and
then screened to produce various grades
of finished products. These processes
have the potential to fracture and
change the nature of the surface
characteristics of the quartz in the
mined commodity. Sorptive minerals
have always been subject to MSHA’s
previous PEL, without exemption.
MSHA examined evidence and
references from the commenters and
conducted its own review of the
scientific literature. MSHA agrees that
there is some evidence to suggest that
occluded silica is less toxic than
unoccluded silica (Wallace et al., 1996).
Animal studies involving respirable
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crystalline silica suggest that the aged
form has lower toxicity than the freshly
fractured form; however, the aged form
still retains significant toxicity
(Shoemaker et al., 1995; Vallyathan et
al., 1995; Porter et al., 2002c). MSHA
finds that ‘‘lower toxicity’’ does not
imply the absence of adverse health
effects. In addition, there is no evidence
that occlusion and the initial reduced
toxicity persist following deposition and
retention of the crystalline silica
particles in the lungs.
There have been few epidemiological
studies focused on workers exposed to
dust generated from sorptive minerals.
Examples include Phibbs et al. (1971)
and Waxweiler et al. (1988). These small
cohort studies did not evaluate
exposures to a wide variety of sorptive
minerals and relied on data from
outdated exposure assessment methods.
These studies neither disprove the
health-based risks associated with
exposure to respirable crystalline silica
nor support a conclusion that sorptive
minerals present no risk. Other
epidemiological studies of workers
exposed to clay-occluded respirable
crystalline silica have shown that
occupational silicosis can occur among
exposed workers (Phibbs et al., 1971;
Love et al., 1995, 1999; Chen et al.,
2005, 2006, 2012; Harrison et al., 2005).
Therefore, MSHA disagrees with these
commenters.
MSHA finds that the limited
epidemiological data involving sorptive
minerals do not refute the conclusions
drawn from other epidemiological and
toxicological studies included in
MSHA’s standalone Health Effects
document. MSHA concludes, from the
best available evidence, that exposure to
the crystalline silica present in sorptive
minerals poses a risk of material
impairment of health or functional
capacity to miners. In the Posthearing
Brief to OSHA, NIOSH (2014)
concluded that ‘‘currently available
information is not adequate to inform
differential quantitative risk
management approaches for crystalline
silica that are based on surface property
measurements.’’ MSHA concurs with
NIOSH’s recommendation for a single
PEL for respirable crystalline silica
without consideration of surface
properties.
C. Summary of Studies Selected for
Modeling
After reviewing the available studies
that support quantitative modeling,
MSHA selected one exposure-response
model from literature for each of the five
health outcomes that are modeled in the
FRA. These selections and the exposureresponse models are discussed below.
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1. Silicosis Morbidity
Due to the long latency periods
associated with chronic silicosis,
OSHA’s respirable crystalline silica
standard relied on the subset of studies
that were able to contact and evaluate
many workers through retirement.
Studies that included retired workers
provides the best available evidence of
lifetime risk of silicosis morbidity.
The health endpoint of interest in
these studies was the appearance of
opacities on chest radiographs
indicative of pulmonary
pneumoconiosis (a group of lung
diseases caused by the lung’s reaction to
inhaled dusts). The most reliable
estimates of silicosis morbidity, as
detected by chest X-rays, come from the
studies that evaluated those X-rays over
time, included radiographic evaluation
of workers after they left employment,
and derived cumulative or lifetime
estimates of silicosis disease risk.
To describe the presence and severity
of pneumoconiosis, including silicosis,
the International Labour Organization
(ILO) developed a standardized system
to classify lung opacities identified on
chest radiographs (X-rays) (ILO, 1980,
2002, 2011, 2022). The ILO system
grades the size, shape, and profusion of
opacities. Although silicosis is defined
and categorized based on chest X-ray,
the X-ray is an imprecise tool for
detecting pulmonary pneumoconiosis
(Craighead and Vallyathan, 1980;
Hnizdo et al., 1993; Rosenman et al.,
1997; Cohen and Velho, 2002). Hnizdo
et al. (1993) recommended that an ILO
category 0/1 (or greater) should be
considered indicative of silicosis among
workers exposed to high respirable
crystalline silica concentrations. They
noted that the sensitivity of the chest Xray as a screening test increases with
disease severity and to maintain high
specificity, category 1/0 (or 1/1) chest Xrays should be considered as a positive
diagnosis of silicosis for miners who
work in low dust occupations (Hnizdo
et al., 1993). MSHA, consistent with
NIOSH’s use of chest X-rays in their
occupational respiratory disease
surveillance program (NIOSH, 2014b),
agrees that a small opacity profusion
score of 1/0 is consistent with chronic
silicosis stage 1. Most of the studies
reviewed by MSHA considered a
finding consistent with an ILO category
of 1/1 or greater to be a positive
diagnosis of silicosis, although some
also considered an X-ray classification
of 1/0 or 0/1 to be positive. The low
sensitivity of chest radiography to detect
minimal silicosis suggests that risk
estimates derived from radiographic
evidence likely underestimate the true
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risk of this disease (Craighead and
Vallyathan, 1980; Hnizdo et al., 1993;
Rosenman et al., 1997; Cohen and
Velho, 2002; Hoy et al., 2023).
OSHA summarized the Miller et al.
(1995, 1998) and Buchanan et al. (2003)
studies in their final respirable
crystalline silica standard in 2016
(OSHA 2016a, 81 FR 16286, 16316).
These researchers reported on a 1991
follow-up study of 547 survivors of a
1,416-member cohort of Scottish coal
workers from a single mine. These men
had all worked in the mine during the
period between early 1971 and mid1976, during which time they had
experienced ‘‘unusually high
concentrations of freshly cut quartz in
mixed coal mine dust.’’ The
population’s exposures to quartz dust
had been measured in unique detail for
a considerable proportion of the men’s
working lives (OSHA, 2013b, page 333).
The 1,416 men had previous chest Xrays dating from before, during, or just
after this high respirable crystalline
silica exposure period. Of these 1,416
men, 384 were identified as having died
by 1990/1991. Of the 1,032 remaining
men, 156 were untraced, and, of the 876
who were traced and replied, 711 agreed
to participate in the study. Of these, the
total number of miners who were
surveyed was 551. Four of these were
omitted, two because of a lack of an
available chest X-ray. The 547 surviving
miners (age range: 29–85 years,
average=59 years) were interviewed and
received their follow-up chest X-rays
between November 1990 and April
1991. The interviews consisted of
questions on current and past smoking
habits and occupational history since
leaving the coal mine, which closed in
1981. They were also asked about
respiratory symptoms and were given a
spirometry test (OSHA, 2013b, pages
333–334).
Exposure characterization was based
on extensive respirable dust sampling;
samples were analyzed for quartz
content by IR spectroscopy. Between
1969 and 1977, two coal seams were
mined. One had produced quarterly
average concentrations of respirable
crystalline silica much less than 1,000
mg/m3 (only 10 percent exceeded 300
mg/m3). The other more unusual seam
(mined between 1971 and 1976) lay in
sandstone strata and generated
respirable crystalline silica levels such
that quarterly average exposures
exceeded 1,000 mg/m3 (10 percent of the
quarterly measurements were over
10,000 mg/m3). Thus, this cohort study
allowed evaluation of the effects of both
higher and lower respirable crystalline
silica concentrations and exposure-rate
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effects on the development of silicosis
(OSHA, 2013b, page 334).
Three physicians read each chest film
taken during the current survey as well
as films from the surveys conducted in
1974 and 1978. Films from an earlier
1970 survey were read only if no films
were available from the subsequent two
surveys. Silicosis cases were identified
if the median classification of the three
readers indicated an ILO category of 1/
1 or greater (Miller et al., 1995, page 24),
plus a progression from the earlier
reading. Of the 547 men, 203 (38
percent) showed progression of at least
1 ILO category from the 1970s’ surveys
to the 1990–91 survey; in 128 of these
(24 percent), there was progression of 2
or more ILO categories. In the 1970s’
surveys, 504 men had normal chest Xrays; of these, 120 (24 percent) acquired
an abnormal X-ray consistent with ILO
category 1/0 or greater at the follow-up.
Of the 36 men whose X-rays were
consistent with ILO category 1/0 or
greater in the 1970s’ surveys, 27 (75
percent) exhibited further progression at
the 1990/1991 follow-up. Only one
subject showed a regression from any
earlier reading, and that was slight, from
1/0 to 0/1. The earlier Miller et al.
(1995) report presented results for cases
classified as having X-ray films
consistent with either 1/0+ and 2/1+
degree of profusion; the Miller et al.
(1998) analysis and the Buchanan et al.
(2003) re-analyses emphasized the
results from cases having X-rays
classified as 2/1+ (OSHA, 2013b, page
334).
MSHA modeled the exposureresponse relationship by using
cumulative exposure expressed as gram/
m3-hours, assuming 2,000 work hours
per year and a 45-year working life (after
adjusting for full-time equivalents,
including miners (excluding contract
miners) and contract miners). MSHA
estimated risk at the existing standard
assuming cumulative exposure to 100
mg/m3 ISO for MNM miners and 85.7 mg/
m3 ISO (100 mg/m3 MRE) for coal
miners. Respirable crystalline silica
exposures were calculated by
commodity, and median exposure
values were used within a variety of
exposure intervals. Risks were
computed using a life table
methodology which iteratively updated
the survival, risk, and mortality rates
each year based on the results of the
preceding year. Covariates in the
regression included smoking, age,
amount of coal dust, and percent of
quartz in the coal dust during various
previous survey periods.
Both Miller et al. papers (1995, 1998)
presented the results of numerous
regression models, and they compared
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the results of the partial regression
coefficients using Z statistics of the
coefficient divided by the standard
error. Also presented were the residual
deviances of the models and the
residual degrees of freedom. In the
introduction to the results section,
Miller et al. (1995) stated that, ‘‘in none
of the models fitted was there a
significant effect of smoking habit
(current, ex-smoker, and never smoker),
nor was there any evidence of any
difference between smoking groups in
their relationship of response with age.’’
They therefore presented the results of
the regression analyses without terms
for smoking effects (i.e., without
including smoking effects as a variable
in the final regression analysis, because
they found that smoking did not affect
the modeling results). The logistic
regression models developed by Miller
et al. (1995) included terms for
cumulative exposure and age. In their
later publication, Miller et al. (1998)
presented models similar to their 1995
report, but without the age variable.
Their logistic regression model A from
Table 7 of their report (page 56)
included only an intercept (¥4.32) and
the respirable crystalline silica (quartz)
cumulative exposure variable (0.416).
They estimated that respirable
crystalline silica exposure at an average
concentration of 100 mg/m3 for 15 years
(2.6 gram/m3-hr assuming 1,750 hours
worked per year) would result in an
increased risk of silicosis (ILO>2/1) of 5
percent (OSHA, 2013b, page 334).
OSHA had a high degree of
confidence in the estimates of silicosis
morbidity risk from this Scotland coal
mine study. This was mainly because of
highly detailed and extensive exposure
measurements, radiographic records,
and detailed analyses of high exposurerate effects. MSHA has reviewed and
agrees with OSHA’s conclusion.
Buchanan et al. (2003) provided an
analysis and risk estimates only for
cases having X-ray films consistent with
ILO category 2/1+ extent of profusion of
opacities, after adjusting for the
disproportionately severe effect of
exposure to high respirable crystalline
silica concentrations. Estimating the risk
of 1/0+ profusions from the Buchanan et
al. (2003) or the earlier Miller et al.
(1995, 1998) publications can only be
roughly approximated because of the
summary information included. Table 4
of Miller et al. (1998, page 55) presents
a cross-tabulation of radiograph
progression, using the 12-point ILO
scale, from the last baseline examination
to the 1990/1991 follow-up visit for the
547 men at the Scottish coal mine. From
this table, among miners having both
early X-ray films and follow-up films,
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44 men had progressed to 2/1+ by the
last follow-up and an additional 105
men had experienced the onset of
silicosis (i.e., X-ray films were classified
as 1/0, 1/1, or 1/2). Thus, by the time
of the follow-up, there were three times
more miners with silicosis consistent
with ILO category 1 than there were
miners with a category 2+ level of
severity ((105 + 44)/44 = 3.38). This
suggests that the Buchanan et al. (2003)
model, which reflects the risk of
progressing to ILO category 2+,
underestimates the risk of acquiring
radiological silicosis by about three-fold
in this population (OSHA, 2013b, page
336). This type of analysis shows that
the risk of developing silicosis
estimated from the Buchanan et al.
(2003) and Miller et al. (1998) studies is
of the same magnitude as the risks
reported by Hnizdo and Sluis-Cremer
(1993) (OSHA, 2013b, page 338).
MSHA estimated silicosis risk by
using the Buchanan et al. (2003) model
that predicted the lifetime probability of
developing silicosis at the 2/1+ category
based on cumulative respirable
crystalline silica exposures. As
discussed previously, MSHA applied
the Buchanan et al. (2003) model,
assuming that miners are exposed for 45
years of working life extending from the
start of age 21 through the end of age 65,
using a life table approach. Buchanan et
al. provides an exposure-response
model using cumulative exposure in
mg/m3-hours as the predictor variable
and lifetime risk of silicosis as the
outcome variable. MSHA assumed 45
years of exposure, each such year
having a duration of 2,000 work hours,
scaled by a weighted average FTE ratio
that accounts for the average annual
hours worked by miners (excluding
contract miners) and contract miners.
2. Accelerated Silicosis and Rapidly
Progressive Pneumoconiosis (RPP)
Study
OSHA concluded in their risk
assessment, and MSHA agrees, that
there is little evidence of a dose-rate
effect at respirable crystalline silica
concentrations in the exposure range of
25 mg/m3 to 500 mg/m3 (81 FR 16286,
16396). OSHA noted that the risk
estimates derived from the Buchanan et
al. (2003) study were not appreciably
different from those derived from the
other studies of silicosis morbidity (see
OSHA 2016a, 81 FR 16286, 16386; Table
VI–1. Summary of Lifetime or
Cumulative Risk Estimates for
Crystalline Silica). However, OSHA also
concluded that some uncertainty related
to dose-rate effects exists at
concentrations far higher than the
exposure range of interest. OSHA stated
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that it is possible for such a dose-rate
effect to impact the results if not
properly addressed in study populations
with high concentration exposures.
OSHA used the model from the
Buchanan et al. (2003) study in its
silicosis morbidity risk assessment to
account for possible dose-rate effects at
high average concentrations (OSHA
2016a, 81 FR 16286, 16396; OSHA,
2013b, pages 335–342). MSHA has
reviewed and agrees with OSHA’s
conclusions.
NIOSH stated in its post-hearing brief
to OSHA that a ‘‘detailed examination of
dose rate would require extensive and
real time exposure history which does
not exist for silica (or almost any other
agent)’’ (81 FR 16285, 16375). Similarly,
Dr. Kenneth Crump, a researcher from
Louisiana Tech University Foundation
who served on OSHA’s peer review
panel for the Review of Health Effects
Literature and Preliminary Quantitative
Risk Assessment, wrote to OSHA that,
‘‘[h]aving noted that there is evidence
for a dose rate effect for silicosis, it may
be difficult to account for it
quantitatively. The data are likely to be
limited by uncertainty in exposures at
earlier times, which were likely to be
higher’’ (OSHA 2016a, 81 FR 16286,
16375). OSHA agreed with the
conclusions of NIOSH and Dr. Crump.
OSHA believed that it used the best
available evidence to estimate risks of
silicosis morbidity and sufficiently
accounted for any dose rate effect at
high silica average concentrations by
using the Buchanan et al. (2003) study
as part of their final Quantitative Risk
Analysis (QRA) (OSHA 2016a, 81 FR
16286, 16396). MSHA has reviewed and
agrees with OSHA’s conclusions.
MSHA is using the Buchanan et al.
(2003) study to explain, in part, the
observed cases of progressive lung
disease in miners, known as RPP in coal
miners (Laney and Attfield, 2010; Wade
et al., 2011; Laney et al., 2012b, 2017;
Blackley et al., 2016b, 2018b; Almberg
et al., 2018a; Reynolds et al., 2018b;
Halldin et al., 2019, 2020; Cohen et al.,
2022) and accelerated silicosis in MNM
miners (Hessel et al., 1988; Mohebbi
and Zubeyri, 2007; Dumavibhat et al.,
2013). This research explains, in part,
the progressive disease observed in
shorter-tenured miners. MSHA believes
that the risks estimated by the Buchanan
et al. model can be applied to all mining
populations that have similar respirable
crystalline silica exposure exceedances.
MSHA data also indicate that a smaller
number of MSHA samples showed
respirable crystalline silica
concentrations well above the existing
MSHA standard of 100 mg/m3. Over the
last 15 years of MNM compliance data,
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188 samples (0.3 percent) were over 500
mg/m3; the upper range of exposure was
4,289 mg/m3 ISO (see FRA Table 4 of the
FRA document). Over the last 5 years of
coal compliance data, eight samples
(<0.1 percent) were over 500 mg/m3; the
upper range of exposure was 791.4 mg/
m3 MRE (see FRA Table 7 of the
standalone FRA document).
Analysis provided by Buchanan et al.
(2003) provides strong evidence of an
exposure-rate effect for silicosis in a
British Pneumoconiosis Field Research
(PFR) coal mining cohort exposed to
high levels of respirable crystalline
silica over short periods of time (OSHA,
2013b, page 335). Exposure was
categorized as pre- and post-1964, the
latter period being that of generally
higher quartz concentrations used to
estimate exposure-rate effects. For the
purpose of this analysis, the results
were presented for the 371 men (out of
the original 547) who were between the
ages of 50 and 74 at the time of the
1990/1991 follow-up, ‘‘since they had
experienced the widest range of quartz
concentrations and showed the
strongest exposure-response relations.’’
Thus, combined with their exposure
history, which went back to pre-1954,
many of these men had 30 to 40+ years
of highly detailed occupational
exposure histories available for analysis.
Of these 371 miners, there were 35 men
(9.4 percent) who had X-ray films
consistent with ILO category 2/1+, with
at least 29 of them having progressed
from less severe silicosis since the
previous follow-up during the 1970s
(from Miller et al., 1998) (OSHA, 2013b,
page 335).
The Buchanan et al. (2003) re-analysis
presented logistic regression models in
stages. In the final stage of modeling,
using only the statistically significant
post-1964 cumulative exposures, the
authors separated these exposures into,
‘‘two quartz concentration bands,
defined by the cut-point 2.0 mg/m3.’’
This yielded the final simplified
equation, adapted from Buchanan et al.,
2003, page 162:
where p2 is the probability of profusion
category 2/1 or higher (2/1+) at follow-up and
E is the cumulative exposure.
risks were estimated for miners who
progressed to silicosis level 2/1+ 15
years after exposure ended. This
analysis showed the increase in
predicted risk with relatively short
periods of quartz exceedance exposures,
over 4, 8, and 12 months. Buchanan et
al. predicted a risk of 2.5 percent for 15
years quartz exposure to 100 mg/m3 (0.1
mg/m3). This risk increased to 10.6
percent with the addition of only 4
months of exposure at the higher
concentration. The risk increased
further to 72 percent with 12 months at
the higher exposure of 2,000 mg/m3 (2.0
mg/m3).
The results indicated miners exposed
to exceedances above MSHA’s existing
standard could develop progression of
silicosis at an exaggerated rate. The
results of Buchanan et al. also indicated
that miners’ exposure to exceedances at
the new PEL will also suffer increased
risk of developing progressive disease,
though at a reduced rate (see Buchanan
et al. (2003), Table 4, page 163).
MSHA used a life table approach to
estimate the lifetime excess silicosis
morbidity from age 21 to age 80,
assuming exposure from the start of age
21 through the end of age 65 (45 years
of working life) and an additional 15
years of potential illness progress
thereafter. MSHA used the Buchanan et
al. (2003) model to estimate the effect of
respirable crystalline silica exposure
exceedances as seen in MSHA’s
compliance data on miners’ silicosis
risk at the existing and new standard.
The model predicted the probability of
developing silicosis at the 2/1+ category
based on cumulative respirable
crystalline silica exposures. Age-specific
cumulative risk was estimated as 1/
(1+EXP(¥(¥4.83+0.443*cumulative
exposure))). The model determined that
even at 17.4 hours on average per year
at an exposure of 1,500 mg/m3 (1.50 mg/
m3), miners’ risk of developing 2/1+
silicosis increased from a baseline of
24.8/1,000 to 29.0/1,000 at the existing
standard and 14/1,000 to 16.6/1,000 at
the new standard. Of course, the more
hours exposed to these levels of
respirable crystalline silica resulted in
even higher increased risk. It is
important to note that NIOSH’s X-ray
classification of the lowest case of
pneumoconiosis is 1/0 profusion of
small opacities (NIOSH, 2008c, page A–
2). Using a case definition of level 2/1+,
the miners studied by Buchanan et al.
(2003) would be more likely to show
clinical signs of disease. MSHA
emphasizes the importance of
maintaining miner exposure to
respirable crystalline silica at or below
the 50 mg/m3 PEL to minimize these
health risks as much as possible.
In this model, both the cumulative
exposure concentration variables were
‘‘highly statistically significant in the
presence of the other’’ (Buchanan et al.,
2003, page 162). Since these variables
were in the same units, mg/m3-hr, the
authors noted that the coefficient for
exposure concentrations >2,000 mg/m3
(>2.0 mg/m3) was three times that for
the concentrations <2,000 mg/m3 (<2.0
mg/m3). They concluded that their latest
analysis showed that ‘‘the risk of
silicosis over a working lifetime can rise
dramatically with exposure to such high
concentrations over a timescale of
merely a few months’’ (Buchanan et al.,
2003, page 163; OSHA, 2013b, page
336).
Buchanan et al. (2003) also used these
models to estimate the risk of acquiring
a chest X-ray classified as ILO category
2/1+, 15 years after exposure ends, as a
function of low <2,000 mg/m3 (<2.0 mg/
m3) and high >2,000 mg/m3 (>2.0 mg/
m3) quartz concentrations. OSHA chose
to use this model to estimate the risk of
radiological silicosis consistent with an
ILO category 2/1+ chest X-ray for
several exposure scenarios. They
assumed 45 years of exposure, 2,000
hours/year of exposure, and no
exposure above a concentration of 2,000
mg/m3 (2.0 mg/m3) (OSHA, 2013b, page
336).
Buchanan et al. (2003) used these
models to estimate the combined effect
on the predicted risk of low quartz
exposures (e.g., 100 mg/m3, equal to 0.1
mg/m3) and short-term exposures to
high quartz concentrations (e.g., 2,000
mg/m3, equal to 2 mg/m3). Predicted
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3. Silicosis and NMRD Mortality
Silicosis mortality was ascertained in
the studies included in the pooled
analysis by Mannetje et al. (2002b).
These studies included cohorts of U.S.
diatomaceous earth workers
(Checkoway et al., 1997), Finnish
granite workers (Koskela et al., 1994),
U.S. granite workers (Costello and
Graham, 1988), U.S. industrial sand
workers (Steenland and Sanderson,
2001), U.S. gold miners (Steenland and
Brown, 1995b), and Australian gold
miners (de Klerk and Musk, 1998). The
researchers analyzed death certificates
across all cohorts for cause of death.
OSHA relied upon the published, peerreviewed, pooled analysis of six
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epidemiological studies first published
by Mannetje et al. (2002b) and a
sensitivity analysis of the data
conducted by ToxaChemica
International, Inc. (2004). OSHA used
the model described by Mannetje et al.
(2002b) and the rate ratios that were
estimated from the ToxaChemica,
International Inc. sensitivity analysis to
estimate the risks of silicosis mortality.
This process better controlled for age
and exposure measurement uncertainty
(OSHA, 2013b, page 295). MSHA has
reviewed and agrees with OSHA’s
conclusions. These studies are
summarized below, including detailed
discussion and analysis of uncertainty
in the studies and associated risk
estimates.
OSHA found that the estimates from
Mannetje et al. (2002b) and
ToxaChemica Inc. probably understated
the actual risk because silicosis is
underreported as a cause of death since
there is no nationwide system for
collecting silicosis morbidity case data
(OSHA, 2016a, 81 FR 16286, 16325). To
help address this uncertainty, OSHA
also included an exposure-response
analysis of diatomaceous earth workers
(Park et al., 2002). This analysis better
recognized the totality of respirable
crystalline silica-related respiratory
disease than the datasets of Mannetje et
al. (2002b) and ToxaChemica
International Inc. (2004). Information
from the Park et al. (2002) study
(described in the next subsection) was
used to quantify the relationship
between cristobalite exposure and
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mortality caused by NMRD, which
includes silicosis, pneumoconiosis,
emphysema, and chronic bronchitis.
The category of NMRD captures much of
the silicosis misclassification that
results in underestimation of the
disease. NMRD also includes risks from
other lung diseases associated with
respirable crystalline silica exposures.
OSHA found the risk estimates derived
from Park et al. (2002) were important
to include in their range of estimates of
the risk of death from respirable
crystalline silica-related respiratory
diseases, including silicosis (OSHA,
2013b, pages 297–298). OSHA
concluded that the ToxaChemica
International Inc. (2004) re-analysis of
Mannetje et al.’s (2002b) silicosis
mortality data and Park et al.’s (2002)
study of NMRD mortality provided a
credible range of estimates of mortality
risk from silicosis and NMRD across
many workplaces. The upper end of this
range, based on the Park et al. (2002)
study, is less likely to underestimate
risk because of underreporting of
silicosis mortality. However, risk
estimates from studies focusing on
cohorts of workers from different
industries cannot be directly compared
(OSHA 2016a, 81 FR 16286, 16397).
a. Silicosis Mortality: Mannetje et al.
(2002b); ToxaChemica, International,
Inc. (2004)
Mannetje et al. (2002b) relied upon
the epidemiological studies contained
within the Steenland et al. (2001a)
pooled analysis of lung cancer mortality
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that also included extensive data on
silicosis. The six cohorts included:
(1) U.S. diatomaceous earth workers
(Checkoway et al., 1997),
(2) Finnish granite workers (Koskela
et al., 1994),
(3) U.S. granite workers (Costello and
Graham, 1988),
(4) U.S. industrial sand workers
(Steenland and Sanderson, 2001),
(5) U.S. gold miners (Steenland and
Brown, 1995b), and
(6) Australian gold miners (de Klerk
and Musk, 1998).
These six cohorts contained 18,364
workers and 170 silicosis deaths, where
silicosis mortality was defined as death
from silicosis (ICD–9 502, n=150) or
from unspecified pneumoconiosis (ICD–
9 505, n=20). Table VI–3 provides
information on each cohort, including
size, time period studied, overall
number of deaths, and number of deaths
identified as silicosis for the pooled
analysis conducted by Mannetje et al.
(2002b). The authors stated this
definition may have underestimated the
number of silicosis deaths some of
which may have been misclassified as
other causes (e.g., tuberculosis or COPD
without mention of pneumoconiosis).
Four cohorts were not included in the
silicosis mortality study. The three
Chinese studies did not use the ICD to
code cause of death. In the South
African gold miner study, silicosis was
not generally recognized as an
underlying cause of death. Thus, it did
not appear on death certificates (OSHA,
2013b, page 292).
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28261
Checkoway et
al., 1997
U.S. diatomaceous
earth
2,342
Time
period of
study
1942-1994
Koskela et al.,
1994
Costello and
Graham, 1988
Steenland et al.,
2001b
Steenland and
Brown, 1995b
de Klerk and
Musk, 1998
Finnish granite
1,026
1940-1993
418
15 ("other"
NMRD, including
silicosis)
14
U.S. granite
5,408
1950-1982
1,762
43
U.S. industrial sand
4,027
1974-1996
860
15
U.S. gold miners
3,348
1940-1996
1,925
39
Australian surface
and underground gold
mmers
2,213
1961-1993
1,351
44
7,065
170
Author
Cohort
Size of cohort
18,364
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Total
Adapted from Mannetje et al. (2002b)
Source: OSHA, 2013b, page 293.
Mannetje et al. (2002a) described the
exposure assessments developed for the
pooled analysis. Exposure information
from each of the 10 cohort studies
varied and included dust measurements
representing particle counts, mass of
total dust, and respirable dust mass.
Measurement methods also changed
over time for each of the cohort studies.
Generally, sampling was performed
using impingers in earlier decades, and
gravimetric techniques later. Exposure
data based on analysis for respirable
crystalline silica by XRD (the current
method of choice) were available only
from the study of U.S. industrial sand
workers. To develop cumulative
exposure estimates for all cohort
members and to pool the cohort data, all
exposure data were converted to units of
mg/m3 (mg/m3) respirable crystalline
silica. Cohort-specific conversion factors
were generated based on the silica
content of the dust to which workers
were exposed. In some instances, results
of side-by-side comparison sampling
were available. Within each cohort,
available job- or process-specific
information on the silica composition or
nature of the dust was used to
reconstruct respirable crystalline silica
exposures. Most of the studies did not
have exposure measurements prior to
the 1950s. Exposures occurring prior to
that time were estimated either by
assuming such exposures were the same
as the earliest recorded for the cohort or
by modeling that accounted for
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documented changes in dust control
measures.
To evaluate the reasonableness of the
exposure assessment for the lung cancer
pooled study, Mannetje et al. (2002a)
investigated the relationship between
silicosis mortality and cumulative
exposure. They performed a nested
case-control analysis for silicosis or
unspecified pneumoconiosis using
conditional logistic regression. Since
exposure to respirable crystalline silica
is the sole cause of silicosis, any finding
for which cumulative exposure was
unrelated to silicosis mortality risk
would suggest that serious
misclassification of the exposures
assigned to cohort members occurred.
Cases and controls were matched for
race, sex, age (within 5 years), and 100
controls were matched to each case.
Each cohort was stratified into quartiles
by cumulative exposure. Standardized
rate ratios (SRRs) were calculated using
the lowest-exposure quartile as the
baseline. Odds ratios (ORs) were also
calculated for the pooled data set
overall, which was stratified into
quintiles based on cumulative exposure.
For the pooled data set, the relationship
between the ORs for silicosis mortality
and cumulative exposure, along with
each of the 95 percent confidence
intervals (95% CI), were as follows:
(1) 4,450 mg/m3-years (4.45 mg/m3years), OR=3.1 (95% CI: 2.5–4.0);
(2) 9,080 mg/m3-years (9.08 mg/m3years), OR=4.6 (95% CI: 3.6–5.9);
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Number of
deaths
Number of
silicosis deaths
749
(3) 16,260 mg/m3-years (16.26 mg/m3years), OR=4.5 (95% CI: 3.5–5.8); and
(4) 42,330 mg/m3-years (42.33 mg/m3years), OR=4.8 (95% CI: 3.7–6.2).
In addition, in seven of the cohorts,
there was a statistically significant trend
between silicosis mortality and
cumulative exposure. For two of the
cohorts (U.S. granite workers and U.S.
gold miners), the trend test was not
statistically significant (p=0.10). An
analysis could not be performed on the
South African gold miner cohort
because silicosis was never coded as an
underlying cause of death, apparently
due to coding practices in that country.
Based on this analysis, Mannetje et al.
(2002a) concluded that the exposureresponse relationship for the pooled
data set was ‘‘positive and reasonably
monotonic.’’ That is, the response
increased with increasing exposure. The
results also indicated that the exposure
assessments provided reasonable
estimates of cumulative exposures. In
addition, despite some large differences
in the range of cumulative exposures
between cohorts, a clear positive
exposure-response trend was evident in
seven of the cohorts (OSHA, 2013b,
page 271).
Furthermore, in their pooled analysis
of silicosis mortality for six of the
cohorts, Mannetje et al. (2002b) found a
clear and consistently positive response
with increasing decile of cumulative
exposure, although there was an
anomaly in the 9th decile. Overall, these
data supported a monotonic exposure-
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response relationship for silicosis.
Although some exposure
misclassification almost certainly
existed in the pooled data set, the
authors concluded that exposure
estimates did not appear to have been
sufficiently misclassified to obscure an
exposure-response relationship (OSHA,
2013b, page 271).
As part of an uncertainty analysis
conducted for OSHA, Drs. Steenland
and Bartell (ToxaChemica International,
Inc., 2004) examined the quality of the
original data set and analysis to identify
and correct any data entry,
programming, or reporting errors
(ToxaChemica International, Inc., 2004).
This quality assurance process revealed
a small number of errors in exposure
calculations for the originally reported
results. Primarily, these errors resulted
from rounding of job class exposures
when converting the original data file
for use with a different statistical
program. Although the corrections
affected some of the exposure-response
models for individual cohorts,
ToxaChemica International, Inc. (2004)
reported that models based on the
pooled dataset were not impacted by the
correction of these errors (OSHA, 2013b,
pages 271–272).
Silicosis mortality was evaluated
using standard life table analysis in
Mannetje et al. (2002b). Poisson
regression, using 10 categories of
cumulative exposure and adjusting for
age, calendar time, and cohort, was
conducted to derive silicosis mortality
rate ratios using the lowest exposure
group of 0–100 mg/m3-years (0–0.1 mg/
m3-year) as the referent group. More
detailed exploration of the exposureresponse relationship using a variety of
exposure metrics, including cumulative
exposure, duration of exposure, average
exposure (calculated as cumulative
exposure/duration), and the log
transformations of these variables, was
conducted via nested case-control
analyses (conditional logistic
regression). Each case was matched to
100 controls selected from among those
who had survived to at least the age of
the case, with additional matching on
cohort, race, sex, and date of birth
within 5 years. The authors explored
lags of 0, 5, 10, 15, and 20 years, noting
that there is no a priori reason to apply
an exposure lag, as silicosis can develop
within a short period after exposure.
However, a lag could potentially
improve the model, as there is often a
considerable delay in the development
of silicosis following exposure. In
addition to the parametric conditional
logistic regression models, the authors
performed some analyses using a cubicspline model, with knots at 5, 25, 50, 75,
and 95 percent of the distribution of
exposure. Models with cohort-exposure
interaction terms were fit to assess
heterogeneity between cohorts (OSHA,
2013b, page 294).
The categorical analysis found a
nearly monotonic increase in silicosis
rates with cumulative exposure, from
4.7 per 100,000 person-years in the
lowest exposure category (0–990 mg/m3years [0–0.99 mg/m3-years]) to 299 per
Risk= 1 - exp (-
.I
100,000 person-years in the highest
exposure category (>28,000 mg/m3-years
[>28 mg/m3-years]). Nested case-control
analyses showed a significant
association between silicosis mortality
and cumulative exposure, average
exposure, and duration of exposure. The
best-fitting conditional logistic
regression model used log-transformed
cumulative exposure with no exposure
lag, with a model c2 of 73.2 versus c2
values ranging from 19.9 to 30.9 for
average exposure, duration of exposure,
and untransformed cumulative exposure
(1 degree of freedom). No significant
heterogeneity was found between
individual cohorts for the model based
on log-cumulative exposure. The cubicspline model did not improve the model
fit for the parametric logistic regression
model using the log-cumulative
exposure (OSHA, 2013b, page 294).
Mannetje et al. (2002b) developed
estimates of silicosis mortality risk
through age 65 for two levels of
exposure (50 and 100 mg/m3 respirable
crystalline silica), assuming a working
life of occupational exposure from age
20 to 65. Risk estimates were calculated
based on the silicosis mortality rate
ratios derived from the categorical
analysis described above. The period of
time over which workers’ exposures and
risks were calculated (age 20 to 65) was
divided into one-year intervals. The
mortality rate used to calculate risk in
any given interval was dependent on the
worker’s cumulative exposure at that
time. The equation used to calculate risk
is as follows:
time, • rate,)
Where timei is equal to 1 year for every
age i, and ratei is the age-, calendar time, and cohort adjusted silicosis mortality
rate associated with the level of
cumulative exposure acquired at age i,
as presented in Mannetje et al. (2002b,
Table 2, page 725). The calculated
absolute risks equal the excess risks
since there is no background rate of
silicosis in the exposed population.
Mannetje et al. (2002b) estimated the
lifetime risk of death from silicosis,
assuming 45 years of exposure to 100
mg/m3, to be 13 deaths per 1,000
workers; at an exposure of 50 mg/m3, the
estimated lifetime risk was 6 per 1,000.
Confidence intervals (CIs) were not
reported (OSHA, 2013b, page 295).
In summary, OSHA’s estimates of
silicosis morbidity risks were based on
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studies of active and retired workers for
which exposure histories could be
constructed and chest X-ray films could
be evaluated for signs of silicosis.
MSHA agrees with OSHA’s estimate of
silicosis morbidity risks.
There is evidence in the record that
chest X-ray films are relatively
insensitive to detecting lung fibrosis
(OSHA 2016a, 81 FR 16286, 16397).
Hnizdo et al. (1993) found chest X-ray
films to have low sensitivity for
detecting lung fibrosis related to initial
cases of silicosis, compared to
pathological examination at autopsy. To
address the low sensitivity of chest Xrays for detecting silicosis, Hnizdo et al.
(1993) recommended that radiographs
consistent with an ILO category of 0/1
or greater be considered indicative of
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silicosis among workers exposed to a
high concentration of respirable
crystalline silica-containing dust. In like
manner, to maintain high specificity,
chest X-rays classified as category 1/0 or
1/1 should be considered as a positive
diagnosis of silicosis in miners who
work in low dust (0.2 mg/m3)
occupations. The studies on which
OSHA relied in its risk assessment
typically used an ILO category of 1/0 or
greater to identify cases of silicosis.
According to Hnizdo et al. (1993), they
were unlikely to have included many
false positives (i.e., assumed diagnosis
of silicosis in a miner without the
disease), but may have included false
negatives (i.e., failure to identify cases of
silicosis). Thus, in OSHA’s risk
assessment, the use of chest X-rays to
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ascertain silicosis cases in the morbidity
studies may have underestimated risk
given the X-rays’ low sensitivity to
detect disease. MSHA agrees with
OSHA’s assessment.
To estimate the risk of silicosis
mortality at the then existing and then
proposed exposure limits, OSHA used
the categorical model described by
Mannetje et al. (2002b) but did not rely
upon the Poisson regression in their
study. Instead, OSHA used rate ratios
estimated from a nested case-control
design implemented as part of a
sensitivity analysis (ToxaChemica
International, Inc., 2004). The casecontrol design was selected because it
was expected to better control for age.
In addition, the rate ratios derived from
the case control study were derived
from a Monte Carlo analysis to reflect
exposure measurement uncertainty (See
ToxaChemica International, Inc. (2004),
Table 7, page 40). The rate ratio for each
interval of cumulative exposure was
multiplied by the annual silicosis rate
assumed to be associated with the
lowest exposure interval, 4.7 per
100,000 for exposures of 990 mg/m3years (0.99 mg/m3-years), to estimate the
silicosis rate for each interval of
exposure. The lifetime silicosis
mortality risk is the sum of the silicosis
rate for each year of life through age 85
and assuming exposure from age 20 to
65. From this analysis, OSHA estimated
the silicosis mortality risk for exposure
to the then existing general industry
exposure limit (100 mg/m3) and then
proposed exposure limit (50 mg/m3) to
be 11 (95% CI 5–37) and 7 (95% CI 3–
21) deaths per 1,000 workers,
respectively. For exposure to 250mg/m3
(0.25 mg/m3) and 500 mg/m3 (0.5 mg/
m3), the range approximating the then
existing construction/shipyard exposure
limit, OSHA estimated the risk to range
from 17 (95% CI 5–66) to 22 (95% CI
6–85) deaths per 1,000 workers (OSHA,
2013b, page 294–295).
In view of the aforementioned
discussion, MSHA agrees with OSHA’s
analysis, and MSHA also selected the
Mannetje et al. (2002b) study for
estimating silicosis mortality risks and
cases. MSHA used a life table analysis
to estimate the lifetime excess silicosis
mortality through age 80. To estimate
the age-specific risk of silicosis
mortality at the existing standards, the
new PEL, and the action level, MSHA
used the same categorical model that
OSHA used in their PQRA (as described
above from Mannetje et al., 2002b;
ToxaChemica International, Inc., 2004)
to estimate lifetime risk following
cumulative exposure of 45 years. MSHA
used the 2018 all-cause mortality rates
(NCHS, Underlying Cause of Death,
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2018 on CDC WONDER Online
Database, released in 2020b) as all-cause
mortality rates. As stated previously, the
general (unexposed) population is
assumed to have silicosis mortality rates
equal to zero.
In response to MSHA’s question about
the PRA in the proposed rule, the
NVMA cited a 2021 study examining
silica exposure in artificial stone
workers, which this commenter asserted
found higher prevalence of silicosis
amongst those who did not use personal
protective equipment (PPE) and
amongst tobacco users (Requena-Mullor
et al., 2021) (Document ID 1441). This
commenter continued that wearing
respirators is a beneficial aid in
protecting workers and that other
technological advances in the mining
industry have reduced exposures to
respirable crystalline silica. However,
this commenter did not elaborate on
how the cited study or the technological
advances within the industry relate to
MSHA’s risk analysis or whether the
commenter believes the presented
information indicate any weaknesses or
shortcomings in MSHA’s modeling.
Further, the particular study this
commenter cited did not find a
statistically significant difference
between tobacco users and non-tobacco
users (Requena-Mullor et al., 2021).
MSHA acknowledges that the
relationship between exposure to
respirable crystalline silica and silicosis
may be confounded by several variables,
including smoking. However,
confounders are discussed in the FRA
and were considered by the original
authors of the studies MSHA selected
for modeling. Park et al. (2002), which
MSHA used to model NMRD mortality,
fit a model that was stratified on
smoking status. Mannetje et al. (2002b)
did not account for smoking but noted
that ‘‘no effect of smoking was detected
in a study of Colorado miners.’’
Moreover, the Mannetje et al. (2002b)
model was used to determine how many
of the NMRD deaths were attributable to
silicosis as opposed to other forms of
NMRD. The total estimate for NMRD
deaths including silicosis is based on
Park et al. (2002), which did account for
smoking status. Buchanan et al. (2003),
which MSHA used to estimate silicosis
morbidity, originally included smoking
status as a covariate, but the authors
removed this variable from the final
model because it did not improve the
model fit by a statistically significant
amount. Further, regarding the
commenter’s assertion that
technological advancements in the
mining industry may reduce exposure
levels, these reductions are accounted
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28263
for in the models, which use recent
exposure data.
b. NMRD Mortality: Park et al. (2002)
In addition to causing silicosis,
exposure to respirable crystalline silica
causes increased risks of other NMRD.
These include chronic obstructive
pulmonary disease (COPD), which
includes chronic bronchitis,
emphysema, and combinations of the
two, and is a cause of chronic airways
obstruction. COPD is characterized by
airflow limitation that is usually
progressive and not fully reversible.
OSHA reviewed several studies of
NMRD morbidity and used a study by
Park et al. (2002) to assess NMRD risk.
Checkoway et al. (1997) originally
studied a California diatomaceous earth
cohort for which Park et al. (2002) then
analyzed the effect of respirable
crystalline silica exposures on the
development of NMRD. The authors
quantified the relationship between
exposure to cristobalite and mortality
from NMRD (OSHA, 2013b, page 295).
The California diatomaceous earth
cohort consisted of 2,570 diatomaceous
earth workers employed for 12 months
or more from 1942 to 1994. As noted
above, Park et al. (2002) was interested
in the relationship between cristobalite
exposure and mortality from chronic
lung disease other than cancer (LDOC).
LDOC included chronic diseases such as
pneumoconiosis (which included
silicosis), chronic bronchitis, and
emphysema, but excluded pneumonia
and other infectious diseases. The
researchers selected LDOC as the health
endpoint for three reasons. First,
increased mortality from LDOC had
been documented among respirable
crystalline silica-exposed workers in
several industry sectors, including gold
mining, pottery, granite, and foundry
industries. Second, the authors pointed
to the likelihood that silicosis as a cause
of death is often misclassified as
emphysema or chronic bronchitis.
Third, the number of deaths from the
diatomaceous earth worker cohort that
were attributed to silicosis was too
small (10) for analysis. Industrial
hygiene data for the cohort were
available from the employer for total
dust, respirable crystalline silica (mostly
cristobalite), and asbestos. Smoking
information was available for about 50
percent of the cohort and for 22 of the
67 LDOC deaths available for analysis,
permitting Park et al. (2002) to partially
adjust for smoking (OSHA, 2013b, pages
295–296).
Park et al. (2002) used the exposure
assessment previously reported by
Seixas et al. (1997) and used by Rice et
al. (2001) to estimate cumulative
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respirable crystalline silica exposures
for each worker in the cohort based on
detailed work history files. The average
respirable crystalline silica
concentration for the cohort was 290 mg/
m3 (0.29 mg/m3) over the period of
employment (Seixas et al., 1997). The
total respirable dust concentration in
the diatomaceous earth plant was 3,550
mg/m3 (3.55 mg/m3) before 1949 and
declined by more than 10-fold after
1973, to 290 mg/m3 (0.29 mg/m3) (Seixas
et al., 1997). The concentration of
respirable crystalline silica in the dust
ranged from 1 to 25 percent and was
dependent on the location within the
worksite. It was lowest at the mine and
greatest in the plant where the raw ore
was calcined into final product. The
average cumulative exposure values for
total respirable dust and respirable
crystalline silica were 7,310 mg/m3-year
(7.31 mg/m3-year) and 2,160 mg/m3-year
(2.16 mg/m3-year), respectively. The
authors also estimated cumulative
exposure to asbestos (OSHA, 2013b,
page 296).
Using Poisson regression models and
Cox proportional hazards models, the
authors fit the same series of relative
rate exposure-response models that
were evaluated by Rice et al. (2001) for
lung cancer (i.e., log-linear, log-square
root, log-quadratic, linear relative rate, a
power function, and a shape function).
In general form, the relative rate model
was:
Rate = exp(α0) × ƒ(E),
where exp(a0) is the background rate
and E is the cumulative respirable
crystalline silica exposure. Park et al.
(2002) also employed an additive excess
rate model of the form:
Rate = exp(α0) + exp(αE),
Relative or excess rates were modeled
using internal controls and adjusting for
age, calendar time, ethnicity, and time
since first entry into the cohort. In
addition, relative rate models were
evaluated using age- and calendar timeadjusted external standardization to
U.S. population mortality rates for 1940
to 1994 (OSHA, 2013b, page 296).
There were no LDOC deaths recorded
among workers having cumulative
exposures above 32,000 mg/m3-years (32
mg/m3-years), causing the response to
level off or decline in the highest
exposure range. The authors believed
the most likely explanation for this
observation (which was also observed in
their analysis of silicosis morbidity in
this cohort) was some form of survivor
selection, possibly smokers or others
with compromised respiratory function
leaving work involving extremely high
dust concentrations. These authors
suggested several alternative
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explanations. First, there may have been
a greater depletion of susceptible
populations in high dust areas. Second,
there may have been greater
misclassification of exposures in the
earlier years where exposure data were
lacking (and when exposures were
presumably the highest) (OSHA, 2013b,
pages 296–297).
Therefore, Park et al. (2002)
performed exposure-response analyses
that restricted the dataset to
observations where cumulative
exposures were below 10,000 mg/m3years (10 mg/m3-years). This is a level
more than four times higher than that
resulting from 45 years of exposure to
the former OSHA PEL for cristobalite
(which was 50 mg/m3 (0.05 mg/m3)
when cristobalite was the only
polymorph present). These researchers
also conducted analyses using the full
dataset (OSHA, 2013b, page 297).
Model fit was assessed by evaluating
the decrease in deviance resulting from
addition of the exposure term, and
cubic-spline models were used to test
for smooth departures from each of the
model forms described. Park et al.
(2002) found that both lagged and
unlagged models fit well, but unlagged
models provided a better fit. In addition,
they believed that unlagged models
were biologically plausible in that
recent exposure could contribute to
LDOC mortality. The Cox proportional
hazards models yielded results that
were similar to those from the Poisson
analysis. Consequently, only the results
from the Poisson analysis were reported.
In general, the use of external
adjustments for age and calendar time
yielded considerably improved fit over
models using internal adjustments. The
additive excess rate model also proved
to be clearly inferior compared to the
relative rate models. With one
exception, the use of cumulative
exposure as the exposure metric
consistently provided better fits to the
data than did intensity of exposure (i.e.,
cumulative exposure divided by
duration of exposure). As to the
exception, when the highest-exposure
cohort members were included in the
analysis, the log-linear model produced
a significantly improved fit with
exposure intensity as the exposure
metric, but a poor fit with cumulative
exposure as the metric (OSHA, 2013b,
page 297).
Among the models based on the
restricted dataset [excluding
observations with cumulative exposures
greater than 10,000 mg/m3-years (10 mg/
m3-years)], the best-fitting model with a
single exposure term was the linear
relative rate model using external
adjustment. Most of the other single-
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term models using external adjustment
fit almost as well. Of the models with
more than one exposure term, the shape
model provided no improvement in fit
compared with the linear relative rate
model. The log-quadratic model fit
slightly better than the linear relative
rate model, but Park et al. (2002) did not
consider the gain in fit sufficient to
justify an additional exposure term in
the model (OSHA, 2013b, page 297).
Based on its superior fit to the cohort
data, Park et al. (2002) selected the
linear relative rate model with external
adjustment and use of cumulative
exposure as the basis for estimating
LDOC mortality risks among exposed
workers. Competing mortality was
accounted for using U.S. death rates
published by the National Center for
Health Statistics (1996). The authors
estimated the lifetime excess risk for
white men exposed to respirable
crystalline silica (mainly cristobalite) for
45 years at 50 mg/m3 (0.05 mg/m3) to be
54 deaths per 1,000 workers (95% CI:
17–150) using the restricted dataset, and
50 deaths per 1,000 using the full
dataset. For exposure to 100 mg/m3 (0.1
mg/m3), they estimated 100 deaths per
1,000 using the restricted dataset, and
86 deaths per 1,000 using the full
dataset. The CIs were not reported
(OSHA, 2013b, page 297).
The estimates of Park et al. (2002)
were about eight to nine times higher
than those that were calculated for the
pooled analysis of silicosis mortality
(Mannetje et al., 2002b). Also, these
estimates are not directly comparable to
those from Mannetje et al. (2002b)
because the mortality endpoint for the
Park et al. (2002) analysis was death
from all non-cancer lung diseases
beyond silicosis (including
pneumoconiosis, emphysema, and
chronic bronchitis). In the pooled
analysis by Mannetje et al. (2002b), only
deaths coded as silicosis or other
pneumoconiosis were included (OSHA,
2013b, pages 297–298).
Less than 25 percent of the LDOC
deaths in the Park et al. (2002) analysis
were coded as silicosis or other
pneumoconiosis (15 of 67). As noted by
Park et al. (2002), it is likely that
silicosis as a cause of death is often
misclassified as emphysema or chronic
bronchitis (although COPD is part of the
spectrum of disease caused by
respirable crystalline silica exposure
and can occur in the absence of
silicosis). Thus, the selection of deaths
by Mannetje et al. (2002b) may have
underestimated the true risk of silicosis
mortality. The analysis by Park et al.
(2002) would have more fairly captured
the total respiratory mortality risk from
all non-malignant causes, including
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silicosis and chronic obstructive
pulmonary disease. Furthermore, Park
et al. (2002) used untransformed
cumulative exposure in a linear model
compared to the log-transformed
cumulative exposure metric used by
Mannetje et al. (2002b). This would
have caused the exposure-response
relationship to flatten in the higher
exposure ranges (OSHA, 2013b, page
298).
It is also possible that some of the
difference between Mannetje et al.’s
(2002b) and Park et al.’s (2002) risk
estimates reflected factors specific to the
nature of exposure among diatomaceous
earth workers (e.g., exposure to
cristobalite vs. quartz). However, neither
the cancer risk assessments nor
assessments of silicosis morbidity
supported the hypothesis that
cristobalite is more hazardous than
quartz (OSHA, 2013b, page 298).
Based on the available risk
assessments for silicosis mortality,
OSHA believed that the estimates from
the pooled study by Mannetje et al.’s
(2002b) likely underestimated mortality
risk given that the study only counted
deaths where silicosis was specifically
identified on death certificates, which
are prone to misclassification. In
contrast, the risk estimates provided by
Park et al. (2002) for the diatomaceous
earth cohort would have captured some
of this misclassification and included
risks from other lung diseases (e.g.,
emphysema, chronic bronchitis) that
have been associated with respirable
crystalline silica exposure. Therefore,
OSHA believed that the Park et al.
(2002) study provided a better basis for
estimating the respirable crystalline
silica-related risk of NMRD mortality,
including that from silicosis. Based on
Park et al.’s (2002) linear relative rate
model [RR = 1 + bx, where b = 0.5469
(no standard error reported) and x =
cumulative exposure], OSHA used a life
table analysis to estimate the lifetime
excess NMRD mortality through age 85.
For this analysis, OSHA used all-cause
and cause-specific background mortality
rates for all males (National Center for
Health Statistics, 2009). Background
rates for NMRD mortality were based on
rates for ICD–10 codes J40–J47 (chronic
lower respiratory disease) and J60–J66
(pneumoconiosis). OSHA believed that
these corresponded closely to the ICD–
9 disease classes (ICD 490–519) used by
the original researchers. According to
CDC (2001), background rates for
chronic lower respiratory diseases were
increased by less than five percent
because of the reclassification to ICD–
10. From the life table analysis, OSHA
estimated that the excess NMRD risk
due to respirable crystalline silica
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exposure at the former general industry
PEL (100 mg/m3) and at OSHA’s final
PEL (50 mg/m3) for 45 years are 83 and
43 deaths per 1,000, respectively. For
exposure at the former construction/
shipyard exposure limit, OSHA
estimated that the excess NMRD risk
ranged from 188 to 321 deaths per 1,000
(OSHA, 2013b, page 298).
Following its own independent
review, MSHA agrees with and has
followed the rationale presented by
OSHA in its selection of the Park et al.
(2002) model to estimate NMRD
mortality risk in miners.
MSHA used a life table analysis to
estimate the lifetime excess NMRD
mortality through age 80. MSHA used
the Park et al. (2002) model to estimate
age-specific NMRD mortality risk as 1 +
0.5469 * cumulative exposure. MSHA
used all-cause and cause-specific
background mortality rates for all males
for 2018 (National Center for Health
Statistics, Underlying Cause of Death
2018 on CDC WONDER Online
Database, released in 2020b).
Background rates for NMRD mortality
were based on rates for ICD–10 codes
J40–J47 (chronic lower respiratory
disease) and J60–J66 (pneumoconiosis).
A state mining association cited CDC
data to state that the largest decrease in
pneumoconiosis deaths over the 1999–
2018 time period was in the coal mining
industry, with a decrease of 69.6
percent, and the largest increase was in
the OSHA construction sector (Bell and
Mazurek, 2020) (Document ID 1368).
This commenter also stated that, beyond
the CDC data, there is little
understanding of pneumoconiosis case
attribution, such as what percentage of
cases were specifically due to miningrelated employment compared to nonmining activities that might lead to
harmful exposure. The commenter’s
point that it is difficult to correctly
attribute pneumoconiosis is precisely
why MSHA’s FRA has relied on peerreviewed epidemiological studies,
which control for confounders where
necessary and quantify the precise
exposure-response relationship.
Regarding pneumoconiosis, the cited
article was about declining
pneumoconiosis deaths in particular.
Other sources, including analysis by
NIOSH, show that the prevalence of
pneumoconiosis illness has risen
substantially among miners since the
1990s (NIOSH, 2021d). This same trend
in pneumoconiosis illness among coal
miners was also mentioned by three
other commenters—the ACLC,
Appalachian Voices, and the UMWA
(Document ID 1445; 1425; 1398). While
it may be true that prevalence of
pneumoconiosis deaths decreased
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among the entire U.S. population during
this period, trends in pneumoconiosis
deaths tend to lag trends in
pneumoconiosis illness because people
can live many years with the disease
prior to death. The increasing
prevalence of the illness among miners
indicates that pneumoconiosis deaths
also are expected to rise in the future.
In addition, trends among the full U.S.
population may not reflect trends
among miners in particular, since the
mining workforce has decreased in size
since the 1990s. Thus, MSHA does not
believe that pneumoconiosis illnesses or
deaths among coal miners would
decline in the future in the absence of
this rule and, therefore, affirms that the
final rule is needed to protect the health
of all miners from various respirable
crystalline silica-related diseases.
4. Lung Cancer Mortality
Since the publication of OSHA’s final
rule in 2016, NIOSH has published two
documents concerning occupational
carcinogens, Chemical Carcinogen
Policy (2017b) and Practices in
Occupational Risk Assessment (2019a).
NIOSH will no longer set recommended
exposure levels for occupational
carcinogens. Instead, NIOSH intends to
develop risk management limits for
carcinogens (RML-Cas) to acknowledge
that, for most carcinogens, there is no
known safe level of exposure. An RML–
CA is a reasonable starting place for
controlling exposures. An RML–CA
limit is based on a daily maximum 8hour TWA concentration of a
carcinogen above which a worker
should not be exposed (NIOSH, 2017b,
page vi). RML-Cas for occupational
carcinogens are established at the
estimated 95% lower confidence limit
on the concentration (e.g., dose)
corresponding to 1 in 10,000 (10¥4)
lifetime excess risk (when analytically
possible to measure) (NIOSH, 2019a).
NIOSH stated that in order to
incrementally move toward a level of
exposure to occupational chemical
carcinogens that is closer to background,
NIOSH will begin issuing
recommendations for RML-Cas that
would advise employers to take
additional action to control chemical
carcinogens when workplace exposures
result in excess risks greater than 10¥4
(NIOSH, 2017b, page vi).
MSHA used the Miller et al. (2007)
and Miller and MacCalman (2010)
studies to estimate lung cancer mortality
risk in miners. In British coal miners,
excess lung cancer mortality was
studied through the end of 2005 in a
cohort of 17,800 miners (Miller et al.,
2007; Miller and MacCalman, 2010). By
that time, the cohort had accumulated
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516,431 person-years of observation (an
average of 29 years per miner), with
10,698 deaths from all causes. Overall
lung cancer mortality was elevated
(Standard Mortality Ratio (SMR) =
115.7, 95% CI: 104.8–127.7), and a
positive exposure-response relationship
with respirable crystalline silica
exposure was determined from Cox
regression after adjusting for smoking
history. Three strengths of this study
were: (1) the detailed time-exposure
measurements of quartz and total mine
dust, (2) detailed individual work
histories, and (3) individual smoking
histories. For lung cancer, analyses
based on Cox regression provided strong
evidence that, for these coal miners,
although quartz exposures were
associated with increased lung cancer
risk, simultaneous exposures to coal
dust did not cause increased lung
cancer risk (OSHA 2016a, 81 FR 16286,
16308).
Miller et al. (2007) and Miller and
MacCalman (2010) conducted a followup study of cohort mortality, begun in
1970. Their previous report on mortality
presented a follow-up analysis on
18,166 coal miners from 10 British coal
mines followed through the end of 1992
(Miller et al., 1997). The 2 reports from
2007 and 2010 analyzed the mortality
experience of 17,800 of these miners
(18,166 minus 346 men whose vital
status could not be determined) and
extended the analysis through the end
of 2005. Causes of deaths that were of
particular interest included
pneumoconiosis, other NMRD, lung
cancer, stomach cancer, and
tuberculosis. The researchers noted that
no additional exposure measurements
were included in the updated analysis,
since all the mines had closed by the
mid-1980s. However, some of these men
might have had additional exposure at
other mines or facilities not reported in
this study (OSHA, 2013b, page 287).
This cohort mortality study used Cox
proportional hazards regression
methods which controlled for a variety
of external and internal factors. The
external controls included British
administrative regional age-, time-, and
cause-specific mortality rates from
which to calculate SMRs. The internal
controls included each miner’s age,
smoking status, and detailed dust and
respirable crystalline silica (quartz)
time-dependent exposure
measurements. Cox regression analyses
were done in stages, with the initial
analyses used to establish what factors
were required for baseline adjustment
(OSHA, 2013b, page 287).
For the analysis using external
mortality rates, the all-cause mortality
SMR from 1959 through 2005 was 100.9
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(95% CI: 99.0–102.8), based on all
10,698 deaths. However, these SMRs
were not uniform over time. For the
period from 1990–2005, the SMR was
109.6 (95% CI:106.5–112.8), while the
ratios for previous periods were less
than 100. This pattern of increasing
SMRs in the recent past was also seen
for cause-specific deaths from chronic
bronchitis, SMR = 330.0 (95% CI:268.1–
406.2); tuberculosis, SMR = 193.4 (95%
CI: 86.9–430.5); cardiovascular disease,
SMR = 106.6 (95% CI: 102.0–111.5); all
cancers, SMR = 107.1 (95% CI:101.3–
113.2); and lung cancer, SMR = 115.7
(95% CI: 104.8–127.7). The SMR for
NMRD was 142.1 (95% CI: 132.9–152.0)
in this recent period and remained
highly statistically significant. In their
previous analysis on mortality from
lung cancer, reflecting follow-up
through 1995, Miller et al. (1997) had
not found any increase in the risk of
lung cancer mortality (OSHA, 2013b,
page 287).
OSHA reported that Miller and
MacCalman (2010) used these analyses
to estimate relative risks for a lifetime
exposure of 5 gram-hours/m3 (ghm¥3) to
quartz (OSHA, 2013b, page 288). This is
equivalent to approximately 55 mg/m3
(0.055 mg/m3) for 45 years, assuming
2,000 hours per year of exposure and/
or 100 ghm¥3 total dust. The authors
estimated relative risks (see Miller and
MacCalman (2010), Table 4, page 9) for
various causes of death including
pneumoconiosis, COPD, ischemic heart
disease, lung cancer, and stomach
cancer. Their results were based on
models with single exposures to dust or
respirable crystalline silica (quartz) or
simultaneous exposures to both, with
and without 15-year lag periods.
Generally, the risk estimates were
slightly greater using a 15-year lag
period.
For the models using only quartz
exposures with a 15-year lag,
pneumoconiosis, RR = 1.21 (95% CI:
1.12–1.31); COPD, RR = 1.11 (95% CI:
1.05–1.16); and lung cancer, RR = 1.07
(95% CI: 1.01–1.13) showed statistically
significant increased risks.
For lung cancer, analyses based on
these Cox regression methods provided
strong evidence that, for these coal
miners, quartz exposures were
associated with increased lung cancer
risk, but simultaneous exposures to coal
dust were not associated with increased
lung cancer risk. The relative risk (RR)
estimate for lung cancer deaths using
coal dust with a 15-year lag in the single
exposure model was 1.03 (95% CI: 0.96
to 1.10). In the model using both quartz
and coal mine dust exposures, the RR
based on coal dust decreased to 0.91,
while that for quartz exposure remained
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statistically significant, increasing to a
RR = 1.14 (95% CI: 1.04 to 1.25).
According to Miller and MacCalman
(2010), other analyses have shown that
exposure to radon or diesel fumes was
not associated with an increased cancer
risk among British coal miners (OSHA,
2013b, page 288).
The RRs in the Miller and MacCalman
(2010) report were used to estimate
excess lung cancer risk for OSHA’s
purposes. Life table analyses were done
as in the other studies above. Based on
the RR of 1.14 (95% CI: 1.04–1.25) for
a cumulative exposure of 5 ghm¥3, the
regression slope was recalculated as b =
0.0524 per 1,000 mg-years (per mg/m¥3years) and used in the life table
program. Similarly, the 95-percent CI on
the slope was 0.0157–0.08926. From
this study, the lifetime (to age 85) risk
estimates for 45 years of exposure to 50
mg/m3 (0.05 mg/m3) and 100 mg/m3
(0.100 mg/m3) respirable crystalline
silica were 6 and 13 excess lung cancer
deaths per 1,000 workers, respectively.
These lung cancer risk estimates were
less by about two- to four-fold than
those estimated from the other cohort
studies described above.
However, three factors might explain
these differences. First, these estimates
were adjusted for individual smoking
histories so any smoking-related lung
cancer risk (or smoking–respirable
crystalline silica interaction) that might
possibly be attributed to respirable
crystalline silica exposure in the other
studies was not reflected in the risk
estimates derived from the study of
these coal miners. Second, these coal
miners had significantly increased risks
of death from other lung diseases, which
may have decreased the lung cancersusceptible population. Of note, for
example, were the higher increased
SMRs for NMRD during the years 1959–
2005 for this cohort (Miller and
MacCalman, 2010, Table 2, Page 7).
Third, the difference in risk seen in
these coal miners may have been the
result of differences in the toxicity of
quartz present in the coal mines as
compared to the work environments of
the other cohorts. One Scottish mine
(Miller et al., 1998) in this 10-mine
study had been cited as having
presented ‘‘unusually high exposures to
[freshly fractured] quartz.’’ However,
this was also described as an atypical
exposure among miners working in the
10 mines. Miller and MacCalman (2010)
stated that increased quartz-related lung
cancer risk in their cohort was not
confined to that Scottish mine alone.
They also stated, ‘‘The general nature of
some quartz exposures in later years
. . . may have been different from
earlier periods when coal extraction was
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largely manual . . .’’ (OSHA, 2013b,
page 288).
All these factors in this mortality
analysis for the British coal miner
cohort could have combined to yield an
underestimation of lung cancer risk
estimates. However, OSHA believed that
these coal miner-derived estimates were
credible because of the quality of several
study factors relating to both study
design and conduct. In terms of design,
the cohort was based on union rolls
with very good participation rates and
good reporting. The study group also
included over 17,000 miners, with an
average of nearly 30 years of follow-up,
and about 60 percent of the cohort had
died. Just as important was the high
quality and detail of the exposure
measurements, both of total dust and
quartz. However, one exposure factor
that may have biased the estimates
upward was the lack of exposure
information available for the cohort after
the mines closed in the mid-1980s.
Since the mortality ratio for lung cancer
was higher during the last study period,
1990–2005, this period contributed to
the increased lung cancer risk. It is
possible that any quartz exposure
experienced by the cohort after the
mines had closed could have
accelerated either death or malignant
tumor (lung cancer) growth. By not
accounting for this exposure, if there
was any, the risk estimates would have
been biased upwards. Although the 15year lag period for quartz exposure used
in the analyses provided slightly higher
risk estimates than use of no lag period,
the better fit seen with the lag may have
been artificial. This may have occurred
because there appeared to have been no
exposures during the recent period
when risks were seen to have increased
(OSHA, 2013b, page 289).
MSHA believes, as OSHA did, that
this study of a large British coal mining
cohort provides convincing evidence of
the carcinogenicity of respirable
crystalline silica. This large cohort
study, with almost 30 years of followup, demonstrated a positive exposureresponse after adjusting for smoking
histories. Additionally, the authors state
that there was no evidence that
exposure to potential confounders such
as radon and diesel exhaust were
associated with excess lung cancer risk
(Miller and MacCalman (2010, page
270). MSHA is relying on the British
studies conducted by Miller et al. (2007)
as well as Miller and MacCalman (2010)
to estimate the lung cancer risk in all
miners.
MSHA found these two studies
suitable for use in the quantitative
characterization of health risks to
exposed miners for several reasons.
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First, their study populations were of
sufficient size to provide adequate
statistical power to detect low levels of
risk. Second, sufficient quantitative
exposure data were available over a
sufficient span of time to characterize
cumulative respirable crystalline silica
exposures of cohort members. Third, the
studies either adjusted for or otherwise
adequately addressed confounders such
as smoking and exposure to other
carcinogens. Finally, these researchers
developed quantitative assessments of
exposure-response relationships using
appropriate statistical models or
otherwise provided sufficient
information that permits MSHA to do
so.
MSHA implemented the risk model in
its life table analysis so that the use of
background rates of lung cancer and
assumptions regarding length of
exposure and lifetime were consistent
across models. Thus, MSHA was able to
estimate lung cancer risks associated
with exposure to specific levels of
respirable crystalline silica of interest to
the Agency. MSHA used the Miller et al.
(2007) and Miller and MacCalman
(2010) model to estimate age-specific
cumulative lung cancer mortality risk as
EXP(0.0524 * cumulative exposure),
lagged 15 years.
MSHA’s FRA uses risk estimates
derived from 10 coal mines in the U.K.
(Miller et al., 2007; Miller and
MacCalman, 2010). These researchers
developed regression analyses for timedependent estimates of individual
exposures to respirable dust. Their
analyses were based on the detailed
individual exposure estimates of the
PFR program. To estimate mortality risk
for lung cancer from the pooled cohort
analysis, MSHA used the same life table
approach as OSHA. However, for this
life table analysis, MSHA used 2018
mortality rates for U.S. males (i.e., allcause and background lung cancer). The
2018 lung cancer death rates were based
on the ICD–10 classification of diseases
codes, C34.0, C34.2, C34.1, C34.3,
C34.8, and C34.9. Lifetime risk
estimates reflected excess risk through
age 80. To estimate lung cancer risks,
MSHA used the log-linear relative risk
model, exp (0.0524 × cumulative
exposure), lagged 15 years. The
coefficient for this model was 0.0524
(OSHA, 2013b, page 290).
MSHA’s use of Miller and MacCalman
(2010) to estimate lung-cancer mortality
risk is in contrast to OSHA’s use of
Steenland et al. (2001a) to estimate
lung-cancer mortality risk. There are
several reasons for MSHA’s use of
Miller and MacCalman (2010). First, it
covers coal mining-specific cohort large
enough (with 45,000 miners) to provide
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adequate statistical power to detect low
levels of risk, and it covers an extended
follow-up period (1959–2006). Second,
the study provided data on cumulative
exposure of cohort members and
adjusted for or addressed confounders
such as smoking and exposure to other
carcinogens. Finally, it developed
quantitative assessments of exposureresponse relationships using
appropriate statistical models or
otherwise provided sufficient
information that permitted MSHA to do
so.
NVMA criticized MSHA’s reliance on
the Miller and MacCalman (2010) study
because, according to the commenter, it
primarily focused on coal miners, does
not consider technological
advancements in the mining sector, and
is ‘‘insufficient for justifying the
implementation of a rule of this
magnitude on MNM mines’’ (Document
ID1441). Commenters from the Black
Lung Clinics and UMWA were in
support of MSHA’s use of Miller and
MacCalman (2010) in assessing lung
cancer mortality (Document ID 1410;
1398).
MSHA does not agree that reliance on
Miller and MacCalman (2010) refutes
the risk of material impairment of health
to MNM miners. MSHA considered
several other studies on lung cancer
mortality, which covered a variety of
populations aside from coal miners,
including gold miners, diatomaceous
earth workers, granite workers,
industrial sand employees, pottery
workers, tin miners, and tungsten
miners. As OSHA showed in its QRA,
the estimates from Miller and
MacCalman (2010) were lower by
roughly two- to four-fold than the
estimates from other cohort studies. In
selecting Miller and MacCalman (2010),
MSHA chose a study that found smaller
risks than the other studies. The Miller
and MacCalman (2010) study has many
strengths, including the fact that it had
very high participation rates, with over
17,000 miners and nearly 30 years of
follow up. In addition to detailed
exposure information, the study also
used individual smoking histories to
adjust its estimates for the effect of
smoking. Further, exposure changes
owing to technological advancements
are accounted for by MSHA’s models
which use recent exposure data.
Urging MSHA to lower the PEL to 25
mg/m3, the AIHA commented that the
work by Steenland and Sanderson
should not be discounted (Document ID
1351). The commenter said that a 2001
Steenland and Sanderson study showed
a significant increase in mortality risk
from lung cancer at average exposure
levels greater than 65 mg/m3, indicating
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that 50 mg/m3 would probably not be
protective of workers’ health.
MSHA clarifies that, although it
departed from OSHA’s risk assessment
by using the exposure-response model
from Miller and MacCalman (2010) to
assess lung cancer mortality, Steenland
and Sanderson’s work was not
discounted. MSHA relied on Steenland
and Sanderson in the standalone Health
Effects document and the FRA. Further,
MSHA acknowledges that there remains
a risk of material impairment of health
at the revised PEL; however, a further
reduction in the PEL is not achievable
at all mines (see MSHA’s Technological
Feasibility analysis). MSHA concludes
that the final PEL will provide a
substantial reduction in the risk of
material impairment of health to miners.
5. ESRD Mortality
Several epidemiological studies have
found statistically significant
associations between occupational
exposure to respirable crystalline silica
and renal disease, although others have
failed to find a statistically significant
association. These studies are discussed
in the standalone Health Effects
document (Section 14). Possible
mechanisms suggested for respirable
crystalline silica-induced renal disease
included a direct toxic effect on the
kidney, deposition of immune
complexes (IgA) in the kidney following
respirable crystalline silica-related
pulmonary inflammation, and an
autoimmune mechanism (Gregorini et
al., 1993; Calvert et al., 1997; Parks et
al., 1999; Steenland, 2005b) (OSHA
2016a, 81 FR 16286, 16310).
MSHA, like OSHA, chose the
Steenland et al. (2002a) study to include
in the FRA. In a pooled cohort analysis,
Steenland et al. (2002a) combined the
industrial sand cohort from Steenland et
al. (2001b), the gold mining cohort from
Steenland and Brown (1995a), and the
Vermont granite cohort studies by
Costello and Graham (1988). All three
were included in portions of OSHA’s
PQRA for other health endpoints: under
lung cancer mortality in Steenland et al.
(2001a) and under silicosis mortality in
the related work of Mannetje et al.
(2002b). In all, the combined cohort
consisted of 13,382 workers with
exposure information available for
12,783. The analysis demonstrated
statistically significant exposureresponse trends for acute and chronic
renal disease mortality with quartiles of
cumulative respirable crystalline silica
exposure (OSHA 2016a, 81 FR 16286,
16310).
The average duration of exposure,
cumulative exposure, and concentration
of respirable crystalline silica for the
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pooled cohort were 13.6 years, 1,200 mg/
m3-years (1.2 mg/m¥3-years), and 70 mg/
m3 (0.07 mg/m3), respectively. Renal
disease risk was most prevalent among
workers with cumulative exposures of
500 mg/m3 or more (Steenland et al.,
2002a). SMRs (compared to the U.S.
population) for renal disease (acute and
chronic glomerulonephritis, nephrotic
syndrome, acute and chronic renal
failure, renal sclerosis, and nephritis/
nephropathy) were statistically
significant and elevated based on
multiple cause of death data (SMR 1.28,
95% CI: 1.10–1.47, 194 deaths) and
underlying cause of death data (SMR
1.41, 95% CI: 1.05–1.85, 51 observed
deaths) (OSHA, 2013b, page 315).
A nested case-control analysis was
also performed which allowed for more
detailed examination of exposureresponse. This analysis included 95
percent of the cohort for which there
were adequate work history and quartz
exposure data. This analysis included
50 cases for underlying cause mortality
and 194 cases for multiple-cause
mortality. Each case was matched by
race, sex, and age within 5 years to 100
controls from the cohort. Exposureresponse trends were examined in a
categorical analysis where renal disease
mortality of the cohort divided by
exposure quartile was compared to U.S.
rates (OSHA, 2013b, page 315).
In this analysis, statistically
significant exposure-response trends for
SMRs were observed for multiple-cause
(p<0.000001) and underlying cause
(p=0.0007) mortality (Steenland et al.,
2002a, Table 1, Page 7).
With the lowest exposure quartile
group serving as a referent, the casecontrol analysis showed monotonic
trends in mortality with increasing
cumulative exposure. Conditional
regression models using log-cumulative
exposure fit the data better than
cumulative exposure (with or without a
15-year lag) or average exposure. Odds
ratios by quartile of cumulative
exposure were 1.00, 1.24, 1.77, and 2.86
(p=0.0002) for multiple cause analyses
and 1.00, 1.99, 1.96, and 3.93 for
underlying cause analyses (p=0.03)
(Steenland et al., 2002a, Table 2, Page
7). For multiple-cause mortality, the
exposure-response trend was
statistically significant for cumulative
exposure (p=0.004) and log-cumulative
exposure (p=0.0002), whereas for
underlying cause mortality, the trend
was statistically significant only for logcumulative exposure (p=0.03). The
exposure-response trend was
homogeneous across the three cohorts
and interaction terms did not improve
model fit (OSHA, 2013b, pages 216,
315).
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Based on the exposure-response
coefficient for the model with the log of
cumulative exposure, Steenland (2005b)
estimated lifetime excess risks of death
(age 75) over a working life (age 20 to
65). At 100 mg/m3 (0.1 mg/m3) respirable
crystalline silica, this risk was 5.1
percent (95% CI 3.3–7.3) for ESRD
based on 23 cases (Steenland et al.,
2001b). It was 1.8 percent (95% CI 0.8–
9.7) for kidney disease mortality
(underlying), based on 51 deaths
(Steenland et al., 2002a) above a
background risk of 0.3 percent (OSHA,
2013b, page 216).
MSHA notes that these studies added
to the evidence that renal disease is
associated with respirable crystalline
silica exposure. Statistically significant
increases in odds ratios and SMRs were
seen primarily for cumulative exposures
of >500 mg/m3-years (0.5 mg/m3-years).
Steenland (2005b) noted that this could
have occurred from working for 5 years
at an exposure level of 100 mg/m3 (0.1
mg/m3) or 10 years at 50 mg/m3 (0.05
mg/m3).
OSHA had a large body of evidence,
particularly from the three-cohort
pooled analysis (Steenland et al.,
2002a), on which to conclude that
respirable crystalline silica exposure
increased the risk of renal disease
mortality and morbidity. The pooled
analysis by Steenland et al. (2002a)
involved a large number of workers
from three cohorts with welldocumented, validated job-exposure
matrices. These researchers found a
positive, monotonic increase in renal
disease risk with increasing exposure
for underlying and multiple cause data.
Thus, the exposure and work history
data were unlikely to have been
seriously misclassified. However, there
are considerably less data available for
renal disease than there are for silicosis
mortality and lung cancer mortality.
Nevertheless, OSHA concluded that the
underlying data were sufficient to
provide useful estimates of risk and
included the Steenland et al. (2002a)
analysis in its PQRA (OSHA, 2013b,
pages 229, 316).
To estimate renal disease mortality
risk from the pooled cohort analysis,
OSHA implemented the same life table
approach as was done for the
assessments on lung cancer and NMRD.
However, for this life table analysis,
OSHA used 1998 all-cause and
background renal mortality rates for
U.S. males, rather than the 2006 rates
used for lung cancer and NMRD. The
1998 rates were based on the ICD–9
classification of diseases, which was the
same as used by Steenland et al. (2002a)
to ascertain the cause of death of
workers in their study. However, U.S.
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cause-of-death data from 1999 to present
are based on the ICD–10, in which there
were considerable changes in the
classification system for renal diseases.
According to CDC (2001), the change in
the classification from ICD–9 to ICD–10
increased death rates for nephritis,
nephritic syndrome, and nephrosis by
23 percent, in large part due to
reclassifying ESRD. The change from
ICD–9 to ICD–10 did not materially
affect background rates for those
diseases grouped as lung cancer or
NMRD. Consequently, OSHA conducted
its analysis of excess renal disease
mortality associated with respirable
crystalline silica exposure using
background mortality rates for 1998. As
before, lifetime risk estimates reflected
excess risk through age 85. To estimate
renal mortality risks, OSHA used the
log-linear model with log-cumulative
exposure that provided the best fit to the
pooled cohort data (Steenland et al.,
2002a). The coefficient for this model
was 0.269 (SE=0.120) (OSHA, 2013b,
page 316). Based on the life table
analysis, OSHA estimated that exposure
to the former general industry exposure
limit of 100 mg/m3 and to the final
exposure limit of 50 mg/m3 over a
working life would result in a lifetime
excess renal disease risk of 39 (95% CI:
2–200) and 32 (95% CI: 1.7–147) deaths
per 1,000, respectively. OSHA also
estimated lifetime risks associated with
the former construction and shipyard
exposure limits of 250 and 500 mg/m3.
These lifetime excess risks ranged from
52 (95% CI 2.2–289) to 63 (95% CI 2.5–
368) deaths per 1,000 workers (OSHA,
2013b, page 316).
MSHA acknowledges the uncertainty
associated with the divergent findings
in the renal disease literature; however,
MSHA concludes that the evidence
supporting causality regarding renal risk
outweighs the evidence casting doubt
on that conclusion.
Upon reviewing the PRA, the NSSGA
commented that it is unclear whether
renal disease is causally related to
occupational respirable crystalline silica
exposure (Document ID 1448,
Attachment 3). The commenter cited a
2017 German Federal Institute for
Occupational Safety and Health
systematic review and meta-analysis on
respirable crystalline silica and nonmalignant renal disease, which
concluded that ‘‘while the studies of
cohorts exposed to silica found elevated
SMRs for renal disease, no clear
evidence of a dose-response relationship
emerged.’’ As detailed above in Section
V. Health Effects Summary and further
discussed in MSHA’s standalone Health
Effects document, MSHA reviewed a
wide variety of studies which suggest
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that occupational exposure to respirable
crystalline silica increases the risk of
renal disease, including the risk of nonmalignant cases. The Steenland et al.
(2002a) study, which was selected for
modeling ESRD risk in the FRA, found
a monotonic increase in renal disease
risk with increasing exposures to
respirable crystalline silica. MSHA
believes that the Steenland et al. (2002a)
study has several strengths, including
(1) a large cohort with well-documented
and validated job-exposure matrices and
(2) low risk of bias from exposure
misclassification. The FRA has selected
studies for modeling risks based on a
thorough evaluation of each study’s
methodology. The fact that other studies
(which MSHA did not use for modeling)
may have found significantly elevated
mortality ratios but inconclusive
exposure-response relationships does
not render invalid the findings or
methodological strengths of Steenland
et al. (2002a). Thus, MSHA concludes
that increasing exposure to respirable
crystalline silica increases a miner’s risk
of renal disease and reaffirms its
decision to model benefits stemming
from reductions in ESRD mortality due
to the final rule in the FRA.
To estimate renal disease mortality
risk from the pooled cohort analysis,
MSHA implemented the same life table
approach as OSHA. However, MSHA’s
life table analysis used 2018 all-cause
and 1998 background renal mortality
rates for U.S. males. The 1998 renal
death rates were based on the ICD–9
classification of diseases, 580–589. This
is the same classification used by
Steenland et al. (2002a) to ascertain the
cause of death of workers in their study.
Consequently, MSHA conducted its
analysis of excess ESRD mortality risk
associated with exposure to respirable
crystalline silica using background
ESRD mortality rates for 1998. The U.S.
cause-of-death data from 2018 were
used as well to estimate the rate of death
due to all causes among the unexposed
population. Lifetime excess risk
estimates reflect the excess risk through
age 80. To estimate ESRD excess
mortality risks, MSHA used the loglinear model with log-cumulative
exposure that provided the best fit to the
pooled cohort data (Steenland et al.,
2002a), as EXP(0.269*ln(cumulative
exposure)). The coefficient for this
model was 0.269 (SE=0.120) (OSHA,
2013b, page 316). 6. Coal Workers’
Pneumoconiosis (CWP) and Progressive
Massive Fibrosis (PMF).
Exposure to respirable coal mine dust
causes lung diseases including CWP,
emphysema, silicosis, and chronic
bronchitis, known collectively as ‘‘black
lung.’’ These diseases are debilitating,
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28269
incurable, and can result in disability
and premature death. There are no
specific treatments to cure CWP or
COPD. These chronic effects may
progress even after miners are no longer
exposed to coal dust.
MSHA’s 2014 Coal Dust Rule
quantified benefits among coal miners
related to reduced cases of CWP due to
lower exposure limits for respirable coal
mine dust. In the FRA, MSHA has not
quantified the reduction in morbidity
risk associated with CWP among coal
miners. Nonetheless, MSHA believes
that the final rule would reduce the
excess risk of morbidity from this
disease. Many coal miners work
extended shifts, increasing their
potential exposure to respirable
crystalline silica; therefore, calculating
exposures based on a full-shift 8-hour
TWA would be more protective. Thus,
the final rule is expected to provide
additional reductions in CWP risk
beyond those ascribed in the 2014 Coal
Dust Rule. However, exposure-response
relationships based on respirable
crystalline silica exposure are not
available for CWP, so the reductions in
this disease due to reductions in silica
exposure cannot be quantified.
In the FRA, PMF deaths are captured
in part by silicosis mortality as defined
by Mannetje et al. (2002b). Those PMF
deaths not captured by the definition in
Mannetje et al. are likely captured by
the definition of NMRD mortality
adopted from Park et al. (2002). Thus,
the FRA fully characterizes the
reduction in lifetime cases of PMF
mortality including mortality due to
complicated CWP and complicated
silicosis. However, the FRA likely
underestimates reduction in PMF
morbidity. This is because the
Buchanan et al. (2003) model, which
was used to model silicosis morbidity,
likely undercounts PMF due to
exclusion of cases below the threshold
of 2/1+ profusion of opacities on a chest
X-ray. While the FRA quantifies
reduction in lifetime mortality cases
from CWP and PMF (which are
included under NMRD), there are likely
additional unquantified morbidity
benefits from CWP and PMF that are not
captured.
Finally, the Appalachian Voices
expressed concern that the modeling
conducted for the rule does not
incorporate data that medical clinics in
Appalachia have reported since 2010
(Document ID 1425). This commenter
stated that, while not all cases can be
attributed directly to silica exposure,
reporting over the last 15 years has led
medical experts to believe that silica is
a significant driver of the increased
prevalence of severe black lung disease
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in Central Appalachia, and that any rule
designed to reduce silica exposure
should consider data from clinics in
Central Appalachia to ensure a more
realistic accounting of current morbidity
and set a high goal for future morbidity.
This commenter urged MSHA to review
data from black lung clinics in Central
Appalachia.
MSHA notes that comprehensive
longitudinal clinical outcome data,
paired with exposure histories, are not
available for U.S. miners. MSHA
acknowledges that these data would be
useful for the purpose of estimating risk
reductions and acknowledges that the
exposure-response models used in this
FRA are not based on current disease
incidence among U.S. miners. While
clinic data help document
pneumoconiosis as an important
problem, these data alone are not
sufficient to estimate the reduction in
excess morbidity and mortality that are
specifically attributable to the new PEL.
Calculating future miners’ reduction in
excess cases from the current disease
incidence reported by clinics would
also require those clinic patients’
exposure and work histories, which are
not available. Moreover, the data from
medical clinics in Appalachia represent
only a portion of miners whose
respirable crystalline silica exposures
may have exceeded the existing
standard and who may have worked
during a time when the coal mining
industry was larger. The methodology of
the FRA is to use peer-reviewed
exposure-response models to estimate
avoided excess deaths and illnesses that
are specifically attributable to reducing
respirable crystalline silica exposure
from, at most, the existing standard to
the new PEL of 50 mg/m3. MSHA has not
quantified reductions in simple or
complicated CWP morbidity, as an
exposure-response model for respirable
crystalline silica and CWP is not
available, and this final rule does not
regulate levels of coal dust. Nonetheless,
miners will likely see reductions in
CWP risk, including risk of severe forms
of CWP such as PMF, due to the final
rule, since respirable crystalline silica
exposure may play a role in
development of CWP, and because
concentrations of mixed coal dust may
decrease due to this rule. These benefits
associated with reductions in CWP
mortality and morbidity are not
quantified in the FRA.
D. Overview of Results
Table VI–4 summarizes the FRA’s
main results: once all miners and
retirees have only been exposed under
the new PEL, the final rule is expected
to result in at least 1,067 avoided deaths
and 3,746 avoided cases of silicosis
morbidity among the working and
future retired miner population. This is
a change from the PRA, which predicted
at least 799 avoided deaths and 2,809
avoided cases of silicosis morbidity in
the working miner population. The
increased avoided deaths and cases in
the FRA are the result of changes to
MSHA’s risk analysis methodology;
specifically, the inclusion of future
retired miners. This methodological
change is discussed in detail in the
standalone FRA. The expected
reductions in death and illness in the
FRA are based on actual exposure
conditions, peer-reviewed exposureresponse models, and the assumption
that miners have 45 years of
employment under the new PEL (from
the beginning of age 21 through the end
of age 65) and 15 years of retirement (up
through the end of age 80). These
estimates of the avoided lifetime excess
mortality and morbidity represent the
final calculations based on the five
selected models and the observed
exposure data. The first group of miners
that will experience the avoided lifetime
deaths and illnesses shown in Table VI–
4 is the population living 60 years after
the start of implementation of the final
rule. In other words, this group will
only contain miners exclusively
exposed under the final rule for the
duration of their working lives. To
calculate benefits associated with the
rulemaking, the economic analysis
monetizes avoided deaths and illnesses
while accounting for the fact that,
during the first 60 years following the
start of implementation of the final rule,
miners will have fewer avoided lifetime
deaths and illnesses because they will
have been exposed under both the
existing standards and the new PEL.
Table VI-4: Lifetime Excess Cases of Death and Illness Avoided Due to Implementation
of New Exposure Limit
Health Outcome
Morbiditv
3,421
325
3,746
Silicosis (excluding deaths)
Total
3,421
325
3,746
Mortality
233
15
248
Silicosis
Lung cancer
75
7
82
NMRD (excluding silicosis deaths)
489
47
536
ESRD
185
15
200
Total
982
85
1,067
Notes:
Due to rounding, some totals do not exactly equal the sum of the corresponding individual entries.
Table VI–5 summarizes miners’
expected percentage reductions in
lifetime excess risk of developing or
dying from certain diseases due to their
reduced respirable crystalline silica
exposure expected to result from
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implementation of the final rule. The
lifetime excess risk reflects the
probability of developing or dying from
diseases over a maximum lifetime of 45
years of exposure during employment
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and 15 years of retirement.25 The excess
25 In the model, not every miner lives through age
80, and deaths occur at the expected rate given the
all-cause mortality rates and given miners’ elevated
mortality risk due to their exposure to respirable
crystalline silica. Excess risks stop accruing after
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Avoided Cases of Death (Mortality) or Illness (Morbidity) by
Sector
MNM
Coal
Total
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risk reduction compares (a) miners’
excess health risks associated with
respirable crystalline silica exposure at
the limits included in MSHA’s existing
standards to (b) miners’ excess health
risks associated with exposure at this
standard’s new PEL. MSHA expects fullscale implementation to reduce lifetime
excess mortality risk by 9.5 percent and
to reduce lifetime excess silicosis
28271
morbidity risk by 41.9 percent. Excess
mortality risk includes the excess risk of
death due to silicosis, NMRD, lung
cancer, and ESRD.
Table VI-5: Lifetime Excess Risk Reduction Due to Implementation of
New Exposure Limit
Percentage Reduction in Lifetime Excess Risk of Death
(Mortalit, ) or Illness (Morbidity) by Sector
MNM
Coal
Total
Health Outcome
Morbidity
Silicosis (excluding deaths)
Total
Mortality
Silicosis
NMRD (excluding silicosis deaths)
Lung cancer
47.2%
47.2%
19.2%
19.2%
41.9%
41.9%
21.2%
20.8%
4.9%
5.8%
17.6%
17.0%
Table VI–6 presents MSHA’s
estimates of lifetime excess risk per
1,000 miners at exposure levels equal to
the existing standards, the new PEL, and
the action level. These estimates are
adjusted for FTE ratios and thus utilize
cumulative exposures that more closely
reflect the average hours worked per
year.26 For an MNM miner who is
presently exposed at the existing PEL of
100 mg/m3 (and given the weighted
average FTE ratio of 0.87),
implementing the new PEL will lower
the miner’s lifetime excess risk of death
by 58.8 percent for silicosis, 45.7
percent for NMRD (not including
silicosis), 52.7 percent for lung cancer,
and 19.9 percent for ESRD. The MNM
miner’s risk of acquiring a non-fatal case
of silicosis will decrease by 80.4
percent.
For a coal miner who is currently
exposed at the existing standard of 85.7
mg/m3 (and given the weighted average
FTE ratio of 0.99), implementing the
new PEL will lower the miner’s lifetime
excess risk of death by 42.6 percent for
silicosis mortality, 40.2 percent for
NMRD mortality (not including
silicosis), 43.4 percent for lung cancer
mortality, and 15.8 percent for ESRD
mortality. The coal miner’s lifetime
excess risk of acquiring non-fatal
silicosis will decrease by 73.8 percent.
While even greater reductions would be
achieved at exposures equal to the
action level (25 mg/m3), some residual
risks do remain at exposures of 25 mg/
m3. Notably, at the action level, ESRD
risk is still 20.7 per 1,000 MNM miners
and 21.6 per 1,000 coal miners. At the
action level, risk of non-fatal silicosis is
16.3 per 1,000 MNM miners and 16.9
per 1,000 coal miners.
death, and the life table methodology accounts for
these deaths. For example, only roughly half of an
original cohort of 21-year-old miners are expected
to be alive at the start of age 80.
26 The FTE ratios used in these calculations are
a weighted average of the FTE ratio for production
employees and the FTE ratio for contract miners.
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23.0%
6.3%
19.0%
4.2%
0.9%
3.2%
ESRD
12.0%
2.8%
9.5%
Total
Notes:
Due to rounding, some totals do not exactly equal the sum of the corresponding individual entries.
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table VI-6: Lifetime Excess Risk (per 1,000 Miners) for Selected Health Endpoints at
Respirable Crystalline Silica Exposure Levels Equal to the Existing Standards, New
PEL, and Action Level
MNM
Health Outcome (Study)
Coal
100 µg/m 3
50 µg/m 3
25 µg/m 3
85.7 µg/m 3
50 µg/m 3
25 µg/m 3
Silicosis Morbidity
(Buchanan et al., 2003)
206.7
43.6
18.7
189.9
54.2
21.0
Silicosis Morbidity
(Net of Silicosis Mortality) 1
192.4
37.7
16.3
175.9
46.1
16.9
Silicosis Mortality
(Mannetje et al., 2002)
14.3
5.9
2.5
14.1
8.1
4.1
NMRD Mortality
(Park et al., 2002)
54.8
27.9
14.1
53.2
31.5
15.9
NMRD Mortality
(Net of Silicosis Mortality)2
40.5
22.0
11.6
39.1
23.4
11.9
Lung Cancer Mortality
(Miller and MacCalman,
2010)
5.5
2.6
1.3
5.3
3.0
1.5
ESRD Mortality
(Steenland et al., 2002a)
32.6
26.1
20.7
32.3
27.2
21.6
Notes:
1. The lifetime excess silicosis morbidity risk (net of silicosis mortality) is the difference between (a) the lifetime excess
silicosis risk computed from the Buchanan et al. model and (b) the lifetime excess risk of silicosis mortality computed from
the Mam1etje et al. model.
2. NMRD (net) mortality risk is the difference between projected total NMRD mortality risk and projected silicosis
mortality risk.
3. Values may not sum to total due to rounding.
4. Lifetime excess risk values are based on annual exposure durations that are scaled by a weighted average FTE ratio for
contract miners and miners (excluding contract miners). For MNM miners, this ratio is 0.87. For coal miners, this ratio is 0.99.
Supporting the need for the proposed
rule overall, the National Black Lung
Association (NBLA) cited a 2023
investigation (Berkes and Hicks, 2023),
which the commenter said reported
21,000 excessive respirable crystalline
silica dust exposures from 1986 to 2016
(Document ID 1402). In its above review
of exposure data, MSHA also found
exposures that exceeded the new PEL.
On the other hand, questioning the
necessity of the proposed rule for the
coal industry, the Pennsylvania Coal
Alliance asserted that only 1.2 percent
of the samples MSHA relied on for its
analysis showed an exceedance of 100
mg/m3 (Document ID 1378).
While coal exposure data since 2016
may indicate a recent trend of less
frequent noncompliance, 6.9 percent of
samples for coal miners showed an
exceedance of the new PEL. As Table
VI–6 demonstrates, reducing a coal
miner’s exposure from 85.7 mg/m3 to 50
mg/m3 is expected to reduce his total
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silicosis morbidity risk by 71 percent
(from 189.9 to 54.2 per 1,000), reduce
his silicosis mortality risk by 43 percent
(from 14.1 to 8.1 per 1,000), reduce his
total NMRD mortality by 41 percent
(from 53.2 to 31.5 per 1,000), reduce his
lung cancer mortality risk by 43 percent
(from 5.3 to 3.0 per 1,000), and reduce
his ESRD mortality by 16 percent (from
32.3 to 27.2 per 1,000). Additionally, for
a typical coal miner exposed between 50
mg/m3 and 85.7 mg/m3, the new PEL is
expected to reduce his silicosis
morbidity risk by 46 percent (from 79.5
to 54.3 per 1,000), reduce his lung
cancer mortality risks by 22 percent
(from 3.6 to 3.0 per 1,000), reduce his
silicosis mortality risk by 15 percent
(from 9.4 to 8.1 per 1,000), reduce his
NMRD mortality risk by 20 percent
(from 37.9 to 31.5 per 1,000), and reduce
his ESRD mortality risk by 6 percent
(from 28.9 to 27.2 per 1,000). The
benefits calculated in the main analysis
of the FRA represent only those benefits
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of reducing exposures from, at most, the
existing standard to the new PEL of 50
mg/m3. Even when assuming compliance
with the existing standard, the results of
the FRA affirm the need for the rule for
all mining industries.
E. Healthy Worker Bias
MSHA accounted for ‘‘healthy worker
survivor bias’’ in estimating the risks for
coal and MNM miners. The healthy
worker survivor bias causes
epidemiological studies to
underestimate excess risks associated
with occupational exposures. As with
most worker populations, miners are
composed of heterogeneous groups that
possess varying levels of background
health. Over the course of miners’
careers, illness tends to remove the most
at-risk workers from the workforce
prematurely, thus causing the highest
cumulative exposures to be experienced
by the healthiest workers who are most
resistant to developing disease. Failing
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to account for this imbalance of
cumulative exposure across workers
negatively biases risk estimates, thereby
underestimating true risks in the
population. Keil et al. (2018) analyzed a
type of healthy worker bias referred to
as the healthy worker survivor bias in
the context of OSHA’s 2016 life table
estimates for risk associated with
respirable crystalline silica exposure.
After analyzing data from 65,999
workers pooled across multiple
countries and industries, Keil et al.
found that the ‘‘healthy worker survivor
bias results in a 28% underestimate of
risk for lung cancer and a 50%
underestimate for other causes of
death,’’ with risk being defined as
‘‘cumulative incidence of mortality [at
age 80].’’
Given that MSHA has calculated risks
using the same underlying
epidemiological studies OSHA used in
2016, the healthy worker survivor bias
is likely impacting the estimates in
Table V–6 of lifetime excess risk and
lifetime excess cases avoided.
Accordingly, as part of a sensitivity
analysis, MSHA re-estimated risks for
MNM and coal miners to account for the
healthy worker survivor bias. MSHA
adjusted for this effect by increasing the
risk estimates of lung cancer risk by 28
percent and increasing the risk of each
other disease by 50 percent. This
produced larger estimates of lifetime
excess risk reductions and lifetime
excess cases avoided, which are
presented in FRA Table 23 through FRA
Table 26 of the FRA document. As these
tables show, when adjusting for the
healthy worker survivor bias, the new
PEL will decrease lifetime silicosis
morbidity risk by 23.9 cases per 1,000
MNM miners (compared to the
unadjusted estimate of 15.9 cases per
1,000 MNM miners, see FRA Table 15
of the FRA document) and 5.8 cases per
1,000 coal miners (compared to 3.8
cases per 1,000 coal miners, see FRA
Table 16 of the FRA document). Still
accounting for the healthy worker
survivor bias, the new PEL will decrease
total morbidity by 5,131 lifetime cases
among MNM miners (compared to 3,421
cases, see FRA Table 17 of the FRA
document) and by 487 lifetime cases
among coal miners (compared to 325
cases, see FRA Table 18 of the FRA
document). Among the current MNM
and coal mining populations,
implementation of the new PEL during
their full lives will have avoided 1,457
deaths and 126 deaths, respectively,
over their lifetimes (compared to
unadjusted estimates of 982 deaths and
85 deaths, respectively).
MSHA believes adjusted estimates for
the healthy worker survivor bias are
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more reliable than unadjusted estimates.
However, given that the literature does
not support specific scaling factors for
each of the health endpoints analyzed,
these adjustments for the healthy
worker survivor bias have not been
incorporated into the final lifetime
excess risk estimates that served as the
basis for monetizing benefits. Because
the monetized benefits do not account
for the healthy worker bias, MSHA
believes the reductions in lifetime
excess risks and lifetime excess cases, as
well as the monetized benefits, likely
underestimate the true reductions and
benefits attributable to the final rule.
The ACLC provided comments that
the agency’s proposed rule would do
little to alter the status quo (Document
ID 1445). Specifically, this commenter
cited the findings of the PRA that
thousands of miners would continue to
get sick and die from overexposure to
silica dust under the new proposed rule
(Document ID 1445). Recommending
that the Agency should focus on entirely
preventing any disability or disease
from inhaling silica dust, the
commenter urged MSHA to strengthen
the proposed rule such that the vast
majority of miner lives will be saved
over the coming decades (Document ID
1445). MSHA acknowledges that
reducing respirable crystalline silica
concentrations to 25 mg/m3 would
further reduce morbidity and mortality
amongst miners. However, MSHA
determined that a PEL of 25 mg/m3
would not be achievable for all mines.
Also, upon reviewing these results,
many commenters, including the ACLC,
the American Thoracic Society, the
American Lung Association, and the
American College of Chest Physicians
(hereafter referred to as ‘‘The American
Thoracic Society et al.’’), Appalachian
Voices, USW, and the AOEC discussed
how silica-related diseases are becoming
more prevalent and/or severe in miners
(Document ID 1445; 1421; 1425; 1447;
1373; 1391; 1439; 1372; 1353; 1375).
They expressed concern that recently
there has been an increase in cases of
black lung disease, pneumoconiosis,
and other related illnesses. The
American Thoracic Society et al. stated
that the increase in the number of cases
is due to increasing silica exposures in
mining processes, citing studies
supporting this point (Cohen et al.,
2016, 2022) (Document ID 1421).
Appalachian Voices added that research
has found that black lung disease is
occurring at its highest level in decades,
is affecting more younger miners now
than in the past, and is more frequently
presenting in its more severe form, PMF
(Document ID 1425). The ACLC echoed
this point, stating that, in the 1990s, the
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worst forms of black lung disease (i.e.,
PMF) had almost been eradicated in the
United States (Document ID 1445). This
commenter expressed concern that the
prevalence of black lung disease has
grown in the past decade, and clinics in
eastern Kentucky and southwest
Virginia have diagnosed hundreds of
cases of PMF. The commenter cited a
new analysis of data from NIOSH and
black lung clinics that, according to the
commenter, reveals more than 4,000
cases of the most advanced form of
black lung since 2010, as well as more
than 1,500 advanced black lung
diagnoses in just the last 5 years
(Document ID 1445). The UMWA
described surveillance findings from the
National Academies of Sciences,
Engineering, and Medicine (NASEM)
that severe pneumoconiosis where
respirable crystalline silica is likely an
important contributor is presenting in
relatively young miners, sometimes in
their late 30s and early 40s (Document
ID1398). The ACLC and UMWA
expressed concern that the risk
estimates presented in the PRA heavily
underestimated the avoided cases
because it severely underestimated
current disease incidence (Document ID
1445; 1398).
There are a number of reasons why
current incidence of disease would be
higher than estimates in the FRA:
• For all diseases except silicosis, the
FRA does not present the total number
of cases that are expected in the future.
The FRA only presents the number of
excess cases that miners experience due
to their occupational exposure to
respirable crystalline silica. For
example, the FRA presents an estimated
1,794 excess ESRD deaths over the next
60 years under the baseline scenario
among coal miners. This estimate would
rise from 1,794 to 2,407 when including
all ESRD deaths and not just the excess
ESRD deaths attributable to respirable
crystalline silica exposure.22 For
silicosis and PMF, the number of excess
cases equals the number of total cases,
since MSHA assumes non-miners have
no background risk of silicosis or PMF.
• There is a lag between the time
when exposure occurred and new
diagnoses. Many of the new cases of
silicosis and PMF that are currently
being diagnosed in coal miners are for
individuals who likely worked during a
time when the coal mining industry was
substantially larger than (e.g., roughly
double) its current size. The number of
miners who are being diagnosed today
belong to larger cohorts than those
currently entering the mining
workforce. Consequently, the number of
disease cases and deaths amongst
retired miners 60 years in the future
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would be expected to be lower than that
amongst currently retired miners
because the latter group is larger in size.
• Additionally, as the FRA explains,
the Baseline scenario involves reducing
all noncompliant exposures to the
existing standard (100 mg/m3 for MNM
or 85.7 mg/m3 for coal). This is done to
avoid attributing benefits to this rule
which should instead be attributed to a
previous rule. Consistent with this
approach, MSHA also has not estimated
the cost to become compliant with
existing standards. Capping
noncompliant exposures at 100 mg/m3
for MNM or 85.7 mg/m3 for coal
increases the discrepancy between the
present-day incidence and expected
future cases under the baseline scenario.
For coal miners, estimates of avoided
cases assume that, in the absence of this
rule, miners would be exposed to the
same levels of respirable crystalline
silica that have been observed in the
coal compliance data from 2016 through
2021. This more recent period was
selected to account for the fact that
MSHA’s 2014 RCMD Standard likely
reduced concentrations of respirable
crystalline silica. Coal miners who are
being diagnosed with silicosis and PMF
today likely suffered from higher
exposures than those represented by
more recent compliance data, which
would lead to higher incidence of
silicosis and PMF than the QRA projects
for future miners.
• For PMF morbidity, not all cases of
this disease are quantified in the FRA.
The term ‘‘PMF’’ is used to refer to
complicated CWP (caused by coal dust
exposure) and to refer to complicated
silicosis (caused by respirable
crystalline silica exposure). The FRA
only captures silicosis profusion 2/1+
morbidity (which may overlap partially
with some definitions of PMF) but does
not quantify benefits associated with
reducing CWP morbidity.
F. Uncertainty Analysis
MSHA conducted extensive
uncertainty analyses to assess the
impact on risk estimates of factors
including treatment of data in excess of
the new PEL, sampling error, and use of
average rather than median point
estimates for risk. The impact of
excluding insufficient mass (weight)
samples was also examined. As
discussed below, some sources of
uncertainty suggest that miners’ risks
may be lower than what MSHA
modeled, and other sources suggest that
risks may be higher. MSHA’s estimates
represent central values, which are
based on the most reliable data and
assumptions. Moreover, the overall
weight-of-evidence indicates that
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increased exposures to respirable
crystalline silica cause increased risk of
mortality and morbidity, from which it
follows that reduced exposures would
lead to reduced risks.
1. Sampling Error in Exposure Data
To quantify the impact of sampling
uncertainty on the risk estimates, 1,000
bootstrap resamples of the original
exposure data were generated (sampling
with replacement). The resamples were
stratified by commodity to preserve the
relative sampling frequencies of coal,
metal, non-metal, sand and gravel,
crushed limestone, and stone
observations in the original dataset. Risk
calculations were repeated on each of
the 1,000 bootstrap samples, thereby
generating empirical distributions for all
risk estimates. From these empirical
distributions, 95 percent confidence
intervals were calculated. These
confidence intervals characterize the
uncertainty in the risk estimates arising
from sampling error in the exposure
data. All lifetime excess risk estimates
had narrow confidence intervals,
indicating that the estimates of lifetime
excess morbidity and mortality risks
have a high degree of precision.
In regard to use of average, rather than
median, point estimates of risk, the
estimates acquired from average
exposures are similar to the estimates
from median exposures, with 95 percent
confidence intervals having similar
widths. However, the 95 percent
confidence intervals are not always
overlapping, and average exposures
tended to yield higher estimates of
reduced morbidity and mortality.
Among MNM miners, MSHA expects
the new PEL to reduce lifetime excess
cases of silicosis morbidity by 3,394–
3,703 when using average exposures to
model risks (see FRA Table 41 of the
FRA document), compared to 3,271–
3,576 fewer cases when using median
exposures to model risks (see FRA Table
37 of the FRA document). Among coal
miners, this reduction in excess cases of
silicosis morbidity is expected to be
328–372 when using average exposures
(see FRA Table 42 of the FRA
document), compared to 305–354 when
using median exposures (see FRA Table
38 of the FRA document). The new PEL
is estimated to prevent 981–1,056 MNM
miner deaths and 87–97 coal miner
deaths when using average exposures to
model risks (see FRA Tables 41 and 42
of the FRA document), compared to
945–1,020 fewer MNM miner deaths
and 80–92 fewer coal miner deaths
using median exposures to model risks
(see FRA Tables 37 and 38 of the FRA
document).
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2. Alternate Treatment of Exposure
Samples in Excess of the New Exposure
Limit
To estimate excess risks and excess
cases under the new PEL, MSHA
assumed that no exposures will exceed
the new limit, which effectively reduced
any exposures exceeding 50 mg/m3 to 50
mg/m3. However, if mines implement
controls with the goal of reducing
exposures to 50 mg/m3 on every shift,
then some exposure currently in excess
of 50 mg/m3 will likely decrease below
the new PEL. For this reason, the
estimation method of capping all
exposure data at 50 mg/m3 represents a
‘‘lowball’’ estimate of risk reductions
due to the new PEL. In this section,
MSHA presents estimates using an
alternate ‘‘highball’’ method wherein
exposures exceeding 50 mg/m3 are set
equal to the median exposure value for
the 25–50 mg/m3 exposure group.
Because this highball method attributes
larger reductions in exposure to the new
PEL, it estimates higher lifetime excess
risk reductions and more avoided
lifetime excess cases.
As with lifetime excess risks, the
highball method also yields larger
reductions in lifetime excess cases.
Using the highball method, MNM
miners are expected to experience 4,148
fewer cases of non-fatal silicosis and
coal miners are expected to experience
446 fewer cases of non-fatal silicosis
over their lifetimes. MNM miners would
experience 1,519 fewer deaths and coal
miners would experience 164 fewer
deaths over their lifetimes. Compared to
the lowball method—which estimates
that the new PEL would avoid a total of
3,746 lifetime cases of non-fatal silicosis
and 1,067 lifetime excess deaths (among
both MNM and coal miners)—the
highball method estimates totals of
4,594 avoided lifetime cases of non-fatal
silicosis and 1,683 avoided lifetime
excess deaths.
3. Samples With Insufficient Mass
The MSHA Laboratory does not
analyze samples for respirable
crystalline silica that do not meet a
minimum threshold for total respirable
dust mass. The MNM exposure data
gathered by enforcement from January 1,
2005, through December 31, 2019,
contain samples that were analyzed
using the P–2 method. As discussed, the
P–2 method specifies that filters are
only analyzed for quartz if they achieve
a net mass (weight) gain of 0.100 mg or
more. If cristobalite is requested, a mass
gain of 0.050 mg or more is required for
a filter to be analyzed (MSHA, 2022c).
During the 15-year sample period for
MNM exposure data, 40,618 MNM
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samples were not analyzed because the
filter failed to meet the P–2 minimum
net mass gain requirements.
Similarly, the coal exposure data
gathered by enforcement from August 1,
2016, through July 31, 2021, contains
samples that were analyzed using the P–
7 method. For samples taken in
underground mines, the P–7 method
requires a minimum sample mass of
0.100 mg 27 of dust for the sample to be
analyzed for quartz. For samples taken
in surface coal mines, the P–7 method
typically requires a minimum sample
mass of 0.200 mg of dust for the sample
to be analyzed for quartz. During the
five-year sample period for coal
exposure data, 32,401 valid full-shift
coal samples were not analyzed because
the P–7 method’s minimum mass
requirement was not met.
MNM and Coal samples that did not
meet the MSHA Laboratory’s minimum
mass criteria were excluded from the
risk analysis because their
concentrations of respirable crystalline
silica are not known. The unanalyzed
samples all had very low total respirable
dust mass, making it unlikely that many
would have exceeded the existing
standards or the new PEL. Nonetheless,
excluding these unanalyzed samples
from the exposure datasets may
introduce bias, potentially causing the
Agency to overestimate the proportion
of high-intensity exposure values.
As a sensitivity analysis, MSHA used
imputation techniques to estimate the
respirable crystalline silica mass for
each sample based on the sample weight
and the median percent silica content
for each commodity and occupation. All
the unanalyzed samples with imputed
concentrations were estimated to be <25
mg/m3, and thus including these
unanalyzed samples in the analysis
leads to lower estimates of estimated
lifetime excess cases for both MNM and
coal miners.
When including the imputed values
for the unanalyzed samples, the new
PEL would result in 2,327 fewer cases
of non-fatal silicosis among MNM
miners and 171 fewer cases among coal
miners, over their lifetimes. The new
PEL would also result in 666 fewer
deaths (due to all 4 diseases) among
MNM miners and 46 fewer deaths
among coal miners, over their lifetimes.
This yields a total reduction in lifetime
excess morbidity of 2,498 miner deaths
and a total reduction in lifetime excess
mortality of 712 miner deaths. While
27 Often the threshold for analyzing Coal samples
is ≥0.1 mg. There are, however, some exceptions
based on Sample Type and Occupation Code. For
samples with Sample Type 4 or 8, if the sample’s
Occupation Code is not 307, 368, 382, 383, 384, or
386, then the threshold is ≥0.2 mg.
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these estimates are lower than those
presented in Table VI–4 (of 3,746
avoided lifetime cases of non-fatal
silicosis and 1,067 avoided lifetime
excess deaths), MSHA nonetheless
believes that—even including these
unanalyzed samples—the new PEL
would still reduce the risk of material
impairment of health or functional
capacity in miners exposed to respirable
crystalline silica. Moreover, the possible
positive bias that may arise when
excluding these samples would be offset
by other negative biases discussed
herein (e.g., the healthy worker survivor
bias and the assumption that full
compliance with the new PEL would
not produce any reductions in exposure
below 50 mg/m3).
It should be noted that the imputation
method has some limitations. For
example, the method assumes that, if
the insufficient mass samples had been
analyzed, every sample would have
possessed a percentage of quartz, by
mass, equal to the median percentage
for that sample’s associated commodity
and occupation. (See Section 17.1 of the
standalone FRA document for a full
discussion of the imputation method.)
However, within a given occupation,
this percentage varies substantially and
is positively correlated with exposure
concentration. Suppressing the variation
in this percentage quartz, by mass,
produces less variation in the resulting
imputed concentrations. Consequently,
the imputation method may
underestimate the number of
unanalyzed samples that would truly
exceed 50 mg/m3.
VII. Feasibility
A. Technological Feasibility
This section, technological feasibility,
presents MSHA’s conclusions on the
technological feasibility of the final rule
for mine operators. The section
considers whether currently available
technologies, used alone or in
combination with each other, can be
used by mine operators to comply with
the final rule and notes and responds to
public comments received regarding
technological feasibility. In the
proposed rule, MSHA preliminarily
determined that it is technologically
feasible for mine operators to achieve
the proposed requirements. In the
proposal, MSHA requested public
comments on these preliminary
conclusions and any other aspects of the
proposed rule. After receiving public
comments, the Agency has reviewed
them and has determined that it is
technologically feasible for mine
operators to conduct air sampling and
analysis and to achieve the final rule’s
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PEL using commercially available
samplers. MSHA has also determined
that these technologically feasible
samplers are widely available, and a
number of commercial laboratories
provide the service of analyzing dust
containing respirable crystalline silica.
In addition, MSHA has determined that
technologically feasible engineering
controls are readily available, can
control crystalline silica-containing dust
particles at the source, provide reliable
and consistent protection to all miners
who would otherwise be exposed to
respirable dust, can be monitored, and
are achievable. MSHA has also
determined that administrative controls,
used to supplement engineering
controls, can further reduce and
maintain exposures at or below the final
rule’s PEL. Moreover, MSHA has
determined the final rule’s respiratory
protection practices for respirator use
are technologically feasible for mine
operators to implement. For MNM
operators, MSHA has determined that
the final rule’s medical surveillance
requirements are technologically
feasible. This section focuses on
technological feasibility; public
comments specifically related to
technological feasibility are addressed
here, other comments are addressed in
Section VIII.B. Section-by-Section
Analysis of this preamble.
MSHA is required to set standards to
assure, based on the best available
evidence, that no miner will suffer
material impairment of health or
functional capacity from exposure to
toxic materials or harmful physical
agents over his working life. 30 U.S.C.
811(a)(6)(A). The Mine Act also
instructs MSHA to set health standards
to attain ‘‘the highest degree of health
and safety protection for the miner’’
while considering ‘‘the latest available
scientific data in the field, the feasibility
of the standards, and experience gained
under this and other health and safety
laws.’’ 30 U.S.C. 811(a)(6)(A). But the
health and safety of the miner is always
the paramount consideration: ‘‘[T]he
Mine Act evinces a clear bias in favor
of miner health and safety,’’ and ‘‘[t]he
duty to use the best evidence and to
consider feasibility are appropriately
viewed through this lens and cannot be
wielded as counterweight to MSHA’s
overarching role to protect the life and
health of workers in the mining
industry.’’ Nat’l Min. Ass’n v. Sec’y,
U.S. Dep’t of Lab., 812 F.3d 843, 866
(11th Cir. 2016); 30 U.S.C. 801(a).
The D.C. Circuit clarified the
Agency’s obligation to demonstrate the
technological feasibility of reducing
occupational exposure to a hazardous
substance. MSHA ‘‘must only
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demonstrate a ‘reasonable possibility’
that a ‘typical firm’ can meet the
permissible exposure limits in ‘most of
its operations.’’ Kennecott Greens Creek
Min. Co. v. Mine Safety & Health
Admin., 476 F.3d 946, 958 (D.C. Cir.
2007) (quoting American Iron & Steel
Inst. v. OSHA, 939 F.2d 975, 980 (D.C.
Cir. 1991)). Additionally, MSHA has
authority to promulgate technologyforcing rules. ‘‘When a statute is
technology-forcing, the agency ‘can
impose a standard which only the most
technologically advanced plants in an
industry have been able to achieve—
even if only in some of their operations
some of the time.’ ’’ Id. at 957 (quoting
United Steelworkers of Am. v. Marshall,
647 F.2d 1189, 1264 (D.C. Cir. 1980)).
This section presents technological
feasibility findings that guided MSHA’s
selection of the final rule’s
requirements, including the PEL.
MSHA’s technological feasibility
findings are organized into two main
sections covering: (1) the technological
feasibility of part 60: PEL and action
level; engineering and administrative
controls; sampling provisions, including
methods of sampling, and sampler and
sample analysis requirements; and
medical surveillance requirements for
MNM mines; and (2) the technological
feasibility of the revision to previous
respiratory protection standards. Based
on the analyses presented in the two
sections, MSHA concludes that the
Agency’s final rule is technologically
feasible. MSHA’s feasibility
determinations in this rulemaking are
supported by its findings that the
majority of the industry is already using
technology that will allow it to
effectively comply with the final rule.
As noted above, MSHA has
determined that part 60 is
technologically feasible. Many mine
operators already maintain respirable
crystalline silica exposures at or below
the final rule’s PEL of 50 mg/m3, and at
mines where there are elevated
exposures, operators are able to reduce
exposures to at or below the PEL by
properly maintaining existing
engineering controls and/or by
implementing new engineering and
administrative controls that are
currently available. In addition, mine
operators can satisfy the exposure
monitoring requirements of part 60 with
existing, validated, and widely used
sampling technologies and analytical
methods.
Second, the analysis shows that the
final rule’s update to MSHA’s prior
respiratory protection requirements is
also technologically feasible. The
mining industry’s existing respiratory
protection practices for selecting, fitting,
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using, and maintaining respiratory
protection include program elements
that are similar to those of ASTM
F3387–19, ‘‘Standard Practice for
Respiratory Protection’’, which MSHA
is incorporating by reference. Existing
respiratory protection programs must be
in writing and developed by a person
with relevant experience and
capabilities.
1. Technological Feasibility of the PEL
a. Methodology
mines operate in a safe and healthy
manner.30
Additionally, MSHA consulted other
published reports, scientific journal
articles, and information from
equipment manufacturers and mining
industry suppliers.31
MSHA did not identify any comments
specific to the technological feasibility
analysis methodology. This final rule
retains the methodology supporting the
technological feasibility analysis of the
PEL in the proposed rule.
b. The Technological Feasibility
Analysis Process
The technological feasibility analysis
for the PEL relies primarily on
information from three key sources:
• MSHA’s Standardized Information
System (MSIS) respirable crystalline
silica exposure data, which includes
57,769 MNM and 63,127 coal mine
compliance samples collected by MSHA
inspectors; these samples were of
sufficient mass gain to be analyzed for
respirable crystalline silica by MSHA’s
analytical laboratory.28
• The NIOSH series on reducing
respirable dust in mines, including:
‘‘Dust Control Handbook for Industrial
Minerals Mining and Processing,
Second Edition’’ (NIOSH, 2019b) and
‘‘Best Practices for Dust Control in Coal
Mining, Second Edition’’ (NIOSH,
2021a).29 With cooperation from the
MNM and coal mining industries,
NIOSH has extensively researched and
documented engineering and
administrative controls for respirable
crystalline silica in mines.
• MSHA’s knowledge of the mining
industry. MSHA has over four decades
of experience inspecting surface mines
at least twice per year and underground
mines at least four times per year and
in assisting mine operators and miners
with technological issues, such as
control of respirable dust (including
respirable crystalline silica) exposure.
MSHA provides compliance assistance,
including informational programs,
training, publications, onsite
evaluations, and investigations that
document conditions in mines and help
Mining Commodity Categories and
Activity Groups
As described in the Preliminary
Regulatory Impact Analysis (PRIA),
MSHA categorized mine types into six
MNM ‘‘commodity categories’’ (using
the method of Watts et al., 2012) based
on similarities in exposure
characteristics. MNM mine categories
include metal, nonmetal, stone, crushed
limestone, and sand and gravel. All coal
mines are categorized together as one
commodity category.
Within each commodity, MSHA
further separated mining operations into
the four activity groups widely used by
the industry: (1) development and
production miners (drillers, stone
cutters); (2) ore/mineral processing
miners (crushing/screening equipment
operators and kiln, mill, and
concentrator workers in mine facilities);
(3) miners engaged in load/haul/dump
activities (conveyor, loader, and large
haulage vehicle operators, such as dump
truck drivers); and (4) miners in all
other occupations (mobile and utility
workers, such as surveyors, mechanics,
cleanup crews, laborers, and operators
of compact tractors and utility trucks).
Before determining the feasibility of
reducing miners’ exposure to respirable
crystalline silica, MSHA gathered and
analyzed information to understand
current miner exposures by creating an
‘‘exposure profile,’’ identified the
existing (i.e., baseline) conditions and
the exposure levels associated with
28 These respirable crystalline silica exposure
data consist of 15 years of MNM mine samples
(January 1, 2005, through December 31, 2019) and
five years of coal mine samples (August 1, 2016,
through July 31, 2021). These MSHA compliance
samples represent the conditions identified by
MSHA inspectors as having the greatest potential
for respirable crystalline silica exposure during the
periodic inspection when sampling occurred. While
MSHA’s laboratory also analyzes mine operators’
respirable coal mine dust samples containing
respirable crystalline silica, those samples are not
included in the data used for this analysis.
29 Together, these two recent reports provide
more than 500 pages of detailed descriptions,
discussion, and illustrations of dust control
technologies currently used in mines.
30 MSHA also analyzes RCMD samples collected
by mine operators, including those containing
respirable crystalline silica, in addition to the
compliance samples collected by MSHA inspectors
(mentioned in the first bullet of this series).
31 Project personnel reviewed 104,365 samples
collected and analyzed by MSHA for respirable
crystalline silica, plus another 103,745 samples
collected but not analyzed due to insufficient
respirable dust collected in the sample. They
examined over 200 published reports, proceedings,
case studies, analytical methods, and journal
articles, in addition to inspecting more than 200
web page, product brochures, user manuals,
service/maintenance manuals and descriptive
literature for dust control products, mining
equipment, and related services.
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those conditions, and determined
whether mines will need additional
control methods, and if so, whether
those methods were available. MSHA’s
exposure datasets for MNM and coal
mining industries are available as part
of the rulemaking record under Docket
ID MSHA–2023–0001–1290.
Exposure Profiles
MSHA classified all valid respirable
crystalline silica samples in the
Agency’s MSIS data,32 grouping the data
by commodity category, followed by
activity group.33 MSHA created an
exposure profile to better examine the
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32 MSHA removed duplicate samples, samples
missing critical information, and those identified as
invalid by the mine inspector, for example because
of a ‘‘fault’’ (failure) of the air sampling pump
during the sampling period.
33 MSHA MSIS respirable crystalline silica data
for the MNM industry, January 1, 2005, through
December 31, 2019 (version 20220812); MSHA
MSIS respirable crystalline silica data for the Coal
Industry, August 1, 2016, through July 31, 2021
(version 20220617). All samples were collected by
mine inspectors and were of sufficient mass to be
analyzed for respirable crystalline silica by MSHA’s
laboratory.
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sample data for each commodity
category. These profiles include basic
summary statistics, such as sample
count, mean, median, and maximum
values, presented as ISO 8-hour TWA
values. They also show the sample
distribution within the following
exposure ranges: ≤25 mg/m3, >25 mg/m3
to ≤50 mg/m3, >50 mg/m3 to ≤100 mg/m3
(equivalent to 85.7 mg/m3 in coal mines
for a sample calculated as an 8-hour
TWA), >100 mg/m3 to ≤250 mg/m3, >250
mg/m3 to ≤500 mg/m3, and >500 mg/m3.34
In Table VII–1, the respirable
crystalline silica exposure data for
MNM miners are summarized by
commodity and for the MNM industry
as a whole, while Table VII–2 presents
the exposure profile as the percentage of
samples in each exposure range.
Overall, approximately 82 percent of the
57,769 MNM compliance samples were
34 MSHA selected these ranges based on the PELs
under consideration, then multiples of 100 mg/m3
to show how data are distributed in the higher
ranges. Table VII–4 also presents additional
exposure ranges corresponding to the 85.7 mg/m3
concentration for coal samples.
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at or below the PEL (50 mg/m3). The
exposure profile shows variability
between the commodity categories:
approximately 73 percent of metal
miner exposures at or below the PEL (50
mg/m3) (the lowest among all MNM
mines), compared with approximately
90 percent of the crushed limestone
miner exposures (the highest among all
MNM mines).
Table VII–3 and Table VII–4 present
the corresponding respirable crystalline
silica exposure information for coal
miners by location (underground or
surface). Overall, approximately 93
percent of the 63,127 samples obtained
by MSHA inspectors for coal miners
were at or below the PEL (50 mg/m3).
There was little variation between
samples for underground miners and
surface miners (with approximately 93
and 92 percent of the samples at or
below 50 mg/m3, respectively). Exposure
values from the coal industry are
expressed as ISO 8-hour TWAs,
compatible with the final rule’s (see
notes, Table VII–3).
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Table VII-1: Summary of Respirable Crystalline Silica Exposures
in the MNM Industry from 2005 to 2019,
by Commodity Category
Commodity
Metal
Nonmetal
Stone
Crushed
limestone
Sand and gravel
Overall: MNM
Activity Group
Overall: metal (all activity
groups)
Overall: nonmetal (all
activity groups)
Overall: stone (all activity
groups)
Overall: crushed limestone
(all activity groups)
Overall: sand and gravel
(all activity groups)
Overall: MNM
Number
of
Samples
3,499
ISO Concentration, µg/m3
Mean
Median
Max
49.1
25.0
3,588
5,165
26.4
11.0
2,124
15,415
36.6
17.0
1,548
15,184
21.7
10.0
4,289
18,506
38.7
20.0
3,676
57,769
33.2
15.0
4,289
Notes:
Summary of personal samples presented as ISO 8-hour TWA concentrations. The permissible
exposure limit (PEL) for all mines is 50 µg/m 3 as an 8-hour time-weighted average (8-hour TWA)
sample collected according to the ISO standard 7708:1995: Air Quality-Particle Size Fraction
Definitions for Health-Related Sampling.
1. The compliance samples summarized in this table were collected by MSHA inspectors as 8-hour
TWAs using ISO-compliant sampling equipment with an air flow rate of 1. 7 L/min, with results
comparable to the PEL.
2. When the mass of respirable crystalline silica collected was too small to be reliably detected by
the laboratory, a mass of2.5 µg for quartz and 5 µg for cristobalite (1/2 the respective limits of
detection for these two forms of crystalline silica) were assumed and used to calculate sample results.
3. The procedure to calculate the ISO 8-hour TWA concentration (µg/m 3) is:
8-hourTWA=
quartzmass
xlOOO...!:....
(480 minutes)
m3
x (air flow rate)
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where: quartz mass is in micrograms (µg); normalized sampling time is 8 hours (480 minutes); flow
rate = 1. 7 L/min; 1000 Liters (L) per cubic meter (m3)
4. Source: MSHA MSIS respirable crystalline silica data for the MNM industry, January 1, 2005,
through December 31, 2019 (version 20220812). All samples were of sufficient mass gain to be
analyzed for respirable crystalline silica.
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Table VII-2: Percentage Distribution ofRespirable Crystalline Silica Exposures
in the MNM Industry from 2005 to 2019, by Commodity Category
Commodity
Activity Group
Percentage of Samples in ISO Concentration Ranges,
µg/m3
Number
of
Samples
~25
> 25 to
~50
>50to
~100
> 100 to
~250
> 250 to
~500
>500
Total
%
Metal
Overall: metal (all
activity groups)
3,499
51.6%
21.3%
16.3%
8.3%
1.9%
0.6%
100%
Nonmetal
Overall: nonmetal
(all activity groups)
5,165
70.5%
15.1%
9.9%
3.8%
0.6%
0.1%
100%
Stone
Overall: stone (all
activity groups)
15,415
60.3%
18.7%
13.6%
6.0%
1.1%
0.3%
100%
Crushed
limestone
Overall: crushed
limestone (all
activity groups)
15,184
77.8%
12.5%
6.9%
2.3%
0.4%
0.2%
100%
Overall: sand and
Sand and gravel gravel (all activity
groups)
18,506
58.6%
20.8%
13.2%
5.7%
1.2%
0.4%
100%
Overall: MNM
57,769
64.7%
17.6%
11.6%
4.8%
1.0%
0.3%
100%
Overall: MNM
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Notes:
1. Personal samples were collected using ISO-compliant sampling equipment and calculated as an 8-hour time-weighted average
(8-hour TWA). Samples were collected using an air flow rate of 1. 7 L/min and reported as 8-hour TWAs. See notes in Summary
Table VII-1 for additional details.
2. Source: MSHA MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through December 31, 2019
(version 20220812). All samples were of sufficient mass to be analyzed for respirable crystalline silica.
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Table VII-3: Summary of Respirable Crystalline Silica Exposures
in the Coal Mining Industry from 2016 to 2021, by Location
Location
Activity Group
Number
of
Samples
ISO Concentration
(8-hour TWA, µ,g/m 3)
Mean
Median
Max
Overall: underground (all
activity groups)
53,095
22.1
16.0
778.6
Surface
Overall: surface (all
activity groups)
10,032
20.5
11.1
747.8
Overall: coal
Overall: coal
63,127
21.9
16.0
778.6
Underground
Notes: Summary of personal samples presented as ISO 8-hour TWA concentrations. The permissible
exposure limit (PEL) for all mines is 50 µg/m 3 as an 8-hour time-weighted average (8-hour TWA)
sample collected according to the ISO standard 7708:1995: Air Quality-Particle Size Fraction
Definitions for Health-Related Sampling.
1. The compliance samples summarized in this table were collected by MSHA inspectors for the
entire duration of each miner's work shift using sampling equipment with an air flow rate of 2 L/min,
with results reported as MRE TWA concentrations. For this rulemaking analysis, MSHA recalculated
the samples as ISO-equivalent 8-hour TWA concentrations, comparable to the PEL (since samples
were not collected using an ISO-compliant sampling method). The procedure to calculate an ISOequivalent concentration from an MRE TWA sample concentration involves normalizing the sample
concentration to an 8-hour TWA and applying the empirically derived conversion factor of 0.857
recommended by NIOSH (1995a) using the following equation:
ISO 8-h our TWA concentrafrnn = (MRE TWA.m µg / m 3) x (originalsamplingtime)
(4B0minutes)
x 0 .857
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where: both concentrations (ISO 8-hour TWA and MRE TWA) are concentrations presented as
µg/m 3 ; sampling time in minutes.
2. When the mass ofrespirable crystalline silica collected was too small to be reliably detected by
the laboratory, a mass of 1.5 µg (1/2 the limit of detection) was assumed and used to calculate sample
results.
3. Source: MSHA MSIS respirable crystalline silica data for the Coal Industry, August 1, 2016,
through July 31, 2021 (version 20220617). All samples were of sufficient mass gain to be analyzed
for respirable crystalline silica.
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Table VII-4: Percentage Distribution ofRespirable Crystalline Silica Exposures as ISO 8-hour TWA
in the Coal Industry from 2016 to 2021, by Location
Activity
Group
Location
Overall:
underground
Underground
(all activity
groups)
Number
of
Samples
Percentage of Samples in ISO Concentration Ranges, 8-hour
TWA, µg/m 3
:5 25
>25to >50to >85.7 > 100 to > 250 to
>500
:5 500
:5 50 :5 85.7 to :5100 :5 250
Total
%
53,095
72.7%
20.6%
5.1%
0.6%
1.0%
0.1%
0.0%
100%
Surface
Overall:
surface (all
activity groups)
10,032
79.5%
12.4%
4.6%
0.8%
2.3%
0.4%
0.1%
100%
Overall: coal
Overall: coal
63,127
73.8%
19.3%
5.0%
0.6%
1.2%
0.1%
0.0%
100%
Existing Dust Controls in Mines
(Baseline Conditions)
MNM and coal mines are controlling
dust containing respirable crystalline
silica in various ways. As shown in
Tables VII–1 through VII–4, respirable
crystalline silica exposures exceeded
the PEL of 50 mg/m3 in about 18 percent
of all MNM samples collected. About
seven percent of all coal samples
exceeded the PEL. Overall, metal mines
and sand and gravel mines had higher
exposure levels than other commodity
mines.
Despite the extensive dust control
methods available, dust control
measures have been implemented in
some commodity categories to a greater
degree than in others. This is partly
because some commodity categories
tend to have larger mines. MSHA has
found that the larger the amount
(tonnage) of material a mine moves
(including overburden and other waste
rock), the faster the mine tends to
operate its equipment (i.e., closer to the
equipment capacity), creating more air
turbulence and therefore generating
more airborne respirable crystalline
silica. The amount of material moved
also influences the number of miners
employed at a mine, and therefore, the
number of miners can be indirectly
correlated to the amount of dust
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generated. MSHA has observed that in
large mines, dusty conditions typically
prompt more control efforts, usually in
the form of added engineering controls.
MSHA has also found that metal
mines, which are typically large
operations with higher numbers of
miners, tend to have available
engineering controls for dust
management. On the other hand, sand
and gravel mines, which generally
employ fewer miners and handle
modest amounts of material, have very
limited, if any, dust control measures.
This is because most of the mined
material is a commodity that only
requires washing and screening into
various sizes of product stockpiles,
generating little waste material.
Nonmetal, stone, and crushed limestone
mines occupy the middle range in terms
of employment, existing engineering
controls, and maintenance practices.
Over the years, staff from multiple
MSHA program areas have worked
alongside miners and mine operators to
improve safety and health by inspecting,
evaluating, and researching mine
conditions, equipment, and operations.
These key programs, each of which has
an onsite presence, include (but are not
limited to) Mine Safety and Health
Enforcement; Directorate of Educational
Policy and Development, which
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includes the National Mine Health and
Safety Academy and the Educational
Field and Small Mine Services; and the
Directorate of Technical Support, which
comprises the Approval and
Certification Center and the Pittsburgh
Safety and Health Technology Center
(including its Health Field Division,
Analytical and Laboratory Services
Division, National Air and Dust
Laboratory, Ventilation Division, and
other specialized divisions). Table VII–
5 reflects the collective observations of
these MSHA programs, presented in
terms of existing dust control (baseline
conditions) and the classes of additional
control measures that will provide those
mines with the greatest benefit to reduce
exposures below the PEL and action
level.
Table VII–5 shows MSHA’s
assessment of existing dust controls in
mines (baseline conditions) and
additional controls needed to meet the
PEL for each commodity category,
including the need for frequent
scheduled maintenance. By conducting
frequent scheduled maintenance, mine
operators can reduce the concentration
of respirable crystalline silica. Table
VII–5 shows that metal mines have
adopted extensive dust controls, while
sand and gravel mines tend to have
minimal engineering controls, if any.
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Notes:
1. Personal samples presented in terms of ISO concentrations, normalized to 8-hour time-weighted averages (TWAs). The
samples were originally collected for the entire duration of each miner's work shift, using an air flow rate of 2 L/min. See notes
in Summary Table VII-3 for additional details.
2. Source: MSHA MSIS respirable crystalline silica data for the coal industry, August 1, 2016, through July 31, 2021 (version
20220617). All samples were of sufficient mass to be analyzed for respirable crystalline silica.
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Table VII-5: Baseline Conditions and Class of Additional Controls Needed, by Commodity
Baseline
(existing) Conditions
Commodity
category
Metal
Nonmetal
Stone
Crushed
limestone
Sand and gravel
Coal
Additional Controls Needed to Achieve the
PEL
Extent of
engineering
controls
adopted
Dust control
equipment
maintenance
practices
Extent of
engineering
controls
needed
Extent of
maintenance
and repair
needed
Extent of
administrative
controls
needed
Extensive
Minimal
Minimal
Extensive
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Minimal
Moderate
Moderate
Moderate
Extensive
Moderate
Moderate
Moderate
Moderate
Moderate
Notes:
1. Extensive, moderate and minimal are relative terms.
2. "Extensive" indicates that the baseline (existing) condition is widely (i.e., predominantly) present among mines
within the commodity group as a whole, or that the additional control class is found to be widely needed (e.g.,
these mines' engineering controls routinely show evidence of needing more attentive maintenance and/or repair
to function as intended).
3. "Moderate" indicates an intermediate level of baseline availability or need.
4. "Minimal" means little or no baseline availability or need as an additional control (for that commodity).
Source: MSHA's experience from multiple program areas.
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Based on MSHA’s experience, NIOSH
research, and effective respirable dust
controls currently available and in use
in the mining industry, MSHA finds
that the baseline conditions include
various combinations of existing
engineering controls selected and
installed by individual mines to address
respirable crystalline silica generated
during mining operations.
Respirable Crystalline Silica Exposure
Controls Available to Mines
Under the final rule, the mine
operator must install, use, and maintain
engineering controls, supplemented by
administrative controls, when
necessary, to keep each miner’s
exposure at or below the PEL.
Engineering controls reduce or prevent
miners’ exposure to hazards.35
35 Control
measures that reduce respirable
crystalline silica can also reduce exposures to other
hazardous particulates, such as RCMD, metals,
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Administrative controls establish work
practices that reduce the duration,
frequency, or intensity of miners’
exposures (under the final rule, the
rotation of miners is not considered an
acceptable administrative control to
comply with the PEL).
MSHA data and experience show that
mine operators already have numerous
engineering and administrative control
options to control miners’ exposures to
respirable crystalline silica. These
control options are widely recognized
and used throughout the mining
industry. NIOSH has extensively
researched and documented engineering
and administrative controls for
respirable crystalline silica in mines. As
noted previously, NIOSH has published
asbestos, and diesel exhaust. Operator enclosures
and process enclosures also reduce hazardous
levels of noise by creating a barrier between the
operator and the noise source.
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a series on reducing respirable dust in
mines (NIOSH, 2019b, 2021a).
(1) Engineering Controls
Examples of existing engineering
controls used at mines and
commercially available engineering
controls that MSHA considered include:
• Wetting or water sprays that
prevent, capture, or redirect dust;
• Ventilation systems that capture
dust at its source and transport it to a
dust collection device (e.g., filter or bag
house), dilute dust already in the air, or
‘‘scrub’’ (cleanse) dust from the air in
the work area;
• Process enclosures that restrict dust
from migrating outside of the enclosed
area, sometimes used with an attached
ventilation system to improve
effectiveness (e.g., crushing equipment
and associated dump hopper enclosure,
with curtains and mechanical
ventilation to keep dust inside);
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• Operator enclosures, such as mobile
equipment cabs or control booths,
which provide an environment with
clean air for an equipment operator to
work safely;
• Protective features on mining
process equipment to help prevent
process failures and associated dust
releases (e.g., skirtboards on conveyors,
which protect the conveyor system from
damage and prevent material on the
conveyor from falling off, which
generates airborne dust);
• Preventive maintenance conducted
on engineering controls and mining
equipment that can influence dust
levels at a mine, to keep them
functioning optimally; and
• Instrumentation and other
equipment to assist mine operators and
miners in evaluating engineering control
effectiveness and recognizing control
failures or other conditions that need
corrective action.36
(2) Administrative Controls
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Administrative controls include
practices that change the way tasks are
performed to reduce a miner’s exposure.
Administrative controls can be very
effective and can even prevent exposure
entirely. MSHA has determined that
various administrative controls are
readily available to provide
supplementary support to engineering
controls. Examples of administrative
controls include housekeeping
procedures; proper work positions of
miners; walking around the outside of a
dusty process area rather than walking
through it; cleaning of spills; and
measures to prevent or minimize
contamination of clothing to help
decrease miners’ exposure to respirable
crystalline silica. However, these
control methods depend on human
behavior and intervention and are less
reliable than properly designed,
installed, and maintained engineering
controls. Therefore, administrative
controls will be permitted only as
supplementary measures, with
engineering controls required as the
primary means of protection.
Nevertheless, administrative controls
play an important role in reducing
miners’ exposure to respirable
crystalline silica.37
36 These instruments include dust monitors;
water, air, and differential air pressure gauges; pitot
tubes and air velocity meters; and video camera
(NIOSH recommends software that pairs video with
a dust monitor to track conditions that could lead
to elevated exposures if not corrected). These
instruments are discussed in NIOSH’s best practices
guides and dust control handbooks.
37 Paragraph 60.11(b) prohibits the use of rotation
of miners as an administrative control used for
compliance with this part.
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(3) Combinations of Controls
Various control options can also be
used in combinations. NIOSH has
documented in detail most control
methods and has confirmed that they
are currently used in mines, both
individually and in combination with
each other (2019b, 2021a).
Maintenance
MSHA finds that a strong preventive
maintenance program plays an
important role in achieving consistently
lower respirable crystalline silica
exposure levels. MSHA has observed
that when engineering controls are
installed and maintained in working
condition, respirable dust exposures
tend to be below the existing exposure
limits. When engineering controls are
not maintained, dust control efficiency
declines and exposure levels rise. When
engineering controls fail due to a lack of
proper maintenance, a marked rise in
exposures can occur, resulting in
noncompliance with MSHA’s existing
exposure limits. Some examples of the
impact that proper maintenance can
have on respirable dust levels include:
• Water spray maintenance: An
experiment using water spray bars that
could be turned on or off showed that
dust reduction was less effective each
time additional spray nozzles were
deactivated. A 10 percent decrease
occurred when three of 21 sprays were
shut off, but a 50 percent decrease
occurred when 12 out of the 21 sprays
were shut off. Decreased total water
spray volume and gaps in the spray
pattern (due to deactivated nozzles)
were both partially responsible for the
decreased dust control (Seaman et al.,
2020).
• Water added to drill bailing air:
When introduced into the drill hole
(with the bailing air through a hollow
drill bit), water mixes with and
moistens the drill dust ejected from the
hole and can reduce respirable dust by
more than 90% (NIOSH, 2019b, 2021a).
NIOSH reports that this same control
measure, and others, are similarly
effective for MNM and surface coal
mine drills preparing the blasting holes
used to expose the material below
(whether ore or coal).
• Ventilation system maintenance:
The amount of air cleaned by an air
scrubber is decreased by up to one-third
(33 percent) after one continuous
mining machine cut. Cleaning the
scrubber screens restores scrubber
efficacy, but this maintenance must be
performed after every cut. Spare
scrubber screens make frequent cleaning
practical without slowing production
(NIOSH, 2021a).
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• Operator enclosure maintenance:
Tests with mining equipment showed
that maintenance activities such as
repairing weather stripping and
replacing clogged and missing cab
ventilation system filters (intake,
recirculation, final filters) increased
miner protection by up to 95 percent
(NIOSH, 2019b, 2021a).
• Filter selection during maintenance:
Airflow is as important as filtration and
pressurization in operator enclosures;
during maintenance, filter selection can
influence all three factors. Performing
serial end-shift testing of enclosed cabs
(on a face drill and a roof/rock bolter)
at an underground crushed limestone
mine, NIOSH compared installed HEPA
filters and an alternative (MERV 16
filters). The latter provided an equal
level of filtration and better overall
miner protection by allowing greater
airflow and cab pressurization. As an
added advantage, NIOSH showed that
these filters cost less and required lessfrequent replacement, reducing
maintenance expenses in this mining
environment (Cecala et al., 2016;
NIOSH, 2019b, 2021a).38 39
• Proper design and installation—
foundation for effective maintenance: A
new replacement equipment operator
enclosure (control booth) installed
adjacent to the primary crusher at a
granite stone quarry initially provided
50 to 96 percent respirable dust
reduction, even with inadequate
pressurization. The protection it offered
miners tripled after the booth’s second
pressurization/filtration unit was
activated (Organiscak et al., 2016).
MSHA has observed that when
engineering controls are properly
maintained, exposure levels decrease or
stay low. Metal mines, which typically
have substantial controls already
installed, primarily need reliable
preventive maintenance programs to
achieve the PEL. It is also important to
repair equipment damage that
contributes to dust exposure (for
example, damage to conveyor
skirtboards that protect the conveyor
system from damage and prevent
spillage which generates airborne dust).
Maintenance and repair programs must
38 NIOSH believes this study, like many of its
other mining studies on operator enclosures and
surface drill dust controls, is relevant to both MNM
mining and coal mining. NIOSH reports on this
study, conducted at an underground limestone
mine, in detail in both its Dust Control Handbook
for Industrial Minerals Mining and Processing
(second edition) (2019b) and its Best Practices for
Dust Control in Coal Mining (second edition)
(2021a).
39 Acronyms: High efficiency particulate air
(HEPA). Minimum efficiency reporting value
(MERV).
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ensure that dust control equipment is
functioning properly.
Some commenters described
conditions where they found
engineering controls were not feasible.
The NSSGA, the NVMA, and US Silica
(a MNM mine operator) cited examples
such as water sprays that freeze in
winter or are not practical where the
product must be kept dry so mine
workers can bag it; and enclosures and
ventilation systems that are sometimes
impractical for portable operations at
some locations and limited (so made
less effective) by the physical
constraints of others (Document ID
1448; 1441;1455). The MNM mine
operator commenter indicated that at
their worksite, these physical conditions
cause engineering controls to be
ineffective more than does lack of effort
(Document ID 1455).
In MSHA’s considerable experience
providing technical support to mines,
there is always a way to eliminate
overexposures to respirable dust
(including respirable crystalline silica)
by using the information contained in
NIOSH best practice guides for mines.
MSHA has found that the number of
control options and level of detail in the
guides make compliance achievable
through engineering controls alone. By
adding administrative controls (or
procedural practices) mines routinely
achieve consistent compliance. MSHA
agrees with commenters that exposed
water sprays are not effective in freezing
weather, however, the Agency has
found that one or more other options is
available for every circumstance. For
example, enclosing the process
equipment is one alternative to using
water sprays for dust control. Rather
than suppressing dust, as water spray
does, enclosing the dusty process
equipment limits the amount of dust
that escapes from the process enclosure,
in turn limiting the amount of dust in
the equipment operator’s breathing
zone. A process equipment enclosure
can be constructed with baffles to help
calm the air inside the enclosure, so
dust settles more quickly inside the
enclosure. As another option, a
ventilation dust collection system can
be paired with a process equipment
enclosure to make both even more
effective. Yet another example is to
enclose the equipment operators (e.g., in
a booth or mobile cab). Furthermore,
MSHA observes that a number of
surface mines operate intermittently;
many of them are closed in seasons with
harsh weather. Typically, those mines
can use water sprays effectively when
they are operating. MSHA notes that
ventilation systems are effective in
every season; a large variety of system
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components and designs provide a
ventilation system that can be
constructed for almost every situation.
As noted in the proposed rule, some
mines might need to work harder than
others (layering different engineering
controls and adding administrative
controls) to achieve compliance.
The Brick Industry Association (BIA)
noted that their industry usually
operates with the minimum number of
personnel even under optimal staffing
conditions and explained that it can be
difficult to avoid rotating workers to
achieve efficient workflow (Document
ID 1422). This commenter also stated
that it could be difficult to maintain
productive operations if management is
not able to either rotate workers to
minimize exposure levels or allow
personnel to wear respirators for day-today tasks.
As MSHA stated in the proposed rule
and, and included in this final rule,
miner rotation is not considered an
acceptable administrative control for
minimizing miner exposure levels or
complying with any provision of
part 60. MSHA understands that mine
operators may assign a variety of work
tasks for business reasons unrelated to
compliance with the PEL. However,
MSHA will not consider as compliance
a mine operator’s implementation of a
varied task schedule for particular
miners for purposes of avoiding conflict
with the PEL, as engineering and
administrative controls can feasibly
reduce exposure levels below the PEL.
This final rule prioritizes engineering
controls for reducing miner exposures,
because they (1) control crystalline
silica-containing dust particles at the
source; (2) provide reliable, predictable,
effective, and consistent protection to
miners who would otherwise be
exposed to dust from that source; and
(3) can be monitored. MSHA maintains
that as described earlier in this section,
a combination of engineering controls
and administrative controls can reduce
miner exposures to levels below the PEL
and that equipment maintenance will
help minimize exposures. Some
examples of engineering controls
include wet dust suppression methods;
enclosure; ventilation—permanent or
portable trunks; pre-cleaning—by
washing or HEPA vacuuming; and
controlling dust sources. Examples of
administrative controls include proper
miner positioning and improved
housekeeping. For a detailed discussion
on rotation of miners, see Section
VIII.B.4. Section 60.11—Methods of
Compliance.
MSHA finds that the technological
feasibility analysis process was effective
and controlling exposure levels to the
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PEL or lower using engineering controls
is both feasible and practical. The final
rule, as did the proposed rule,
emphasizes engineering controls,
supplemented with administrative
controls, to control miner exposure.
c. Feasibility Determination of Control
Technologies
MSHA’s final PEL is 50 mg/m3 for
MNM and coal mines. As NIOSH
(2019b, 2021a) has documented, the
mining industry has a wide range of
options for controlling dust exposure
that are already in various
configurations in mines. NIOSH has
carefully evaluated most of the dust
controls used in the mining industry
and found that many of the controls
may be used in combination with other
control options. NIOSH has documented
protective factors and exposure
reductions of 30 to 90 percent or higher
for many engineering and
administrative controls.
Effective maintenance will also help
mine operators comply with the final
rule. MSHA finds that maintaining
(including adjusting) or repairing
existing equipment will help achieve
exposures at or below 50 mg/m3. For
example, NIOSH (2019b) found that
performing maintenance on an operator
enclosure can restore enclosure
pressurization and reduce the respirable
dust exposure of a miner by 90 to 98.9
percent (e.g., by maintaining weather
stripping, reseating or replacing leaking
or clogged filters, and upgrading
filtration). When an equipment operator
remains inside a well-maintained
enclosure for a portion of a shift (for
example 75 percent of an 8-hour shift),
the cab can reduce the exposure of the
equipment operator proportionally, to a
level of 50 mg/m3 (or lower). This point
is demonstrated by the following
example involving a bulk loading
equipment operator in a poorly
maintained booth, exposed to respirable
crystalline silica near the existing
exposure limit (in the MNM sectors, 100
mg/m3, as ISO 8-hour TWA value; in the
coal sector, 85.7 mg/m3 ISO, calculated
as an 8-hour TWA). During the 25
percent of their shift (two hours of an
eight-hour shift) that the miner works in
the poorly maintained enclosure, their
exposure will be 100 mg/m3, while for
the other six hours (operating mobile
equipment with a fully refurbished
protective cab), the exposure level will
be 90 percent lower, or 10 mg/m3,
resulting in an 8-hour TWA exposure of
33 mg/m3 for that miner’s shift.40 Greater
40 Calculating the exposure for the shift: 8-hour
TWA = [(10 mg/m3 × 6 hours) + (100 mg/m3 × 2
hours)]/8 hours = 33 mg/m3.
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exposure reductions could also be
achieved by repairing or replacing the
poorly maintained enclosure, or
modifying the miner’s schedule so that
the miner works seven hours, rather
than six, inside the well-maintained
enclosure.
Other engineering controls (e.g.,
process enclosure, water dust
suppression, dust suppression hopper,
ventilation systems) could reduce dust
concentrations in the area surrounding
the poorly maintained enclosure, which
reduces the exposure of the equipment
operator inside. As a hypothetical
example, if the poorly maintained
enclosure was an open-air control booth
(windows do not close) at a truck
loading station, adding a dust
suppression hopper (which reduces
respirable dust exposure by 39 to 88
percent during bulk loading) (NIOSH,
2019b), will lead to lower exposure
during the two hours the miner is inside
the open-air booth. The calculated
respirable crystalline silica 8-hour TWA
exposure of that miner could be reduced
from 33 mg/m3 (with improved
equipment operator enclosure alone) to
23 mg/m3 (improved equipment operator
enclosure plus dust suppression
hopper).41 As an added benefit, any
helper or utility worker in the truck
loading area will also experience
reduced exposure.
A similar hypothetical example is a
coal miner helper who spends 90
minutes (1.5 hours) per 8-hour shift
assisting a drilling rig operator (in a
protective operator’s cab) drilling blast
holes. The combination of controls used
to control drilling dust (including water
added to the bailing air, which can
reduce airborne respirable dust
emissions by up to 96 percent) can keep
the helper’s respirable crystalline silica
exposure in the range of 35 mg/m3 (ISO)
as an 8-hour TWA. If, however, the
drill’s on-board water tank runs dry due
to poor maintenance, the respirable
crystalline silica concentration near the
drill will rise by 95 percent, meaning
that the concentration is 20 times
greater than the usual level (NIOSH,
2021a). If the drill operator idles the
drill and calls for water resupply, the
helper will not experience an elevated
exposure. The hypothetical helper’s
exposure level rises higher the longer
the drill is operated. If the drill is
operated dry for another 30 minutes
until water resupply arrives, the helper
will experience a respirable crystalline
silica exposure of 77 mg/m3 (ISO) as an
8-hour TWA. If dry drilling continued
for 1.5 hours, the helper would have an
exposure of 160 mg/m3 ISO as an 8-hour
TWA.42 After water is delivered, drill
respirable dust emissions will return to
their normal level once water is again
introduced into the drill bailing air.
41 Calculating the exposure with both the wellmaintained operator enclosure (6 hours) and dust
suppression hopper, assuming only the minimum
documented respirable dust concentration
reduction (39 percent): [(10 mg/m3 × 6 hours) + (100
mg/m3 × (1¥0.39) × 2 hours)]/8 hours = 23 mg/m3.
42 The 8-hour TWA exposure level of the helper,
including the 30-minute period of elevated
exposure, is calculated as: [(35 mg/m3 × 7.5 hours)
+ (35 mg/m3 × 20 × 0.5 hours)]/8 hours = 77 mg/m3.
Drill bits designed for use with water may need to
be replaced sooner if used dry.
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Based on these examples and the
wide range of effective exposure control
options available to the mining
industry, MSHA finds that control
technologies capable of reducing
miners’ respirable crystalline silica
exposures are available, proven,
effective, and transferable between
mining commodities; however, they
must be well-designed and consistently
used and maintained. MSHA also finds
that methods of maintaining engineering
controls are known, available, and
effective.
Feasibility Findings for the PEL
Based on the exposure profiles in
Table VII–1 and Table VII–2 for MNM
mines, and in Table VII–3 and Table
VII–4 for coal mines, and the examples
in the previous section that demonstrate
the beneficial effect of combined
controls, MSHA finds that the PEL of 50
mg/m3 is technologically feasible for all
mines.
Table VII–6 summarizes the
technological feasibility of control
technologies available to the mining
industry, by commodity. MSHA finds
that control technologies are
technologically feasible for all six
commodities and their respective
activity groups. Under baseline
conditions, mines in each commodity
category have already achieved
respirable crystalline silica exposures at
or below 50 mg/m3 for most of the
miners represented by MSHA’s 57,769
samples for MNM miners and 63,127
samples for coal miners.
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Table VII-6: Summary of Technological Feasibility of Control Technologies in the
Mining Industry, by Commodity, Indicating Activity Groups Affected by Respirable
Crystalline Silica Exposures
Commodity
category
Total
number
of
affected
activity
groups 1
79
4
4
4
4
4
4
0
0
0
Feasible
Feasible
Feasible
90
4
4
0
Feasible
79
4
4
0
Feasible
93
7
7
0
Feasible
--
27
100%
0%
Feasible
%
samples
::; 50
µg/m3
Metal
Nonmetal
Stone
Crushed
limestone
Sand and
Gravel
Coal (underground and
surface)4
Overall
Number of
activity groups
for which the
PEL is NOT
achievable with
engineering and
administrative
controls
Number of
activity groups
for which the
PEL is achievable
with engineering
and
administrative
controls2 • 3
73
86
Feasibility
finding, by
commodity
category
Notes:
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Feasibility Findings for the Action Level
MSHA finds that mine operators can
achieve exposure levels below the
action level of 25 mg/m3 for most miners
by implementing additional engineering
controls and more flexible and
innovative administrative controls, in
addition to the existing control methods
already discussed in this technological
feasibility analysis. The exposure
profiles in Tables VII–1 and VII–2 for
MNM mines, and Tables VII–3 and VII–
4 for coal mines, indicate that mine
operators have already achieved the
action level for at least half of the
miners MSHA has sampled in each
commodity category. However, to
reliably maintain exposures below the
action level for all miners, operators
will need to upgrade equipment and
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facility designs, particularly in mines
with higher respirable crystalline silica
concentrations, which may be due to an
elevated silica content in materials.
One control option is increased
automation, such as expanding the use
of existing autonomous or remotecontrolled drilling rigs, roof bolters,
stone cutting equipment, and
packaging/bagging equipment. This type
of automation can reduce exposures by
increasing the distance between the
equipment operator and the dust source.
Other options include completely
enclosing most processes and
ventilating the enclosures with dust
extraction equipment or controlling the
speed of mining equipment (e.g.,
longwall shearers, conveyors, dump
truck emptying) and process equipment
(e.g., crushers, mills) to reduce
turbulence that increases dust
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concentrations in air. Additionally,
where compatible with the material,
exposure levels can be reduced by
increased wetting to constantly
maintain the material, equipment, and
mine facility surfaces damp through
added water sprays and frequent
housekeeping (i.e., hosing down
surfaces as often as necessary). In
addition, vacuuming minimizes the
amount of dust that becomes airborne
and prevent dust that does settle on a
surface from being resuspended in air.
Mines that only occasionally work
with higher-silica-content materials may
not be equipped with the controls
required to achieve the action level of
25 mg/m3, or they may not currently
have procedures to ensure miners are
protected when they do work with these
materials. Examples of these activities
include cutting roof or floor rock with
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1. Activity groups include 1) production and development miners; 2) ore/mineral processing miners; 3) miners
engaged in load/haul/dump activities; and 4) miners in all other occupations.
2. Engineering controls include wetting and water sprays, ventilation systems, enclosure of dusty processes, and
operator enclosures (equipment cabs and control booths). For the purposes of this table, effective maintenance is
also an engineering control.
3. Administrative controls encompass both mine operator policies and miner work practices, such as written
operating procedures, miner training, keeping operator enclosure door and windows closed to exclude dust; or
walking around, rather than through a dusty area.
4. Coal mines include three activity groups underground and four surface activity groups.
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a continuous mining machine in
underground coal mines; packaging
operations that involve materials from
an unfamiliar supplier, including
another mine; and rebuilding or
repairing kilns. To address these
activities, under the final rule, mine
operators will have to add engineering
controls to address any foreseeable
respirable crystalline silica
overexposures. Examples of additional
controls include pre-testing batches of
new raw materials; improving hazard
communication when batches of
incoming raw materials contain higher
concentrations of crystalline silica, and
augmenting enclosure and ventilation
(e.g., adding ventilation to all crushing
and screening equipment, increasing
mine facility ventilation to 30 air
changes per hour, and fully enclosing
and ventilating all conveyor transfer
locations). NIOSH (2019b, 2021a)
describes all of the dust control methods
outlined in this section, which are
already used in mines, although to a less
rigorous extent than will be necessary to
reliably and consistently achieve
exposure levels of 25 mg/m3 or lower for
all miners.
MSHA finds that the action level of 25
mg/m3 is technologically feasible for
most mines. This finding is based on the
exposure profiles, presented in Tables
VII–1 and VII–2 for MNM mines, and
Tables VII–3 and VII–4 for coal mines,
which show that within each
commodity category, the exposure
levels are at or below 25 mg/m3 for at
least half of the miners sampled.
MSHA’s finding is also based on the
extensive control options documented
by NIOSH, which can be used in
combinations to achieve additional
reductions in respirable crystalline
silica exposure. Although most mines
will need to adopt and rigorously
implement a number of the control
options mentioned in this section, the
technology exists to achieve this level,
is already in use in mines, and is
available for most mines.
MSHA received numerous comments
related to exposure control methods.
Several commenters recommended that
the standard incorporate by reference
certain materials to assist mine
operators with compliance. The
International Society of Environmental
Enclosure Engineers (ISEEE) discussed
ISO 23875 (Document ID 1377).43 The
commenter explained that this ISO
standard is a widely adopted
international standard for cab air
43 ISO 23875:2021 (Mining—Air quality control
systems for operator enclosures—Performance
requirements and testing methods) and
Amendments.
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quality, as a practical and cost-effective
engineering control that would help
mine operators meet the final rule’s
requirements since the desired outcome
in all ISO 23875 cabs is compliance
with air quality regulations at the 25 mg/
m3 level. The commenter added that
increased awareness of the standard and
compliant cabs would lead to the
development of a standardized cab
design that could be mass-produced and
therefore reduce costs. Another
commenter, the APHA, stated that
guides prepared by NIOSH for coal
mines and metal and non-metal mines
contain helpful illustrations of
technologically feasible engineering
controls that reduce exposure to
respirable dust (Document ID 1416).
MSHA has reviewed the comments
and suggested material. The Agency
agrees that ISO 23875 is a useful tool
that promotes feasible dust control
equipment manufacture and
maintenance practices. Although MSHA
has not incorporated it into the final
rule, the Agency will keep this standard
in mind during future initiatives. MSHA
acknowledges that many other
organizations and agencies, including
NIOSH with its detailed and carefully
illustrated best practice guides for the
mining industries, have published
extensive information that may be
helpful to mine operators seeking
methods to protect miners. The Agency
encourages mine operators to use these
tools to identify proper and adequate
engineering controls, choose those that
will be useful in their mines, and ensure
that the controls are correctly installed,
implemented, and maintained.
MSHA received several comments
regarding the description and use of
feasible engineering controls. The
NVMA requested that MSHA supply a
definition for what is ‘‘feasible’’
(Document ID 1441).
Within MSHA’s standard
development process, the term
‘‘feasible’’ generally means ‘‘capable of
being done.’’ In the case of respirable
crystalline silica exposure controls,
these controls exist already and are not
technology-forcing. Based on its
extensive experience inspecting and
providing compliance assistance and
technical support in mines, MSHA has
observed that U.S. mines are already
using an extensive array of engineering
controls. As documented by NIOSH in
its best practices guides and other
resources for the mining industry, the
numerous readily available engineering
controls provide evidence that it is
technologically feasible for mine
operators to reduce miner respirable
crystalline silica exposure to levels at or
below the PEL and, in some cases,
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below the action level (NIOSH, 2019b,
2021a).
These engineering controls, including
examples and data, were discussed in
more detail previously in this
Technological Feasibility section (see
Section VII.A.1.b. The Technological
Feasibility Analysis Process). That
section explains that engineering
controls reduce or prevent miners’
exposure to hazards, while
administrative controls establish work
practices that reduce the duration,
frequency, or intensity of miners’
exposures. The different functional
types of engineering controls (wetting or
water sprays, ventilation systems,
process enclosures, equipment operator
enclosures, the associated preventive
maintenance that keeps the control
equipment operating effectively, and
instrumentation to monitor function and
identify need for corrective actions)
work alone or in combination with the
same or other controls to provide
additional protections. To further
ensure that mine operators can achieve
the PEL under diverse mining
conditions, the final rule allows
operators who seek an added measure of
protection for miners to supplement
engineering controls with
administrative controls (e.g.,
housekeeping procedures; proper work
positions of miners; walking around the
outside of a dusty process area rather
than walking through it; cleaning of
spills; and measures to prevent or
minimize contamination of clothing to
help decrease miners’ exposure). This
strategy allows a mine operator to select
the set of engineering controls that will
be most effective given the mining
conditions and the mine environment.
MSHA acknowledges that some mines
will need to work harder than others;
however, with the wide array of control
options, MSHA is confident that the
PEL is technologically feasible. As
stated earlier with respect to a feasibility
finding: ‘‘MSHA does not need to show
that every technology can be used in
every mine. The agency must only
demonstrate a ‘reasonable possibility’
that a ‘typical firm’ can meet the
permissible exposure limits in ‘most of
its operations.’ ’’ Kennecott Greens
Creek Min. Co. v. Mine Safety & Health
Admin., 476 F.3d 946, 958 (D.C. Cir.
2007) (quoting Am. Iron & Steel Inst. v.
Occupational Safety & Health Admin.,
939 F.2d 975, 980 (D.C. Cir. 1991)).
Some commenters, including the
UMWA, American Federation of Labor
and Congress of Industrial
Organizations (AFL–CIO), Black Lung
Clinics, and AIHA echoed the
availability of effective engineering
controls in the mining industry
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(Document ID 1398; 1449; 1410; 1351).
Two labor organizations stated that
mine operators should already be
utilizing engineering and administrative
controls in accordance with the law and
their existing ventilation plans
(Document ID 1398; 1449). The Black
Lung Clinics, AIHA, and UMWA
expressed support for engineering and
administrative controls as means to
keep miners’ exposures to respirable
crystalline silica below the proposed
PEL (Document ID 1410; 1351; 1398).
Agreeing with MSHA that
technologically feasible engineering
controls are available, the AIHA stated
that these methods can control
crystalline silica-containing dust
particles at the source and provide
reliable and consistent protection to all
miners who would otherwise be
exposed to respirable dust (Document
ID 1351).
MSHA concurs with these comments.
MSHA’s experience is consistent with
these comments. Based on MSHA’s
experience, consideration of the OSHA
silica rule (2016), and documentation
from NIOSH as discussed in this section
of the preamble, MSHA determines that
engineering controls exist for mining
operations to reduce miners’ exposure
to the level of the PEL (50 mg/m3). The
Agency finds that engineering controls:
(1) control crystalline silica-containing
dust particles at the source; (2) provide
reliable, predictable, effective, and
consistent protection to miners who
would otherwise be exposed to dust
from that source; and (3) can be
monitored. The technological feasibility
analysis of the PEL in the proposed rule
remains in effect for this final rule.
MSHA received several comments on
the technological feasibility of the
action level (25 mg/m3). Commenters
including the Arizona Mining
Association and American Iron Steel
Institute (AISI) stated that the action
level would not be achievable with
current technology (Document ID 1368;
1426). The AIHA opposing the proposed
action level, stated that the action level
should be removed and the PEL should
instead be set at the proposed action
level of 25 mg/m3 (Document ID 1351).
After careful consideration of the
comments, MSHA has determined a
full-shift 8-hour TWA action level of 25
mg/m3 is feasible, and the final rule is
the same as the proposal. MSHA
acknowledges that its FRA finds that
there will be a greater reduction of risk
for morbidity and mortality at the action
level than the final PEL of 50 mg/m3.44
44 Some residual risks remain even at exposures
of 25 mg/m3 of respirable crystalline silica. For
example, at 25 mg/m3, end stage renal disease
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Additionally, MSHA’s exposure profile
(Section VII.A.1.b, Tables VII–1 through
VII–4) indicates, based on MSHA
compliance samples, that operators at
most mines are already achieving
exposure levels less than 25 mg/m3 for
most miners. Tables VII–1 and VII–3 (in
this section) show that the overall
median MNM miner exposure is 15 mg/
m3 and the overall median coal miner
exposure is 16 mg/m3.45 Although these
medians indicate that mine operators
have already achieved exposure levels
below 25 mg/m3 for more than half of all
miners sampled by MSHA, the Agency
acknowledges that, for some mines,
consistently achieving a PEL of 25 mg/
m3 for all the miners it employs could
present a substantial challenge (i.e., a
PEL of 25 mg/m3 is technically feasible,
but the actions required might not be
practical for many mines).46 MSHA
finds, however, that the concentration of
25 mg/m3 is an appropriate and
necessary action level, which most mine
operators can (and may already have)
achieve for many miners. The action
level is consistent with MSHA’s
statutory purpose under the Mine Act—
to provide the highest level of health
protection for the miner. MSHA
establishes the action level and sets a
sampling frequency for concentrations
above the action level to require mine
operators to be proactive and act before
miners are overexposed. Under the final
rule, where some miners have exposures
at or above the action level (25 mg/m3),
but not exceeding the PEL, mine
operators are not required to install
additional controls, but instead (in
accordance with § 60.12(a)(3)) must
sample those miners quarterly to
confirm exposures remain below the
PEL. Alternatively, the mine operator
may choose to take actions to further
reduce exposures below 25 mg/m3 and,
where successful, discontinue sampling
(after meeting the sampling
requirements under § 60.12(a)(4)).
Comments on the analytical limit of
detection and reliability relative to the
action level relate to analytical
methodology and are addressed in
Section VII.2.b. Analytical Methods and
Feasibility of Measuring Below the PEL
and Action Level.
Section VIII.B.2.a. Action Level also
addresses these and other comments
related to the action level (25 mg/m3).
The action level is an important
provision of this final rule, necessary to
protect miners’ health. According to
NIOSH research, wherever exposure
measurements are above one-half the
PEL, the employer cannot be reasonably
confident that the employee is not
exposed to levels above the PEL on days
when no measurements are taken
(NIOSH, 1975). Thus, an action level (in
this case set at one-half of the PEL)
allows mine operators to take action
before overexposures occur. The action
level of 25 mg/m3 remains unchanged in
the final rule and the methodology
supporting the technological feasibility
analysis for the action level in the
proposed rule remains in effect for this
final rule.
MSHA finds that the PEL of 50 mg/m3
is technologically feasible. This
determination is based on MSHA’s
sound methodology and process for
analyzing technological feasibility and
control technology currently used in
mines (described in this section and
Section VII.A.1.b.), including the MSHA
exposure profiles in Tables VII–1
through VII–4, which show that using
the exposure control measures already
in place, most mine operators are
already achieving the PEL for most
miners.
(ESRD) risk is 20.7 per 1,000 MNM miners and 21.6
per 1,000 coal miners.
45 The median exposure level is the midpoint
concentration of all samples; in other words, half
(50%) of all the miner exposure samples are below
the median, and the remaining half are above.
Tables VII–2 (MNM mines) and VII–4 (coal mines)
show the percent of MSHA compliance exposure
samples that are less than 25 mg/m3.
46 For example, MSHA preliminarily reviewed
control measures the could reliably maintain
exposures throughout mines to levels of 25 mg/m3
or lower and determined these likely would
include, as a minimum, installing multiple layers
of engineering controls at every point throughout
the entire mine site by: concurrently enclosing and
installing ventilation along the full length of every
conveyor, fully enclosing all process equipment,
doubling or quadrupling all ventilation system
airflow, rebuilding ventilation systems to capture
dust at its source, installing HEPA filters at air
exhaust points, converting to automated processes,
and maintaining all worksurfaces damp at all times.
MSHA’s final rule requires mine
operators in both MNM and coal mines
to conduct sampling for respirable
crystalline silica using respirable
particle size-selective samplers that
conform to the ‘‘International
Organization for Standardization (ISO)
7708:1995: Air Quality—Particle Size
Fraction Definitions for Health-Related
Sampling’’ standard. The ISO
convention defines respirable
particulates as having a 4 micrometer
(mm) aerodynamic diameter median cutpoint (i.e., 4 mm-sized particles are
collected with 50 percent efficiency),
which approximates the size
distribution of particles that when
inhaled can reach the alveolar region of
the lungs. For this reason, the ISO
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2. Technological Feasibility of Sampling
and Analytical Methods
a. Sampling Methods
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convention is widely considered
biologically relevant for respirable
particulates and provides appropriate
criteria for equipment used to sample
respirable crystalline silica.
MSHA received supportive comments
from Badger Mining Corporation (BMC),
National Mining Association (NMA),
and SKC Inc., regarding the requirement
for samplers to conform to ISO
7708:1995 (Document ID 1417; 1428;
1366). BMC reported having no
objection to MSHA’s sampling device
provisions proposed here (Document ID
1417). NMA encouraged MSHA to
clarify that any sampling technology
that meets the characteristics for
respirable-particle-size-selective
samplers that conform to the ISO
7708:1995 standard is acceptable for air
sampling under the rule (Document ID
1428). NMA, BMC, and SKC, Inc. each
mentioned currently available sampling
equipment that meets the ISO criteria
(Document ID 1428; 1417; 1366), and
the manufacturer SKC, Inc. pointed out
that, for respirable crystalline silica
sampling, mine operators can use any
respirable dust sampling device that
conforms to ISO 7708:1995 (and where
appropriate, meets MSHA permissibility
requirements) (Document ID 1366). In
the Section-by-Section analysis of this
preamble, MSHA clarifies that mine
operators are allowed to use any type of
sampling device for respirable
crystalline silica sampling, as long as
the device is designed to meet the
characteristics for respirable-particlesize-selective samplers that conform to
the ISO 7708:1995 standard and, where
appropriate, meet MSHA permissibility
requirements.47 48
The American Exploration & Mining
Association (AEMA), NMA, and
Portland Cement Association expressed
concern that sufficient samplers (and
sampling pumps) might not be available
by the proposed compliance date
(Document ID 1424; 1428; 1407).
As discussed in more detail in Section
VIII.B. Section-by-Section Analysis,
47 To comply with the final rule requirement for
using respirable particulate samplers that meet the
ISO 7708:1995 criteria, those coal mine operators
that currently use coal mine dust personal sampler
units (CMDPSU) will need to adjust their samplers
to the flow rate specified by the sampler
manufacturer for complying with the ISO standard.
This means that mine operators who wish to use
sampling devices that include a Dorr-Oliver cyclone
can adjust the associated sampling pumps so they
operate at a flow rate of 1.7 L/min to meet the ISO
criteria. MSHA reminds mine operators that they
must continue to ensure any sampling equipment
used in underground coal mines is approved under
Title 30 Part 74—Coal Mine Dust Sampling Devices.
48 Mine operators must continue to ensure
sampling equipment used in underground coal
mines is approved under Title 30 Part 74—Coal
Mine Dust Sampling Devices.
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MSHA has extended the compliance
dates for the final rule (24 months from
publication of the final rule for MNM
and 12 months from publication for
coal) in response to concerns about the
availability of sampling equipment,
among other things. MSHA believes that
this will resolve compliance date
concerns but if concerns are not
resolved by the time operators must
comply, MSHA may exercise
enforcement discretion as necessary.
MSHA received comments both for
and against the proposed requirement of
sampling within 180 days after the
effective date of the final rule to
complete the baseline sampling
requirements, with most commenters
stating, for a variety of reasons, that it
was not enough time and
recommending a longer period ranging
from 1 year to 3 years. The Metallurgical
Coal Producers Association (MCPA) and
MSHA Safety Services, Inc. stated that
providing only 180 days to complete
baseline sampling is not sufficient
because of the limitation of available
resources for conducting sampling
(Document ID 1406; 1392). The Portland
Cement Association, SSC, and the NMA
stated that this requirement may not be
feasible for many operators because of
competition for outsourced resources
such as rental equipment, media,
professional services, and laboratory
sample analysis (Document ID 1407;
1432;1428). Concerned that mine
operators will be competing to obtain
these resources, the Portland Cement
Association and National Lime
Association (NLA) stated that small
mines are likely to have the greatest
difficulty in finding these resources in
a short period of time (Document ID
1407; 1408). The NSSGA, NLA, BMC,
and the Arizona Mining Association
each expressed concerns about
performing other tasks within the
proposed timeframe for compliance,
including establishing contracts with
accredited laboratories and other service
providers necessary for sampling,
performing sampling for all miners who
may reasonably be expected to be
exposed to respirable crystalline silica,
and designing and implementing new
engineering controls (Document ID
1448; 1408; 1417; 1368). The NSSGA
also urged MSHA to factor in the
increased demand that might result
from the state of California’s effort to
promulgate an Emergency Temporary
Standard on silica (Document ID 1448).
The MCPA and the Portland Cement
Association recommended a phased
timeline similar to the OSHA silica rule
(which gave employers one year before
the commencement of most
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requirements and two years before the
commencement of sample analysis
methods) and the MSHA 2014 RCMD
Standard (which gave operators 18
months after the rule became effective)
for completing sampling (Document ID
1406; 1407).
Other commenters considered the rule
feasible and practical. The AFL–CIO
stated that technologically feasible air
sampling and analysis exist to achieve
the proposed PEL using commercially
available samplers (Document ID 1449).
This commenter noted that these
technologically feasible samplers are
widely available, and a number of
commercial laboratories provide the
service of analyzing dust containing
respirable crystalline silica. One
individual supported the proposed
requirement that baseline sampling be
conducted within 180 days of the rule’s
effective date (Document ID 1367).
Samplers used in both MNM and coal
mines can be used to perform the
sampling, and because other
commercially available (already on the
market) samplers also conform to the
ISO standard, MSHA finds that
sampling in accordance with the ISO
standard is technologically feasible and
the technological feasibility analysis
supporting the sampling methods
provisions in the proposed rule remain
in effect for this final rule.
b. Analytical Methods and Feasibility of
Measuring Below the PEL and Action
Level
After a respirable dust sample is
collected and submitted to a laboratory,
it must be analyzed to quantify the mass
of respirable crystalline silica present.
The laboratory method must be
sensitive enough to detect and quantify
respirable crystalline silica at levels
below the applicable concentration. The
analytical limit of detection (LOD) and/
or limit of quantification (LOQ),
together with the sample volume,
determine the airborne concentration
LOD and/or LOQ for a given air sample.
MSHA’s final PEL for respirable
crystalline silica is 50 mg/m3 as a full
shift, 8-hour TWA for both MNM and
coal mines. Several analytical methods
are available for measuring respirable
crystalline silica at levels well below the
PEL of 50 mg/m3 and action level of 25
mg/m3.
MSHA uses two main analytical
methods (1) P–2: X-Ray Diffraction
Determination Of Quartz And
Cristobalite In Respirable Metal/
Nonmetal Mine Dust (analysis by X-ray
diffraction, XRD) for MNM mines and
(2) P–7: Determination Of Quartz In
Respirable Coal Mine Dust By Fourier
Transform Infrared Spectroscopy
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(analysis by infrared spectroscopy, FTIR
or IR) for coal mines.49 The MSHA P–
2 and P–7 methods reliably analyze
compliance samples collected by MSHA
inspectors. The exposure profile portion
of this technological feasibility analysis
included 15 years of MNM compliance
samples and 5 years of coal industry
compliance samples MSHA analyzed
with these methods. These methods can
measure respirable crystalline silica
exposures at levels below the PEL and
action level.
For an analytical method to have
acceptable sensitivity for determining
exposures at the PEL of 50 mg/m3 and
action level of 25 mg/m3, the LOQ must
be at or below the amount of analyte
(e.g., quartz) that will be collected in an
air sample where the concentration of
analyte is equivalent to the PEL or
action level. To determine the minimum
airborne concentration that can be
quantified, the LOQ mass is divided by
the sample air volume, which is
determined by the sampling flow rate
and duration. Table VII–7 presents
minimum quantifiable quartz
concentrations that can be measured
using particle size-selective samplers
under various sampling parameters and
established analytical method reporting
limits.
BILLING CODE 4520–43–P
Table VII-7: Minimum Quantifiable Quartz Concentrations,
Determined by Reporting Limit or LOQ and Sampling Volume
Sampling Parameters
(examples)
Reporting Limit or
Reporting Limit or
LOQ=5µg
LOQ = 9.76 µg
Reporting Limit or
LOQ= 12 µg
6.1 µg/m 3
12.0 µg/m 3
14.7 µg/m 3
4.2 µg/m 3
8.1 µg/m 3
10 µg/m 3
3.8 µg/m 3
7.4 µg/m 3
9.1 µg/m 3
2.5 µg/m 3
4.8 µg/m 3
6.0 µg/m 3
Airflow rate: 1.7 L/min
Sampling minutes: 480
Sample air volume: 816 L
Airflow rate: 2.5 L/min
Sampling minutes: 480
Sample air volume: 1,200 L
Airflow rate: 2.75 L/min
Sampling minutes: 480
Sample air volume: 1,320 L
Airflow rate: 4.2 L/min
Sampling minutes: 480
Sample air volume: 2,016 L
Notes:
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BILLING CODE 4520–43–C
Two commenters mentioned the need
for sampling devices with real-time or
near real-time sample analysis
capabilities for respirable crystalline
silica (Document ID 1428; 1449). One of
these commenters, the NMA, noted that
personal dust monitoring devices with
real-time analysis did not appear in the
proposed respirable crystalline silica
rule, noting that this equipment was
included in MSHA’s 2014 Coal Dust
49 Other similar XRD methods include NIOSH–
7500 and OSHA ID–142. XRD methods distinguish
between the different polymorphs—quartz,
cristobalite and tridymite. Other IR methods
include NIOSH 7602 and 7603. IR methods, while
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Rule (Document ID 1428). The
commenter recommended that MSHA
adopt new technology from the
domestic or international mining
community to better protect miners.
Also interested in new technology, the
AFL–CIO stated that, to more
appropriately characterize exposures,
MSHA should incorporate continuous
and rapid quartz monitoring systems
into the rule (Document ID 1449).
MSHA agrees with these commenters
that new technology, such as real-time
dust monitors and NIOSH’s rapid fieldbased quartz monitoring (RQM) system
with end-of-shift reporting 50 can help
mine operators, for example by
identifying overexposure conditions
while the operator evaluates and
implements controls to reduce
exposure. MSHA is not, however,
including instruments such as those
mentioned by the commenters in the
efficient, are prone to interferences and should only
be used with a well-characterized sample matrix
(e.g., coal dust).
50 NIOSH Information Circular 9533, ‘‘Direct-onfilter Analysis for Respirable Crystalline Silica
Using a Portable FTIR Instrument’’ provides
detailed guidance on how to implement a fieldbased end-of-shift respirable crystalline silica
monitoring program.
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ER18AP24.151
1. An analytical method LOQ may be referred to as a reporting limit (RL) or reliable quantitation limit (RQL).
2. RL and LOQ values are limits reported by (1) commercial laboratories (5 µg) (EMSL Analytical, Inc., 2022; RJ
Lee Group, 2021; SGS Galson, 2016), (2) OSHA ID-142 (9.76 µg), and (3) MSHA P-2 and P-7 (12 µg).
3. The minimum quantifiable concentration may change based on the laboratory's analytical method and
instrumentation.
4. Airflow rates are typical of sampler manufacturer recommendations for complying with ISO 7708: 1995.
5. Sample air volume (in liters) calculation: (sampling minutes) x (air flow rate as L/min)
6. Minimum quantifiable concentration (µg/m 3) calculation: (LOQ) / (L air volume) x 1000 L/m3
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
final rule because the Agency has
reviewed the information on these
instruments and decided that analysis of
samples using accredited laboratories is
the most accurate and reliable method
of determining respirable crystalline
silica exposures for compliance
purposes. The final rule is the same as
the proposal. Nevertheless, MSHA
recommends that operators stay aware
of and evaluate advances in
technologies to identify control options
that facilitate compliance, improve mine
operator and miner awareness, and
improve miner health.
A commenter, AISI, expressed
concern that the action level was too
close to the limit of accurate detection
of respirable crystalline silica
(Document ID 1426) and one
commenter, SSC, stated that there is
little confidence in the reliability of
sampling results below 50 mg/m3
(Document ID 1432).
MSHA agrees that limits of detection
and reliability are important
considerations, and, in this context, the
agency carefully reviewed currently
available sampling equipment and
analytical methods as part of the final
rule and in Table VII–7. In Table VII–
7, MSHA demonstrates how exposure
levels well below the PEL and action
level can be reliably quantified using
particle size-selective samplers under
various sampling parameters and
established analytical method reporting
limits. The minimum quantifiable
quartz concentrations shown in Table
VII–7 are all less than 25 mg/m3 and all
but one are 12 mg/m3 or less, therefore
well below the action level (25 mg/m3).
MSHA finds that current analytical
methods are sufficiently sensitive to
meet the PEL and action level in the
final rule. This finding is based on
information presented in this section
showing the availability and sensitivity
of MSHA, NIOSH, and OSHA analytical
methods capable of measuring
respirable crystalline silica
concentrations below 50 mg/m3 and 25
mg/m3.
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c. Laboratory Capacity
MSHA’s final rule requires, for
sample analysis, that mine operators use
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laboratories that meet ISO 17025,
General Requirements for the
Competence of Testing and Calibration
Laboratories (ISO 17025). The majority
of U.S. industrial hygiene laboratories
that perform respirable crystalline silica
analysis are accredited to ISO 17025 by
the American Industrial Hygiene
Association (AIHA) Laboratory
Accreditation Program (LAP). The AIHA
LAP lists 30 accredited commercial
laboratories nationwide that, as of
November 2023, performed respirable
crystalline silica analysis using an
MSHA, NIOSH, or OSHA method.
MSHA received comments in support
of the requirement for sample analysis
by the AIHA and the American
Association for Laboratory
Accreditation (A2LA) (Document ID
1351; 1388). Both commenters agreed
that MSHA should rely on laboratories
accredited to the ISO 17025 standards.
The A2LA explained that relying on
accredited laboratories’ impartiality,
expertise, and accuracy will permit
MSHA to focus time and resources on
policy, enforcement actions and other
Agency responsibilities (Document ID
1388).
MSHA interviewed three AIHA LAP
accredited laboratories (one smallcapacity laboratory,51 one mediumcapacity laboratory,52 and one largecapacity laboratory 53) to estimate their
sample-processing capacity. Insights
from these interviews suggest that
laboratories have the ability to provide
demand capacity during the phase-in of
the final rule. Collectively, these three
laboratories could process
approximately 33,240 samples by XRD
51 The small capacity laboratory has a maximum
respirable crystalline silica sample analysis
capacity of 300 samples per month (280 additional
samples per month above the current number of
samples analyzed), a level which the laboratory
could sustain for two months.
52 The medium capacity laboratory has a
maximum respirable crystalline silica sample
analysis capacity of 2,025 samples per month. Surge
from the mining industry is considered to replace,
rather than be in addition to the current number of
samples analyzed.
53 The large capacity laboratory has a maximum
respirable crystalline silica sample analysis
capacity of 4,500 samples per month (3,700
additional samples per month above the current
number of samples analyzed).
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(suitable for MNM mines) and 1,752
samples by FTIR or IR (suitable for coal
mines) within a 6-month period.
Extrapolating this across all laboratories
that can analyze respirable crystalline
silica samples, MSHA estimates that
analysis will be available for 664,800
samples for MNM mines and 35,000
samples for coal mines over any oneyear period. Separately, in its FRIA (and
summarized in Table VII–8), MSHA
estimates the numbers of miners for
whom the various types of sampling is
required under the final rule, in the first
and each subsequent year after the final
rule goes into effect.54 As shown in
Table VII–8, MSHA anticipates that
within the first 12 months after the final
rule effective date, mines will seek
analysis for a total of 41,599 respirable
crystalline silica samples (all for coal
mines). In the subsequent 12-month
period, mines will require analysis for
216,183 samples (primarily for MNM
mines). The number of analyses will
begin declining in Year 3, as mine
operators reduce some miner exposures
below the action level. Comparing these
figures with the demand capacity
estimates noted above, MSHA finds that
there is sufficient processing capacity to
meet the sampling analysis schedule in
the final rule.
BILLING CODE 4520–43–P
54 The estimated sample counts are based on
MSHA’s existing mine population data and its
exposure profile, developed using 15 years of MNM
compliance sampling exposure data and 5 years of
data from the coal industry, stratified by exposure
level (less than the action level, from the action
level to the final rule PEL, and above the final rule
PEL). That process was described in the proposed
rule and is summarized in Section VII.A
Technological Feasibility (see Subsections VII.A.1.a
Methodology and VII.A.1.b The Technological
Feasibility Analysis Process). From these data,
MSHA estimated for its FRIA how many first- and
second-time samples will represent miners likely to
have exposure below the action level and require
no further sampling. Based on its knowledge and
experience of the mining industry, MSHA further
estimated how rapidly mine operators will be able
to reduce the exposures of the remaining miners to
levels below the anticipated PEL or action level,
and calculated how many quarterly, corrective
actions, and post-evaluation samples that the mines
will collect (and require analysis for) over time.
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Table VII-8: Summary of the Estimated Number of Samples
Taken by Type and Year
All mines,
Total, all
samples
Sector
Sector
Subtotal,
all samples
First-time
and
secondtime
samples
Aboveactionlevel
samples
Corrective
actions
samples
Postevaluation
samples
Yearl
Year2
Year3
41,599
216,183
143,881
Coal
MNM
Coal
MNM
Coal
MNM
41,599
-
19,475
196,708
19,025
124,855
29,796
-
596
124,288
596
2,486
5,423
-
10,556
36,442
10,170
66,764
1,991
-
3,934
23,414
3,871
43,041
4,390
-
4,390
12,564
4,390
12,564
BILLING CODE 4520–43–C
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First- and Second-Time Sampling
MSHA’s final rule requires mine
operators to commence sampling, by the
compliance date in the final rule, for
each miner who is or may reasonably be
expected to be exposed to respirable
crystalline silica.55 This requirement
simplifies the initial sampling
requirement described in the proposed
rule, which called for a baseline sample
followed by a confirmatory sample (or
other data, as described below) if
samples revealed concentrations below
the action level. The final rule
eliminates the option of using objective
data or historical sample data (mine
operator and MSHA sample data from
the prior 12 months); all exposure
samples used to comply with the rule
55 Where several miners perform similar activities
on the same shift, only a representative fraction of
miners (minimum of two miners) would need to be
sampled, including those expected to have the
highest exposures.
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must be collected and analyzed in
accordance with the final rule. The
changes to the proposed rule increase
the number of samples that mine
operators will collect and send to
laboratories for analysis. The increased
sampling will require an initial increase
in analytical laboratory capacity of
approximately 41,599 FTIR sample
analyses in the first year (between the
final rule’s effective date and the coal
mine compliance date), with 29,796 of
these for first-time and second-time
sampling. In the following year, MSHA
estimates that MNM mine operators will
require 196,708 XRD sample analyses
(in the second year due to the extended
MNM mine compliance date) of which
approximately 124,288 will be first-time
and second-time samples.56
All mine operators covered by the
rule must initiate sampling by the
56 Also in the second year, MSHA anticipates that
the coal mining industry will require 19,475
analysis by FTIR method; relatively few (596) of
these will be for first- and second-time samples.
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compliance dates, potentially creating a
peak demand for analysis around those
dates. MSHA finds, however, that the
final rule is feasible for mine operators
to secure the services of analytical
laboratories. First, the extended MNM
compliance date permits more time to
accommodate and prepare for any
increase in demand. MSHA expects
many mine operators will avoid lastminute sampling and begin the
sampling process earlier than required;
thus, the sampling and associated
analysis will be spread over many
months, meaning that any eventual peak
period for laboratory analysis will be
longer and less intense (i.e., fewer
analyses per month required) than it
might be otherwise. Additionally,
MSHA expects that the extended lead
time will be sufficient for laboratories to
increase their analytical capacity. For
example, laboratories may acquire
additional instrumentation, train
additional analysts, or add a second or
third operating shift. This is particularly
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Notes:
1.
MNM mines begin collecting samples in Year 2, due to extended MNM compliance date.
2.
Component values may not sum to totals due to rounding.
Source: Summarized from MSHA's FRIA, Table 4-5. Estimated Number ofSamples Taken by Type and Year
(dated 11/27/2023).
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
likely given that demand will be based
on a regulatory requirement. MSHA has
determined that the final rule is
technologically feasible for mine
operators to secure laboratories’
analytical services.
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Above-Action-Level, Corrective Actions,
and Post-Evaluation Sampling
Under § 60.12(a), (b), and (d), mine
operators may be required to conduct
additional sampling. First, when the
most recent sampling indicates that
miner exposures are at or above the
action level (25 mg/m3) but at or below
the PEL (50 mg/m3), the mine operator
is required to sample within 3 months
of that sampling and continue to sample
within 3 months of the previous
sampling until two consecutive
samplings indicate that miner exposures
are below the action level. Second,
where the most recent sampling
indicates that miner exposures are
above the PEL, the mine operator is
required to sample after corrective
actions are taken to reduce
overexposures and continue conducting
corrective actions sampling until
sampling results indicate miner
exposures are at or below the PEL.
Third, if the mine operator determines,
as a result of the periodic evaluation,
that miners may be exposed to
respirable crystalline silica at or above
the action level, the mine operator is
required to perform sampling to assess
miners who are or may reasonably be
expected to be exposed at or above the
action level.
In its standalone Final Regulatory
Impact Analysis (FRIA) document
(referred to as the standalone FRIA
document throughout the preamble),
Table 4–5 ‘‘Estimated Number of
Samples Taken by Type and Year,’’
MSHA estimates that, starting in the
first 12-month period after the rule’s
effective date, coal mine operators will
secure laboratory services for analysis of
5,423 above-action-level samples (those
samples required when the previous
sample is at or above the action level,
but at or below the PEL), 1,991
corrective actions samples, and 4,390
post-evaluation samples, in addition to
the 29,796 first-time and second-time
samples mentioned in the previous
subsection. MSHA assumes that coal
industry analytical needs will be
reduced in subsequent years as mine
operators reduce miner exposures to
levels below the PEL or action level. In
the second 12-month period, in addition
to 596 first-time and second time
samples, coal mine operators will secure
laboratory services for analysis for
10,556 above-action-level, 3,934
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corrective actions, and 4,390 postevaluation samples.
Similarly, starting in the second 12month period (due to the extended
MNM compliance date), MSHA
estimates that MNM mine operators will
secure laboratory analysis for 36,442
above-action-level, 23,414 corrective
actions, and 12,564 post-evaluation
samples (plus the 124,288 first-time and
second-time samples discussed
previously). MSHA estimates that the
MNM industry’s need for analysis will
be lower in the following years as mine
operators reduce miner exposures to
levels below the PEL or action level. In
the third 12-month period after the rule
goes into effect, MNM mines are
projected to need analysis for 2,486
first-time and second-time, 66,764
above-action-level, 43,041 corrective
actions, and 12,564 post-evaluation
samples.57 Together, mine operators
will require fewer sample (at least
10,000 fewer) analyses in each
subsequent year than in the first 12month period (coal sector) and second
12-month period (MNM mines), which
are considered the ‘‘worst case’’ or
highest demand periods for analysis
under this rule.
MSHA estimated that the total
number of analyses (699,800) that
laboratories will be able to perform per
year is nearly three times the maximum
total estimated number of samples
analyses required (216,183).58 The
maximum number of sample analyses
required will occur in the second year
after the rule goes into effect.59 Based on
MSHA’s evaluation, the Agency finds
that above-action-level, corrective
57 As noted in Section VII.A.2.c (First- and
second-time sampling) coal mines will have
completed most of their first- and second-time
sampling during the first year after the rule’s
effective date and MNM mines will complete most
of it in the second year after the rule goes into
effect. MSHA expects only a relatively modest
amount of this sampling to continue in subsequent
years (coal mining industry requiring 596 analyses
per year and MNM mining industry 2,486 analyses
per year) due to a steady background level of new
activities starting or new mines opening.
58 Excess capacity calculated as: (estimated
annual demand capacity of 30 AIHA LAP
accredited laboratories for sample analysis) divided
by (maximum number of XRD and FTIR samples for
which mines will seek analysis) = 699,800/216,183
= 3.2 times more analysis available on a yearly basis
than the number of sample analyses labs will
complete in the peak year.
59 The maximum number of samples (the peak)
will occur in the second 12-month period (second
year) after rule’s effective date, which is the period
when MNM mines will conduct most of their firsttime and second-time sampling as well as initiate
above-action-level, corrective actions, and postevaluation sampling. Concurrently, coal mines will
continue conducting first-time and second-time,
above-action-level, corrective actions, and postevaluation sampling at somewhat lower rates. See
Table 4–5 of the standalone FRIA document
(estimates presented here are as of 11/26/2023).
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actions, and post-evaluation sampling
are technologically feasible for mine
operators both in the early years after
the rule becomes effective, and in
subsequent years.60
The AEMA and NMA expressed
concern that laboratory capacity might
not be available by the proposed
compliance date (Document ID 1424;
1428). As discussed in more detail in
Section VIII.B. Section-by-Section
Analysis, MSHA has extended the
compliance dates in the final rule for
MNM and coal (24 months and 12
months from publication of the final
rule, respectively) in response to
concerns about the availability of
laboratory capacity, among other things.
MSHA believes that this will resolve
compliance date concerns but if
concerns are not resolved by the time
operators must comply, MSHA may
exercise enforcement discretion as
necessary.
As part of the proposed rule, MSHA
examined the capacity of laboratories
that meet the ISO 17025 standard to
conduct respirable crystalline sample
analyses. MSHA made the preliminary
determination that there would be
sufficient processing capacity to meet
the sampling analysis schedule
envisioned by the proposed rule, and
that the proposed rule is technologically
feasible for laboratories to conduct
baseline sampling analyses (88 FR
44923). MSHA also preliminarily
determined that the availability of
samplers needed to conduct the
required baseline sampling is
technologically feasible (88 FR 44921).
This preliminary determination,
however, only examined whether
sampler technology exists to conduct
the respirable crystalline silica sampling
as required under the proposal, not the
availability of that technology to meet
the demands that the final rule will
impose.
MSHA agrees with commenters that
the sampling requirements of the final
rule will create an initial rush for
sampling devices and related equipment
and services. MSHA understands that
there are more sampling devices (as well
as related services and supplies)
currently available in the market now
than prior to OSHA’s proposed silica
rule. Nevertheless, based on OSHA’s
successful promulgation of that
Agency’s 2016 respirable crystalline
silica final rule that included new silica
sampling requirements (with similar
60 Surplus analyses calculated: estimated annual
surge capacity of 30 AIHA LAP accredited
laboratories for sample analysis) minus (maximum
number of XRD and FTIR samples for which mines
will seek analysis) = 699,800¥216,183 = 483,617
surplus analyses.
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ISO compliant sampling equipment and
analytical method provisions for both
general industry and the construction
industry), MSHA expects that there will
be another additional increase in
demand (for equipment, services, and
supplies) caused by this final rule.
MSHA expects that the sampling device
market will respond to the Agency’s
rule. MSHA does not expect that mines
will experience a shortage of sampling
resources due to a California emergency
temporary standard (ETS) to address
silicosis among engineered stone
fabrication facility workers (e.g., kitchen
countertop shop employees who often
use powered hand tools to grind/shape
engineered stone, which has a quartz
content greater than most natural
stone).61 Any increased demand of
sampling equipment, services, or silica
analysis for the mining industry will be
related to MSHA’s rule.
Resource limitations may be an issue
for MNM mine operators since there are
far more MNM mines in the U.S.
compared to coal mines (in 2021, there
were 11,231 MNM mines compared to
931 coal mines). As such, the expected
demand for sampling devices, supplies,
and services to meet the sampling
requirements of this final rule is
expected to be greater for MNM mines
compared to coal mines.
MSHA carefully considered the above
information about availability of
laboratory capacity and sampling
devices, including the likely increase in
demand for such services and devices.
MSHA acknowledges commenters’
concerns about the need for more time
to conduct sampling and implement
necessary engineering controls.
Accordingly, MSHA has adjusted the
requirements in the final rule to allow
MNM mine operators a total of 24
months after the publication date of the
final rule to comply. This will provide
sufficient time for MNM mine operators
to comply with the requirements of part
60. Actions the operator may take in
preparation for compliance with part 60
may include, for example, purchasing
sampling equipment, securing sampling
services, making arrangements with
laboratories, and performing sampling.
MSHA has changed the requirements in
the final rule to allow coal mine
operators a total of 12 months after
publication of the final rule to come into
compliance. MSHA expects that the
extended time for compliance will
provide coal mine operators with time
61 The California ETS went into effect on
December 29, 2023. The ETS includes revisions to
protect workers engaged in high-exposure tasks
(cutting, grinding, etc.) involving artificial stone
and natural stone containing more than 10%
crystalline silica.
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to purchase additional sampling
equipment and acquire necessary
laboratory services. MSHA also notes
that the AIHA, an accrediting body for
commercial laboratories that analyze
respirable crystalline silica, concurred
with MSHA’s findings that
technologically feasible samplers are
widely available, and a number of
commercial laboratories provide the
service of analyzing dust containing
respirable crystalline silica (Document
ID 1351). Additional discussion of the
compliance dates can be found in
Section VIII.A.1.c. Compliance Dates.
3. Technological Feasibility of
Respiratory Protection (Within Part 60)
Under MSHA’s final rule, respiratory
protection will not be allowed for
compliance. As discussed elsewhere,
MSHA has determined that the PEL is
feasible for all mines and all mines must
comply with it. However, when
exposures are above the PEL, mine
operators must take immediate
corrective actions, provide miners with
respirators, and ensure that they are
worn until exposures are below the PEL.
There is a sufficient supply of
respirators for mine operators to obtain
and maintain for temporary use.
Therefore, MSHA has determined that
the requirements in the final rule for
respirator use are technologically
feasible. This finding is supported by
the Agency’s knowledge of and
experience with the mining industry,
evidence presented by NIOSH (2019b,
2021a), and Tables VII–1 through VII–4
(exposure profiles for MNM and coal
mines). These tables indicate that the
PEL (50 mg/m3) has already been
achieved for approximately 82 percent
of the MNM miners and approximately
93 percent of the coal miners sampled
by MSHA. MSHA believes that this data
supports the Agency’s approach to
respirator use in the final rule.
Section 60.14(b) requires that any
miner unable to wear a respirator must
receive a temporary job transfer to an
area or to an occupation at the same
mine where respiratory protection is not
required. The paragraph also requires
that a miner transferred under this
requirement continue to receive
compensation at no less than the regular
rate of pay in the occupation held by
that miner immediately prior to the
transfer. MNM mine operators must
already comply with the job transfer
provisions under the existing standard
in § 57.5060(d)(7) that requires mine
operators to transfer miners unable to
wear a respirator to work in an existing
position in an area of the mine where
respiratory protection is not required.
Section 60.14(b) is similar to these
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existing requirements. MSHA finds that
mine operators will have a similar
experience implementing the job
transfer provisions of § 60.14(b). As
discussed in Section VIII.B.7.b. Section
60.14(b)—Miners unable to wear
respirators, MSHA concludes that
temporary transfer of miners unable to
wear respirators to a separate area or
occupation to ensure their health and
safety is feasible. As noted elsewhere in
the preamble, any respirator use will be
temporary to protect miners from
overexposures during activities such as
the implementation or development
engineering controls. Therefore, MSHA
finds that the requirement in § 60.14(b)
is technologically feasible.
For miners who need to wear
respiratory protection on a temporary
basis, section 60.14(c)(1) requires the
mine operator to provide NIOSHapproved atmosphere-supplying
respirators or NIOSH-approved airpurifying respirators equipped with
high-efficiency particulate filters in one
of the following NIOSH classifications
under 42 CFR part 84: 100 series or High
Efficiency (HE). As discussed below in
the Section-by-Section analysis, MSHA
finds that particulate respirators
meeting these criteria will offer the best
filtration efficiency (99.97 percent) and
protection for miners exposed to
respirable crystalline silica and are
widely available and used by most
industries. This finding is based on the
characteristics of the 100 series as
compared to the other two most
common series (95 and 99). The 95- and
99-series particulate respirators do not
offer as high a degree of protection as
the 100-series (95 percent and 99
percent efficiency, respectively), and are
less likely to provide the expected level
of protection due to concerns about poor
fit and vulnerability to mishandling
such as folding or crushing. The NIOSHapproved 100-series particulate
respirators also have broad commercial
availability.62 NIOSH publishes a list of
approved respirator models along with
manufacturer/supplier information. In
November 2022, the NIOSH-approved
list contained 221 records on
atmosphere-supplying respirator
models, 160 records on elastomeric
respirators with P–100 classification,
and 23 records on filtering facepiece
respirators with P–100 classification
(NIOSH, 2022a list P–100 elastomeric,
P–100 filtering facepiece, and
atmosphere-supplying respirator
62 Class 100 particulate respirators (currently the
most widely used respirator filter specification in
the U.S.) are available from numerous sources
including respirator manufacturers, online safety
supply companies, mine equipment suppliers, and
local retail hardware stores.
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a. Incorporation by Reference
This section discusses the update to
MSHA’s existing respiratory protection
standards in 30 CFR 56.5005, 57.5005,
and 72.710 which deal with other
airborne contaminants and do not
include respirable crystalline silica.
Respiratory protection requirements for
respirable crystalline silica are in final
§ 60.14 and are substantially similar to
MSHA existing standards. Respirators
are used by mine operators to protect
miners against respiratory hazards,
including particulates, gases, and
vapors. Under existing standards, for
MNM and coal mine operators,
respirators must not be used in place of
engineering controls to control airborne
contaminants. If respirable coal mine
dust samples exceed the standard, coal
mine operators must make approved
respiratory equipment available to
affected miners while taking immediate
corrective actions to lower the
concentration of respirable dust to at or
below the respirable dust standard.
Metal and nonmetal mine operators
must provide miners with respirators
and miners must use respirators while
engineering control measures are being
developed or when necessary by the
nature of work involved (for example,
while establishing controls or
occasional entry into hazardous
atmospheres to perform maintenance or
investigation).
Where respirators are used, they must
seal and isolate the miner’s respiratory
system from the contaminated
environment. The risk that a miner will
experience an adverse health effect from
a contaminant when relying on
respiratory protection is a function of
the toxicity or hazardous nature of the
air contaminants present, the
concentrations of the contaminants in
the air, the duration of exposure, and
the degree of protection provided by the
respirator. When respirators fail to
provide the expected protection, there is
an increased risk of adverse health
effects. Therefore, it is critical that
respirators perform as they are designed.
Accordingly, MSHA is incorporating
by reference ASTM F3387–19 by
amending §§ 56.5005, 57.5005, and
72.710 to replace the Agency’s existing
respiratory protection standard in those
sections. Final §§ 56.5005, 57.5005, and
72.710 requires mine operators to
develop a written respiratory protection
program meeting the requirements in
accordance with ASTM F3387–19.
These requirements allow for achieving
expected protection levels from
respirator use. This revision to MSHA’s
existing standards will better protect
miners who temporarily wear
respiratory protection.
The American National Standards
Practices for Respiratory Protection
ANSI Z88.2—1969 was previously
incorporated by reference in §§ 56.5005,
57.5005, and 72.710.64 Since MSHA
adopted these standards, respirator
technology and knowledge on respirator
protection have advanced and as a
result, changes in respiratory protection
standard practices have occurred.
ASTM F3387–19 is the most recent
respirator practices consensus standard
and provides more comprehensive and
detailed guidance. MSHA finds, based
on observations during enforcement
inspections and compliance assistance
visits to mines, that mines using
respiratory protection have also already
implemented current respiratory
protection recommendations and
standards such as ANSI/ASSE Z88.2—
2015 ‘‘Practices for Respiratory
Protection’’ standard, its similar ASTM
replacement (the F3387–19 standard), or
OSHA 29 CFR 1910.134—Respiratory
protection. ASTM F3387–19 standard
practices are substantially similar to the
standard practices included in ANSI/
ASSE Z88.2—2015 or OSHA’s
respiratory protection standards.
63 The NIOSH list of approved models does not
guarantee that each model is currently
manufactured. However, the list does not include
obsolete models, and the more popular models are
widely available, including in bulk quantities.
64 ASTM 3387–19 is the revised version of ANSI/
ASSE Z88.2—2015. In 2017, the Z88 respirator
standards were transferred from ANSI/ASSE to
ASTM International (source: F3387–19, Appendix
XI).
models).63 Based on this information
regarding the level of protection and the
market availability, MSHA finds that
§ 60.14(c)(1) is technologically feasible.
Section 60.14(c)(2) incorporates the
ASTM F3387–19 ‘‘Standard Practice for
Respiratory Protection’’ to ensure that
the most current and protective
respiratory protection practices are
implemented by mine operators who
temporarily use respiratory protection to
control miners’ exposures to respirable
crystalline silica. The Agency is also
incorporating this respiratory protection
consensus standard under §§ 56.5005,
57.5005, and 72.710. This update is also
addressed in the next section (see
Technological feasibility of updated
respiratory protection standards). Based
on the information contained in that
section, MSHA finds that § 60.14(c)(2) is
technologically feasible.
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4. Technological Feasibility of Updated
Respiratory Protection Standards
(Amendments to 30 CFR Parts 56, 57,
and 72)
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b. Availability of Respirators
The updated respiratory protection
standard reflects current practice at
many mines that use respiratory
protection and does not require the use
of new technology. Thus, MSHA finds
that the update is technologically
feasible for affected mines of all sizes.
c. Respiratory Protection Practices
By amending existing standards to
incorporate the updated respiratory
protection consensus standard (ASTM
F3387–19), MSHA intends that mine
operators will develop effective
respiratory protection practices that
meet the updated consensus standard
and that will better protect miners from
respiratory hazards.
MSHA presumes that most mines
with respiratory protection programs,
and particularly those MNM mines that
have operations under both MSHA and
OSHA jurisdiction, are already
following either the ANSI/ASSE
Z88.2—2015 standard, the ASTM
F3387–19 standard, or OSHA 29 CFR
1910.134. As several commenters noted,
consistency between OSHA and MSHA
requirements is beneficial for
organizations regulated by both
agencies, as it permits them to more
easily comply with a single, consistent
set of requirements. Mine operators with
operations under OSHA jurisdiction
would, by this logic, choose to comply
with 29 CFR 1910.134 across all
operations rather than develop separate
programs for MSHA-regulated facilities.
The respiratory protection program
elements under ASTM F3387–19 are
largely similar to those in the previous
standard.
MSHA expects that some operators
may need to adjust their current
respiratory protection practices and
standard operating procedures to reflect
ASTM F3387–19 standard practices.
Examples of adjustments include
formalizing annual respirator training
and fit testing; updating the training
qualifications of respirator trainers,
managers, supervisors, and others
responsible for the respiratory
protection program; reviewing the
information exchanged with the
physician or other licensed health care
professional (PLHCP) conducting
medical evaluations; and formalizing
internal and external respiratory
protection program reviews or audits.
Overall, MSHA finds that the
amendments to parts 56, 57, and 72 are
technologically feasible because the
requirements of ASTM F3378–19 have
already been implemented at many
mines.
MSHA received several comments on
the Agency’s decision to limit respirator
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use to temporary and non-routine use.
Many commenters opposed this
limitation in the proposal, including
AIHA, Miners Clinic of Colorado, ACLC,
and Black Lung Clinics (Document ID
1351; 1418; 1445; 1410), while others
requested more information to help
them properly interpret the
requirement, including SSC, AMI Silica
LLC, NSSGA, and AFL–CIO (Document
ID 1432; 1440; 1448; 1449). The AFL–
CIO requested that MSHA clarify
temporary and non-routine to specify
circumstances and time limitations
(Document ID 1449). Appalachian
Voices stated that mine construction
and coal production should be excluded
from the temporary and non-routine use
of respirators (Document ID 1425).
The Construction Industry Safety
Coalition (CISC) suggested that coal
miners should be prohibited from
working in overexposures while using
respirators, stating that the working
conditions, especially in underground
coal mines, make it very difficult for
miners to communicate and work safely
while wearing respirators (Document ID
1430). Many commenters suggested that
MSHA utilize the full hierarchy of
controls to recognize respirators as an
acceptable solution when combined
with other efforts to lower exposure
levels, including Arizona Mining
Association, AEMA, NMA, NVMA,
NSSGA, US Silica, SSC, BMC, Illinois
Association of Aggregate Producers
(IAAP) (Document ID 1368; 1424; 1428;
1441; 1448; 1455; 1432; 1417; 1456).
Advocating expanded use of respiratory
protection, but differing in their
approach, a few commenters, including
SSC, NSSGA, US Silica, and IAAP,
wrote that respirators are the only
feasible means of protection for certain
tasks, including housekeeping, dust
collector maintenance and repair, and
bagging operations (Document ID 1432;
1448; 1455; 1456). The AEMA stated
that MSHA should allow the use of
respirators, including PAPRs, whenever
miners are working in exposures above
the PEL (Document 1424). Another
commenter stated that miners should
always use respirators, to ensure
complete protection from respirable
crystalline silica exposures. MSHA
finds that engineering controls,
supplemented by administrative
controls, are technologically feasible
and provide reliable, consistent
protection for miners engaged in the
identified tasks; MSHA declines to
expand the allowable use of respiratory
protection. MSHA emphasizes that both
in the existing standards for MNM
mines and in § 60.14, respiratory
protection use is required to be
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temporary. The Agency emphasizes that
it will continue to enforce ‘‘temporary’’
use of respirators as meaning that
respirators are used for only a short
period of time.
MSHA clarifies that the final rule
does not permit the use of respirators in
lieu of feasible engineering and
administrative controls. If anything,
MSHA has provided greater protection
for miners by requiring (as opposed to
making available) usage of respirators
for all miners when exposed to
respirable crystalline silica above the
PEL.
5. Technological Feasibility of Medical
Surveillance (Within Part 60)
Under the final rule, MNM mine
operators will be required to provide
periodic medical examinations
performed by a physician or other
licensed health care professional
(PLHCP) or specialist, at no cost to the
miner. 30 CFR 60.15. The medical
surveillance standards extend to MNM
miners similar protections to those
available to coal miners under existing
standards in 30 CFR 72.100. The
requirements in § 60.15 are consistent
with the Mine Act’s mandate to provide
maximum health protection for miners,
which includes making medical
examinations and other tests available
to miners at no cost. 30 U.S.C. 811(a)(7).
Under the final rule, all MNM miners
who are employed or have already
worked in the mining industry must be
provided the opportunity for an initial
voluntary examination starting during
an initial 12-month period that begins
no later than the compliance date or
during a 12-month period that begins
whenever a new mine commences
operations. Subsequent medical
examinations must be available at least
every 5 years during a 6-month period
that begins no less than 3.5 years and
not more than 4.5 years from the end of
the previous 6-month period. MNM
miners who begin work in the mining
industry for the first time must receive
an initial examination within 60 days of
beginning employment. After their
initial examination, these new miners
must be provided a follow-up
examination within 3 years. If the 3-year
follow-up examination indicates any
medical concerns associated with chest
X-ray findings or decreased lung
function, these miners must have
another follow-up examination in 2
years. After this 2-year follow-up
examination, or if the 3-year follow-up
examination indicates no medical
concerns associated with chest X-ray
findings or decreased lung function,
these miners will be eligible for
voluntary periodic 5-year examinations,
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transferring them into the larger cohort
of miners already employed in the
mining industry.
The final rule requires that medical
examinations include a review of the
miner’s medical and work history, a
physical examination with special
emphasis on the respiratory system, a
chest X-ray, and a pulmonary function
test. The medical and work history
covers a miner’s present and past work
exposures, illnesses, and any symptoms
indicating respirable crystalline silicarelated diseases and compromised lung
function. The required chest X-ray must
be classified by a NIOSH-certified B
Reader, in accordance with the
Guidelines for the Use of the
International Labour Office (ILO)
International Classification of
Radiographs of Pneumoconioses. The
ILO recently made additional standard
digital radiographic images available
and has published guidelines on the
classification of digital radiographic
images (ILO, 2022). These guidelines
provide standard practices for detecting
changes of pneumoconiosis, including
silicosis, in chest X-rays. The required
pulmonary function test must be
conducted by either a spirometry
technician with a current certificate
from a NIOSH-approved Spirometry
Program Sponsor, or, as discussed in
Section VIII.B.8.a. 60.15(a)—Medical
surveillance of this preamble, a
pulmonary function technologist with a
current credential from the National
Board for Respiratory Care.
MSHA has determined that it is
technologically feasible for MNM mine
operators to provide periodic
examinations as described in the
previous paragraph. Under the rule, a
PLHCP, as defined, does not have to be
an occupational medicine physician or
a physician to conduct the initial and
periodic examinations required by the
rule, but can be any health care
professional who is state-licensed to
provide or be delegated the
responsibility to provide those services.
The procedures required (i.e., medical
history, physical examination, chest Xray, pulmonary function test) for initial
and periodic medical examination are
commonly conducted in the general
population by a wide range of
practitioners with varying medical
backgrounds. Because the medical
examinations consist of procedures
conducted in the general population
and because MSHA will be giving MNM
mine operators flexibility in selecting a
PLHCP or specialist able to offer these
services, MSHA determined that
operators will not experience difficulty
in finding PLHCPs or specialists who
are licensed to provide these services.
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Overall, MSHA finds that the medical
surveillance provisions are
technologically feasible and in the final
rule maintains the proposed medical
surveillance provisions, with some
modifications.
MSHA received several comments on
the feasibility of proposed § 60.15(a).
The AIHA, the American Association of
Nurse Practitioners (AANP), and
CertainTeed, LLC supported MSHA’s
proposal to require MNM mine
operators to provide MNM miners with
medical examinations performed by a
PLHCP or specialist (Document ID 1351;
1400; 1423). The Arizona Mining
Association and the BIA expressed
concerns with this requirement and
asserted that many MNM mines may
experience issues with access to a
PLHCP or specialist qualified to perform
the examinations (Document ID 1368;
1422). The APHA, the AOEC, and the
ACOEM advocated for medical
surveillance to be performed by
physicians who are board-certified in
occupational medicine or pulmonary
medicine (Document ID 1416; 1373;
1405). The Hon. Rep. Robert C. ‘‘Bobby’’
Scott and an individual recommended
that MNM miners should be able to
choose their own health care provider
(Document ID 1439; 1412). The AIHA
and Black Lung Clinics stated that
MSHA should require MNM miners to
use NIOSH-approved facilities
(Document ID 1351; 1410) while the
AEMA and the NMA (Document ID
1424; 1428) expressed concerns about
the limited availability of these
facilities. The NMA, the Portland
Cement Association, and the AEMA
noted that there are only a limited
number of B Readers available
(Document ID 1428; 1407; 1424).
MSHA reviewed these comments and
made one change to § 60.15(a) in the
final rule. Under the proposed rule, a
pulmonary function test must be
administered by a spirometry technician
with a current certificate from a NIOSHapproved Spirometry Program Sponsor.
In the final rule, paragraph
60.15(a)(2)(iv) retains that language but
adds pulmonary function technologists
with current credentials from the
National Board for Respiratory Care as
individuals who may administer
pulmonary function tests. This addition
to the final rule text should further
expand the pool of individuals eligible
to administer pulmonary function tests.
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MSHA determined that MNM mine
operators should not experience any
significant issues identifying a PLHCP
or specialist to conduct medical
examinations and emphasizes the final
rule allows flexibility by not mandating
that the medical examinations be
conducted by full-time health care
professionals employed by mine
operators. As stated in the proposal, a
PLHCP is an individual whose legally
permitted scope of practice (i.e., license,
registration, or certification) allows that
individual to independently provide or
be delegated the responsibility to
provide some or all of the required
health services (i.e., chest X-rays,
pulmonary function test, symptom
assessment, and occupational history).
Specialist is defined in § 60.2 as an
American Board-Certified Specialist in
Pulmonary Disease or an American
Board-Certified Specialist in
Occupational Medicine. MSHA also
clarifies that if medical examinations
are integrated within health care plans,
mine operators must ensure that the
examinations are conducted in
accordance with the requirements in
§ 60.15. MSHA determined that the
requirements for testing and
interpretation of results are
technologically feasible.
The Agency has reviewed the
comments related to availability of B
Readers. MSHA has determined that,
based on technological improvements
that remove the need for geographic
proximity between patients and
technicians such as B Readers, as well
as widespread availability of tests such
as X-rays, getting X-ray tests and the
results classified by B Readers is
technologically feasible. With respect to
chest X-ray classification, the
availability of digital X-ray technology
permits electronic submission to
remotely located B Readers for
interpretation. After consulting NIOSH,
MSHA determined there are B Readers
with remote reading capabilities
available to meet the demands of the
final rule. Therefore, MSHA finds that
the limited number of B Readers in
certain geographic locations will not be
an obstacle for MNM operators. MSHA
further concludes that any increase in
demand for these services can be
addressed by providers. Further
discussion regarding NIOSH-approved
facilities and B Readers can be found in
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Section VIII.B.8.a. Section 60.15(a)—
Medical Surveillance of this preamble.
MSHA’s experience with the coal
mine medical surveillance program has
shown the Agency that PLHCPs who
have the required NIOSH or other
certifications have the training to
effectively examine miners and identify
the occurrence or progression of silicarelated diseases, even if they may not
operate within NIOSH-approved
facilities. MSHA’s updated research
continues to support OSHA’s
conclusion in its 2016 silica final rule
that the number of B Readers in the
United States is adequate to classify
chest X-rays (OSHA 2016a, 81 FR
16286, 16821). Further, an increased
demand for B Readers as a result of this
final rule will lead to additional training
for many health care providers. In
addition, digital X-rays can be easily
transmitted electronically to B Readers
anywhere in the United States. The final
rule ensures that medical examinations
are comprehensive and tailored to
discern and mitigate potential health
risks associated with miners’
occupational exposures to respirable
crystalline silica. The final rule will
ensure that the medical examinations
are both robust and flexible enough to
accommodate advancements and
variations in medical evaluation
techniques. Further discussion
regarding NIOSH-approved facilities
and B Readers can be found in Section
VIII.B.8.a. Section 60.15(a)—Medical
Surveillance of this preamble.
The final rule does not require that
examinations conducted under this
section occur in NIOSH-approved
facilities. There are only 168 NIOSHapproved health clinics nationwide.
NIOSH manages the Coal Workers’
Health Surveillance Program and the
program’s facilities are concentrated in
geographies where coal mining is
prevalent (e.g., Appalachia, the Illinois
Basin, and Powder River Basin). The
NIOSH-approved facilities are not
uniformly distributed across the U.S.
and there are many areas that have
MNM mines but do not have NIOSHapproved facilities (e.g., the states
California, Idaho, Nevada, and
Washington). Therefore, MSHA has
determined that it is not feasible to
require NIOSH-approved facilities for
medical surveillance in MNM mines.
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6. Conclusions
Based on MSHA’s technological
feasibility analysis, MSHA has
determined that all elements of the rule
on Lowering Miners’ Exposure to
Respirable Crystalline Silica and
Improving Respiratory Protection are
technologically feasible.
B. Economic Feasibility
MSHA considers economic feasibility
in terms of industry-wide revenue and
overall costs incurred by the mining
industry (inclusive of MNM and coal)
under a given rule. To establish
economic feasibility, MSHA uses a
revenue screening test—whether the
estimated yearly costs of a rule are less
than 1 percent of estimated revenues or
are negative (i.e., provide net cost
savings)—to presumptively establish
that compliance with the regulation is
economically feasible for the mining
industry. If annualized compliance costs
comprise less than 1 percent of revenue,
the Department concludes that the
entities can incur the compliance costs
without significant economic impacts.65
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65 MSHA is not required to produce hard and
precise estimates of cost to establish economic
feasibility. Rather, MSHA must provide a
reasonable assessment of the likely range of costs
of its standard, and the likely effects of those costs
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MSHA received comments on economic
feasibility. Several commenters argued
that it would cost thousands or millions
of dollars in exposure control costs to
meet the new PEL (Document ID 1419;
1441; 1448; 1455). Others noted that the
action level will result in more sampling
above the action level and additional
engineering controls needed to get
below the action level, leading to greater
costs (Document ID 1419, 1455).
Based on its analysis of the Agency’s
sampling database, MSHA believes
roughly 90 percent of mines will be able
to meet the PEL without incurring
additional costs, and only 580 mines
will need to install engineering control
to meet the new PEL (see standalone
FRIA document Section 4). In response
to public comments that MSHA
underestimated the cost of
implementing necessary exposure
controls, MSHA increased its estimate
of the number of mine operators that
will have to implement additional
exposure controls to meet the
requirements of the final rule.
One commenter pointed out that
engineering controls need to factor in
site-specific conditions (Document ID
1441). MSHA acknowledges that the
on the industry. See United Steelworkers, 647 F.2d
at 1264; see also Nat’l Min. Ass’n, 812 F.3d at 865.
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exposure control costs will differ
depending on the size of the mine, the
current level of exposure to respirable
crystalline silica, existing engineering
and administrative controls, the mine
layout, work practices, and other
variables. MSHA’s price and cost
estimations are based on a variety of
sources including market research and
MSHA’s experience and sample data.
Some of the cost estimates from
commenters—such as those from very
large mines or those representing many
mines controlled by one operator—are
impossible to meaningfully compare to
MSHA’s estimates. Nonetheless, these
and other public comments about the
costs of the final rule are addressed in
more detail below in Section IX.
Summary of Final Regulatory Impact
Analysis and Regulatory Alternatives, as
well as in Section 8 of the standalone
FRIA document.
For the MNM and coal mining sectors,
MSHA estimates the projected impacts
of the rule by calculating the annualized
compliance costs for each sector as a
percentage of total estimated revenues
for that sector. To be consistent with
costs that are calculated in 2022 dollars,
MSHA first inflated estimated mine
revenues in 2019 to their 2022
equivalent using the GDP Implicit Price
Deflator. See Table VII–9.
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Table VII-9: Total Mines, Estimated Revenues (in millions of 2022 dollars) and
Employment by Sector
Mine Sector
2019 Mines
Total
Metal/Nonmetal
Coal
12,631
11,525
1,106
2019 Revenues
Inflated to 2022
Dollars
$124,169
$95,070
$29,099
2019 Miners
Including Contract
Miners 1
284,779
211,203
73,576
Note: 1. The estimated current and future number of mines and miners are based on 2019 data (MSHA, 2019a,b,
2022d) and are assumed to have remained constant through the 60 years following the start of implementation of the
rule.
Table VII–10 compares aggregate
annualized compliance costs for the
MNM and coal sectors at a 0 percent, 3
percent, and 7 percent discount rates to
each sector’s total annual revenues. At
a 3 percent discount rate, total aggregate
annualized compliance costs for the
entire mining industry are projected to
be $90.3 million (including both 30 CFR
part 60 and 2019 ASTM costs), while
aggregate revenues are estimated to be
$124.2 billion in 2022 dollars. MSHA
estimates that the mining industry is
expected to incur compliance costs that
comprise 0.07 percent of total revenues.
For the MNM sector, MSHA estimated
that the annualized compliance costs of
the final rule (including both 30 CFR
part 60 and 2019 ASTM update costs)
would be $82.1 million at a 3 percent
discount rate, which is approximately
0.09 percent of the total estimated
annual revenue of $95.1 billion for
MNM mine operators. For the coal
sector, MSHA estimated that the
annualized cost of the final rule
(including both 30 CFR part 60 and
2019 ASTM costs) will be $8.2 million
at a 3 percent discount rate, which is
approximately 0.03 percent of the total
estimated annual revenue of $29.1
billion for coal mine operators.
The ratios of screening analysis are
well below the 1.0 percent of total
revenues threshold. Therefore, MSHA
concludes that the requirements of the
final rule are economically feasible, and
no sector will likely incur a significant
cost.
Table VII-4: Percentage Distribution ofRespirable Crystalline Silica Exposures as ISO 8-hour TWA
in the Coal Industry from 2016 to 2021, by Location
Number
of
Samples
Activity
Group
Location
Overall:
underground
Underground
(all activity
groups)
Percentage of Samples in ISO Concentration Ranges, 8-hour
TWA,µg/m 3
:'.525
>25 to > 50 to >85.7 > 100 to > 250 to
>500
:'.550 :'.585.7 to :'.5100 :'.5250
:'.5500
Total
%
53,095
72.7%
20.6%
5.1%
0.6%
1.0%
0.1%
0.0%
100%
Surface
Overall:
surface (all
activity groups)
10,032
79.5%
12.4%
4.6%
0.8%
2.3%
0.4%
0.1%
100%
Overall: coal
Overall: coal
63,127
73.8%
19.3%
5.0%
0.6%
1.2%
0.1%
0.0%
100%
As previously mentioned, under the
final rule, MSHA amends its existing
standards on respirable crystalline silica
or quartz, after considering all the
testimonies and written comments the
Agency received from a variety of
stakeholders, including manufacturers,
medical professionals, miners, mining
associations, mining companies, labor
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organizations that represent mine
workers, health associations, and safety
associations in response to its notice of
proposed rulemaking. The final rule
establishes a PEL of respirable
crystalline silica at 50 mg/m3 for a fullshift exposure, calculated as an 8-hour
TWA for all mines. The final rule also
establishes an action level for respirable
crystalline silica of 25 mg/m3 for a fullshift exposure, calculated as an 8-hour
TWA for all mines. In addition to the
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PEL and action level, the final rule
includes provisions for methods of
compliance, exposure monitoring,
corrective actions, respiratory
protection, medical surveillance for
MNM mines, and recordkeeping. The
final rule also replaces existing
requirements for respiratory protection
and incorporates by reference ASTM
F3387–19 Standard Practice for
Respiratory Protection.
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ER18AP24.153
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VIII. Summary and Explanation of the
Final Rule
ER18AP24.148
Notes:
1. Personal samples presented in terms of ISO concentrations, normalized to 8-hour time-weighted averages (TWAs). The
samples were originally collected for the entire duration of each miner's work shift, using au air flow rate of 2 L/min. See notes
in Summary Table VII-3 for additional details.
2. Source: MSHA MSIS respirable crystalline silica data for the coal industry, August 1, 2016, through July 31, 2021 (version
20220617). All samples were of sufficient mass to be aualyzed for respirable crystalline silica.
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The sections that follow address
testimonies and written comments
received on general issues and specific
provisions in the proposal and MSHA
provides its responses and final
conclusions.
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A. General Issues
In this section, MSHA addresses
comments that relate to the rulemaking
as a whole and that are not specific to
a single section of the final rule. MSHA
identified six general issues for
discussion below: Existing Respirable
Dust Standards for Coal Mines; Training
for Miners—Respirable Crystalline
Silica; Sorptive Minerals; OSHA Table 1
Approach for Compliance; Medical
Removal/Transfer; and Compliance
Assistance.
1. Existing Respirable Dust Standards
for Coal Mines
MSHA will enforce the final rule’s
requirements for respirable crystalline
silica in coal mines within the context
of the Agency’s existing standards for
miners’ exposure to respirable coal mine
dust in 30 CFR parts 70, 71, and 90.
Some commenters, including the
Wyoming County WV Black Lung
Association, AFL–CIO, and two
individuals, were concerned that
controls implemented as immediate
corrective actions for respirable
crystalline silica at coal mines would
not be incorporated into an
underground coal mine’s approved
ventilation plan required under 30 CFR
part 75 (Document ID 1393; 1449; 1399;
1412).
Under the final rule, mine operators
are required to install, use, and maintain
feasible engineering and administrative
controls to keep each miner’s exposure
to respirable crystalline silica at or
below the PEL. Mine operators must use
feasible engineering controls as the
primary means of controlling respirable
crystalline silica; administrative
controls can only be used, when
necessary, as a supplementary control.
Rotation of miners—that is, assigning
more than one miner to a high-exposure
task or location, and rotating them to
keep each miner’s exposure below the
PEL—is prohibited as a means of
complying with the rule.
For underground coal mines, the
necessary controls to maintain
compliance with existing respirable coal
mine dust and respirable crystalline
silica standards are contained in the
ventilation plan that is approved by the
appropriate District Manager. Under 30
CFR 75.370(a)(1), the approved
ventilation plan shall control methane
and dust and contains the detailed
engineering controls that the operator
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will use to comply with the existing
dust standards.
Under the existing respirable dust
standards for coal mines, MSHA
evaluates the approved ventilation plan
to ensure that it is suitable to current
conditions and mining systems at the
mine. During each shift, the plan must
be followed to protect miners from
overexposure to respirable coal mine
dust, which includes respirable
crystalline silica. Currently, only MSHA
sampling is used to evaluate miners’
exposure to respirable crystalline silica.
When respirable coal mine dust or
respirable crystalline silica
overexposures are documented, MSHA
may consider the relevant portion of the
ventilation plan deficient and require
that the plan be revised to include
additional ventilation controls, or the
plan can be revoked by the Agency, as
appropriate. MSHA evaluates the
approved ventilation plan at least every
6 months, or more often if there are
changes in the mine, mining processes,
dust controls, or conditions at the mine
affecting miners’ exposure to respirable
coal mine dust or respirable crystalline
silica dust. MSHA typically samples all
mechanized mining units and Part 90
miners (coal miners with evidence of
pneumoconiosis) during each quarterly
regular inspection of underground coal
mines. MSHA typically samples the
Designated Areas (DA)—outby areas of
the mine—at least annually. This
sampling represents an evaluation of
dust exposure compliance and dust
controls that are in the approved
ventilation plan to ensure that they are
effective. MSHA intends to continue
conducting this sampling.
Under the existing respirable dust
standards for coal mines, as in the final
silica rule, when miners are
overexposed, the operator must take
immediate corrective actions to lower
the miner’s exposure to at or below the
standard and sample to verify that the
corrective actions are effective. The
mine operator determines necessary
engineering controls but must address
the underlying conditions and practices
which caused the overexposure.
Corrective action sampling will be
conducted with the control measures in
place. Under the final silica rule, mine
operators must report overexposures to
the District Manager and corrective
actions must be described in the record
mandated in § 60.16. If a silica
overexposure occurs, operators remain
responsible for adjusting ventilation
plans to account for additional controls
needed to prevent future overexposures.
The existing respirable dust standards
for coal mines will also maintain silica
controls through mine operators’ pre-
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shift and on-shift examinations. These
examinations must ensure the
ventilation controls that have been
evaluated and found effective are
maintained. The examinations protect
miners from health and safety hazards
between and on sampling shifts.
The UMWA, AFL–CIO, Wyoming
County WV Black Lung Association,
and an individual requested that
additional sampling be conducted at
coal mines (Document ID 1398; 1449;
1393; 1382). UMWA and an individual
supported the standalone silica PEL but
urged MSHA to retain the reduced dust
standard concept due to the large
number of quarterly dust samples
operators must take that indirectly
monitor silica exposure (Document ID
1398; 1382).
MSHA’s enforcement of respirable
coal mine dust under the existing
respirable coal mine dust standards will
continue. The final rule establishes a
standalone silica PEL and adds operator
silica sampling that may result in
additional operator silica sampling
(every three months) in many
underground coal mines. It also requires
immediate corrective actions and
resampling if exposures exceed the PEL.
The final rule also requires periodic
evaluations at least every 6 months, or
whenever there is a change in
production; processes; installation and
maintenance of engineering controls;
installation and maintenance of
equipment; administrative controls; or
geologic conditions. Dependent on the
results of the periodic evaluation in this
final rule, coal mine operators may have
to perform additional sampling. MSHA
expects the final rule’s requirements
will result in sufficient sampling to
accurately detect miners’ exposures to
silica at coal mines.
The final rule requires that mine
operators sample miners exposed or
reasonably expected to be exposed to
respirable crystalline silica. If samples
are above the action level and below the
PEL, mine operators must continue to
sample within three months. Operators
must conduct representative sampling
(at least two samples) of the occupations
at highest risk of respirable crystalline
silica exposure. The existing standards
for respirable coal mine dust sampling
require 15 valid representative
consecutive shift samples for certain
high-dust occupations, followed by
more samples in other identified
occupations and areas the District
Manager designates based on
anticipated or actual exposures.
The final rule decouples silica
sampling and enforcement from the
existing respirable dust standard
requirements that reduce the total
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respirable coal mine dust limit based on
the percentage of silica in the dust (an
indirect way of controlling silica).
Occupations and areas designated for
dust sampling are likely to be the
occupations and areas with the highest
levels of respirable crystalline silica
exposure. MSHA expects many of the
same occupations will be sampled
under this final rule and that the
requirement that two samples be taken
will mean an increased ability to
accurately assess exposure. Also, the
standalone respirable crystalline silica
PEL allows for immediate MSHA
oversight of corrective actions and
resampling. Unlike the existing reduced
dust standard protocols under which
silica overexposures are not directly
citable except through enforcement of
the reduced dust standard, under the
final rule, MSHA can withdraw miners
under Mine Act section 104(b) if
respirable crystalline silica
overexposure citations are not corrected
and occupations resampled within the
abatement time MSHA sets. In response
to comments, and to ensure that MSHA
is informed of silica overexposures, the
final rule requires that mine operators
immediately report respirable
crystalline silica samples above the PEL
to the District Manager or other office
designated by the District Manager.
2. Training for Miners—Respirable
Crystalline Silica
MSHA received several comments
both in favor of and against including
respirable crystalline silica training for
miners in 30 CFR part 46 (Training and
Retraining of Miners Engaged in Shell
Dredging or Employed at Sand, Gravel,
Surface Stone, Surface Clay, Colloidal
Phosphate, or Surface Limestone Mines)
(part 46) and 30 CFR part 48 (Training
and Retraining of Miners) (part 48). Two
mining trade associations suggested that
existing training requirements under
parts 46 and 48 for new miner training,
experienced miner training, annual
refresher training, and task training
remain sufficient and that an additional
training requirement would be
unnecessary (Document ID 1424, 1441).
Other commenters, including a mining
labor union and several professional
associations, stated that the final rule
should include new training
requirements separate from parts 46 and
48 (Document ID 1398; 1351; 1377;
1373).
MSHA believes existing training
standards in parts 46 and 48 require
appropriate training regarding health
hazards, including exposure to
respirable crystalline silica dust.
Part 46 requires new miners and
newly hired experienced miners to
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receive training on the health and safety
aspects of the tasks to be assigned,
including the safe work procedures of
such tasks, the mandatory health and
safety standards pertinent to such tasks,
information about the physical and
health hazards of chemicals in the
miner’s work area, the protective
measures a miner can take against these
hazards, and the contents of the mine’s
HazCom program. They must also
receive instruction and demonstration
on the use, care, and maintenance of
self-rescue and respiratory devices, if
used at the mine.
Annual refresher training conducted
under part 46 must include instruction
on changes at the mine that could
adversely affect the miner’s health or
safety and other health and safety
subjects relevant to mining operations at
the mine, including mandatory health
and safety standards, health, and
respiratory devices.
For new task training, part 46 requires
miners to receive training in the health
and safety aspects of the task to be
assigned, including the safe work
procedures of such tasks, information
about the physical and health hazards of
chemicals in the miner’s work area, the
protective measures a miner can take
against these hazards, and the contents
of the mine’s HazCom program. Section
46.9 requires records of training and
includes specific provisions for the
record requirements.
Part 48 requires new miners to receive
training on health including instruction
on the purpose of taking dust, noise,
and other health measurements, and any
health control plan in effect at the mine
shall be explained. New miners must
also receive training in the health and
safety aspects of the tasks to be
assigned, including the safe work
procedures of such tasks, the mandatory
health and safety standards pertinent to
such tasks, information about the
physical and health hazards of
chemicals in the miner’s work area, the
protective measures a miner can take
against these hazards, and the contents
of the mine’s HazCom program.
Experienced miner training under
Part 48 must include instruction in
health, including the purpose of taking
dust, noise, and other health
measurements, where applicable, and
review of the health provisions of the
Mine Act. Experienced miners must also
receive training in the health and safety
aspects of the tasks to be assigned,
including the safe work procedures of
such task, information about the
physical and health hazards of
chemicals in the miner’s work area, the
protective measures a miner can take
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against these hazards, and the contents
of the mine’s HazCom program.
For new task training, part 48 requires
miners to receive training on the health
and safety aspects and safe operating
procedures for work tasks, equipment,
and machinery, including information
about the physical and health hazards of
chemicals in the miner’s work area, the
protective measures a miner can take
against these hazards, and the contents
of the mine’s HazCom program.
Annual refresher training conducted
under part 48 must include instruction
on mandatory health and safety
standard requirements which are related
to the miner’s tasks and on the purpose
of taking dust, noise, and other health
measurements, as well as an
explanation of any health control plan
in effect at the mine. The health
provisions of the Mine Act and warning
labels must also be explained. Sections
48.9 (Underground Miners) and 48.29
(Surface Miners) require records of
training.
Training is also a required element of
the mine operator’s respiratory
protection program. Miners required to
wear a respirator must be trained in
accordance with the provisions of
ASTM F3387–19 and records must be
retrained in accordance with the
provisions of section 9.
MSHA expects mine operators to
include information in their existing
training plans about respirable
crystalline silica hazards and
protections, including: the PEL and
action level; sampling requirements;
miners who are reasonably expected to
be exposed to respirable crystalline
silica; engineering and administrative
controls used at the mine; the
importance of maintaining controls;
and, for MNM mines, medical
surveillance requirements, including the
importance of early disease detection.
MSHA remains available to assist mine
operators with their training plans.
3. Sorptive Minerals
The SMI, EMA, and Vanderbilt
Minerals, LLC requested that MSHA
follow OSHA’s approach to sorptive
minerals and exclude them from the
scope of the final rule (Document ID
1446; 1442; 1419). These commenters
asserted that lower toxicity of occluded
and aged crystalline silica indicates a
lack of health risks stemming from
inhaling sorptive mineral dust
containing respirable crystalline silica.
After considering the commenters’
statements and evidence, as well as
OSHA’s approach to the issue, MSHA
has determined that sorptive minerals
should not be excluded from the scope
of this rulemaking.
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MSHA evaluated all the evidence
submitted by commenters during the
rulemaking process, including the
hearings, and concludes that the balance
of the best available evidence supports
that there is increased risk of material
impairment of health or functional
capacity over the course of a miner’s
working life associated with regular
exposure to respirable crystalline silica
present at sorptive mineral mines.
MSHA’s approach is consistent with
NIOSH’s recommendation for a single
PEL for respirable crystalline silica
without consideration of surface
properties. MSHA is unable to
substantiate one commenter’s statement
that, in every instance, the silica in
sorptive minerals is either amorphous
(i.e., opal) or occluded. Sorptive
minerals occur as part of a geological
formation with its own depositional
history beginning with a volcanic
eruption. The mining process will
encounter all mineral constituents in
the deposit, including all forms of
respirable crystalline silica. To remove
overburden and extract sorptive
minerals, miners use large mining
equipment that can disturb sedimentary
and other silica-rich rock that could
contain unoccluded respirable
crystalline silica. In addition, the
milling, screening, crushing, and
bagging processes can and do affect the
respirable crystalline silica dust
liberated at these mines. The commenter
did not submit evidence demonstrating
that all sorptive mineral commodities
mined in the United States exclusively
contain fully or even partially occluded
quartz. MSHA does not agree that
occlusion is always present, that
occlusion definitively provides
adequate protection from adverse health
effects, or that occlusion always
provides any level of protection for
miners exposed to respirable crystalline
silica in this industry.
MSHA’s method for analyzing
respirable dust samples cannot
differentiate between ‘‘freshly
fractured’’ and occluded crystalline
silica. Respirable dust enforcement
samples in MNM mines are prepared for
crystalline silica analysis using the
MSHA P–2 method for X-ray diffraction
(XRD). Crystalline materials each have
their own unique diffraction patterns
and are quantitatively discriminated
between other crystalline and noncrystalline materials through XRD
analysis. Potential interferences from
other minerals are removed from the
result by scanning the sample at
multiple diffraction angles specific to
crystalline silica and using profile
fitting software to separate adjacent
diffraction peaks. MSHA cannot
determine if crystalline silica particles
in the sample are ‘‘freshly fractured’’ or
occluded with a layer of clay, only that
the diffraction pattern matches that of
the pure crystalline silica standard
reference material.
MSHA’s enforcement data in Table
VIII–1 below show that miners working
in this industry are exposed to
respirable quartz at concentrations
above both the former PEL (100 mg/m3)
and new PEL (50 mg/m3). Table VIII–1
shows exposure data by contaminant
code for respirable dust samples
collected at ‘‘clay’’ or ‘‘bentonite’’
operations from 2005 to 2019. The
samples were analyzed for respirable
crystalline silica (quartz) and the results
were calculated based on an 8-hour
TWA.
Table VIII-1: Number of Samples by Contaminant Code and Quartz Concentration (20052019)
Number of Samples by Quartz Concentration
Contaminant Total
Analyzed
Code
The results in the table indicate that
5.1 percent of miners working at these
operations during the relevant period
were exposed to levels of respirable
crystalline silica over the former PEL of
100 mg/m3, and 17.6 percent were
exposed over the new PEL of 50 mg/m3.
MSHA disagrees with commenters’
statements that the silica contained in
sorptive minerals does not pose health
risks. MSHA does not equate ‘‘lower
toxicity’’ with other toxicological terms
such as ‘‘non-hazardous’’, ‘‘non-toxic’’,
or ‘‘safe.’’ ‘‘Lower toxicity’’ does not
mean the absence of adverse health
effects, disease, or risk of material
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impairment of health or functional
capacity. For example, the bioactivity of
respirable crystalline silica (quartz)
originating from bentonite deposits is
well-recognized and documented on
sorptive mineral-based pet litter safety
data sheets (SDSs). MSHA concludes
from its own sampling data and
analyses that the mining of sorptive
minerals creates an inhalation hazard.
As confirmed by MSHA’s review of
epidemiological and toxicological
studies, these mineral dusts are toxic
and can lead to serious adverse health
effects in miners such as silicosis or
lung cancer. Accordingly, MSHA
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concludes that there is a risk of material
impairment of health or functional
capacity in mining, whether or not that
risk is equal to unoccluded quartz
encountered in other workplaces.
In its 2016 final rule, OSHA
concluded that quartz originating from
bentonite deposits had some biological
activity but ‘‘lower toxicity’’ than quartz
encountered in most workplaces (81 FR
16377). OSHA also found that the
record provided no sound basis for
determining significance of risk for
exposure to sorptive minerals
containing quartz, and thus decided to
exclude sorptive minerals from the
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::: 50 µg/m 3
> 50 µg/m 3
> 100 µg/m 3
121
323
323
0
0
131
364
364
0
0
523
1,325
971
354
103
All Codes
2,012
1,658
354
103
Contaminant Code Descriptions:
121 - Respirable Dust Analyzed for Quartz,< 1 %, Listed Nuisance Dust
131 - Respirable Dust Analyzed for Quartz, < 1 %, Not Listed Nuisance Dust
523 - Respirable Dust Analyzed for Quartz, 2: 1 %
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scope of the final rule (OSHA, 2016).
MSHA, unlike OSHA, has no
requirement to identify a ‘‘significant
risk’’ before promulgating rules to
protect miners’ health and safety. Nat’l
Mining Ass’n v. United Steel Workers,
985 F.3d 1309, 1319 (11th Cir. 2021)
(‘‘[T]he Mine Act does not contain the
‘significant risk’ threshold requirement
. . . from the OSH Act.’’). The OSH Act
is a ‘‘differently worded statute,’’ and
the Mine Act ‘‘[a]rguably . . . does not
mandate the same risk-finding
requirements as OSHA.’’ Nat’l Min.
Ass’n v. Mine Safety & Health Admin.,
116 F.3d 520, 527 (D.C. Cir. 1997).
Moreover, OSHA does not regulate
mining; mining presents unique risks to
miners’ health because it exposes
miners to hazards that are not present in
operations regulated by OSHA,
including hazards in overburden
removal and milling.
MSHA has examined research
references from commenters and has
conducted its own review of the
scientific literature. These studies do
not disprove the health-based risks
associated with exposure to respirable
crystalline silica or support a
conclusion that sorptive minerals
present no risk.
As presented by SMI, there have been
few epidemiological studies of workers
exposed to dust generated from sorptive
minerals (Document ID 1446,
Attachment 2). Two examples include
Phibbs et al. (1971) and Waxweiler et al.
(1988). These small cohort studies did
not evaluate exposures to a wide variety
of sorptive minerals and relied on data
from outdated exposure assessment
methods. MSHA finds that the limited
epidemiological data involving sorptive
minerals do not refute the conclusions
drawn from other epidemiological
studies included in MSHA’s standalone
Health Effects document and in the
Agency’s standalone FRA document
(2023). MSHA concludes, from the best
available evidence, that exposure to the
crystalline silica present in sorptive
minerals poses a risk of material
impairment of health or functional
capacity to miners.
MSHA disagrees with the comment
that the occluded surface of the silica
that may be found in sorptive minerals
protects miners from material
impairment of health, including
silicosis and lung cancer. Furthermore,
there is no evidence to suggest that the
occluded layer of the quartz particles
that are inhaled remains unchanged
over time following deposition
throughout the respiratory tract. It is not
understood how conditions and
physiological responses may alter the
characteristics of occluded quartz
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particles deposited in the respiratory
tract. Likewise, while animal studies
involving respirable crystalline silica
suggest that the aged form has lower
toxicity than the freshly fractured form,
the aged form still retains significant
toxicity (Shoemaker et al., 1995;
Vallyathan et al., 1995; Porter et al.,
2002c).
MSHA considered commenters’
statements and evidence regarding the
toxicity of quartz in sorptive minerals.
MSHA’s conclusions are consistent with
those that NIOSH provided to OSHA
(NIOSH Posthearing Brief to OSHA,
2014d). NIOSH corrected various
erroneous statements that referenced
published papers (e.g., Waxweiler et al.,
1988; Phibbs et al., 1971) and reports
(e.g., EPA, 1996; WHO, 2005), which are
also a part of this rulemaking record.
Four examples are provided here. First,
as noted by NIOSH, Phibbs et al. (1971)
advised that ‘‘[b]entonite dust, once
believed to be harmless, must now be
added to the list of potentially
hazardous dusts because of its content
of free crystalline silica.’’ (Document ID
0693, pg. 43). Second, NIOSH stated
that, ‘‘[w]hile no exposure-response
relationship can be drawn from the
Phibbs et al. [1971] study, it can be
concluded that when exposures to
respirable crystalline silica are high
enough in mining/processing bentonite,
severe and fatal occupational silicosis
can occur among exposed workers.’’
(Document ID 0693, pg. 44). Third,
contrary to comments regarding the
WHO report (2005), NIOSH stated,
‘‘Although the respirable crystalline
silica particles to which these bentonite
workers were exposed may be less toxic
than, say, respirable crystalline silica
particles resulting from sandblasting,
there is no way to assess relative
toxicities from these two studies.
Regardless of relative toxicity, the
findings from these two studies indicate
that, at the levels to which the workers
in the studies were exposed, the
crystalline silica particles were toxic
enough to cause severe, disabling, and
fatal silicosis in a relatively short period
of time.’’ Fourth, NIOSH disagreed with
the commenter’s reference to the lack of
reporting of silicosis among cohorts of
coal miners with pneumoconiosis to
support its conclusion that aged/
occluded silica particles do not
represent a risk for silica-related health
outcomes.
NIOSH addressed a commenter’s
presumption that further study was
needed on occluded quartz before
regulation was warranted. NIOSH
explained that further study on
occluded quartz was less pertinent for
OSHA’s rulemaking than the fact that
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the OSHA PEL was consistent with the
NIOSH REL in not distinguishing
respirable crystalline silica exposures
based on relative age or degree of
occlusion of particle surfaces. MSHA
concurs with NIOSH’s conclusion that
‘‘currently available information is not
adequate to inform differential
quantitative risk management
approaches for crystalline silica that are
based on surface property
measurements.’’ For these reasons,
MSHA does not exempt the sorptive
minerals sector from the requirements of
this final rule.
4. OSHA Table 1 Approach for
Compliance
OSHA’s ‘‘Table 1—Specified
Exposure Control Methods When
Working With Materials Containing
Crystalline Silica’’ (Table 1) (29 CFR
1926.1153(c)(1)) identifies common
construction equipment and tasks that,
when properly controlled, are expected
to generate levels of respirable
crystalline silica below the PEL.
Construction employers who follow
these engineering and work practice
control methods and provide the
required respiratory protection outlined
in Table 1 are generally not required to
sample their workers’ exposures to
silica and are presumed to be in
compliance with OSHA’s standard.
MSHA did not propose adopting
specified exposure control methods for
task-based work practices, similar to
OSHA’s Table 1. However, in the
proposal, MSHA sought comments on
specific tasks and exposure control
methods appropriate for a Table 1
approach for the mining industry that
would also adequately protect miners
from risk of exposure to respirable
crystalline silica.
MSHA has decided not to include a
Table 1 approach for the mining
industry in the final rule. After
considering input from stakeholders on
specific tasks and exposure control
methods suitable for a Table 1 approach,
MSHA determined that such an
approach would not provide the
necessary protection for miners against
overexposure to respirable crystalline
silica under all mining conditions. The
Agency has concluded that because of
the changing nature of the mining
environment, exposure monitoring is
essential to ensure that controls are
functioning effectively, properly
maintained, and adjusted as necessary
to ensure compliance.
Under the final rule, mine operators
are required to implement feasible
engineering controls, and administrative
controls, when necessary, to maintain
each miner’s exposure below the PEL.
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Operators are required to conduct
exposure monitoring (sampling) in
accordance with § 60.12 to verify that
the implemented controls effectively
protect miners and ensure compliance
with the final rule. Compliance with the
PEL and corrective actions after
overexposures is required. This final
rule does not allow the use of
respiratory protection to achieve
compliance.
Commenters from an industrial
hygiene association and labor
organizations, supported MSHA’s
decision not to include a Table 1
approach for mining activities
(Document ID 1351; 1398; 1449). The
UMWA stated that this approach is not
necessary since mine operators already
have access to proper dust control
systems and MSHA-approved
ventilation plans (Document ID 1398).
This commenter also noted that,
because mining conditions are
constantly changing, it would be
incorrect to assume that operators using
a Table 1 approach to control respirable
crystalline silica exposure would always
be in compliance. Two commenters (a
professional association and a labor
union) stated that the Table 1 approach
would be neither protective nor feasible
in the mining context, while one of
those commenters stated that delaying
the final rule to develop a Table 1
approach will create more harm for
workers (Document ID 1351; 1398).
MSHA agrees that due to constantly
changing mining conditions, OSHA’s
Table 1 is not the most effective
approach for protecting miners’ health.
A fundamental aspect of mining is that
the mine environment is dynamic,
resulting in varying exposures to
respirable crystalline silica for miners.
Silica exposures can fluctuate based on
the amount of silica present in rock,
which depends on the geological
composition of the rock. Miners engaged
in tasks that generate dust from this rock
material may face elevated exposure
levels. For example, activities that
involve cutting, grinding, drilling, or
crushing rock with higher-silica levels
can generate dust with high silica
content. In addition, mining operations
are diverse, involving different types of
mining, each with various mining
processes. Each process involves
specific equipment and methods
tailored to the unique characteristics of
the material being mined.
Many commenters, including trade
associations, mining related businesses,
a labor union, and a MNM operator
urged MSHA to include a provision like
Table 1 in the final rule, with Portland
Cement Association, NSSGA, and
CertainTeed, LLC submitting example
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tables for MSHA to consider (Document
ID 1407; 1408; 1424; 1441; 1448; 1404;
1409; 1429; 1442; 1417; 1431; 1423).
SSC noted that certain tasks, processes,
and environments are at least somewhat
similar or common across many MNM
mines and may be characterized by the
extent to which they may release
respirable crystalline silica, mechanisms
for doing so, and effective exposure
controls (Document ID 1432). This
commenter also stated that a Table 1
approach would provide mine operators
with a choice between using their own
controls and sampling to evaluate
effectiveness (and compliance with the
standard) or using the controls listed in
the table. SSC noted that a clear list of
controls required for each type of task,
exposure, or process would simplify
compliance and enforcement. SSC
further noted that if a mine operator
relied on the table and implemented or
used all the engineering and
administrative controls in the table, they
would know that, in so doing, they
would achieve compliance.
MSHA has determined that reliance
on a task-based approach would not
address all mining tasks and situations
that could result in respirable
crystalline silica exposures, leaving
miners without adequate protection. In
addition, a task-based approach may not
address cumulative exposures over a
shift for miners who perform multiple
tasks that generate respirable silica
during a single shift. MSHA has
determined that because mining
involves a wide range of activities, each
with its own potential for different dust
generating sources and potential silica
exposure, a task-based approach does
not protect miners, especially those
miners who perform multiple tasks
involving silica exposures during a
single shift.
MSHA agrees with commenters that
there are many job positions in the
mining industry that have similar
exposure risks. However, as one
commenter testified, miners may work
at multiple job positions or tasks
throughout the shift or a workweek.
This commenter noted that a miner may
work as a laborer, crusher operator, or
a loader operator in a single shift.
Another commenter acknowledged that
it would be difficult for a Table 1
approach to work because of the various
tasks a miner performs (this commenter
referenced a discussion on this topic
between a mine operator and the
Agency at the Denver, Colorado public
hearing). MSHA’s data indicates that a
significant number of miners are
classified as laborers, mobile workers,
and utility workers. Approximately 31
percent of the MNM miners are mobile
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workers and approximately 39 percent
of coal miners are laborers, utility
workers and other workers who do not
have specific job categories. These are
job positions that perform different
work activities during a shift. MSHA
has determined that OSHA’s Table 1
would be difficult to implement for
most mines, especially mines that
employ laborers, mobile workers, and
utility workers.
The Portland Cement Association and
NSSGA stated that OSHA’s 2019 RFI,
which assessed the effectiveness of
Table 1, demonstrated that it was
effective in lowering exposures and
encouraged the adoption of engineering
controls (Document ID 1407; 1448).
However, AIHA explained that research
indicates that worker exposure in the
construction industry can exceed the
OSHA PEL of 50 mg/m3 even with Table
1 controls in place (Document ID 1351).
Portland Cement Association
recommended that MSHA should adopt
an OSHA Table 1 approach that
encourages mine operators to install
engineering controls and remove the
operator’s obligation to assess exposures
in work environments where individual
miner’s respirable crystalline silica
exposures are controlled by engineered
devices to ensure compliance with the
action level and the PEL (Document ID
1407). Under OSHA’s approach,
prescribed engineering controls and
work practice methods, along with
respiratory protection, are assumed to
be sufficiently effective in reducing
miners’ exposures; exposure monitoring
to ensure compliance with the PEL is
not required. MSHA, however, has
determined that exposure monitoring is
critical in safeguarding miners’ health. It
provides the quantitative data needed to
assess the effectiveness of engineering
controls and is essential to ensuring that
controls remain effective at all times.
This is consistent with NIOSH’s
recommendation to OSHA during its
rulemaking that Table 1 should not
replace sampling requirements for the
construction industry because even
fully implementing the control methods
and respiratory protection described in
OSHA’s Table 1 would not ensure
compliance with the PEL. In addition,
MSHA, in this final rule, does not allow
respiratory protection as a means to
achieve compliance.
OSHA’s Table 1 approach relies on
respiratory protection when engineering
and administrative controls are not
sufficient to limit exposures.
Respiratory protection is used for
compliance when control methods
cannot reduce exposures below the PEL.
MSHA has determined that existing
engineering controls are the most
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effective way to protect miners from
exposures to respirable crystalline
silica. Engineering controls, when
properly designed, implemented, and
maintained, can reduce the
concentration of respirable crystalline
silica and protect miners from
overexposures. Well designed and
maintained controls can eliminate or
minimize respirable silica dust at the
source, preventing dispersion of the
silica dust into the workplace.
Respiratory protection, however, has
limitations and is not as reliable as
engineering controls in reducing miners’
exposures to respirable crystalline
silica. MSHA has determined that
reliance on respiratory protection would
risk miners’ exposure to silica and
undermine the Agency’s mandate to
address respiratory hazards at the
source, providing the highest level of
health protection for miners.
The mining industry encompasses a
wide range of processes and equipment
due to the diversity of mined
commodities. However, as commenters
noted, processes and equipment are
tailored to the type of material mined.
SSC noted that certain tasks, processes,
and environments are at least somewhat
similar or common across many MNM
mines and may be characterized by the
extent to which they may release
respirable crystalline silica, mechanisms
for doing so, and effective exposure
controls (Document ID 1432). IME
recommended that MSHA adopt a Table
1 approach for rock drilling operations
that use a dust collection system around
the drill bit and the use of low-flow
water spray to wet the dust discharged
from the dust collector (Document ID
1404). This commenter also noted that
all drill rigs used by the explosives
industry have fully enclosed cabs to
isolate operators from dusty conditions.
EMA suggested that a Table 1 approach
could include processes with
consistent/predicable dust generation
characteristics, such as mobile
equipment cabs, control rooms with
proper ventilation and seals on doors
and windows, utility vehicles, handheld
power tools such as jackhammers, and
tasks performed in potentially high
exposure areas, such as crushing or
bagging (Document ID 1442). This
commenter submitted that many
engineering and administrative controls
or work practices can be gleaned from
NIOSH’s updated Dust Control
Handbook for Industrial Minerals
Mining and Processing, Second Edition.
The commenter further noted that the
NIOSH Dust Control Handbook is an
excellent resource and could reduce the
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amount of research necessary to create
a usable Table 1.
MSHA has determined that these
controls cannot be relied on without
independent assessment (exposure
monitoring) to ensure that they are
effective and continue to protect miners.
For example, MSHA has found that
equipment operators who are working
in enclosed cabs report some of the
highest exposures. These miners are
exposed to high silica exposures
because the enclosures are not properly
maintained. Under a Table 1 approach,
equipment operators would be
presumed to be protected by enclosed
cabs and not exposed to silica above the
PEL.
A fundamental feature of mining is
that the mine environment constantly
changes. MSHA has concluded that
miners’ exposures to respirable
crystalline silica vary with much greater
frequency than in general industry,
construction, or maritime settings. A
feasible engineering control
implemented in a mine (including a
mill) cutting into or processing lowerquartz-containing rock might not be
appropriate for a mine cutting into rock
with a higher percentage of quartz or
using a different mining process or
modified equipment.
In addition, certain mining
environments must take into account
bystander exposure. For example, in
underground mining environments, the
ventilation is often in a series
configuration, where the exhaust of one
miner’s controls could be the intake for
other miners downwind. This results in
the upwind engineering controls having
an effect on all of the miners that are
downwind. In contrast, OSHA’s
construction and general industry
worksites have controls that can be
exhausted to the outside atmosphere
and will not affect other workers nearby.
MSHA has determined that, in the
context of mining, Table 1 controls
cannot be relied on without
independent assessment (exposure
monitoring) to ensure that they are
effective, maintained, and continue to
protect miners. MSHA’s enforcement
experience and data show that some of
the highest respirable crystalline
exposures result from mine operators
not maintaining engineering controls.
Poor maintenance of engineering
controls, without exposure monitoring,
can result in miners working above the
PEL for extended periods, jeopardizing
their health. For example, a miner
working at a surface MNM mine was
exposed to 192 mg/m3 of respirable
crystalline silica. The miner was
working in a control booth, but the
control booth ventilation system was
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not maintained, and the door seals were
defective and leaking. A second
example involved a bulldozer operator
working at a surface coal mine who was
exposed to 109 mg/m3 of respirable
crystalline silica. The cab’s door seals
were crushed, and the cab filter was
broken. A third example involved a
miner operating a front-end loader at
surface MNM mine, who was exposed to
213 mg/m3 of respirable crystalline
silica. The cab air-conditioner was not
functioning. These examples illustrate
the importance of regular exposure
monitoring to alert mine operators to
take necessary corrective actions to
repair and maintain equipment to
protect miners’ health. The exposure
monitoring requirements in the final
rule provide mine operators, miners,
and MSHA with information necessary
to verify that miners’ exposures remain
below the PEL at all times, therefore
protecting miners’ health. Also, the final
rule does not allow respiratory
protection to achieve compliance.
In addition, geological formations and
quantities of quartz are not always
predictable and the Agency believes that
controlling exposures to respirable
crystalline silica to below the PEL
through sampling is the best way to
protect miners’ health. Accordingly,
MSHA has concluded that because of
the dynamic, constantly changing
nature of the mining environment,
exposure monitoring is essential to
ensure that controls are functioning
effectively, properly maintained, and
adjusted as necessary to ensure
compliance.
In response to MSHA’s solicitation for
stakeholder input on a Table 1
approach, commenters representing the
stone, sand, and gravel industries
provided information and data on an
alternative Table 1 for MSHA’s
consideration. The NSSGA provided a
proposed Table 1 that grouped various
equipment operator positions by
equipment and tasks (including a
description of operation and tasks
performed) and identified engineering
and work practice control methods for
the equipment and tasks (Document ID
1448). The commenter noted that this
Table 1 is protective of workers and
does not give operators an ‘‘out’’ when
a worker performs a task that is listed
on the table. The commenter further
noted that under their proposed Table 1,
the operator must ensure all engineering
and work practice control methods are
done to comply with the table and not
engage in exposure monitoring. The
commenter stated their Table 1
approach works because sampling has
been done that demonstrates these
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controls work and keep workers below
the action level.
The Portland Cement Association
provided respirable crystalline silica
exposure data by job classification and
an alternative Table 1 that identified
equipment/tasks, engineering and work
practice controls, and required
respiratory protection and assigned
protection factor (Document ID 1407).
As the commenter noted, the table
shows control measures in widespread
use in the cement manufacturing
industry, which the commenter believes
some MNM mine operators use at their
operations.
MSHA considered commenters’ Table
1 approaches. Like OSHA, the
commenters’ alternative approaches
provide specific guidance on how to
control work exposures to respirable
crystalline silica for specific tasks. The
suggested Table 1 approaches list the
equipment/task and identify the
similarly exposed positions and
appropriate engineering and work
practice control methods.
MSHA has determined that because
mining involves a wide range of
activities, from drilling and blasting to
crushing and processing materials, each
with its own potential for different dust
generating sources and potential silica
exposure, as well as differing silicabearing strata, a task-based approach
does not protect miners, especially
those miners who perform multiple
tasks involving silica exposures during
a single shift. A Table 1 approach can
be effective for construction activities.
However, Table 1’s applicability to
mining and milling operations is limited
due to the complexity, variability, and
unique challenges inherent in mining
and milling operations. Activities in
these operations are highly variable, due
to the types of ores, minerals, and
materials processed. Mining and milling
operations run continuously, unlike
some construction activities which may
not be continuous or steady. Continuous
operations require different control
measures and monitoring strategies to
address sustained miner exposures over
an extended period. In addition, MSHA
has determined that specified control
methods may not provide a continued
and verifiable level of protection to
miners. Exposure monitoring is
essential to ensure that the controls
remain effective at all times. Further, as
stated earlier, this final rule does not
allow respiratory protection as a means
to achieve compliance.
MSHA also received comments
stating that a Table 1 approach would
benefit intermittent and seasonal mining
operations. The NSSGA stated that these
mine operators do not have as much
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time to conduct sampling and would
benefit from a Table 1 approach
(Document ID 1448). Similarly, North
America’s Building Trades Unions
(NABTU) noted that being able to
implement controls according to job
function, without having to take air
samples, would help portable mines and
construction contractors to achieve
compliance in dynamic work
environments (Document ID 1414). CISC
explicitly requested that MSHA conduct
a final review and produce a report for
comment analyzing silica exposure from
all jobs associated with quarrying
operations, and either exclude them
from the proposed rule or create a Table
1 approach, indicating that most jobs in
surface quarrying operations are
incapable of exceeding the proposed
PEL (Document ID 1430). As noted
above, MSHA has determined that, due
to the diverse range of activities
involved in mining, and constantly
changing mining conditions—including
drilling, blasting, crushing, and material
processing, each with its unique
potential for silica exposure—a Table 1
approach does not adequately protect
miners. This is particularly true for
miners who are engaged in multiple
tasks involving silica exposure within a
single shift. MSHA has also concluded
that control methods must be assessed
to ensure they provide sufficient
protection; therefore, exposure
monitoring is essential to verify the
ongoing effectiveness of implemented
controls.
The Agency also received comments
about alternative approaches to Table 1type guidance. NSSGA stated that jobs
where workers are in enclosed cabs,
booths, and buildings have consensus
standards and should be in Table 1
(Document ID 1448). Some commenters,
including AIHA and IEEE, suggested
that MSHA incorporate or recommend
relevant control standards designed to
protect workers performing certain
tasks, such as ISO 23875: 2021, to
provide operators with more tools to
protect workers while continuing
mandated exposure monitoring
(Document ID 1351; 1377). Draeger, Inc.
stated that MSHA should consider
incorporating Table 1 content into a
silica guidance document (Document ID
1409). NVMA suggested that MSHA
should allow operators to develop their
own Table 1 as part of their dust
protection plan but cautioned that
MSHA should not be permitted to cite
the development of an internal tool
unless the PEL is exceeded, and a
respirator is not used (Document ID
1441). Draeger, Inc. also acknowledged
that creating a Table 1 approach would
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be a significant effort and suggested that
MSHA initially consider high-risk tasks
in developing the control methods
(Document ID 1409). EMA
recommended that MSHA should
consult the Dust Control Handbook for
Industrial Minerals Mining and
Processing, Second Edition, to reduce
the amount of research necessary to
create a Table 1 approach (Document ID
1442).
MSHA acknowledges that consensus
standards can assist mine operators in
the development and selection of proper
engineering controls for their mine sites
and supports the use of consensus
standards in the design of operator
enclosures for hazardous environments.
MSHA also recognizes the value of
providing guidance on engineering and
work practice control methods for
similar exposure groups to ensure
compliance with the final rule. The
Agency supports and encourages the use
of NIOSH’s Dust Handbook by mine
operators to determine feasible and
appropriate engineering controls for
their mine sites. MSHA will work with
operators and miners to develop and
implement effective controls, including
necessary exposure monitoring. MSHA
encourages mine operators to be
proactive in their approach to protecting
miners from silica exposures. MSHA
encourages operators to develop dust
control plans or other engineering tools
in their operations. MSHA also commits
to developing guidance that includes
information on consensus standards
related to control methods. MSHA will
collaborate with stakeholders, including
industry and labor, as well as NIOSH, to
help mine operators and miners in
implementing appropriate control
methods. MSHA will also provide
education and training to mine
operators and miners covering all
aspects of the final rule.
5. Medical Removal/Transfer
MSHA does not include a medical
removal/transfer option for MNM
miners with evidence of silica-related
disease in the final rule. MSHA intends
to consider this issue in a future
rulemaking.
In the proposed rule, MSHA solicited
comments on whether the final rule
should include a medical removal/
transfer option for MNM miners who
have developed evidence of silicarelated disease that is equivalent to the
transfer rights and exposure monitoring
provided to coal miners in 30 CFR part
90 (part 90). Under part 90, any coal
miner who has evidence of the
development of pneumoconiosis based
on a chest X-ray or other medical
examination has the option to work in
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an area of the mine where the average
concentration of respirable dust in the
mine atmosphere during each shift to
which that miner is exposed is
continuously maintained at or below the
standard for Part 90 miners. Part 90
miners are ‘‘entitled to retention of pay
rate, future actual wage increases, and
future work assignment, shift and
respirable dust protection.’’ 30 CFR
90.3(b).
MSHA received comments from labor
organizations, mining trade
associations, black lung clinics, a
federal elected official, an industrial
hygiene professional association, an
advocacy organization, a medical
professional association, and an
individual generally supporting medical
removal/transfer rights. These
commenters urged MSHA to include the
provisions of part 90 in the rule and
stated these protections should apply
for a medically confirmed diagnosis of
silicosis for any miner (Document ID
1351; 1398; 1416; 1418; 1421; 1424;
1439; 1441; 1449). Many of these
commenters, as well as the Black Lung
Clinics, the USW, and an individual
stated that MNM miners should be
provided similar medical removal/
transfer rights as coal miners (Document
ID 1410; 1447; 1437). The UMWA, Black
Lung Clinics, and AFL–CIO noted that
a medical removal/transfer program
helps address the barriers related to fear
of retaliation and income loss workers
face when choosing to participate in
medical surveillance (Document ID
1398; 1410; 1449).
After reviewing the comments and
based on its experience with part 90 for
coal miners, MSHA agrees that medical
removal/transfer would enhance health
protections for MNM miners who
choose to exercise their rights; however,
the Agency has determined that this
would be more appropriately addressed
in a future rulemaking. MSHA believes
that the NIOSH-established reporting
system referenced in the final rule needs
to be developed and implemented
before implementing medical removal/
transfer requirements. For example,
under part 90, NIOSH administers
medical surveillance and notifies mine
operators when a miner exercises their
part 90 rights. Under this final rule,
MNM medical surveillance is
administered independent of NIOSH,
and there are many more MNM miners
than coal miners. Because of these
differences, the Agency concluded that
medical removal/transfer would benefit
from additional notice and comment on
a number of decision points, including
protecting miners’ privacy, adequacy of
forms for notification, timing of benefits,
what area of the mine the miner would
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be transferred to, whether NIOSH must
make the determination, and consistent
ILO classification. Further, MSHA
agrees with the many commenters that
urged the Agency to issue this final rule
without delay.
MSHA also clarifies that, under final
§ 60.14(b), a mine operator must, upon
receiving written notification from a
PLHCP, facilitate the temporary transfer
of an affected miner who cannot wear a
respirator to a different area or
occupation within the same mine where
respiratory protection is not necessary.
The final rule requires that transferred
miners continue to receive
compensation at no less than the regular
rate of pay in the occupation that they
held immediately prior to the transfer.
appropriate engineering controls for
their mine sites. MSHA encourages
mine operators to use this resource.
MSHA will work with mine operators
and miners to develop and implement
effective controls, including evaluating
exposure monitoring results. MSHA
encourages mine operators to be
proactive in their approach to protecting
miners from silica exposures and to
develop dust control plans or other
engineering tools in their operations.
MSHA also commits to developing
guidance that includes information on
consensus standards related to control
methods. MSHA will also provide
education and training to mine
operators and miners covering all
aspects of the final rule.
6. Compliance Assistance
MSHA will provide compliance
assistance to the mining community
(including industry and labor) after
publication of the final rule. This
assistance will include guidance to
assist mine operators in developing and
implementing appropriate controls;
outreach seminars (onsite and virtual,
dates and locations will be posted on
MSHA’s website); dust control
workshops held at the National Mine
Health and Safety Academy; support
from the Educational Field and Small
Mine Services staff; support from
MSHA’s Technical Support staff; silica
training and best practice materials; and
information on MSHA’s enforcement
efforts.
Additionally, MSHA will continue its
Silica Enforcement Initiative by
evaluating all sampling data and
enforcement actions and providing
compliance assistance on specific
engineering controls. MSHA will
continue to maintain a team of experts
in regulatory compliance and respirable
dust control to conduct compliance
assistance visits. These visits will
evaluate the conditions, mining
practices, and controls that lead to silica
dust overexposures. MSHA will discuss
its results with mine operators and
miners and make recommendations as a
part of the Agency’s compliance
assistance activities.
As a part of its ongoing alliance
agreements, MSHA will discuss issues
and questions in regular alliance safety
and health meetings. MSHA will
continue to work with NIOSH in the
development and delivery of
compliance assistance materials.
Compliance assistance materials will be
posted on MSHA’s and NIOSH’s
website, some of which may be reposted
to the MSHA app. NIOSH’s Dust Control
Handbook is a useful tool for mine
operators to determine feasible and
B. Section-by-Section Analysis
Part 60 of the final rule establishes
uniform mandatory health standards for
exposure to respirable crystalline silica
in MNM and coal mines. Part 60
includes 10 sections: Scope and
compliance dates; Definitions;
Permissible exposure limit (PEL);
Methods of compliance; Exposure
monitoring; Corrective actions;
Respiratory protection; Medical
surveillance for metal and nonmetal
mines; Recordkeeping requirements;
and Severability. For each section
below, MSHA discusses the
requirements of the final rule and
addresses the public comments received
in response to the July 2023 proposed
rule.
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1. Section 60.1—Scope; Compliance
Dates
The final rule establishes
requirements for the scope of the rule
and the compliance dates in § 60.1.
Section 60.1 paragraph (a) identifies the
scope of the final rule, and the language
is unchanged from the proposal. In a
change from the proposal, paragraph (b)
identifies the separate compliance dates
for coal mine operators in paragraph
(b)(1) and for metal and nonmetal mine
operators in paragraph (b)(2). Paragraph
(b)(1) establishes a compliance date for
coal mine operators of 12 months after
publication of the final rule. Paragraph
(b)(2) establishes a compliance date for
metal and nonmetal mine operators of
24 months after publication of the final
rule. Below is a detailed discussion of
the comments received on this section
and modifications made in response to
the comments.
a. Scope
MSHA received many comments
regarding the scope of the rule. Some
commenters, including the AIHA,
ACOEM, APHA, expressed support for
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the proposed rule’s unified approach to
regulating respirable crystalline silica
exposures at both MNM and coal mines,
as well as at both underground and
surface mines (Document ID 1351; 1405;
1416; 1412). Several other commenters,
including labor organizations, advocacy
organizations, mining trade
associations, and MNM operators,
recommended separate approaches to
regulating MNM and coal mines; those
commenters differed on which mines
should or should not be regulated and
why (Document ID 1398; 1431; 1445;
1448; 1411; 1415; 1427; 1440; 1452;
1424; 1430; 1441; 1443; 1429; 1392;
1383). Several commenters, including
mining-related businesses and MNM
operators, stated that the proposed rule
should not apply to MNM mines
(Document ID 1392; 1383; 1411; 1415;
1427). The reasons for the commenters’
position included: past precedent of
separate rules (e.g., Document ID 1448;
1440; 1445), a need for consistency with
OSHA’s silica standard (e.g., Document
ID 1392; 1383; 1411; 1415; 1427; 1431),
lower incidence of silicosis among
MNM miners (e.g., Document ID 1431;
1413; 1448; 1456), and higher
compliance costs under the unified
approach (Document ID 1392; 1411;
1415; 1427). The Pennsylvania Coal
Alliance questioned the need for the
rule to apply to the coal industry,
stating that there had been no marked
increase in compensation claims for
pneumoconiosis or silicosis in coal
mines (Document ID 1378). Other
commenters, including a black lung
clinic, a medical professional
association, advocacy organizations, and
a labor union, noted the risks that silica
exposure poses to all miners (Document
ID 1418; 1421; 1445; 1425; 1447). The
Miners Clinic of Colorado at National
Jewish Health observed that information
about silicosis disease rates among
MNM miners is less readily available in
part due to a lack of medical
surveillance (Document ID 1418).
However, even with less information on
silicosis disease rates than in coal, this
commenter relayed their observations of
substantial silicosis rates in MNM
miners.
MSHA continues to believe that a
unified approach to controlling
respirable crystalline silica provides the
greatest level of health protection for
MNM and coal miners. The purpose of
this final rule is to reduce respirable
crystalline silica-related occupational
diseases in miners and to improve
respiratory protection against airborne
contaminants. Based on MSHA’s review
of the adverse health effects related to
respirable crystalline silica—a known
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carcinogen—MSHA concludes that the
health risks threaten all miners exposed
to respirable crystalline silica. It is
important that the mandatory health
standards for MNM and coal miners be
consistent to ensure that all miners are
equally protected from exposure.
Selected surveillance data for both
silicosis cases and deaths are reported
in the standalone Health Effects
document and in the preamble in
Section V. Health Effects Summary.
Additionally, further discussion of risk
related to silica exposure is located in
the standalone FRA document.
While MSHA acknowledges that
MNM and coal mines have been
regulated separately in the past, there is
precedent for a unified approach. For
example, MSHA’s health standard for
occupational noise covers both MNM
and coal mines, as discussed in
‘‘Evaluating hearing loss risks in the
mining industry through MSHA
citations’’ (Sun and Azman, 2018). Like
respirable crystalline silica,
occupational noise is a hazard for all
miners. MSHA’s survey and
enforcement data indicate that since the
occupational noise rule became effective
in September of 2000, there has been a
drastic decrease in the rate of
overexposures at both MNM and coal
mines. Because the hazards and control
methods of respirable crystalline silica
are common to both coal and MNM,
MSHA believes a unified standard will
offer miners consistent improvement of
working conditions in both sectors.
As addressed in the standalone Health
Effects document, MSHA has reviewed
studies supporting increased risk of
adverse health effects for miners
working in both coal and MNM mines.
After decades of declining prevalence of
pneumoconiosis among underground
coal miners in the U.S., prevalence,
including more advanced forms of
disease, has increased since the late
1990s (Laney and Weissman, 2012;
Blackley et al., 2014a, 2018a; Hall et al.,
2019b).
MSHA does not agree with the
assertion that silicosis or other diseases
linked to respirable crystalline silica are
not risks for MNM miners. MSHA
reviewed a wide range of studies that
demonstrated disease risks among
miners occupationally exposed to
respirable crystalline silica. These
studies were not limited to coal miners
and covered occupations relevant to
MNM mining such as sandblasters
(Hughes et al., 1982; Abraham and
Wiesenfeld, 1997), industrial sand
workers (Vacek et al., 2019), hard rock
miners (Verma et al., 1982, 2008), gold
miners (Carneiro et al., 2006a; Tse et al.,
2007b), metal miners (Hessel et al.,
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1988; Hnizdo and Sluis-Cremer, 1993;
Nelson, 2013), and nonmetal miners
such as silica plant and ground silica
mill workers, whetstone cutters, and
silica flour packers (Mohebbi and
Zubeyri, 2007; NIOSH, 2000a,b; Ogawa
et al., 2003a). Of the MNM exposure
samples MSHA collected over the 2005–
2019 period, 17.7 percent exceed the
new PEL of 50 mg/m3, and 6.1 percent
exceed the current PEL of 100 mg/m3.
Further discussion on this analysis is
presented in the standalone FRA
document.
This rule will strengthen miners’
health protections by reducing
exposures to respirable crystalline
silica, which is the root cause of silicarelated disease. MSHA believes that this
uniform approach provides a more
protective, coherent, logical, and
predictable standard for miners and
mine operators. Unlike the existing
standards, this final rule establishes a
single, uniform PEL and action level,
and eliminates any need for conversion
based on percent respirable crystalline
silica and any variations in calculation
for different silica polymorphs. The
final uniform PEL will provide all
miners with a consistent level of
protection that is similar to the
protection provided to workers in
industries covered by OSHA’s silica
standards, and consistent with the
recommendations of NIOSH.
b. Applicability to Contractors, Portable
Mines, and Sorptive Minerals Industry
Several commenters requested
clarification of applicability or
exemptions to specific sectors of the
mining industry: mining contractors,
portable mines, and the sorptive
minerals sector.
Contractors
Some commenters from industry trade
associations and mining trade
associations requested that MSHA
clarify the rule’s applicability to mining
contractors in the final rule (Document
ID 1422; 1433; 1424; 1428; 1378).
Consistent with the Mine Act, MSHA’s
existing standards, and the Agency’s
longstanding policy, independent
contractors engaging in mining
activities, including construction,
maintenance, and drilling, are required
to comply with the requirements in this
final rule. See 30 U.S.C. 802(d) (defining
‘‘operator’’ to include ‘‘any independent
contractor performing services or
construction’’ at a mine) and § 802(g)
(defining ‘‘miner’’ as ‘‘any individual
working in a coal or other mine’’).
MSHA has a long history and practice
of enforcing its standards and
regulations for mine operators and
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independent contractors designated
under part 45 of 30 CFR. The Agency
believes that the industry is familiar
with and understands this history and
practice. Based on MSHA’s experience
and practice, and depending upon the
activities that they perform for
production operators, MSHA expects
that some part 45 independent
contractors will comply with the
requirements of this final rule, as it
relates to their miners. For example,
MSHA expects that drilling and blasting
contractors, who perform services at
different mines, generally separate from
production activities, will comply with
the requirements of the final rule. For
other part 45 independent contractors,
MSHA anticipates that the production
operator may comply with the
requirements of this final rule for their
miners, depending upon the types of
services provided. For example, MSHA
expects that production operators will
generally comply with the requirements
of this final rule for independent
contractors that perform hauling
services for mines. This final rule
provides improved health protections
for miners of both part 45 independent
contractors and production operators.
As with the implementation of any new
MSHA standard, the Agency expects
that production operators and part 45
independent contractors will
communicate and coordinate with each
other, as appropriate, to comply with
the final rule and ensure that miners’
safety and health are protected.
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Portable Mines
Some commenters (MNM operators
and a mining-related business)
requested that MSHA exempt portable
mine operations from exposure
monitoring (Document ID 1392; 1415;
1427; 1435; 1436). The mining-related
business commented that an exemption
should be granted for portable mines
that are shut down for more than 3
months out of the year or operate in a
pit for less than 30 days before moving
(Document ID 1392). Several portable
mine operators, including B & B Roads,
Inc., stated that rock crushing jobs are
typically completed within 4 to 10 days,
at which point the portable mine moves
to another job location, which could be
between 30 to 200 miles away
(Document ID 1427; 1436). These
commenters specifically requested
exemptions for sites that they do not
own, stating that sampling data would
not be applicable if done at pits where
they do not conduct operations
regularly. However, these commenters
expressed that they were not asking for
exemptions to pits where they regularly
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conduct operations or to locations they
control.
MSHA reviewed the comments and
determined that because of MSHA’s
clear mandate to protect the health of all
miners, the final rule does not exempt
portable mines. Under existing MNM
standards for airborne contaminants,
portable operations are not exempt from
any regulatory requirements or any
other health standards. This final rule,
like existing standards, requires portable
mine operators to protect their miners
from overexposure to respirable
crystalline silica and other airborne
contaminants, and to monitor miners’
exposures to airborne contaminants,
including silica. Portable mine
operations often involve crushing,
which can generate substantial amounts
of dust, and they handle a variety of
commodities generating varying
amounts of respirable crystalline silica
depending on the geological features of
the pit.
The final rule requires that all mine
operators, including portable mine
operators, conduct exposure monitoring
in accordance with § 60.12, including
first-time sampling. With respect to
portable mine operators, MSHA has
taken into consideration that these
mines are unique and may move
frequently. However, the final rule does
not exempt portable mine operators
because miners must be protected at all
times, and the methods of compliance,
sampling and evaluation provisions are
necessary to protect miners.
Sampling ensures engineering
controls put in place by mine operators
are effective in protecting miners. If the
portable mine operator anticipates being
at the site for at least three months,
MSHA expects the portable mine
operator to conduct the second-time
sampling at that site within the threemonth timeframe under § 60.12(a)(2). If
the portable mine operator moves to a
different site before conducting its
second-time sampling within threemonths, the operator is required to
conduct the second-time sample at the
next site. If either operator or MSHA
samples are at or above the action level
and at or below the PEL, portable
operators must sample every three
months under § 60.12(a)(3). Similarly, if
the most recent sampling was above the
PEL, the portable mine operator must
take immediate corrective actions,
immediately report the overexposure to
MSHA, ensure provided respirators are
worn appropriately by affected miners
before the start of the next work shift,
and resample, regardless of whether the
portable mine has moved to a different
site by the time the sampling results are
received. Under the final rule, at least
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every 6 months or if there are any
changes in processes, production,
equipment, or geological conditions,
mine operators are required to conduct
a qualitative evaluation. Protecting
miners’ health requires monitoring and
controlling levels of respirable
crystalline silica, and, consistent with
the Mine Act, miners at portable mines
must be afforded the same health
protections and informational
awareness of their exposures as all other
miners.
If the results of the evaluation reveal
that their miners may be reasonably
exposed to respirable crystalline silica
at or above the action level but at or
below the PEL, the sampling provisions
of the final rule apply. Also, if sampling
indicates levels above the PEL, under
the final rule, portable mine operators
must take immediate corrective actions,
resample, and record these actions.
MSHA provides two examples that
illustrate how and why the final rule
will affect portable mine operators. In
example 1, the portable mine operator
conducts first-time sampling on mine
site A and the sample result is below 25
mg/m3. One month later, the portable
mine operator moves to mine site B. The
operator performs a qualitative
evaluation, which the operator
determines does not trigger postevaluation sampling. Within two
months (three months from the date of
the first-time sample), the portable mine
operator must take a second sample.
This sample result is also under 25 mg/
m3. Under the final rule, this portable
mine operator can discontinue
sampling. The portable mine operator
then moves to mine site C. The portable
mine operator must conduct a
qualitative evaluation and, depending
on the results of the evaluation, may
need to perform sampling.
In example 2, the portable mine
operator is located on mine site X. The
portable mine operator conducts a
qualitative evaluation and determines
that miners’ exposures may reasonably
be at or above the action level, triggering
sampling. The portable mine operator
conducts sampling, and the results are
above the PEL. The mine operator takes
immediate corrective actions,
immediately reports the overexposure to
MSHA, ensures provided respirators are
worn appropriately by affected miners
before the start of the next work shift,
and resamples. The operator then moves
to mine site Y before corrective actions
sampling results are received.
Depending on the results of the
corrective actions sampling from mine
site X, the portable mine operator must
conduct either above-action-level
sampling or corrective actions sampling
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at mine site Y. MSHA expects that all
corrective actions, including any new or
improved engineering controls, will
remain in place at mine site Y.
Additionally, at mine site Y, the
operator must perform another
qualitative evaluation at the new mine
site. Each time the operator moves to a
new site, it must perform a new
qualitative evaluation.
These examples illustrate that when
sampling is required at one portable
mine site, the requirement continues
when the portable mine moves to a new
mine site. Sampling across different
portable mine sites is needed to
determine whether the engineering
controls applied to the portable mine
(for example, dust collection or water
spray) are effective to keep miners
healthy. Periodic evaluations will also
be critical for mines that move
frequently and encounter different
conditions that expose miners to
respirable crystalline silica. These
evaluations and any related samplings
will allow operators to verify that
adequate engineering controls are
effective and are maintained properly to
protect miners as they move to different
worksites, regardless of mining location
or commodity mined or milled.
MSHA encourages portable mine
operators to work with their District
Managers to develop an appropriate
compliance approach that protects
miners’ health. MSHA will provide
compliance assistance to portable mine
operators.
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Sorptive Minerals
The applicability of the rule to one
specific industry within MNM—the
sorptive minerals industry—was the
subject of several comments from SMI,
EMA, and Vanderbilt Minerals, LLC
(Document ID 1446; 1442; 1419). These
commenters requested that the sorptive
minerals industry be exempted from the
rule. The commenters stated that this
industry exposes workers only to aged
quartz, and that aged quartz is less toxic
than freshly fractured quartz in other
industries. After careful consideration,
MSHA has decided not to exempt
sorptive minerals mines. The Agency’s
rationale for this decision is discussed
in detail above in Section VIII.A.
General Issues.
c. Compliance Dates
This final rule will take effect 60 days
after publication in the Federal
Register. In response to comments,
MSHA is establishing two compliance
dates for the final rule—one for MNM
mine operators and the other for coal
mine operators. MNM operators will be
required to comply starting 24 months
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after publication of the final rule,
whereas coal mine operators will be
required to comply starting 12 months
after publication of the final rule.
MSHA received comments both in
support of and against having
compliance commence immediately
when the final rule takes effect. Some
commenters, including labor
organizations, an industrial hygiene
professional association, and an
advocacy organization, supported the
proposed effective date, citing the need
for the new rule to be implemented as
soon as possible to protect miners’
health (Document ID 1398; 1425; 1351;
1449). Appalachian Voices and the
AFL–CIO stated that the technologies
and practices necessary to reduce dust
and silica exposure are well-known and
that mine operators have had ample
notice that this rule was forthcoming
(Document ID 1425; 1449). In contrast,
several commenters, including multiple
mining trade associations and a mining
industry organization, expressed the
need for a longer preparation period
prior to compliance (Document ID 1428;
1407; 1408; 1442; 1441; 1448). Some
commenters, including a state mining
association, a MNM operator, and an
industry trade association, suggested
that MSHA allow more time, ranging
from one to three years, to comply with
the final rule (Document ID 1441; 1432;
1442; 1448; 1392). Some cited reasons
for allowing more time include: the twoyear preparation period that OSHA
provided for compliance with its 2016
silica rule; the time needed for operators
to plan, purchase, and implement
engineering controls; and the challenges
that the rule could present for MNM
mine operators new to sampling and
medical surveillance (Document ID
1407; 1419; 1424; 1428). Other
commenters, including a professional
association, industry trade associations,
mining trade associations, and MNM
operators, suggested a phased approach
to implementation, with different
compliance dates for the different
requirements in the rule (Document ID
1377; 1407; 1413; 1428; 1424; 1456;
1417; 1453). Examples given of past
rules that had used this approach
included: OSHA’s silica rule (which
became effective 90 days after
publication, but, for example, for
construction, allowed one year after the
effective date for compliance with most
of the rule requirements, and two years
for compliance with certain laboratory
requirements); MSHA’s diesel
particulate matter rule (which included
incremental reductions in the PEL over
two years); and MSHA’s 2014 RCMD
Standard (which allowed operators 18
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months after the effective date to
comply with sampling requirements and
24 months to implement the standards)
(Document ID 1407; 1424; 1441; 1442).
Several commenters, including three
industry trade associations, a mining
trade association, and a MNM operator,
expressed concern that the rule would
lead to excessive demand and backlogs
for sampling devices, industrial
hygienists, labs, medical facilities, and
B Readers (Document ID 1407; 1404;
1413; 1428; 1419). The NSSGA stated
that over 80 percent of aggregate
companies have fewer than 25
employees and therefore will likely rely
on their insurance companies or
industrial hygiene consultants for
sampling, and that scheduling of
sampling will be based on priorities
outside the control of the mine operator
(Document ID 1448). A mining trade
association, industry trade associations,
and a MNM operator also asserted that
because post-pandemic supply chain
delays are continuing, and in some
cases escalating, operators are facing
long lead times for procurement of
critical infrastructure items, including
those essential for mandatory health and
safety requirements (Document ID 1428;
1404; 1407; 1419). Finally, these
commenters expressed concern that
requiring mine operators to comply with
the final rule 120 days after publication
would not provide enough time for
MSHA to issue guidance and for mine
operators to digest relevant
implementation and compliance
guidance documents (Document ID
1428; 1404; 1407; 1419).
After careful consideration, MSHA
has decided to provide additional time
for mine operators to prepare for
compliance with the final rule. MNM
mine operators must comply with the
final rule by 24 months after publication
of the final rule, while coal mine
operators will have 12 months to come
into compliance with the rule (except
for medical surveillance, which applies
only to MNM mines). MSHA believes
that this final compliance date gives
coal mine operators sufficient time to
plan and prepare for effective
compliance with the new standards,
while also ensuring that improved
protections for miners from the hazards
of respirable crystalline silica take effect
as soon as practically possible. Unlike
MNM mines, underground and surface
coal mine operators have considerable
experience with frequent sampling, and
they can more quickly integrate the
sampling requirements in this final rule
into their existing underground mine
ventilation plans and surface mine
respirable dust control plans. In
addition, coal mines already have
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existing controls in place that control
for dust; therefore, coal mine operators
should not need as much time to
maintain, repair or implement controls.
As mentioned earlier, coal mine
operators will not have to implement
medical surveillance under this rule.
In the case of MNM mines, MSHA has
adjusted the requirements in the final
rule to allow operators a total of 24
months after the publication of the final
rule to comply. MSHA is allowing this
longer period for compliance because
MNM operators, particularly small
mines, may have less experience with
sampling and may also need time to
prepare for compliance with medical
surveillance. The longer period for
compliance is generally responsive to
some commenters. The Agency believes
the longer period for compliance will
provide operators adequate time to meet
their compliance obligations under the
final rule. MSHA believes that mine
operators will use the compliance
period to familiarize themselves with
the new standard; evaluate, update, and
enhance existing engineering controls;
research, purchase, and install new or
additional engineering controls, if
necessary; arrange for sampling; and
commence sampling. MSHA notes that
the 24 months provided for MNM
operators is the same as that provided
in the OSHA rule and the same as
MSHA provided in the 2014 RCMD
Standard. MSHA believes that there are
enough laboratories, sampling
equipment, medical service providers,
respiratory equipment, and contractor
service providers for sampling to meet
any increase in demand for equipment
or services required by this final rule.
The additional 24 months will provide
MNM operators additional time to
procure equipment and services. For a
detailed discussion of the availability of
respirators and laboratory and medical
services necessary for compliance with
the rule, see Section VII.A.
Technological Feasibility.
MSHA believes that these compliance
periods in the final rule provide
operators adequate time to prepare for
successful implementation, balanced
against the Agency’s priority goal and
statutory mandate to move quickly to
protect miners against respirable
crystalline silica hazards. Mine
operators in both MNM and coal have
had many years of experience with
monitoring and controlling airborne
contaminants, including respirable
crystalline silica, and this experience
should facilitate implementation of the
final rule. MSHA data show that many
mines are already meeting the respirable
crystalline silica PEL of 50 mg/m3 for a
full-shift, calculated as an 8-hour TWA,
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using a variety of engineering controls.
In addition, to ensure successful
implementation, MSHA plans to
provide compliance assistance to the
mining industry. This assistance will
include the development and
distribution of compliance guidance
materials for mine operators and
training materials for miners, as well as
technical assistance for small mines.
Compliance assistance and training are
discussed in more detail above in
Section VIII.A. General Issues.
2. Section 60.2—Definitions
The final rule, like the proposal,
includes definitions for the following
terms in § 60.2: ‘‘action level,’’
‘‘respirable crystalline silica,’’ and
‘‘specialist.’’ In a change from the
proposal, MSHA removes the definition
of ‘‘objective data’’ from the final rule.
MSHA received multiple comments on
the proposed definitions of action level
and objective data, as discussed in more
detail below. The Agency did not
receive any comments on the proposed
definitions of respirable crystalline
silica or specialist.
a. Action Level
The final rule, like the proposal,
defines ‘‘action level’’ as ‘‘an airborne
concentration of respirable silica of 25
micrograms per cubic meter of air (mg/
m3) for a full-shift exposure, calculated
as an 8-hour time-weighted average
(TWA).’’ If respirable crystalline silica
concentrations are at or above the action
level but at or below the PEL, operators
are subject to the ongoing sampling
requirements detailed in § 60.12. The
action level enables mine operators to
maintain compliance with the PEL and
provide necessary protection to miners
before overexposures occur.
MSHA received several comments in
support of and against the proposed
adoption of an action level. Several
commenters including labor unions,
medical professional associations, and
advocacy organizations supported the
proposal to institute an action level of
25 mg/m3 (Document ID 1398; 1447;
1416; 1421; 1393; 1438). The UMWA
and USW stated that the proposed
action level was consistent with NIOSH
and IARC findings and would reduce
the risk of death and disease (Document
ID 1398; 1447). Other commenters,
including state mine organizations,
mining trade associations, and MNM
mine operators, did not support the
proposed action level of 25 mg/m3 for all
mines (Document ID 1368; 1441; 1424;
1432; 1440; 1378; 1392; 1408; 1426).
The commenters stated that it would not
be achievable with current technology
(Arizona Mining Association, Document
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ID 1368) and would not improve
miners’ health (AMI Silica LLC,
Document ID 1440). The NLA stated
that MSHA should consider setting only
a PEL and not an action level because
there is less need for an action level in
the mining industry than in OSHAregulated industries (Document ID
1408). The AEMA, NVMA, and Tata
Chemicals Soda Ash Partners, LLC,
stated that the action level should be
developed on a per-mine or percompany basis or should be an internal
control only (Document ID 1424; 1441;
1452). The Arizona Mining Association
suggested a phased approach with
incremental changes (Document ID
1368). The ACOEM, although in support
of the action level and proposed PEL,
urged a further lowering of the PEL to
25 mg/m3 in the future (Document ID
1405).
After careful consideration of the
comments, MSHA has determined an
action level of 25 mg/m3 is feasible, and
the definition of action level in the final
rule is the same as the proposal.
MSHA’s FRA shows that there will be
a greater reduction of morbidity and
mortality at the action level, but
acknowledges that it may not be
achievable for all mines to consistently
maintain an exposure limit below 25 mg/
m3. According to NIOSH research,
wherever exposure measurements are
above one-half the PEL, the employer
cannot be reasonably confident that the
employee is not exposed to levels above
the PEL on days when no measurements
are taken (NIOSH, 1975). MSHA
establishes the action level and sets a
sampling frequency for concentrations
at or above the action level to allow
mine operators to act before
overexposures occur. MSHA
acknowledges that, even at exposures of
25 mg/m3, some residual risks remain.
For example, at 25 mg/m3, end stage
renal disease (ESRD) risk is 20.7 per
1,000 MNM miners and 21.6 per 1,000
coal miners.
Commenters stated that MSHA should
not have an action level. The AEMA and
NVMA said the Agency does not use an
action level in other air contaminant
exposure rules (Document ID 1424;
1441).
At exposures of 25 mg/m3 or lower,
risk of adverse health effects remains.
The Agency has established action
levels equivalent to 50 percent of the
PEL for occupational noise exposure in
MNM and coal mines (30 CFR 62.101)
and equivalent to 50 percent of the
exhaust gas monitoring standards for
underground coal mines (30 CFR
70.1900). MSHA survey and
enforcement data indicate that the
action levels in the occupational noise
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and exhaust gas rules have contributed
to greater compliance and fewer
overexposures. Based on its experience,
MSHA knows that action levels
encourage mine operators to be more
proactive in providing necessary health
and safety protection to miners.
Furthermore, MSHA was able to learn
about the health benefits of an action
level for respirable crystalline silica
through the implementation of OSHA’s
silica final rule (2016a). In developing
this final rule, MSHA took into
consideration experience gained under
other safety and health standards
including those established by OSHA.
Several OSHA standards established
action levels for airborne contaminants,
especially toxins such as benzene,
inorganic arsenic, ethylene oxide, and
methylene chloride.
Some commenters, including trade
associations, MNM operators, a state
mining association, and a miningrelated business, stated that the action
level would increase costs for mine
operators (Document ID 1408; 1442;
1419; 1440; 1441; 1392). MSHA
recognizes that costs may increase as a
result of the sampling requirements in
the final rule. Mine operators are
encouraged to reduce exposures below
the action level to avoid additional costs
associated with the sampling
requirements triggered when exposures
are at or above the action level. The
Agency emphasizes that the
requirements of the final rule are
established to protect miners from the
adverse health effects resulting from
exposure to respirable crystalline silica.
Several commenters, including
industry trade associations, MNM
operators, and a mining trade
association, cautioned that the action
level was too close to the limit of
accurate detection of respirable
crystalline silica (Document ID 1426;
1413; 1432; 1440; 1448). SSC stated that
there is little confidence in the
reliability of sampling results below 50
mg/m3 (Document ID 1432).
MSHA’s analytical methods for air
samples can reliably detect respirable
crystalline silica at or below the action
level. The MSHA P–2 and P–7
analytical methods have a reporting
limit of 12 mg for quartz in mine dust.
Both methods are sufficiently sensitive
to quantify levels of quartz collected on
air samples from concentrations at the
action level. Most accredited
laboratories that offer crystalline silica
analysis by X-ray diffraction use either
the OSHA ID–142 or NIOSH 7500
methods. The OSHA method specifies a
reliable quantification limit of 12 mg/m3
for quartz, and the NIOSH method states
that the estimated detection limit for
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quartz is 5 mg. The NIOSH infrared
methods, 7603 and 7602, state estimated
detection limits of 1 and 5 mg of quartz,
respectively.
The AEMA and NVMA disagreed
with MSHA’s calculation of the action
level as an 8-hour TWA (Document ID
1424; 1441). These commenters said
NIOSH recommends calculating
exposure levels for a 10-hour shift.
The final rule includes an 8-hour
TWA because it provides more
protection to miners who work
extended shifts. Further discussion of
the 8-hour TWA is discussed below
under Section 60.10—Permissible
Exposure Limit (PEL).
The Arizona Mining Association
stated the proposed action level is not
achievable with current available
technology (Document ID 1368). The
commenter provided testimonial
information about a mine that
conducted a baseline test with a
continuous dust monitor in an office
setting and was close to the proposed
action level.
MSHA clarifies that the action level
applies only to respirable crystalline
silica, which is a component of
respirable dust. If an office or other
setting contains levels of respirable
crystalline silica that meet or exceed the
action level, sampling is required under
the final rule.
After careful consideration of the
rulemaking record, MSHA has
determined the action level is
appropriate. The Agency’s experience
with existing standards indicates that an
action level of one-half the PEL provides
necessary information to mine operators
on actions they need to take to reduce
miners’ exposures below the action
level, where feasible. Operator sampling
at or above the action level but at or
below the PEL also provides critical
information to miners on their
exposures. Under § 60.12(g), operators
must share sampling records and
laboratory reports with miners so that
they have an awareness and
understanding of the important role that
engineering and administrative controls
play in protecting their health. Mine
operators who keep their exposures
below the action level avoid the costs of
required compliance with provisions
triggered by the action level, provide
improved health protection for miners,
and may experience better miner health
and less turnover. MSHA concludes that
an action level is needed at one-half the
PEL based on residual risk at the PEL of
50 mg/m3; the feasibility of measuring
exposures at an action level of 25 mg/m3;
and the administrative convenience of
having the action level at one-half the
PEL, as it is in other MSHA standards.
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As discussed in the standalone Health
Effects document and standalone FRA
document, risk remains at the PEL of 50
mg/m3. Accordingly, MSHA is finalizing
these additional requirements to reduce
remaining risk when those requirements
will afford benefits to miners and are
feasible.
b. Objective Data
Under the proposal, operators could
use ‘‘objective data’’ to confirm
sampling results below the action level
and discontinue sampling.
MSHA removes the definition of
‘‘objective data’’ in the final rule. The
term ‘‘objective data’’ was defined in the
proposed rule as ‘‘information such as
air monitoring data from industry-wide
surveys or calculations based on the
composition of a substance that
indicates the level of miner exposure to
respirable crystalline silica associated
with a particular product or material or
a specific process, task, or activity.’’
MSHA received several comments on
the proposed definition of objective
data, with numerous commenters
stating that the definition was vague and
overly broad. Some commenters,
including labor organizations, a Federal
elected official, and an industry trade
association, requested clarification on
how to determine the validity and
acceptability of objective data and who
should make the determinations
(Document ID 1398; 1449; 1439; 1442).
Others, such as AIHA, Black Lung
Clinics, and AFL–CIO, commented that
objective data is not an accurate or
reliable measure of exposure to
respirable crystalline silica and that
objective data should not be used to
exempt operators from sampling.
(Document ID 1351; 1410; 1449; 1412).
The Agency agrees with commenters
who asserted sampling is more accurate
than using objective data as defined in
the proposed rule. Additional
discussion on the comments received on
objective data and MSHA’s response
regarding the proposal are discussed in
Section VIII.B.5. Section 60.12.—
Exposure Monitoring.
c. Respirable Crystalline Silica
The final rule, like the proposal,
defines ‘‘respirable crystalline silica’’ as
‘‘quartz, cristobalite, and/or tridymite
contained in airborne particles that are
determined to be respirable by a
sampling device designed to meet the
characteristics for respirable-particlesize-selective samplers that conform to
the International Organization for
Standardization (ISO) 7708:1995: Air
Quality—Particle Size Fraction
Definitions for Health-Related
Sampling.’’
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MSHA did not receive any comments
on the definition of respirable
crystalline silica. The final rule’s
definition has two main advantages.
First, the ISO 7708:1995 definition of
respirable particulate mass represents
an international consensus, and by
adopting the ISO 7708:1995 criterion,
MSHA is able to harmonize its
standards with the standards used by
other occupational health and safety
organizations in the U.S. and
internationally, including ACGIH,
OSHA (29 CFR 1910.1053 and 29 CFR
1926.1153), NIOSH (2003b, Manual of
Analytical Methods), and the European
Committee for Standardization (CEN)
(ISO 7708:1995). Second, the definition
eliminates inconsistencies in the
existing standards for MNM and coal
mines. Defining respirable crystalline
silica to include quartz, cristobalite,
and/or tridymite and establishing a PEL
for exposure to respirable particles of
any combination of these three
polymorphs provides consistency across
different mining sectors.
d. Specialist
The final rule, like the proposal,
defines ‘‘specialist’’ as ‘‘an American
Board-Certified Specialist in Pulmonary
Disease or an American Board-Certified
Specialist in Occupational Medicine.’’
The definition is applicable to § 60.15,
which addresses medical surveillance
for MNM mines. Under the medical
surveillance requirements, MNM mine
operators are required to provide miners
with medical examinations performed
by a specialist in pulmonary disease or
occupational medicine or a PLHCP.
MSHA did not receive any comments
on the definition of specialist. The
medical surveillance provisions for
MNM mines require a specialist to
conduct a follow-up medical
examination no later than 2 years after
the follow-up examination for new
miners if the chest X-ray shows
evidence of pneumoconiosis or the
spirometry examination indicates
evidence of decreased lung function
(§ 60.15(c)(3)). The provision is
intended to ensure that any miner who
shows evidence of pneumoconiosis or
decreased lung function is seen by a
professional with expertise in
respiratory disease. The definition is
important because it ensures miners
benefit from expert medical judgment
and receive advice regarding how work
practices and personal habits could
affect their health.
3. Section 60.10—Permissible Exposure
Limit (PEL)
The final rule, like the proposal,
requires the mine operator to ensure
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that no miner is exposed to respirable
crystalline silica in excess of 50 mg/m3
for a full-shift exposure, calculated as an
8-hour TWA for all mines. The PEL is
the same for both MNM mines and coal
mines. For coal mines, this provision
establishes a PEL for respirable
crystalline silica independent from the
existing respirable coal mine dust
standards. The PEL in the final rule
replaces the Agency’s existing exposure
limits for respirable crystalline silica or
respirable quartz in 30 CFR parts 56, 57,
70, 71, and 90. (The existing respirable
coal mine dust standards unrelated to
quartz remain the same.) Below is a
detailed discussion of the comments
received on this section and
modifications made in response to the
comments.
a. PEL of 50 mg/m3
MSHA analyzed and considered the
comments received in response to the
proposed PEL of 50 mg/m3. Most
commenters supported lowering the
existing quartz or silica exposure limits,
and many specifically expressed
support for the proposed PEL, including
labor organizations, an advocacy
organization, medical professional
associations, and mining trade
associations, (Document ID 1398; 1447;
1449; 1416; 1421; 1424; 1428; 1418;
1439; 1443). Some of these commenters,
including AEMA and NMA, noted that
the proposed PEL aligns with OSHA’s
PEL for non-mining industries, as well
as with NIOSH recommendations
(Document ID 1424; 1428). Several
commenters, including Black Lung
Clinics, APHA, and Miners Clinic of
Colorado, underscored that substantial
risk of silica-related disease exists at 100
mg/m3 compared to lower risks at 50 mg/
m3 (Document ID 1410; 1416; 1418).
Black Lung Clinics noted that the
indirect approach to limiting silica
exposure in coal miners has not been
effective (Document ID 1410). Other
commenters, including the AFL–CIO
and NABTU, stated that the proposed
PEL is technologically and economically
feasible and would reduce the risk of
death and disease to miners (Document
ID 1449; 1414). Other commenters
similarly expressed support for the
proposed PEL, with the USW stating
that the proposed PEL is necessary and
feasible, and The American Thoracic
Society et al. stating that it is supported
by science and could be readily
achieved with currently available
engineering interventions (Document ID
1447; 1421).
AIHA and MSHA Safety Services did
not believe the proposed PEL was
appropriate, with the AIHA stating that
the proposed PEL of 50 mg/m3 does not
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protect miners from adverse health
effects and recommending a PEL of 25
mg/m3 instead (Document ID 1351;
1392). While some commenters such as
the USW and the AFL–CIO did support
MSHA’s proposal to lower the existing
exposure limits, these commenters
noted that several other countries or
jurisdictions have set standards
reducing legal permissible limits to 25
mg/m3 (Document ID 1447; 1449). One
commenter, MSHA Safety Services Inc.,
opposed the rule stating that the
existing standards (i.e., 100 mg/m3), if
followed, would be more than sufficient
(Document ID 1392). This commenter,
citing data retrieved from MSHA’s Mine
Data Retrieval System (MDRS), stated
that silicosis and pneumoconiosis affect
only underground coal miners and not
MNM miners.
After considering the data and
evidence in the rulemaking record, the
final rule establishes a PEL of 50 mg/m3.
MSHA’s examination of health effects
evidence (discussed in the preamble in
Section V. Health Effects and Section
VI.—Final Risk Analysis Summary, as
well as in the standalone Health Effects
document and standalone FRA
document) demonstrates that exposure
to respirable crystalline silica at the
existing exposure limits results in a risk
of material impairment of health or
functional capacity, and that exposure
at the lower level of the PEL will reduce
that risk. MSHA’s FRA indicates that 45
years of exposure to respirable
crystalline silica under the new PEL
would lead to a total of 1,067 lifetime
avoided deaths, including 248 avoided
deaths from silicosis, 536 avoided
deaths from all forms of non-malignant
respiratory disease (including silicosis
as well as other diseases such as chronic
bronchitis and emphysema), 82 avoided
deaths from lung cancer, and 200
avoided deaths from renal diseases.
As some commenters noted, the PEL
is consistent with NIOSH’s respirable
crystalline silica recommended
exposure limit of 50 mg/m3 for workers
and with the PEL of 50 mg/m3 for
respirable crystalline silica covering
U.S. workplaces regulated by OSHA. In
1974, NIOSH recommended that
occupational exposure to crystalline
silica be controlled so that ‘‘no worker
is exposed to a TWA of silica [respirable
crystalline silica] greater than 50 mg/m3
as determined by a full-shift sample for
up to a 10-hour workday over a 40-hour
workweek’’ (NIOSH, 1974). In 2016,
OSHA promulgated a rule establishing
that, for construction, general industry,
and the maritime industry, workers’
exposures to respirable crystalline silica
must not exceed 50 mg/m3, averaged
over an 8-hour day (29 CFR
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1910.1053(c); 29 CFR
1926.1153(d)(1)).66
As discussed in the standalone Health
Effects document, occupational
exposure to respirable crystalline silica
is detrimental to an individual’s health.
Silicosis and other diseases caused by
respirable crystalline silica exposure are
irreversible, disabling, and potentially
fatal. At the same time, these diseases
are exposure-dependent and are
therefore preventable. The lower a
miner’s exposure to respirable
crystalline silica, the less likely that
miner is to suffer from adverse health
effects.
Regarding the comments
recommending MSHA adopt a PEL of 25
mg/m3 and some comments noting that
other countries or provinces have set
standards reducing permissible limits to
25 mg/m3, MSHA considered
establishing a PEL of 25 mg/m3 as part
of MSHA’s Regulatory Alternative 2.
Under this regulatory alternative, a more
stringent PEL of 25 mg/m3 is combined
with less stringent monitoring
provisions compared to the final rule.
MSHA estimated that there will be a
greater reduction of morbidity and
mortality cases as a result of lowering
the PEL to 25 mg/m3. MSHA also
estimated that the compliance costs
would outweigh the benefits resulting in
negative net benefits. MSHA’s
enforcement experience shows that for
mining occupations exposed to the
highest levels of respirable crystalline
silica, in both MNM mines and coal
mines, a PEL of 25 mg/m3 is not
generally achievable. For example,
MSHA reviewed exposures of
designated occupations in underground
coal mines and crusher and equipment
operators in MNM mines, and
determined that on average, miner
exposures exceed 25 mg/m3 when all
feasible engineering controls are used.
Although other countries and
jurisdictions may have adopted a PEL of
66 NIOSH conducted a literature review of studies
containing environmental data on the harmful
effects of exposure to respirable crystalline silica.
Based on these studies, and especially fifty years’
worth of studies on Vermont granite workers during
which time dust controls improved, exposures fell,
and silicosis diagnoses neared zero, NIOSH
recommended an exposure limit of 50 mg/m3 for all
industries. OSHA’s examination of health effects
evidence and its risk assessment led to the
conclusion that occupational exposure to respirable
crystalline silica at the previous PELs, which were
approximately equivalent to 100 mg/m3 for general
industry and 250 mg/m3 for construction and
maritime industries, resulted in a significant risk of
material health impairment to exposed workers,
and that compliance with the revised PEL would
substantially reduce that risk. (81 FR at 16755).
OSHA considered the level of risk remaining at the
revised PEL to be significant but determined that a
PEL of 50 mg/m3 is appropriate because it is the
lowest level feasible.
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25 mg/m3, MSHA did not choose this
regulatory alternative because a PEL of
25 mg/m3 may not be achievable for all
mines (Document ID 1447; 1449). For
some mines, a PEL of 25 mg/m3 would
present a substantial challenge.
Commenters did not provide specific
information on the regulatory programs
for the countries and jurisdictions that
have established a PEL of 25 mg/m3.
Further explanation and discussion of
the regulatory alternatives can be found
in the standalone FRIA document and
in the preamble in Section IX. Summary
of Final Regulatory Impact Analysis and
Regulatory Alternatives.
An individual urged MSHA to adopt,
in addition to the proposed PEL of 50
mg/m3, an upper exposure level of 100
mg/m3 that would trigger the withdrawal
of miners from the affected area rather
than permit continued miner work in
affected jobs in extremely elevated
concentrations above the PEL
(Document ID 1367). Because MSHA
has determined that the final rule’s
sampling obligations will reduce
overexposures and that the corrective
actions requirements establish strong
protections for miners when they are
exposed over the PEL, the Agency has
not set an upper limit that would
automatically trigger the withdrawal of
miners. As discussed at the public
hearings and required in § 60.12,
operators must immediately report all
exposures above the PEL from operator
sampling to the MSHA District Manager
or any other MSHA office designated by
the District Manager, so that MSHA
enforcement will be apprised of
exposures above the PEL and can take
appropriate actions. As discussed above
in Section VIII.A. General Issues, failure
to abate miners’ exposures above the
PEL could merit a withdrawal order
under section 104(b) of the Mine Act.
In conclusion, MSHA has determined,
as presented in the standalone FRA
document accompanying this final rule,
that: (1) under previous respirable
crystalline silica or quartz standards,
miners were exposed to respirable
crystalline silica at concentrations that
result in a risk of material impairment
of health or functional capacity and (2)
lowering the PEL to 50 mg/m3 will
substantially reduce this risk. According
to the CDC, between 1999 and 2014,
miners died from silicosis, COPD, lung
cancer, and NMRD at substantially
higher rates than did members of the
general population; for silicosis, the
proportionate mortality ratio for miners
was 21 times as high.67 Evidence in the
67 Data
on occupational mortality by industry and
occupation can be accessed by visiting the CDC
website at https://www.cdc.gov/niosh/topics/noms/
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standalone Health Effects document
demonstrates that exposure to respirable
crystalline silica at levels permitted
under previous standards contributes to
this excess mortality. Based on the
evidence and data evaluated during the
rulemaking process, MSHA has
determined that a PEL of 50 mg/m3 is
appropriate and is technologically and
economically feasible for all mines.
Mine operators will be able to maintain
miner exposures at or below the PEL of
50 mg/m3 through some combination of
properly maintaining existing
engineering controls, implementing new
engineering controls (e.g., ventilation
systems, dust suppression devices, and
enclosed cabs or control booths with
filtered breathing air), and requiring
changes to work practices through
administrative controls. MSHA
determined not to set the PEL at 25 mg/
m3. MSHA’s enforcement experience
shows that for mining occupations
exposed to the highest levels of
respirable crystalline silica, in both
MNM mines and coal mines, a PEL of
25 mg/m3 is not generally achievable.
For example, MSHA reviewed
exposures of designated occupations in
underground coal mines and crusher
and equipment operators in MNM
mines, and determined that on average,
miner exposures exceed 25 mg/m3 when
all feasible engineering controls are
used. While MSHA estimated that there
would be a greater reduction of
morbidity and mortality cases as a result
of lowering the PEL to 25 mg/m3, the
Agency estimates that compliance costs
of Regulatory Alternative 2 establishing
a PEL of 25 mg/m3 would outweigh the
benefits, resulting in negative net
benefits. A PEL of 25 mg/m3 may not be
achievable for all mines. MSHA did not
choose this regulatory alternative.
b. PEL in Coal Mines
In the case of coal mines, the final
rule establishes a PEL for respirable
crystalline silica independent from the
respirable coal mine dust (RCMD)
standard. The 2014 RCMD Standard
does not directly limit coal miners’
exposure to respirable crystalline silica;
under the existing coal mine respirable
dust standard, MSHA cannot issue a
separate citation for silica or quartz.
Separating the respirable crystalline
silica PEL from the respirable coal mine
dust standard allows for coal miners’
exposure to respirable crystalline silica
to be controlled directly, rather than
only indirectly through the respirable
default.html (last accessed Jan. 10, 2024). The
NOMS database provides detailed mortality data for
the 11-year period from 1999, 2003 to 2004, and
2007 to 2014.
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coal mine dust standard. This will
ensure greater health protection for coal
miners.
MSHA solicited comments on
whether to eliminate the reduced
standard for total respirable dust when
quartz is present at coal mines and
received feedback from stakeholders
generally agreeing with the Agency’s
proposal to establish a standard for
respirable crystalline silica that is
independent from the respirable coal
mine dust standard, including other
mine industry organizations, a labor
union, mining trade associations, and
Black Lung Clinics (Document ID 1378;
1398; 1406; 1428; 1410). The ACLC
expressed support for a standalone and
separately enforceable PEL, but
recommended maintaining a reduced
standard for respirable dust when silica
is present in coal mines, which would
ensure that standalone effects of silica
and coal dust are accounted for and
allow for better monitoring overall
(Document ID 1445). The NMA, the
MCPA, and the Pennsylvania Coal
Alliance supported the removal of the
respirable dust standards when quartz is
present (i.e., §§ 70.101 and 71.101, and
90.101), reasoning that they are no
longer needed since the rule proposes a
standalone standard for respirable
crystalline silica (Document ID 1428;
1406; 1378).
MSHA has concluded that
establishing an independent and lower
PEL for respirable crystalline silica for
coal mines allows more effective control
of respirable crystalline silica than the
existing reduced standards because the
separate standard is less complicated
and more protective. MSHA believes
that the adoption of a separate improved
standard that carries risk of a citation
and monetary penalty when
overexposures of the respirable
crystalline silica PEL occur is thus more
protective than the indirect method
under the existing reduced standards.
MSHA clarifies that mine operators will
continue to sample for respirable coal
mine dust under existing §§ 70.100,
71.100, and 90.100. MSHA agrees with
the commenters supporting the removal
of §§ 70.101, 71.101, and 90.101. With
the PEL and action level (both
calculated as a full-shift 8-hour TWA),
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sampling, recordkeeping, and reporting
requirements in this final rule, MSHA
does not believe that retaining the
reduced standard is necessary. MSHA
believes that the implementation of the
separate silica standard will ensure that
operators are correctly evaluating and
implementing controls to protect miners
from respirable crystalline silica.
Further, MSHA will continue its
sampling. Under the final rule, MSHA is
removing these sections in their entirety
since they are no longer needed. See
Section VIII.C. Conforming
Amendments for additional details.
c. Full Shift, 8-Hour TWA
Under the final rule, the PEL and the
action level apply to a miner’s full-shift
exposure, calculated as an 8-hour TWA.
This limit means that over the course of
any work shift, exposures can fluctuate
but the average exposure to respirable
crystalline silica cannot exceed 50 mg/
m3 for the PEL and 25 mg/m3 for the
action level. Under this final rule, a
miner’s work shift exposure is
calculated as follows:
Total mass of respirable crystalline silica (µg) collected over a full shift
Air flow rate (liters per minute) x 480 minx 0.001 m3 /L
Regardless of a miner’s actual working
hours (full shift), 480 minutes is used in
the denominator. This means that the
respirable crystalline silica collected
over an extended period (e.g., a 12-hour
shift) is calculated (or normalized) as if
it were collected over 8 hours (480
minutes). For example, if a miner was
sampled for 12 hours and 55 mg of
respirable crystalline silica was
collected in the sample over that 12hour period, the miner’s respirable
crystalline silica 8-hour TWA exposure
would be 67 mg/m3, calculated as
follows:
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calculation method and against it. Some
commenters, including the AFL–CIO
and USW, stated that they support the
proposed calculation method of fullshift monitoring and calculating
exposures over an 8-hour period (i.e.,
using 480 minutes in the denominator)
to actively capture the total cumulative
exposure to silica dust (Document ID
1449; 1447). The American Thoracic
Society et al. stated that working longer
shifts means miners have longer
exposure periods, which increases the
cumulative burden of exposure and
reduces the rest time miners have for
recuperating and clearing their lungs
(Document ID 1421). In contrast, other
commenters, including other mine
industry organizations, mining trade
associations, state mining associations,
and MNM operators preferred the use of
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the full shift time period in the
calculation method denominator (i.e.,
using the entire duration of the miner’s
extended work shift in the
denominator), stating that normalizing
the extended shift sampling result to an
8-hour period (i.e., using 480 minutes in
the denominator) inaccurately skews the
results (Document ID 1378; 1424; 1428;
1441; 1443; 1432). These commenters
stated that the proposed method
improperly inflates the sampling results
and actually makes the standard more
stringent by effectively lowering the PEL
for longer shifts. Some of these
commenters, including MSHA Safety
Services Inc. and NVMA, further stated
that MSHA’s statement in the proposal
that the Agency uses NIOSH’s
recommendation is misleading because
the NIOSH recommendation is,
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This calculation method (i.e., full
shift, 8-hour TWA) is the one that
MSHA uses to calculate exposures of
MNM miners to respirable crystalline
silica and other airborne contaminants
under the existing standards (30 CFR
56.5001, 57.5001); it differs from the
existing method of calculating a coal
miner’s exposure to respirable coal mine
dust (30 CFR 70.101, 71.101, and
90.101). For coal miners, the existing
calculation method uses the entire
duration of a miner’s work shift in both
the numerator and denominator,
resulting in the total mass of respirable
coal mine dust collected over an entire
work shift scaled by the sample’s air
volume over the same period. This is
referred to as ‘‘full shift TWA’’ hereafter.
MSHA received comments both in
agreement with the proposed
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55 (µg)
1.7 (liters per minute) x 480 minx 0.001 m 3 /L
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according to the commenters, for a 10hour workday during a 40-hour
workweek (Document ID 1392; 1441).
Under the final rule, the PEL and
action level applies to a miner’s fullshift exposure, calculated as an 8-hour
TWA. MSHA agrees with commenters
who stated that the full shift, 8-hour
TWA captures cumulative exposure to
silica dust accurately. The goal of the
respirable crystalline silica final rule is
to prevent miners at all times from
suffering a body burden high enough to
cause adverse health effects.
‘‘Body burden’’ refers to the total
amount of a substance that has
accumulated in the body at any given
time (ATSDR, 2009). This reflects the
interplay between cumulative exposure,
pulmonary deposition, and lung
clearance, in the case of respirable
crystalline silica.68 69 As discussed in
the standalone FRA document,
cumulative exposure to respirable
crystalline silica is well established as
an important risk factor in the
development of silica-related disease.
MSHA has determined that it is
important to specify that exposures be
normalized to 8-hour TWAs.70 This is
68 The pulmonary uptake and clearance of
airborne mine dust are dependent upon many
factors, including a miner’s breathing patterns,
exposure duration, concentration (dose), particle
size, and durability or bio-persistence of the
particle. These factors also affect the time it takes
to clear particles, even after exposure ceases.
69 Respirable crystalline silica is cleared slowly
from the body and remains in the lungs longer than
most other, more soluble minerals and organic
particulates in mine air. Pairon et al. (1994) counted
respirable crystalline silica particles in the
bronchoalveolar fluid of individuals occupationally
exposed to silica-bearing respirable dust and
confirmed that respirable crystalline silica was one
of the most persistent (i.e., most slowly eliminated)
mineral particles in the lung. The slow clearance of
silica particles explains the accumulation (buildup) of particles in the human lung that can occur
with repeated exposures to airborne silica as well
as its detection in lung tissue years after exposure
stops (Dobreva et al., 1975; Case et al., 1995;
Loosereewanich et al., 1995; Dufresne et al., 1998;
Borm and Tran, 2002).
70 The ACGIH (2022) acknowledges the issue of
extended work shifts for airborne contaminants,
including respirable crystalline silica, stating,
‘‘numerous mathematical models to adjust for
unusual work schedules have been described. In
terms of toxicologic principles, their general
objective is to identify a dose that ensures that the
daily peak body burden or weekly peak body
burden does not exceed that which occurs during
a normal 8-hour/day, 5-day/week shift.’’ There are
associated concerns with the body burden from an
‘‘unusual work schedule’’ such as a 10- or a 12hour shift. As Elias and Reineke (2013) stated, ‘‘if
the length of the workday is increased, there is
more time for the chemical to accumulate, and less
time for it to be eliminated. It is assumed that the
time away from work will be contamination free.
The aim is to keep the chemical concentrations in
the target organs from exceeding the levels
determined by the TLVs® (8-hour day, 5-day week)
regardless of the shift length. Ideally, the
concentration of material remaining in the body
should be zero at the start of the next day’s work.’’
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because working longer hours can lead
to the inhalation of more respirable
crystalline silica into the lungs, and the
PEL and action level must take this into
account. For example, working 12 hours
leads to 50% more silica entering the
lung compared with working 8 hours,
assuming other factors are equal (e.g.,
concentration of respirable crystalline
silica and breathing parameters). By
normalizing daily exposures to 8-hour
workdays, the final rule provides miners
working longer shifts a level of
protection against cumulative inhaled
doses that is reasonably equivalent to
the protection provided to miners
working shorter shifts. This is a relevant
issue because MSHA has observed that
miners commonly work extended shifts,
with many working 10-hour or longer
shifts.71 72 MSHA’s calculation method
(like the existing MNM calculation
method) normalizes to an 8-hour TWA.
If a miner works an extended shift of 12
hours and a sample of 55 mg of
respirable crystalline silica is collected,
the full shift 8-hour TWA calculation for
that sample is 67 mg/m3. This result
treats the full cumulative exposure
occurring over the entire shift in the
same way as if it occurred over 8 hours.
The full shift TWA (the existing
calculation method for coal miners)
71 Sampling hours of coal mine dust samples
approximate the working hours of coal miners who
were sampled. According to the coal mine dust
samples for a 5-year period (August 2016–July
2021), 90 percent of the samples by MSHA
inspectors were from miners working 8 hours or
longer and about 43 percent of the samples from
miners working 10 hours or longer. The dust
samples by coal mine operators show that over 98
percent of them were from miners working 8 hours
or longer and over 26 percent from the miners
working 10 hours or longer. Of the MNM dust
samples by MSHA inspectors for a 15-year period
(January 2005–December 2019), approximately 78
percent were from miners working longer than 8
hours. These dust samples are available at Mine
Data Retrieval System | Mine Safety and Health
Administration (MSHA), https://www.msha.gov/
data-and-reports/mine-data-retrieval-system (last
accessed Jan. 10, 2024).
72 Unlike workers in many other sectors, miners
not only work longer shifts but also typically work
much longer than 40 hours per week. According to
BLS data, between 2017 and 2022, the average
number of weekly working hours for all miners
ranged from 45.1 to 46.7. (Bureau of Labor
Statistics, Average weekly hours of production and
nonsupervisory employees, mining (except oil and
gas), not seasonally adjusted, Series ID
CEU1021200007, data for 2017–2022, retrieved
March 9, 2024.) From a body burden standpoint,
this means that longer working shifts for miners are
likely also associated with a greater number of
cumulative hours of exposure. That suggests that it
is not the case that miners are working four 10-hour
shifts instead of five 8-hour shifts, giving them
shorter recovery time between some shifts but then
a longer recovery time (e.g., 3 days off
continuously). Instead, many miners are likely
working more long shifts—e.g., five 10-hour shifts
in a week, given the average of more than 45 hours
for all miners—leaving their lungs very little
recovery time after silica exposure.
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would yield a calculated exposure of 45
mg/m3, based on the entire duration of
the miner’s work shift. The full shift 8hour TWA calculation provides more
protection for miners than the full shift
TWA calculation that makes no
adjustment for extended shifts.
Because the full shift, 8-hour TWA
calculation takes this additional factor
into account, sampling using this
calculation method likely results in
more sampling results that show
overexposures, which leads to exposure
monitoring, corrective actions, and/or
respiratory protection for miners that
may not have otherwise been provided
using the full shift TWA calculation.
The concept of adjusting occupational
exposure limits for ‘‘extended shifts’’
has been addressed by researchers (Brief
and Scala, 1986; Elias and Reineke,
2013). Their research is based on the
industrial hygiene concept that longer
workdays lead to more time for the
workplace chemical to accumulate in
the body and less time for it to be
eliminated. To account for this, the
research establishes models that adjust
(i.e., lower) the exposure limits using
formulas that factor in the longer
workdays and the corresponding shorter
recovery periods.
This final rule establishes a lower PEL
and applies it to all miners using a
consistent method for calculating
exposures. These changes improve the
health and safety of miners while
making compliance more
straightforward and transparent. NIOSH
has also supported the use of the TWA
and has discussed this term since the
publication of the NIOSH Pocket Guide
to Chemical Hazards (First Edition,
1978) (the ‘‘White Book’’).
MSHA’s PEL for a miner’s full-shift
exposure calculated as an 8-hour TWA
differs from OSHA standards for
extended work shifts. In the OSHA
standards, sampling for extended work
shifts is conducted using the worst (i.e.,
highest-exposure) 8 hours of a shift or
collecting multiple samples over the
entire work shift and using the highest
samples to calculate an 8-hour TWA. 81
FR 16286, 16765. This differs from
MSHA’s calculation method because,
under MSHA’s standards, miners are
sampled for the duration of their work
shift and the total respirable crystalline
silica collected over the entire duration
of that extended work shift, not the
worst 8 hours only, is used in the
calculation.
The NMA and AEMA disagreed with
how MSHA calculates the full shift 8hour TWA and stated that if MSHA does
not use the entire duration worked, the
Agency should instead use OSHA’s
method of sampling for the worst 8-hour
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time period for extended work shifts
(Document ID 1428; 1424).
MSHA has not included the
commenter’s suggestion in the final
rule. MSHA’s requirement in the final
rule to sample miners for the entire
duration of their work shift will provide
an accurate representation of their
exposures. Calculating the full shift 8hour TWA will better protect the health
of miners who work extended shifts
because it considers the heightened
risks posed by increased cumulative
exposure and shorter recovery time. The
final rule full shift 8-hour TWA
calculation is consistent with MSHA’s
longstanding MNM calculation method,
which is based on the guidance
provided by the ACGIH in 1973 (TLVs®
Threshold Limit Values for Chemical
Substances in Workroom Air Adopted
by ACGIH for 1973). This calculation
method is supported by NIOSH and
continues to be supported in the current
guidance provided by the ACGIH.
d. Error Factor
Some commenters, including NSSGA
and SSC, expressed concerns about
whether silica can be accurately and
consistently measured at the action
level and PEL (Document ID 1448;
1432). The AIHA suggested that
statistics of sampling and sample
analysis should be considered to
identify upper and lower confidence
limits (Document ID 1351). Several
commenters, including NMA and West
Virginia Coal Association (WVCA),
recommended that the PEL and action
level should have a margin of error, or
error factor, to account for sampling and
analysis errors (Document ID 1428;
1443). WVCA recommended that, as in
the 2014 RCMD Standard, MSHA
should apply an error factor to the PEL
to normalize results to account for errors
in sampling and weighing that cause
deviations in individual concentration
measurements (Document ID1443). The
NMA cited sources to assist with
determining the error factor (Document
ID 1428).
In Section VII.A. Technological
Feasibility, MSHA determined that
current methods to sample respirable
dust and analyze samples for respirable
crystalline silica by XRD and IR
methods are capable of reliably
measuring silica concentrations in the
range of the final rule’s PEL and action
level. This finding is based on the
following considerations: (1) there are
many sampling devices available that
conform to the ISO specification for
particle-size selective samplers with an
acceptable level of measurement bias,
and (2) both the XRD and IR methods
can measure respirable crystalline silica
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with acceptable precision at amounts
that would be collected by samplers
when airborne concentrations are at or
around the PEL and action level. Thus,
MSHA finds that the sampling and
analysis requirements under the final
rule are technologically feasible.
MSHA is confident that current
sampling and analytical methods for
respirable crystalline silica provide
accurate estimates of measured
exposures. Because there are multiple
sampling methods that comply with the
ISO 7708:1995 standard and variations
in laboratory analysis methods, this
final rule does not include a specific
error factor. Mine operators can rely on
sampling results from ISO-accredited
laboratories to meet the sampling
requirements of § 60.12(f) to determine
their compliance with the PEL and
action level under the final rule. Miners
should be confident that those exposure
results provide them with reasonable
estimates of their exposures to
respirable crystalline silica.
4. Section 60.11—Methods of
Compliance
The final rule identifies the methods
for compliance in § 60.11. Section 60.11
paragraph (a), unchanged from the
proposal, requires mine operators to
install, use, and maintain feasible
engineering controls, supplemented by
administrative controls when necessary,
to keep each miner’s exposure to
respirable crystalline silica at or below
the PEL. Paragraph (b), unchanged from
the proposal, states that rotation of
miners shall not be considered an
acceptable administrative control used
for compliance with the PEL. Below is
a detailed discussion of the comments
received on this section and
modifications made in response to the
comments.
a. 60.11(a)—Engineering and
Administrative Controls
Paragraph (a) requires mine operators
to use feasible engineering controls as
the primary means of controlling
respirable crystalline silica;
administrative controls can be used,
when necessary, as supplementary
controls.
Examples of engineering controls
include, but are not limited to,
ventilation systems, dust suppression
devices, enclosed cabs or control booths
with filtered breathing air, and changes
in materials handling or equipment
used. Engineering controls generally
suppress (e.g., using water sprays,
wetting agents, foams, water infusion),
dilute (e.g., ventilation), divert (e.g.,
water sprays, passive barriers,
ventilation), or capture dust (e.g., dust
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28317
collectors) to minimize the exposure of
miners working in the surrounding
areas. The use of automated oreprocessing equipment and remote
monitoring can also help to reduce or
eliminate miners’ exposures to
respirable crystalline silica.
Examples of administrative controls
include, but are not limited to, work
practices that change the way tasks are
performed to reduce a miner’s exposure.
These practices could include work
process training; housekeeping
procedures; proper work positions of
miners; cleaning of spills; and measures
to prevent or minimize contamination of
clothing to help decrease miners’
exposure to respirable crystalline silica.
MSHA requested comments on the
proposed requirement that mine
operators install, use, and maintain
feasible engineering and administrative
controls to keep miners’ exposures to
respirable crystalline silica at or below
the proposed PEL. The Agency received
comments both supporting and
opposing the proposal.
Several commenters, including an
industrial hygiene professional
association, a labor union, and black
lung clinics, expressed support for the
use of feasible engineering controls and
administrative controls to keep miners’
exposures to respirable crystalline silica
below the proposed PEL (Document ID
1351; 1398; 1410; 1353). AFL–CIO,
UMWA, and NMA stated that mine
operators should already be utilizing
feasible engineering and administrative
controls to comply with law and with
their existing ventilation plans
(Document ID 1449; 1398; 1428). Black
Lung Clinics urged MSHA to require
that mine operators rely primarily on
engineering controls to limit dust
exposure, with administrative controls
serving as supplemental measures
(Document ID 1410).
Other commenters identified
limitations with engineering controls.
NSSGA, US Silica, and a presenter at
one of the hearings provided the
following examples where engineering
controls will not suffice due to the
nature of the work: non-routine
maintenance tasks; periodic
maintenance tasks; tasks of limited
duration; and seasonal tasks (Document
ID 1448; 1455; 1353). US Silica also
stated that MSHA must offer more
flexible options for control methods and
give more consideration to the
challenges of implementing certain
controls at certain mines (Document ID
1455).
After carefully considering the
comments, MSHA has concluded that
the requirement for installation, use,
and maintenance of feasible engineering
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controls, supplemented by
administrative controls, when
necessary, will remain unchanged from
the proposal. In MSHA’s experience,
engineering controls are the most
effective method of compliance and the
most protective means of controlling
dust generation at the source.
Engineering controls, which address
the generation of dust at its source,
minimize respirable crystalline silica
exposures of all miners, including those
in surrounding work areas, who may not
be working at the dust generating
source. In contrast to other controls and
other interventions, engineering
controls can be regularly evaluated and
monitored, which increase their
effectiveness.
NIOSH has long promoted the use of
engineering controls to control miners’
exposures to respirable crystalline
silica. This final rule aligns with the
1995 NIOSH recommendation that ‘‘the
mine operator shall use engineering
controls and work practices
[administrative controls] to keep worker
exposures at or below the REL
[recommended exposure limit]’’
(NIOSH, 1995, page 5). Specifically,
NIOSH recommends the use of
engineering controls to keep free silica
dust exposures below the REL of 50 mg/
m3 (NIOSH, 1974). NIOSH also
supported the use of engineering
controls as the primary means of
protecting miners from exposure to
respirable crystalline silica in its public
response to MSHA’s 2019 RFI (AB36–
COMM–36). NIOSH stated that
‘‘[r]espirators should only be used when
engineering control systems are not
feasible. Engineering control systems,
such as adequate ventilation or
scrubbing of contaminants, are the
preferred control methods for reducing
worker exposures.’’
Requiring engineering controls as the
primary method of compliance is
consistent with generally accepted
industrial hygiene principles, existing
Agency standards, and the Mine Act.
See 30 U.S.C. 801(e) (explaining that
operators have the ‘‘primary
responsibility to prevent the existence
of [unhealthy] conditions’’ in mines); 30
U.S.C. 841(b) (requiring underground
coal mine operators to keep work
environments sufficiently free from
respirable dust); 30 U.S.C. 842(h)
(stating primacy of engineering controls
for underground coal mines). MSHA’s
existing MNM standards for airborne
contaminants require that mine
operators control miners’ exposure to
airborne contaminants, where feasible,
through preventing contamination,
using exhaust ventilation to remove
contaminants, or diluting with
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uncontaminated air (30 CFR 56.5005
and 57.5005). The existing MSHA
standards for respirable coal mine dust
(RCMD) require mine operators to
implement engineering controls to
maintain compliance. In MSHA’s 2014
RCMD Standard, the Agency required
operators to use engineering and
administrative controls and did not
permit the use of respirators, including
powered air-purifying respirators
(PAPRs), as a method to achieve
compliance. Additionally, numerous
commenters representing industry,
labor, and public health supported the
proposal’s priority of engineering
controls as the primary means of
reducing exposure to respirable
crystalline silica.
Some commenters provided specific
examples when discussing engineering
control limitations. The IME stated that
MSHA should allow the use of
equivalent dust suppression methods,
where an alternative exists, and its
effectiveness can be demonstrated
(Document ID 1404). USW explained
that engineering controls must be
capable of dealing with all belt speeds
for collection and suppression and be
protected from freezing in cold weather
which can increase their exposure
(Document ID 1447). Conspec Controls
questioned whether MSHA will explain
how to reduce dust particulate during
operations and how different systems
will be prioritized in instances where an
action improves the dust conditions but
exacerbates gas readings (Document ID
1324).
After reviewing these comments, the
Agency agrees that differences in mine
size, job duties, commodity mined,
equipment, and environmental
conditions across the mining industry
necessitate different types of
engineering controls. However, in
MSHA’s experience, the mine operator
has the information and experience at
their mine to determine which
engineering controls are feasible and
effective at reducing respirable
crystalline silica exposures for their
mining conditions. For example, MSHA
agrees with commenters that exposed
water sprays are not effective in freezing
weather; however, the Agency has
found that at least one, or more, option
is available for every circumstance. For
example, enclosing the process
equipment or using water sprays are two
options for controlling dust. Water
sprays suppress dust, and enclosures
limit the amount of dust in the
equipment operator’s breathing zone.
Equipment enclosures can be
constructed with baffles to slow the
airflow inside the enclosure, so dust
settles more quickly inside the
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enclosure. As another option, a
ventilation dust collection system can
be paired with an equipment enclosure
to make both more effective for
controlling dust. MSHA intends to work
with stakeholders, mine operators, and
the mining community to develop
compliance assistance materials and
share best practices on engineering
controls during and after the
implementation of the final rule.
MSHA received several comments on
the use of administrative controls. AIHA
emphasized that administrative
controls, when used to supplement
engineering controls, can further reduce
exposures, and maintain them at or
below the PEL (Document ID 1351).
Several commenters, including mining
trade associations, state mining
associations, and MNM operators, stated
that OSHA’s 2016 silica rule treats
engineering and administrative controls
as equally effective in reducing silica
dust exposures and urged MSHA to
consider broader use of administrative
controls and personal protective
equipment to achieve compliance
(Document ID 1428; 1424; 1432; 1455;
1441; 1443).
MSHA has reviewed the comments
and concludes that administrative
controls are effective in protecting
miners from respirable crystalline silica
exposures when they are used as a
supplement to engineering controls. For
example, NIOSH has co-developed a
clothes cleaning system that can clean
dusty work clothes throughout the
workday. This is an example of an
administrative control that is a safe and
effective method to remove silica dust
from a miner’s clothing, reducing
exposures to respirable crystalline
silica. In the final rule, administrative
controls are secondary to engineering
controls because administrative controls
require significant oversight by mine
operators to ensure miners understand
and follow the prescribed work
processes. If not properly implemented,
understood, or followed, administrative
controls may not be effective in
preventing miners’ overexposure to
respirable crystalline silica.
MSHA clarifies that administrative
controls, except for rotation of miners,
can be used as a method of compliance
if engineering controls are not feasible.
However, as MSHA discussed in the RFI
and in its previous 2014 RCMD
Standard, engineering controls remain
the primary means to control all forms
of respirable dust, including respirable
crystalline silica, in the mine
atmosphere (84 FR 45454; 65 FR 4214;
68 FR 10798–10799, 10818).
For these reasons, final paragraph
§ 60.11(a) is the same as the proposal.
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b. 60.11(b)—Rotation of Miners
Paragraph (b) prohibits mine
operators from using miner rotation as
an administrative control.
As noted above, prioritizing
engineering controls is consistent with
accepted industrial hygiene principles,
MSHA’s existing standards, and the
Mine Act. In particular, the prohibition
against rotation of miners to achieve
compliance with the PEL is consistent
with MSHA’s June 6, 2005, diesel
particulate matter (DPM) final rule (70
FR 32867) and its 2014 Coal Dust Rule
(79 FR 24813). Under the existing
standards in the 2014 Coal Dust Rule,
MSHA does not permit rotation of
miners to reduce exposures to coal mine
dust if feasible engineering controls are
in use (79 FR 24909). In the DPM final
rule, MSHA prohibited rotation of
miners to reduce miners’ exposure to
diesel particulate matter, an airborne
contaminant that is also a carcinogen.
71 FR 28926; 30 CFR 57.5060(e).
MSHA received several comments on
the feasibility of prohibiting miner
rotation. AISI and SSC requested that
MSHA permit the use of rotation of
miners when engineering controls are
not feasible (Document ID 1426; 1432).
Some commenters, including Portland
Cement Association, NSSGA,
Pennsylvania Coal Alliance,
Pennsylvania Aggregates & Concrete
(PACA), BMC, CISC, and Tata
Chemicals Soda Ash Partners, LLC,
added that, because miner rotation
historically has been used to lower
miners’ exposures, it should continue to
be a part of the hierarchy of controls
(Document ID 1407; 1448; 1378; 1413;
1417; 1430; 1452; 1364). BIA stated that,
in their operations, which are already
understaffed, worker rotation is
necessary to ensure miners are not
exposed to levels above the PEL,
particularly if MSHA also discontinues
the use of respirators as a method of
control (Document ID 1422). Other
commenters, including MSHA Safety
Services, Inc., and BIA, stated that some
mine operators will be substantially
impacted by prohibiting miner rotation
(Document ID 1392; 1422), while a few
commenters, including NSSGA and
IAAP stated that worker rotation is
sometimes the only feasible control to
limit overexposure, such as when
miners perform periodic or non-routine
tasks that do not allow for engineering
controls (Document ID 1448; 1456).
UMWA, AFL–CIO, and Black Lung
Clinics stated that worker rotation could
be acceptable to minimize
musculoskeletal stress, but not for work
involving respirable dust or
carcinogens, since the practice would
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expose more miners to the hazards
(Document ID 1398; 1449; 1410). Black
Lung Clinics further stated that, because
the risk of silica-related disease appears
to be continuous, rather than associated
with a threshold exposure, worker
rotation does not reduce the risk of
disease (Document ID 1410).
However, some commenters
disagreed. NVMA stated that miner
rotation is standard practice when
dealing with non-carcinogens and since
there is not enough data on whether
silica exposure alone, as opposed to in
combination with tobacco use, is the
carcinogen causing respiratory issues,
worker rotation should not be
prohibited (Document ID 1441). NSSGA
provided literature expressing a wellestablished threshold for silicosis and
lung cancer and stated that the use of
miner rotation to reach that limit of
exposure should be allowed (Document
ID 1448).
After considering the comments, the
final rule prohibits rotation of miners.
MSHA does not consider it to be an
effective control because it does not
address the root cause of the hazard,
requires continuous attention and
actions on the part of miners and
management, and increases risks to
additional miners. MSHA considers that
worker rotation, which may be an
appropriate control to minimize
musculoskeletal stress or heat stress, is
not an acceptable control for silica,
which is classified as a Group 1 human
carcinogen (IARC, 1997). For example,
MSHA’s existing standards for diesel
particulate matter prohibit rotation of
miners as an acceptable administrative
control because diesel particulate matter
is a probable human carcinogen. 30 CFR
57.5060. MSHA’s risk assessment for the
diesel particulate matter rule noted the
majority of scientific data for regulating
exposures to carcinogens supports that
job rotation is an unacceptable method
for controlling exposure to both known
and probable human carcinogens
because it increases the number of
persons exposed. The Agency concludes
that the rotation of miners would
increase the number of miners exposed
to the hazard of respirable crystalline
silica.
MSHA considered these comments in
light of the Agency’s longstanding
prohibition against rotation of miners as
a means of compliance for exposures to
carcinogens. Commenters did not
provide specific data in support of their
position that mine operators will be
substantially impacted by the
prohibition of miner rotation for
reducing silica exposure. The intent of
this final rule is to provide health
protection to as many miners as possible
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28319
from the adverse health effects of
respirable crystalline silica exposure.
The Agency has found that a
combination of engineering and
administrative controls can reduce
miner exposures to levels at or below
the PEL and is feasible for mine
operators.
MSHA also received comments
requesting clarification on the
implementation of the prohibition of
rotation of miners under the final rule.
NLA and NSSGA stated that MSHA has
not adequately explained the proposed
prohibition of miner rotation, which
creates confusion as to whether worker
rotation can be used for other purposes
and how the provision will be enforced
(Document ID 1408; 1448). NSSGA
further stated that, if MSHA does not
remove the prohibition in the final rule,
it should at a minimum, confirm that it
will not prohibit miner rotation for
purposes other than compliance with
the PEL, or rotating employees to
maintain exposure below the action
level (Document ID 1448). Similarly,
some commenters, including NLA,
AEMA, NMA, and NSSGA suggested
that MSHA should clarify that miner
rotation can still occur for legitimate
reasons, including avoidance of heat
stress or musculoskeletal stress
(Document ID 1408; 1424; 1428; 1448).
SSC asked MSHA to explain whether an
operator who rotates workers to comply
with part 62 will be cited if part 60
prohibits the rotation of that miner
(Document ID 1432).
MSHA clarifies that this provision is
not a general prohibition of worker
rotation wherever workers are exposed
to respirable crystalline silica and is
intended only to prohibit its use as a
compliance method for the PEL. It is not
intended to bar the use of miner rotation
as deemed appropriate by the mine
operator in activities such as crosstraining or to allow workers to alternate
physically demanding tasks with less
strenuous activities.
MSHA received comments on the
proposed rule’s alignment with industry
standards. MSHA Safety Services, Inc.
stated that the rotation of miners is
accepted by everyone except MSHA
(Document ID 1392). California
Construction and Industrial Materials
Association (CalCIMA) stated that miner
rotation is recommended by NIOSH,
and under the OSHA respirable
crystalline standard, the rotation of
employees as an administrative control
is not prohibited (Document ID 1433). A
couple commenters, including NSSGA,
an individual, and Vanderbilt Minerals,
LLC, stated that MSHA had
mischaracterized the NIOSH
recommendations on worker rotation
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since, according to the commenters, it
selectively used only parts of the
language in the NIOSH Chemical
Carcinogen Policy document to justify
its position on worker rotation
(Document ID 1448; 1367; 1419).
Because of this alleged
mischaracterization, an individual
warned that MSHA’s prohibition against
miner rotation is ripe for litigation, not
because MSHA chose to ban the
practice, but because MSHA has not
sufficiently explained their basis for
doing so (Document ID 1367). MSHA
acknowledges that the Agency may have
mischaracterized NIOSH’s position on
worker rotation since its Chemical
Carcinogen Policy is silent on the issue
of worker rotation. In this final rule,
MSHA clarifies its reference to the
NIOSH policy.
Respirable crystalline silica has long
been recognized as a carcinogen (IARC,
1997). The Agency considers it more
protective of miner safety and health to
limit the number of miners exposed to
respirable crystalline silica. MSHA does
not consider rotation of miners to be an
effective control because it does not
address the source of the hazard.
NIOSH’s publication entitled ‘‘Current
Intelligence Bulletin 68: NIOSH
Chemical Carcinogen Policy,’’
recommends that occupational
exposures to carcinogens should be
reduced as much as possible through
the hierarchy of controls, most
importantly, the elimination or
substitution of other chemicals that are
known to be less hazardous and
engineering controls (NIOSH, 2017b).
According to Stewart (2011), ‘‘rotation
of workers may reduce overall average
exposure for the workday but it
provides periods of high short-term
exposure for a larger number of workers.
As more becomes known about
toxicants and their modes of action,
short-term peak exposures may
represent a greater risk than would be
calculated based on their contribution to
average exposure.’’ Miner rotation is not
allowed in assessing coal miners’
exposure to respirable coal mine dust;
coal operators must sample occupations
or areas, not individual miners, to
ensure that the environment is
controlled. The Agency has determined
it more protective of miner safety and
health to limit the number of miners
exposed to respirable crystalline silica
and require engineering controls,
supplemented by administrative
controls, excluding rotation of miners.
For these reasons, final paragraph
§ 60.11(b) is the same as the proposal.
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c. Feasible Engineering Controls
MSHA received comments regarding
the definition of the term ‘‘feasible’’ and
the use of feasible engineering controls.
NVMA requested that MSHA supply a
definition for what is ‘‘feasible’’
(Document ID 1441). Arizona Mining
Association stated that the cost-benefit
analysis of the proposed standard is
flawed and that many mines will face
more financial hardship and require far
longer implementation times than
MSHA has anticipated (Document ID
1368). NMA stated that engineering
controls are not always economically
feasible, particularly for small
businesses (Document ID 1428).
MSHA clarifies that the courts have
interpreted the term ‘‘feasible’’ as
meaning ‘‘ ‘capable of being done,
executed, or effected,’ both
technologically and economically.’’ See
Kennecott Greens Creek Min. Co. v.
Mine Safety & Health Admin, 476 F.3d
946, 957 (D.C. Cir. 2007) (quoting Am.
Textile Mfrs. Inst. v. Donovan, 452 U.S.
490, 508–09 (1981)). Further, ‘‘MSHA
does not need to show that every
technology can be used in every mine.
The agency must only demonstrate a
‘reasonable possibility’ that a ‘typical
firm’ can meet the permissible exposure
limits in ‘most of its operations.’ ’’ Id. at
958 (quoting Am. Iron & Steel Inst. v.
Occupational Safety & Health Admin.,
939 F.2d 975, 980 (D.C. Cir. 1991)).
Based on MSHA’s experience and
enforcement and sampling data,
consideration of the OSHA silica rule,
and documentation from NIOSH as
discussed in Section VII.A.
Technological Feasibility, MSHA has
determined that feasible engineering
controls exist for mining operations to
reduce miners’ exposures so that they
would not exceed the PEL. The Agency
has found that feasible engineering
controls: (1) control crystalline silicacontaining dust particles at the source;
(2) provide reliable, predictable, and
consistent protection to all miners who
would otherwise be exposed to dust
from that source; and (3) can be
monitored. Additionally, MSHA
believes this rule is feasible because a
review of the Agency’s available silica
sampling data showed that many mines
are already in compliance with the PEL
in § 60.10. Further explanation and
discussion of the economic feasibility
can be found in the standalone FRIA
document and in the preamble in
Section IX. Summary of Final
Regulatory Impact Analysis and
Regulatory Alternatives.
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d. Hierarchy of Controls and Respiratory
Protection
MSHA received comments about how
the proposed rule related to the
hierarchy of controls. Several
commenters, including NMA, SSC, US
Silica, AEMA, WVCA, and American
Road and Transportation Builders
Association, stated MSHA should allow
mine operators to effectively utilize the
hierarchy of controls to comply with the
proposed silica standard (Document ID
1428; 1432; 1455; 1424; 1443; 1353).
These commenters defined the most
effective controls according to the
hierarchy as: elimination, substitution,
engineering, administrative, and
personal protective equipment (i.e.,
respirators). Arizona Mining
Association stated that the hierarchy of
controls is recognized world-wide,
including by OSHA, and provides
flexibility to allow mine operators to
make decisions for maintaining safe
production (Document ID 1368).
Other commenters stated that
respirators should be permitted to be
used as a method of compliance. WVCA
stated that the differences between
mining environments across the
industry mean that while engineering
controls may be the most effective
controls in some mines, other controls,
like respirators, might protect miners
more effectively in others (Document ID
1443). US Silica asked MSHA to treat
respirators as engineering controls
(Document ID 1455). IME stated that
although engineering controls are
preferred, it does not make sense to
require the use of engineering and work
practice controls the operator believes
or knows would be inadequate to meet
the PEL, knowing that respirators may
be more effective for a given task
(Document ID 1404). Some commenters,
including the Arizona Mining
Association, NVMA, and US Silica,
stated that the OSHA standard
recognizes the priority of engineering
controls but allows respiratory
protection programs as substitutes when
engineering controls are not feasible
(Document ID 1368; 1441; 1455; 1353;
1424; 1428).
Some commenters provided specific
situations or conditions in which they
believe respirators should be used as a
method of compliance. NSSGA
suggested that to prevent mine operators
from relying on respirators for
compliance, MSHA could require
operators to outline their process for
determining when respirators will be
used in their respiratory protection
plans (Document ID 1448). A few
commenters, including SSC, WVCA,
Vanderbilt Minerals, LLC, and IME,
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asked MSHA to allow for NIOSHapproved respirators as a recognized
control, and not just for instances of
unexpected exposures where respirator
use may be temporary (Document ID
1432; 1443; 1419; 1404). The AEMA and
NMA suggested adding language as
reflected in OSHA’s lead standard
(Document ID 1424; 1428). US Silica
stated that MSHA is inconsistently
recognizing when the use of personal
protective equipment for compliance
purposes may occur since MSHA’s
occupational noise exposure health
standards in 30 CFR part 62 allow it,
while the proposed rule does not
(Document ID 1455).
MSHA also received comments that
supported this provision of the
proposed rule, stating that respirators
are an ineffective method of
compliance. Black Lung Clinics
discussed the limitations of respirators,
stating that facial hair can interfere with
the use of respirators, respirators do not
provide real-time feedback on their
effectiveness, miners’ communication
abilities may be impeded, and there is
uncertainty about whether respirators
are actually effective in the working
environment in coal mines (Document
ID 1410). USW stated that respiratory
protection must never be defined as an
engineering control because its
effectiveness depends on too many
variables (Document ID 1447).
BlueGreen Alliance also supported the
prohibition on respirators as a method
of compliance and suggested that MSHA
should strengthen the penalties for
noncompliance (Document ID 1438).
MSHA understands that employers
across many industries follow the
NIOSH Hierarchy of Controls in
structuring and applying their industrial
hygiene programs and practices. This
reflects a generally accepted industrial
hygiene principle that recommends the
use of engineering and administrative
controls to implement effective control
solutions, in the following order (1)
elimination; (2) engineering controls; (3)
administrative controls; and finally, (4)
personal protective equipment. MSHA
recognizes that while elimination of all
respirable crystalline silica from a mine
environment would be the most
effective means of risk reduction, it is
generally not feasible. Under the final
rule, mine operators are required to use
engineering or environmental controls
as the primary means of maintaining
compliance. MSHA acknowledges that
administrative controls may be
necessary to further lower exposure
levels and encourages mine operators to
use such controls (with the exclusion of
miner rotation).
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MSHA does not agree that respirators
are an engineering control. Engineering
controls provide consistent and reliable
protection to miners; these controls
work independently and verifiably.
Engineering controls do not depend on
individual performance, supervision, or
intervention, to function as intended,
and they can be continually evaluated
and monitored relatively easily. Unlike
PAPRs or supplied-air helmets,
engineering controls operate at the
hazard generation source, providing
protection against both primary (miners
directly involved in the task or
immediate area) and secondary (miners
not directly in the task or working in
surrounding areas) exposures to the
hazard.
MSHA’s enforcement and compliance
assistance experience substantiate that
respirators are not as reliable as
engineering controls in reducing miners’
exposure to toxic substances such as
respirable crystalline silica. Respirator
effectiveness depends on a number of
factors, including a properly developed
and fully implemented respiratory
protection program; individual
performance in donning, wearing, and
doffing the respirator; and proper
supervision to ensure that the protection
factor is fully achieved.
In response to comments regarding
the use of respirators, MSHA amended
the final rule, paragraph 60.14(a), to
require MNM operators to provide
respiratory protection for temporary use
when miners’ exposures are above the
PEL. For MNM operators, temporary use
of respirators is required while
engineering control measures are being
developed and implemented, which
includes taking corrective actions to
ensure miner exposures are at or below
the PEL. Under the final rule, MNM
mine operators are also required to use
respirators, on a temporary basis, when
exposures are above the PEL, and it is
necessary by the nature of work
involved (for example, occasional entry
into hazardous atmospheres to perform
maintenance or investigation). The
Agency believes this will provide MNM
miners additional protection during
these specific circumstances. However,
respiratory use under this provision
does not constitute compliance with the
PEL; all exposures above the PEL violate
the standard. Further discussion on
respiratory use in the final rule is
located in Section 60.14—Respiratory
protection.
e. Consensus Standards and Other
Guidance
MSHA received one comment from
ISEEE suggesting that the Agency
incorporate by reference ISO 23875, Cab
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28321
Air Quality Standard, to assist mine
operators with compliance for installing
and using filtration systems to maintain
exposures at or below the PEL in
operator cabs (Document ID 1377). ISO
23875 is an international standard that
unifies the design, testing, operation,
and maintenance of air quality control
systems for heavy machinery cabs and
other operator enclosures. ISEEE stated
that the standard provides practical and
cost-effective requirements and testing
methods for engineering controls that
would meet the proposed rule’s
requirements, given that the desired
outcome in all cabs that meet the
standard’s requirements is compliance
with air quality regulations at the 25 mg/
m3 level. The commenter added that by
implementing this consensus standard,
it would lead to the development of a
standardized design that could be massproduced and therefore reduce costs.
MSHA has reviewed the comment
and has determined that an evaluation
of the costs and benefits for economic
and technological feasibility would
need to be conducted, along with an
examination of the costs to implement
the standard for mine operators.
Therefore, the Agency does not include
the requirements of ISO 23875 in this
final rule; however, the Agency will
evaluate the standard and encourages
the use of new technologies and
consensus standards to improve miner
safety and health.
APHA stated that guides prepared by
NIOSH for MNM mines and coal mines
contain helpful illustrations of feasible
engineering controls that reduce
exposure to respirable dust (Document
ID 1416). MSHA acknowledges that
NIOSH and other organizations and
agencies have published information
that may be helpful to mine operators.
MSHA has worked in partnership with
NIOSH in developing this final rule and
will continue to do so and use
information from NIOSH to facilitate
implementation of the final rule. The
Agency encourages mine operators to
use NIOSH information to ensure that
feasible and effective engineering
controls are installed, used, and
maintained.
5. Section 60.12—Exposure Monitoring
The final rule establishes
requirements for exposure monitoring in
§ 60.12. Section 60.12 paragraph (a)
establishes the requirements for
sampling. Paragraph (a)(1) requires mine
operators to commence sampling by the
compliance date to assess the full shift,
8-hour TWA exposure of respirable
crystalline silica for each miner who is
or may reasonably be expected to be
exposed to respirable crystalline silica.
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Paragraph (a)(2) is restructured from the
proposal and states how the mine
operator shall proceed if the sampling
under (a)(1) is: (i) below the action level,
(ii) at or above the action level, or (iii)
above the PEL. Paragraph (a)(3) mirrors
language in the proposal indicating that
where the most recent sampling
indicates that miner exposures are at or
above the action level but at or below
the PEL, the mine operator shall
continue to sample within 3 months of
the previous sampling. Paragraph (a)(4)
states that mine operators may
discontinue sampling when two
consecutive samplings indicate that
miner exposures are below the action
level. In a change from the proposal,
paragraph (a)(4) also specifies that the
second sampling must be taken after the
operator receives the results of the prior
sampling but no sooner than 7 days after
the prior sampling was conducted.
Paragraph (b) states that where the most
recent sampling indicates that miner
exposures are above the PEL, the mine
operator shall sample after corrective
actions are taken pursuant to § 60.13
until the sampling indicates that miner
exposures are at or below the PEL. In a
change from the proposal, paragraph (b)
also requires the mine operator to
immediately report all operator samples
above the PEL to the MSHA District
Manager or to any other MSHA office
designated by the District Manager.
Paragraph (c) requires mine operators to
conduct periodic evaluations at least
every 6 months to determine whether
changes may reasonably be expected to
result in new or increased respirable
crystalline silica exposures. In a change
from the proposal, paragraph (c) also
requires mine operators to conduct an
evaluation whenever there is a change
in production, processes, installation
and maintenance of engineering
controls, installation and maintenance
of equipment, administrative controls,
or geological conditions. Paragraph
(c)(1) requires mine operators to make a
record of the evaluation and the date of
the evaluation. In a change from the
proposal, paragraph (c)(1) also requires
the record of the evaluation to include
the evaluated change and the impact on
respirable crystalline silica exposure.
Paragraph (c)(2) requires mine operators
to post the record on the mine bulletin
board and, if applicable, by electronic
means, for the next 31 days. Paragraph
(d) is unchanged from the proposal and
includes the requirements for postevaluation sampling. Paragraph (e)
includes requirements for how mine
operators must take samples. Paragraph
(e)(1) requires that sampling be
performed for the duration of a miner’s
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regular full shift and during typical
mining activities. In a change from the
proposal, paragraph (e)(1) specifically
includes shaft and slope sinking,
construction, and removal of
overburden. Paragraph (e)(2) requires
the full-shift, 8-hour TWA exposure for
miners to be measured based on: (i)
personal breathing-zone air samples for
metal and nonmetal operations and (ii)
occupational environmental samples
collected in accordance with
§ 70.201(c), § 71.201(b), or § 90.201(b) of
this chapter for coal operations.
Paragraph (e)(3) includes the
requirement for sampling a
representative fraction of miners and is
unchanged from the proposal. Paragraph
(e)(4), unchanged from the proposal,
includes the requirement for mine
operators to use respirable-particle-sizeselective samplers that conform to ISO
7708:1995 to determine compliance
with the PEL. Paragraph (f) is
unchanged from the proposal and
includes the methods of sample
analysis. Paragraph (g) is unchanged
from the proposal and includes the
requirements for sampling records.
The exposure monitoring
requirements help facilitate operator
compliance with the PEL and
harmonize MSHA’s approach to
monitoring and evaluating respirable
crystalline silica exposures to better
protect all miners’ health. Below is a
discussion of the comments received on
this section and modifications made in
response to the comments.
a. Section 60.12(a)—Sampling
Under the final rule, mine operators
are required to commence sampling by
the compliance date to assess miners’
exposures to respirable crystalline
silica. Samples will be compared to the
action level and the PEL to determine
the effectiveness of existing controls and
the need for additional controls.
Change in Terminology
Under the final rule, MSHA removes
references to ‘‘baseline sampling’’ and
‘‘periodic sampling’’ and only uses the
term ‘‘sampling’’. MSHA also removes
proposed § 60.12(a)(2)(i), which allowed
mine operators to discontinue sampling
based on objective data or historical
sample data, i.e., sampling conducted
by the Secretary or mine operator
sampling conducted within the previous
12 months.
MSHA determined that the terms
‘‘baseline sampling’’ and ‘‘periodic
sampling’’ are no longer needed to
describe the sampling requirements
under the final rule. With the removal
of objective data and historical sample
data, under the final rule, discontinuing
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sampling is contingent upon the results
of two consecutive samplings indicating
that miner exposures are below the
action level.
Removal of Objective Data
Under the final rule, MSHA removes
the use of ‘‘objective data’’ as a method
of discontinuing sampling. Proposed
paragraph (a)(2) allowed operators to
discontinue sampling when, among
other things, objective data indicated
that miner exposures were below the
action level. As discussed earlier, in the
proposal, MSHA defined objective data
as information such as air monitoring
data from industry-wide surveys or
calculations based on the composition
of a substance, demonstrating miner
exposure to respirable crystalline silica
associated with a particular product or
material or a specific process, task, or
activity. The data must reflect mining
conditions closely resembling or with a
higher exposure potential than the
processes, types of material, control
methods, work practices, and
environmental conditions in the
operator’s current operations.
MSHA received several comments on
its proposed use of objective data as a
means for operators to discontinue
periodic sampling, with some
commenters in support of using
objective data and some commenters
against it. Several commenters,
including mining and industry trade
associations and a state mining
association, expressed support for the
use of objective data, with some
commenters noting that it would reduce
the sampling burden on mine operators
(Document ID 1442; 1406; 1408; 1441;
1424; 1428). Some commenters,
including the AEMA, NMA, and
Vanderbilt Minerals, LLC, stated that
objective data more than 12 months old
should be permitted because exposures
may not change, or the data may still be
valid in certain circumstances
(Document ID 1424; 1428; 1419).
Several other commenters, including
AIHA, UMWA, USW, and Appalachian
Voices, opposed the use of objective
data, with most arguing that sampling is
more accurate than objective data and
that such data should not be used to
exempt operators from sampling
(Document ID 1351; 1398; 1447; 1425;
1412). AFL–CIO, NVMA, and Rep.
Robert C. ‘‘Bobby’’ Scott, stated that the
term ‘‘objective data’’ is unclear, too
subjective, and capable of being
manipulated; that various mining
aspects could invalidate or skew
objective data results; and that the
proposal’s use of objective data is at
odds with the Mine Act’s requirement
that newly promulgated health and
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safety standards do not reduce
protection for miners (Document ID
1449; 1441; 1439).
While the Agency acknowledges that
the use of objective data would ease
operators’ sampling burden, MSHA has
determined that objective data cannot be
used to discontinue sampling because it
is not likely to represent mining
conditions closely resembling the
processes, types of material, control
methods, work practices, and
environmental conditions in the mine
operator’s current operations. The
Agency agrees with commenters who
stated that sampling is more accurate
than using objective data and that the
use of objective data as a means for
operators to discontinue sampling, may
be too subjective to confirm that sample
results are below the action level.
Furthermore, objective data, as defined
in the proposal, utilized a historical
approach, while the collection of
samples will more accurately reflect
respirable crystalline silica
concentrations under current mining
conditions.
Removal of Operator and Secretary
Sampling From Preceding 12 Months
MSHA also removes the provisions in
proposed paragraph (a)(2) allowing
operators to discontinue sampling when
sampling conducted by the Secretary or
the mine operator within the preceding
12 months confirmed that miner
exposures were below the action level.
Some commenters, including SSC,
NVMA, Vanderbilt Minerals, LLC, and
Portland Cement Association, supported
the use of past sampling to discontinue
sampling, noting that many operators
already use such data to implement
their current monitoring programs
(Document ID 1432; 1441; 1419; 1407).
However, the UMWA opposed allowing
past sampling to be used to discontinue
sampling (Document ID 1398). The
UMWA stated that exempting mine
operators from sampling based on past
sampling fails to protect miners from
unhealthy levels of respirable
crystalline silica or ensure that
operators are complying with the
standard. The UMWA recommended
that MSHA, not mine operators,
regularly sample all miners.
MSHA agrees that operators cannot
rely on samples taken within the
preceding 12 months prior to the first
sampling under the final rule to
discontinue sampling. This is because
past samples may not accurately
represent miners’ current exposures.
However, operators still have pathways
to discontinue sampling; the final rule
requires two consecutive sample results
below the action level that may come
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from operator or MSHA sampling.
MSHA will continue to perform its own
dust samplings as part of its regular
health inspections and take necessary
enforcement actions.
Change in Sampling Compliance Date
In a change from the proposal, the
final rule requires MNM mine operators
to comply with the requirements and
commence sampling within 24 months
of the publication date and requires coal
mine operators to comply with the
requirements and commence sampling
within 12 months after the publication
date.
Under the proposal, both MNM and
coal mine operators would have been
required to perform the first sampling
under this standard within the first 180
days (6 months) after the effective date
of the final rule. MSHA received
comments both for and against the
proposed 180-day compliance period,
with many commenters from the MNM
mining industry stating that it was not
enough time and recommending a
longer period ranging from 1 year to 3
years (Document ID 1408; 1432; 1433;
1417; 1392). Some commenters,
including Portland Cement, SSC,
CalCIMA, and NLA, stated that
providing only 180 days to commence
sampling was not sufficient because of
the limitation of available resources for
conducting sampling (Document ID
1407; 1432; 1433; 1408). Portland
Cement, SSC, and AEMA stated that this
requirement may not be feasible for
many operators because of competition
for outsourced resources such as rental
equipment, media, professional
services, and laboratory sample analysis
(Document ID 1407; 1432; 1424).
Commenters expressed concerns about
performing other tasks within the
proposed timeframe for compliance,
including establishing contracts with
accredited laboratories and other service
providers necessary for sampling;
performing sampling for all miners who
may reasonably be expected to be
exposed to respirable crystalline silica;
and designing and implementing new
engineering controls. These commenters
recommended a phased timeline similar
to OSHA’s final requirement in its silica
rule (which gave employers one year
before the commencement of most
requirements and two years before the
commencement of sample analysis
methods) and MSHA’s final requirement
in its 2014 RCMD Standard (which gave
operators 18 months after the rule
became effective). The NLA stated that
small mines are likely to have the
greatest difficulty competing for
resources in a short period of time
(Document ID 1408).
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In contrast, some commenters,
including AIHA and SKC Inc., stated
that technologically feasible air
sampling and analysis exists to allow
mine operators to achieve compliance
with the PEL using commercially
available samplers (Document ID 1351;
1366). These commenters stated that
technologically feasible samplers are
widely available, and a number of
commercial laboratories provide the
service of analyzing dust containing
respirable crystalline silica. Other
commenters, including AFL–CIO and
UMWA, supported requiring first-time
sampling within 180 days of the rule’s
effective date (Document ID 1449; 1398).
Some commenters, including
Appalachian Voices, Rep. Robert C.
‘‘Bobby’’ Scott, and Robert Cohen,
emphasized the need to implement the
final rule quickly to protect miners
(Document ID 1425; 1439; 1372).
Appalachian Voices stated that the
technologies and practices necessary to
reduce dust and silica exposure are
well-known and that mine operators
have had ample warning that this rule
was forthcoming (Document ID 1425).
Under the proposal, MSHA examined
the capacity of laboratories that meet the
ISO/IEC 17025 standard to conduct
respirable crystalline sample analyses.
MSHA made the preliminary
determination that there would be
sufficient processing capacity to meet
the sampling analysis schedule and that
it would be technologically feasible for
laboratories to conduct the required
sampling analyses (88 FR 44923).
MSHA also preliminarily determined
that the availability of samplers needed
to conduct the required sampling is
technologically feasible (88 FR 44921).
This preliminary determination,
however, only examined whether
sampler technology exists to conduct
the respirable crystalline silica sampling
as required under the proposed rule, not
the availability of that technology to
meet the demands that the final rule
would impose.
MSHA agrees with commenters that
the sampling requirements of the final
rule may create initial increased
demand for sampling devices and
related equipment and services. MSHA
understands that there are more
sampling devices (as well as related
services and supplies) currently
available based on the increased
demand resulting from the
promulgation of the OSHA silica rule in
2016, and MSHA expects that there may
be another increase in demand because
of this final rule. MSHA expects that the
sampling device market will respond, as
it did for OSHA, with an increase in the
supply of sampling devices to meet the
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increased demand because of this final
rule. However, AIHA stated that they
concur with MSHA that technologically
feasible samplers are widely available,
and a number of commercial
laboratories provide the service of
analyzing dust containing respirable
crystalline silica. The AIHA is the
organization that is responsible for the
AIHA-Laboratory Accreditation Program
(AIHA LAP) that accredits the majority
of laboratories analyzing industrial
hygiene samples. MSHA has also
identified more AIHA laboratories with
respirable crystalline silica analysis in
their scope of accreditation in 2023
compared to 2022, indicating an
increase in such capabilities.
MSHA carefully considered the above
information about availability of
laboratory capacity and sampling
devices, including the likely increase in
demand for such services and devices.
MSHA acknowledges commenters’
concerns about the need for more time
to conduct sampling and implement
necessary engineering controls. All
mine operators covered by the rule must
initiate sampling by the compliance
dates, potentially creating a peak
demand for sampling and analysis
around those dates. The extended
compliance dates permit more time to
accommodate and prepare for any
increase in demand. MSHA expects
many mine operators will avoid lastminute sampling and begin the
sampling process earlier than required;
thus, the sampling and associated
analysis will be spread over many
months, meaning that any eventual peak
period for laboratory analysis will be
longer and less intense (i.e., fewer
analyses per month required) than it
might be otherwise. Additionally,
MSHA expects that the extended lead
time will be sufficient for laboratories to
increase their analytical capacity. More
discussion can be found in Section
VII.A. Technological Feasibility.
Additional discussion of the compliance
date requirements can be found under
Section 60.1—Scope; compliance dates.
Sampling Requirements for New Mines
A few commenters, including Petsonk
PLLC and Appalachian Voices,
requested that MSHA clarify the
sampling requirement for mines that
begin operations after the rule goes into
effect (Document ID 1399; 1425).
Petsonk PLLC suggested amending
proposed § 60.12(a)(1) to require
sampling within 180 days after the rule
becomes effective or 180 days after the
mine commences production,
whichever occurs later.
MSHA disagrees with the commenters
regarding the need to specify a separate
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sampling schedule for new mines since
mine operators would have knowledge
of the sampling requirements before
commencing operations. The Agency
expects that new mines begin sampling
immediately upon commencing
operations in accordance with the
exposure monitoring requirements in
§ 60.12. Coal mine operators are
required to begin sampling within 12
months of the publication of the final
rule. Operators of new coal mines that
begin operation after the 12 months
must begin sampling upon commencing
operations. MNM mine operators are
required to begin sampling within 24
months of the publication date of the
final rule. Operators of new MNM mines
that begin operation after the 24 months
must begin sampling upon commencing
operations.
Reasonably Be Expected
Under the final rule, mine operators
are required to assess the exposure of
each miner ‘‘who is or may reasonably
be expected to be exposed to respirable
crystalline silica.’’
In the proposal, MSHA requested
comments on the Agency’s assumption
that most miners are exposed to at least
some level of respirable crystalline
silica, and on the proposed requirement
that these miners should be subject to
sampling. MSHA described its
assumption that most occupations
related to extraction and processing
would meet the ‘‘reasonably be
expected’’ threshold for sampling.
Further, MSHA assumed that some
miners may work in areas or perform
tasks where exposure is not reasonably
expected, if at all.
MSHA received many comments from
advocacy organizations, mining and
industry trade associations, MNM mine
operators, labor organizations, and a
state mining association on the
‘‘reasonably be expected’’ basis for
sampling (Document ID 1398; 1407;
1417; 1419; 1424; 1425; 1428; 1441;
1445; 1448; 1449). Commenters were
generally divided on whether most
miners are exposed to at least some
level of respirable crystalline silica. The
UMWA agreed with MSHA’s
assumption and stated that most mining
occupations would reasonably be
expected to be exposed to silica and
thus meet the threshold for sampling,
while some miners may not be
reasonably expected to be exposed to
silica, depending on their occupation
(Document ID 1398). In contrast,
Vanderbilt Minerals, LLC stated that it
is not reasonable to assume that most
miners are exposed to at least some
level of respirable crystalline silica
(Document ID 1419). This commenter
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cited MSHA’s Mine Data Retrieval
System (MDRS) data that shows many
mine locations do not have any
detectable exposure to respirable
crystalline silica. Appalachian Voices,
questioning MSHA’s assumption about
occupations related to extraction and
processing meeting the ‘‘reasonably be
expected’’ threshold for sampling,
described testimony from several miners
who worked in non-production
positions and were exposed to high
levels of silica dust (Document ID 1425).
This commenter requested expansion of
the interpretation to include or consider
non-production work above ground
because of the placement of engineering
controls, such as return air entries near
mine offices. Further, other
commenters, including NSSGA and
BMC, requested clarification on what
the ‘‘reasonably be expected’’ threshold
means since it was not defined in the
proposal (Document ID 1448; 1417).
MSHA has considered these
comments. Based on the Agency’s
enforcement and compliance assistance
experience and sampling data, the final
rule retains the language in the
proposal. This data considers MSHA
and operator sampling experience,
miners’ job tasks and occupations, and
mining conditions when overexposures
are identified and need to be corrected.
Operators already are expected to know
whether their miners are exposed or
reasonably are expected to be exposed
to respirable crystalline silica, given
coal operators’ existing sampling
regimen (that includes regular sampling)
and MNM’s requirements under
§§ 56.5002 and 57.5002 to conduct
surveys (sampling) ‘‘as frequently as
necessary to determine the adequacy of
control measures.’’ MSHA believes that
most occupations related to extraction
and processing which generate dust are
likely to meet the ‘‘reasonably be
expected’’ threshold. However, MSHA
clarifies that sampling should not be
limited to extraction and processing
occupations; in every instance, the mine
operator must determine whether
exposure to respirable crystalline silica
is or may reasonably be expected. In the
example given by the commenter,
miners performing above-ground nonproduction work who were exposed to
high levels of silica dust would
reasonably be expected to be exposed to
respirable crystalline silica and thus
would be required to be sampled. On
the other hand, MSHA recognizes that
some miners are not exposed to
respirable crystalline silica in day-today mining operations, may work in
areas or perform tasks where respirable
crystalline silica exposures are not
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reasonably likely, or may work in silicafree environments. Based on the
Agency’s experience, mine operators
have familiarity with the occupations,
work areas, and work activities where
respirable crystalline silica exposures
occur or are most likely to occur. Based
on this knowledge, MSHA expects that
operators will be able to assess the
threshold conditions for sampling.
Many commenters stated that MSHA
should require an exposure ‘‘trigger’’
level to be used as a basis for
conducting sampling. Several
commenters, including NMA, BMC,
NSSGA and AEMA, stated that the
‘‘reasonably be expected’’ threshold for
sampling should be associated with the
action level of 25 mg/m 3, similar to the
OSHA standard (Document ID 1428;
1417; 1448; 1424). Some of these
commenters stated that without a trigger
level, even the general public would
meet the criterion of ‘‘reasonably
expected to be exposed’’ because the
proposed requirement is too broad and
lacks any meaning in the context of a
standard.
Under the final rule, MSHA
concludes that an action level trigger for
initial sampling is not appropriate for
mining conditions. The extraction and
milling of minerals can reasonably be
expected to expose most miners to some
level of respirable crystalline silica. In
MSHA’s experience, dust generation is
common in the mining process, and the
approach in the final rule ensures that
mine operators have the necessary data
and information to understand which
miners may be exposed to respirable
crystalline silica, can make
determinations regarding the adequacy
of existing engineering and
administrative controls, and can make
necessary changes to ensure miners are
not overexposed.
Sampling
In the final rule, MSHA requires mine
operators to sample within 3 months of
the previous sampling when the most
recent sampling indicates that miner
exposures are at or above the action
level but at or below the PEL. The most
recent sampling could be a first sample
under the standard, a corrective action
sample, a post-evaluation sample, or a
sample taken by MSHA during its
inspections. Sampling must continue
until two consecutive sample analyses
show miners’ exposures are below the
action level. Once this happens, mine
operators may discontinue sampling for
miners whose exposures are represented
by these samples, until such time that
a subsequent MSHA sampling or postevaluation sampling by the mine
operator indicates that miners may be
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exposed at or above the action level.
MSHA clarifies that during the
compliance period, the two consecutive
samplings needed to discontinue further
sampling may not begin with an MSHA
sampling followed by an operator
sampling conducted within 3 months of
that MSHA sampling; however, it may
begin with an operator sampling (e.g.,
the operator’s first sampling during the
compliance period) followed by an
MSHA sampling conducted within 3
months of that operator sampling. This
is because the first sampling that
operators must conduct during the
compliance period includes a larger
group of miners (i.e., each miner who is
or may reasonably be expected to be
exposed to respirable crystalline silica)
as compared to the targeted group of
miners sampled by MSHA during its
inspections.
MSHA received many comments on
the proposed frequency of sampling,
with some commenters stating that the
3-month sampling frequency is too
frequent and other commenters stating
that the sampling is not frequent
enough. Some MNM mine operators,
including SSC and NLA, stated that
mines with sampling results
consistently above the action level but
below the PEL should not be required to
sample every 3 months, and instead the
frequency should be annual (Document
ID 1432; 1408). The NVMA stated that
the 3-month frequency should be
associated with the PEL rather than the
action level (Document ID 1441). The
AISI stated that the frequency of
sampling should be dictated by the
history of miner exposures, noting that
some miners should not be sampled as
frequently as others and some miners
should not be sampled at all (Document
ID 1426). Portland Cement Association,
NSSGA, BMC, and Vanderbilt Minerals,
LLC, stated that MSHA should model its
sampling requirements after OSHA’s
silica rule, where repeat monitoring is
conducted within 6 months for
exposures above the action level but
below the PEL and within 3 months for
exposures above the PEL (Document ID
1407; 1448; 1417; 1419). The AEMA and
NMA, stated that follow-up sampling
should occur no more frequently than
every 6 months, as proposed in MSHA’s
Regulatory Alternative #1 (Document ID
1424; 1428). The commenters stated that
sampling each miner whose exposure is
at or above the action level but at or
below the PEL every 3 months is
excessive and causes undue burden on
mine operators.
Other commenters, including
advocacy organizations and labor
unions, stated that MSHA’s proposed
sampling frequency was not enough
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28325
(Document ID 1434; 1447; 1449; 1412;
1445; 1398; 1385). The USW and the
AFL–CIO stated that the periodic
sampling requirement in the proposal is
not sufficient to assess silica
concentrations in mining and prevent
overexposures and noted the coal
mining industry is already required to
perform quarterly periodic sampling
which they believe is not frequent
enough (Document ID 1447; 1449). An
individual stated that MSHA’s proposed
sampling frequency is not aligned with
a 2014 NIOSH study cited by the
Agency that referenced a 2020 report
from DOL’s Inspector General, which
recommended more frequent monitoring
where there is wide variability in silica
levels (Document ID 1412). ACLC
recommended that MSHA require
weekly sampling (over multiple shifts)
by operators and monthly sampling by
MSHA inspectors (Document ID 1445).
The USW, AFL–CIO, and Nicholas
County Black Lung Association
supported more frequent sampling by
MSHA without suggesting a specific
schedule and stated that mines should
be constantly checking for silica dust,
especially where continuous mining
machine operators and roof bolters are
working (Document ID 1447; 1449;
1385).
As commenters noted, OSHA requires
a 6-month sampling interval for
monitoring exposures between the
action level and PEL and a 3-month
interval for monitoring exposures above
the PEL. 29 CFR 1910.1053(d)(3)(iii) and
(iv). OSHA explained, ‘‘[i]n general, the
more frequently periodic monitoring is
performed, the more accurate the
employee exposure profile.’’ 81 FR
16766. Accordingly, OSHA noted that
‘‘[s]electing an appropriate interval
between measurements is a matter of
judgment,’’ and determined that the 6month and 3-month frequencies were
both ‘‘practical for employers and
protective of employees.’’ Id. MSHA
took into account OSHA’s approach in
developing its final rule.
MSHA’s sampling provisions
differentiate between miners based on
their exposure levels. The sampling
provisions require first-time sampling of
miners exposed or reasonably expected
to be exposed to respirable crystalline
silica, and subsequent sampling of
miners exposed at or above the action
level. In MSHA’s experience, everchanging mining conditions require a
shorter interval between samplings to
ensure that miners are protected.
MSHA’s monitoring approach is
consistent with NIOSH’s
recommendation to monitor miners’
silica exposures frequently due to the
variability of silica content in mining
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environments (NIOSH, 2014e). The 3month interval is appropriately
protective of miners, providing a higher
degree of confidence that miners will
not be exposed to concentrations of
respirable crystalline silica above the
PEL. As discussed in Section VII.
Feasibility and Section IX. Summary of
Final Regulatory Impact Analysis, this
sampling frequency is technologically
and economically feasible for mine
operators.
Under the final rule, when exposures
are above the PEL, mine operators must
take immediate corrective actions and
sample until exposures are at or below
the PEL. Like the proposal, the final rule
does not define a specific sampling
frequency above the PEL but anticipates
that operators will sample upon taking
corrective actions and sample as
frequently as needed until corrective
actions have resolved the overexposure.
Once at or below the PEL, mine
operators will resume the 3-month
schedule.
Two Consecutive Samplings Below the
Action Level
In the final rule, MSHA allows mine
operators to discontinue sampling when
two consecutive samplings indicate that
miner exposures are below the action
level. MSHA believes a short period of
time—within three months—between
samples is needed to verify current
conditions and lack of exposure to
respirable crystalline silica. In addition,
MSHA sampling may indicate exposure
levels that require mine operators to
commence sampling. The Agency also
requires operators to conduct periodic
evaluations at least every 6 months or
whenever there is a change in
production, processes, installation or
maintenance of engineering controls,
installation or maintenance of
equipment, administrative controls, or
geological conditions, to evaluate
whether the change may reasonably be
expected to result in new or increased
respirable crystalline silica exposures.
This will ensure that mine operators
continue to monitor changes in mining
conditions and practices that may
impact exposure levels and lead to
further sampling.
MSHA received several comments on
using two consecutive samples as a
means of discontinuing sampling
requirements. The AIHA and AFL–CIO
expressed doubt that two samples can
provide confidence that a task is safe
from harmful exposures (Document ID
1351; 1449). A MNM operator noted that
one or two sample results below the
action level do not necessarily equate to
overall lower exposures and it is likely
that many two-samples below action
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level results will occur merely by
chance (Document ID 1417). In contrast,
the NMA agreed with using two
consecutive samples and stated that
OSHA has a similar requirement
(Document ID 1428). The NMA stated
that two samples should be enough to
confirm lack of exposure in theory and
in practice. Other comments from
professional associations, labor
organizations, and a miner health
advocate questioned whether mine
operators should be permanently
exempted from sampling at all
(Document ID 1372; 1377; 1398; 1449;
1405).
MSHA agrees with the commenter
who stated that two consecutive
samples should be enough to confirm
lack of exposure to respirable crystalline
silica. In response to the commenters’
concern about discontinuing sampling,
MSHA is confident that the results from
two consecutive samplings will provide
data to confirm that the operator’s
controls are working effectively and that
miners’ exposures are below the action
level. MSHA also believes that two
consecutive samplings below the action
level indicate a low probability that,
under the prevailing conditions,
exposure levels exceed the PEL. As
such, unchanged from the proposal, the
final rule includes a requirement for two
consecutive samples below the action
level to discontinue sampling.
Mine operators may discontinue
sampling once two consecutive sample
analyses show the miners’ exposures are
below the action level. Specifically, in
paragraph 60.12(a)(4), to discontinue
sampling, the second sampling must be
taken after the operator receives the
results of the prior sampling but no
sooner than 7 days after the prior
sampling was conducted. However,
MSHA clarifies that the final rule
includes two scenarios where mine
operators are required to resume
sampling with actual or expected miner
exposures at or above the action level
but below the PEL. First, mine operators
must conduct sampling within 3 months
if sampling by the operator or MSHA
indicates that miner exposures are at or
above the action level but at or below
the PEL (§ 60.12(a)(3)), and mine
operators must continue to sample until
two consecutive samplings indicate that
miner exposures are below the action
level. Second, mine operators must
conduct post-evaluation sampling if
they determine, as a result of their
periodic evaluation, that miners may be
exposed to respirable crystalline silica
at or above the action level (§ (60.12(d)).
A miner health advocate stated that
an inadequacy of the proposal was that
it failed to address a situation in which
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a mine operator took multiple samples
at the same time (Document ID 1372).
The commenter was concerned that if
one of these samples was under the
action level and others were over, the
operator would choose the sample
under the action level as the basis for
discontinuing sampling.
MSHA clarifies that, under the final
rule, as in the proposal, mines that have
any miners with silica exposures at or
above the action level but at or below
the PEL are required to continue
conducting sampling for those miners at
or above the action level but at or below
the PEL in accordance with § 60.12(a).
Minimum Time Between Samplings
Under final paragraph (a)(4), for the
purposes of discontinuing sampling,
MSHA clarifies that subsequent
sampling must be taken after the
operator receives the results of the prior
sampling but no sooner than 7 days after
the prior sampling was conducted. In
response to comments, this is a change
from the proposed rule.
In the proposal, MSHA requested
comment on whether consecutive
samples should be taken at least 7 days
apart. MSHA received comments from
AIHA, MCPA, and SSC in response to
the minimum time period between
consecutive samplings (Document ID
1351; 1406; 1432). The MCPA expressed
concern that requiring 7 days between
samplings, combined with the time it
would take a laboratory to process the
samples, could result in a miner having
to wear a respirator for 3–4 weeks
despite effective engineering controls
being in place (Document ID 1406). This
commenter also asked if MSHA
considered the time it takes to obtain
sample results from a laboratory. The
AIHA stated that consecutive samples
do not necessarily need to be at least 7
days apart, depending on workplace
circumstances (Document ID 1351). The
SSC stated that a time limit between
consecutive samples is not needed and
stated that MSHA has not offered any
reason or justification for requiring 7
days (Document ID 1432). The ISEEE
cautioned that, without a clear
requirement in the rule, mine operators
might take consecutive samples only
during the most favorable times, i.e.,
when exposures are naturally mitigated
by snow or rain (Document ID 1377).
MSHA reviewed the comments and
decided that a minimum time between
samplings is necessary to ensure that
controls are in place and are effective in
reducing miners’ exposures to respirable
crystalline silica. The final rule requires
that, to discontinue sampling,
subsequent sampling must be taken after
the operator receives the results of the
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prior sampling but no sooner than 7
days after the prior sampling was
conducted. This requirement is
necessary to prevent situations where
operators attempt to rely on samples
taken too close together that do not
adequately reflect representative
exposure levels during regular
operations, for instance, while
performing a low dust generating task.
MSHA notes that OSHA’s silica final
rule provides a 7-day minimum period
between consecutive samplings under
the standard for general industry and
maritime (29 CFR 1910.1053 (d)(3)(v))
and construction (29 CFR 1926.1153
(d)(2)(iii)). In addition, MSHA
understands that it typically takes 2
weeks or less for mine operators to
receive sampling results from the
laboratory. MSHA also clarifies that the
7-day minimum interval is not included
in § 60.12(b) or between samples not
used as a basis for discontinuation.
b. Section 60.12(b)—Corrective Actions
Sampling
In the final rule, as in the proposal,
where the most recent sampling
indicates that miner exposures are
above the PEL, MSHA requires the mine
operator to conduct sampling after
corrective actions are taken and until
sampling indicates that miner exposures
are at or below the PEL. In a change
from the proposal, MSHA also requires
mine operators to immediately report all
exposures above the PEL from operator
sampling to the District Manager or to
any other MSHA office designated by
the District Manager.
Portland Cement Association
recommended that MSHA adopt
OSHA’s standard for corrective actions
sampling and suggested that operators
repeat sampling at 3-month intervals
until exposures are at or below the PEL
(Document ID 1407). An individual
expressed concern that the proposal
does not require a minimum number of
full-shift samples to validate the
effectiveness of corrective actions
(Document ID 1412).
Section 60.13 requires mine operators
to take corrective actions when
sampling results show exposure levels
above the PEL. Sampling after taking
corrective actions provides operators
with specific information regarding the
effectiveness of the corrective actions
for the mine environment and provides
additional data for use in making
decisions about updating or improving
controls. Once sampling shows that
exposures are at or below the PEL, the
Agency requires mine operators to
conduct repeat sampling within 3month intervals as long as previous
sampling results indicate miners’
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exposures are at or above the action
level but at or below the PEL. Corrective
action sampling is required for all
samples over the PEL at all mines,
including portable operations.
Some commenters, including a miner
health advocate and an advocacy group,
questioned whether citations will be
issued if exposures are over the PEL,
with Hon. Robert C. ‘‘Bobby’’ Scott
suggesting that MSHA incorporate
reporting requirements for dust samples
(Document ID 1425; 1439; 1399). AMI
Silica, LLC stated that requiring
operators to report overexposures was a
departure from MSHA’s current practice
and requires operators to ‘‘selfincriminate’’ (Document ID 1440).
However, other commenters including
labor organizations and a miner health
advocate requested more MSHA
oversight of operator sampling to ensure
compliance (Document ID 1449; 1398;
1399).
Under the final rule, MSHA requires
mine operators to immediately report all
exposures above the PEL to the District
Manager or to any other MSHA office
designated by the District Manager. This
is responsive to comments requesting
that the Agency be more actively
involved in operator sampling and
consistent with the approach MSHA
outlined at a public hearing. Requiring
mine operators to report sampling
results over the PEL will ensure that
MSHA is aware of all overexposures and
can take appropriate action, including
compliance assistance and enforcement
action. Samples indicating
concentrations over the PEL should be
reported immediately, without delay
once the operator becomes aware of the
information, and in accordance with
guidance from the MSHA District
Office. Once MSHA is aware that a
sample indicates overexposure, the
Agency can provide appropriate
assistance and monitor progress toward
abatement of the condition.
Enforcement actions for samples that are
over the PEL, where appropriate, will be
handled on a case-by-case basis.
Enforcement practices are discussed in
Section VIII.A. General Issues.
c. Section 60.12(c) and (d)—Periodic
Evaluation and Post-Evaluation
Sampling
Under the final rule, mine operators
are required to conduct periodic
evaluations at least every 6 months or
whenever there is a change in:
production; processes; installation and
maintenance of engineering controls;
installation and maintenance of
equipment; administrative controls; or
geological conditions. Mine operators
are required to make a record of the
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28327
periodic evaluation and post it on the
mine bulletin board and, if applicable,
by electronic means, for the next 31
days. If the mine operator determines, as
a result of the periodic evaluation, that
miners may be exposed to respirable
crystalline silica at or above the action
level, the mine operator shall perform
sampling for each of those miners who
may be exposed at or above the action
level.
Periodic Evaluation
The final rule is modified from the
proposal, which would have only
required operators to conduct periodic
evaluations every 6 months. In addition
to requiring mine operators to conduct
periodic evaluations at least every 6
months, the final rule also requires mine
operators to conduct an evaluation
whenever there is a change in
production, processes, installation and
maintenance of engineering controls,
installation and maintenance of
equipment, administrative controls, or
geological conditions.
MSHA received comments from
mining trade associations, labor unions,
miner health advocates, professional
associations, an advocacy organization,
a black lung clinic, and a federal elected
official on the proposed semi-annual
evaluation requirement. The UMWA,
ACOEM, APHA, and AEMA stated that
mine operators should be constantly
conducting qualitative evaluations any
time a change occurs that may
reasonably be expected to result in new
or increased respirable crystalline silica
exposures (Document ID 1398; 1405;
1416; 1424). The ISEEE stated that it is
crucial to regularly reevaluate and
address any deficiencies across all
aspects of the mine site to prevent
unnecessary exposures and emphasized
that conducting timely risk assessments
is a standard practice in the mining
industry (Document ID 1377). The
UMWA and AFL–CIO stated the
proposed evaluation requirement could
create the possibility for miners to be
exposed to dangerous levels of silica for
up to six months (Document ID 1398;
1449). The AEMA believed the
proposed evaluation requirement would
be excessive given the lack of frequency
with which changes occur (Document
ID 1424). The AEMA and NMA
recommended MSHA require an annual
evaluation (Document ID 1424; 1428).
The NSSGA stated that MSHA should
adopt OSHA’s requirement to reassess
respirable crystalline silica exposures
whenever there has been a change that
may reasonably be expected to result in
new or additional exposures at or above
the action level, or when the employer
has any reason to believe that new or
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additional exposures at or above the
action level have occurred (29 CFR
1910.1053(d)(4) and 29 CFR
1926.1153(d)(2)(iv)) and eliminate the 6month qualitative evaluation
requirement (Document ID 1448).
Finally, the AFL–CIO stated mine
operators should report significant
changes that could increase silica
concentrations to MSHA, while the
Miners Clinic of Colorado and a miner
health advocate stated that MSHA, not
mine operators, should be responsible
for deciding whether additional
sampling should be conducted as a
result of the qualitative evaluation
(Document ID 1449; 1418; 1399).
MSHA agrees with commenters who
stated that mine operators should be
required to conduct a qualitative
evaluation when a change occurs to
help minimize overexposures to
respirable crystalline silica. The
requirement to conduct a qualitative
evaluation at least every 6 months or
whenever a change occurs in
production, processes, controls, or
geological conditions ensures that mine
operators are assessing changing
processes, conditions, and practices that
may impact miner exposure levels on a
regular basis to determine if additional
sampling is needed. The requirement to
conduct an evaluation whenever a
change occurs is consistent with the
existing MNM requirement to conduct
surveys as frequently as necessary to
determine the adequacy of control
measures (§§ 56.5002 and 57.5002),
while the minimum 6-month
requirement is consistent with the
underground coal requirement to review
the ventilation plan every 6 months to
assure that it is suitable to current
conditions (§ 75.370(g)). This
requirement is also consistent with the
existing MNM standard for controlling
diesel particulate matter (DPM), which
requires that mine operators monitor as
often as necessary to effectively
determine, under conditions that can be
reasonably anticipated in the mine,
whether the average personal full-shift
airborne exposure to DPM exceeds the
DPM limit (57.5071(a)). Under the final
rule, mine operators are responsible for
conducting periodic evaluations. The
Agency emphasizes that it will not
conduct periodic evaluations but may
use its enforcement discretion to review
a mine’s records of periodic evaluations,
when necessary.
In response to a comment from a
miner health advocate, the final rule
modifies proposed paragraph(c)(1),
which required operators to ‘‘[m]ake a
record of the evaluation and the date of
the evaluation.’’ The commenter stated
MSHA should require the record of the
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evaluation to specify all changes that
could affect respirable crystalline silica
exposures and the effect of the changes
on exposure levels (Document ID 1372).
MSHA agrees with the commenter who
stated the record of the evaluation needs
to be more informative and responds by
requiring the record of the evaluation to
also include the evaluated change and
the impact the change has on respirable
crystalline silica exposure. The
additional required data will provide
MSHA, mine operators, and miners with
information on the specific changes that
may reasonably be expected to result in
new or increased respirable crystalline
silica exposures.
Unchanged from the proposal, under
the final rule, MSHA requires mine
operators to post the record on the mine
bulletin board and, if applicable, by
electronic means, for 31 days. The
NSSGA stated that MSHA’s requirement
to post results on a bulletin board is too
prescriptive and may cause an issue for
operators who do not have a bulletin
board (Document ID 1448). The final
rule includes this requirement because
it is consistent with MSHA’s existing
standards and gives miners ready access
to recent sampling results, providing
additional accountability for mine
operators, and necessary information for
miners. Also, section 109(a) of the Mine
Act requires mines to have a bulletin
board where information can be posted
and shared with miners and their
representatives. 30 U.S.C. 819(a). For
portable operations and other operators
who prefer to communicate
electronically, the final rule permits
electronic notification in addition to
posting the record on the bulletin board.
Post-Evaluation Sampling
Under the final rule, like the proposal,
mine operators are required to conduct
post-evaluation sampling to assess the
full shift, 8-hour TWA exposure of
respirable crystalline silica when the
results of the periodic evaluation show
that miners may be exposed to
respirable crystalline silica at or above
the action level.
MSHA received some comments on
the post-evaluation sampling proposal
from an advocacy organization, a labor
union, a federal elected official, a
medical professional association, and a
black lung clinic stating that MSHA
should require sampling whenever there
are any changes in mine conditions that
could lead to an increased risk of
respirable crystalline silica exposures
(Document ID 1416; 1398; 1439; 1405;
1418). A miner health advocate stated
that mine operators should not have the
discretion to decide whether miners
may be exposed to respirable crystalline
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silica at or above the action level or
whether they should perform sampling
to assess miners’ exposure levels as a
result (Document ID 1399). The same
commenter suggested that MSHA
should provide simple and
straightforward triggers that mandate
sampling, rather than just the
requirement to conduct an evaluation
that might lead to additional sampling.
Post-evaluation sampling is needed to
ensure workers are protected from
respirable crystalline silica when a
change may increase their exposure.
MSHA believes that mine operators
have the most knowledge about their
mine’s operations and conditions. Mine
operators are aware of the extent and
degree of miners’ exposures to
respirable crystalline silica because they
have been complying with respirable
dust standards for over 40 years. Mine
operators are also aware of the
occupations, work areas, and work
activities where overexposures to
respirable crystalline silica are most
likely to occur. Further, MSHA believes
that mine operators will make goodfaith efforts to comply with the postevaluation sampling requirements to
ensure healthy working conditions for
miners. The final rule, in a change from
the proposal, requires mine operators to
conduct an evaluation whenever there
are changes that may reasonably be
expected to result in new or increased
respirable crystalline silica exposures
and to require operators to maintain
more detailed records of the evaluation.
These records will allow miners, their
representatives, and MSHA to hold
operators accountable for conducting
timely and appropriate evaluations and
required sampling.
d. Section 60.12(e)—Sampling
Requirements
The final rule includes sampling
requirements to ensure mine operators’
respirable crystalline silica monitoring
is representative of miners’ actual
exposure levels. The sampling
requirements in the final rule are the
same sampling requirements from the
proposal, with a few modifications.
Each of the sampling requirements is
discussed in more detail below.
Typical Mining Activities
In the final rule, MSHA includes shaft
and slope sinking, construction, and
removal of overburden to clarify that
these mining activities are within the
scope of the final rule.
Several commenters stated the
proposal was vague and did not clearly
specify what ‘‘typical mining activities’’
includes. Black Lung Clinics, Hon.
Robert C. ‘‘Bobby’’ Scott, and a miner
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health advocate emphasized that MSHA
should ensure the final rule covers all
aspects of mining operations, including
construction and development activities
(Document ID 1410; 1439; 1372). The
American Thoracic Society et al. and
Appalachian Voices stated it was
unclear whether slope mining, shaft
mining, or exploratory mining were
considered typical mining activities
under the proposal (Document ID 1421;
1425). The UMWA, Miners Clinic of
Colorado, AFL–CIO, and a miner health
advocate asserted that high silicacutting activities such as blasting,
drilling, excavation, cutting overcasts,
cutting belt channels, and other outby
construction should be considered
typical mining activities under the final
rule (Document ID 1398; 1418; 1449;
1399).
MSHA agrees with commenters that
construction and development activities
are typical mining activities and
clarifies this in the final rule. The
Agency is aware that many construction
and development activities generate
silica dust, which can lead to respirable
crystalline silica exposures well above
the PEL. MSHA stated at the public
hearings and clarifies in this final rule
that typical mining activities include
shaft and slope mining, construction,
and removal of overburden. In June
2022, MSHA implemented its Silica
Enforcement Initiative (SEI) for MNM
and coal mines. The purpose of the SEI
is to reduce silica exposures in MNM
and coal mines, and to provide
compliance assistance to mine
operators, where appropriate. The SEI
was posted on MSHA’s website and
discussed with the mining community
at safety and health conferences and
during frequent MSHA stakeholder
calls.73 The SEI specifically addresses
silica exposures in shaft and slope
mining, construction, and removal of
overburden. MSHA’s Enforcement and
Educational Field and Small Mine
Services staff also discussed the SEI
with the mining community. In
response to commenters’ examples,
MSHA agrees that exploratory mining,
and blasting, drilling, or cutting rock are
all considered typical mining activities.
MSHA also clarifies that the existing
requirements for respirable coal mine
dust sampling differ from this final
rule’s requirements for respirable
crystalline silica sampling. Under the
existing standards for respirable coal
mine dust sampling, the operator is
required to sample coal mine dust
exposures for specific occupations and
73 https://www.msha.gov/safety-and-health/
safety-and-health-initiatives/2022/06/08/silicaenforcement-initiative (last accessed Jan. 10, 2024).
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areas during consecutive normal
production shifts where coal mine dust
is generated from production activities.
Under the final rule, MSHA interprets
construction and development activities
as typical mining activities subject to
respirable crystalline silica sampling,
even though they may not be considered
production activities under the
requirements for respirable coal mine
dust sampling.
Environmental Conditions
Under the final rule, MSHA does not
specify any operating conditions or
environmental conditions for the
purposes of conducting respirable
crystalline silica sampling.
In the proposal, MSHA requested
comments on whether the Agency
should specify environmental
conditions for sampling. The AEMA,
NMA, and NSSGA recommended that
MSHA not specify typical operating
conditions or environmental conditions
(Document ID 1424; 1428; 1448). MSHA
Safety Services Inc. stated that it is
impossible to predict the weather
(Document ID 1392). The AFL–CIO
cautioned that sampling while it is
raining—a natural dust suppressant—
could skew results, while two
commenters stated that some mines
operate in areas where rain, snow, and
wind are common and requiring
sampling in their absence is not feasible
(Document ID 1449; 1424; 1428). The
NLA stated that sampling should be
performed under normal or typical
operating conditions while also
emphasizing the need for mine
operators to have flexibility to
determine whether conditions for
testing are appropriate on any day
(Document ID 1408). Black Lung Clinics
specified that sampling should be
conducted at something approaching
full production for typical tasks
(Document ID 1410).
MSHA recognizes the existence of
exposure variability due to changing
mining operations and environmental
conditions and agrees with commenters
that operators should have the
flexibility, within reason, to determine
what constitutes typical operating
conditions and normal production
levels at their mine. MSHA also agrees
with the commenters who stated it
would be impossible to predict the
weather, and thus determined that
including specific environmental
conditions would make conducting
exposure sampling unduly complicated
or at times difficult to achieve. MSHA
believes that the consistent use of
effective engineering controls and
workplace practices will help reduce
exposure variability and provide
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operators with greater confidence that
they are complying with the PEL.
However, MSHA acknowledges that an
operator’s conscientious application and
maintenance of all feasible engineering
controls and workplace practices cannot
eliminate exposure variability.
Sampling Device Placement
Under the final rule, MSHA requires
personal breathing-zone air samples for
MNM operations and requires
occupational environmental samples
collected in accordance with § 70.201I
(underground coal mines), § 71.201(b)
(surface coal mines and surface work
areas of underground coal mines), or
§ 90.201(b) (coal miners who have
evidence of the development of
pneumoconiosis) for coal operations.
MSHA received a few comments on
the proposed sampling device
placement requirements. The AIHA and
NMA expressed support for taking
samples from MNM miners’ personal
breathing-zones with the latter
commenter stating that the approach
makes sense because MNM miners
perform various job functions over the
course of a shift (Document ID 1351;
1428). NMA also reasoned that the
personal breathing-zone method would
be preferable for coal miners, rather
than the proposed occupational
environmental sampling, because
occupational environmental samples
may measure several miners performing
the same job function over the course of
a shift and make it more difficult to
maintain compliance with the PEL. The
NVMA stated that providing two
different sampling methods under the
same standard does not make sense and
suggested MSHA have two separate
rulemakings—one for coal mines and
one for MNM mines (Document ID
1441).
The Agency reiterates that the final
rule creates a uniform standard that
establishes consistent, industry-wide
requirements to address the adverse
health effects of overexposure to
respirable crystalline silica for all
miners, while still recognizing the
differences between MNM and coal
operations. MSHA believes that the
consistent use of effective engineering
controls and workplace practices will
help all mines—MNM and coal—
maintain compliance with the PEL and
ensure effective health protection of
miners. MSHA established the
requirements for personal breathingzone air samples for MNM miners and
occupational environmental samples for
coal miners to mirror existing sampling
requirements for both industries. These
sampling methods are tools that, when
used appropriately, achieve the purpose
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of the Mine Act by identifying the need
for additional controls to help operators
to maintain good air quality.
A miner health advocate
recommended that MSHA require coal
mine operators to conduct both
designated area sampling and
designated occupation sampling, rather
than allowing them the discretion to
sample either (Document ID 1399). This
is a misinterpretation of the rule. Final
paragraph (e)(2)(ii), which was proposed
as paragraph (f)(2)(ii), states that ‘‘[t]he
full-shift, 8-hour TWA exposure for
such miners shall be measured based on
. . . Occupational environmental
samples collected in accordance with
§ 70.201(c), § 71.201(b), or § 90.201(b) of
this chapter for coal operations.’’
Sections 70.201(c) and 71.201(b) both
prescribe processes for occupational
samples, including conversion of
designated areas to Other Designated
Occupations and requirements for how
sampling devices must be used and
worn. Paragraph (e)(2)(ii) does not
change operators’ discretion under
section 70.201(c) or 71.201(b).
Representative Sampling
As a general principle, mine operators
must accurately characterize miners’
exposure to respirable crystalline silica.
In some cases, this requires sampling all
exposed miners, while in other cases,
sampling a ‘‘representative’’ fraction of
miners is sufficient. When a mine
operator elects to engage in
representative sampling, the mine
operator may take, and submit for
analysis, fewer samples. Under this rule,
mine operators must assess the typical
circumstances of each shift and each
employee to identify miners most at risk
for overexposure (for example, miners
working near where dust collector
cleaning or bagging operations are
taking place) and choose those miners to
be ‘‘representative’’ for sampling
purposes. This approach allows mine
operators to assess the highest likely
exposure levels and implement and
adjust engineering controls to address
the highest likely concentrations of
respirable crystalline silica. MSHA finds
that representative sampling is
sufficient to measure the effectiveness of
the engineering controls in place. This
applies to miners who were not
included in the sampling but who are
represented by the representative
samples.
Under the final rule, like the proposal,
where several miners perform the same
tasks on the same shift and in the same
work area, mine operators may sample
a representative fraction (at least two) of
these miners. When sampling a
representative fraction of miners, mine
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operators are required to select the
miners expected to have the highest
exposure to respirable crystalline silica.
For example, sampling a representative
fraction may involve monitoring the
exposure of those miners who are
closest to the dust source. The sampling
results for these miners can then be
attributed to the remaining miners in
the group. When miners are performing
different tasks, a representative sample
of miners in the same working area is
not sufficient to characterize actual
exposures, and therefore individual
samples are necessary.
MSHA received many comments on
the proposed representative sampling
requirements from MNM mine
operators, mining and industry trade
associations, labor unions, and an
industrial hygiene professional
association, with many commenters
supporting the proposal (Document ID
1398; 1392; 1351; 1407; 1432; 1448;
1417; 1378; 1424; 1419; 1441; 1378;
1399). The AIHA, Portland Cement
Association, SSC, and NSSGA suggested
that ‘‘similar exposure groups,’’ or SEGs,
be used as a method to determine which
miners to sample for representative
sampling and to reduce operator costs
for complying with the exposure
monitoring requirements in the rule
(Document ID 1351; 1407; 1432; 1448).
Arizona Mining Association stated that
mine operators should be allowed to use
SEGs because the alternative of viewing
all miners’ exposure as the same will
result in large cost increases and wasted
resources (Document ID 1368).
MSHA did not adopt an SEG
approach in the final rule. The Agency
agrees that mine operators do not
always need to conduct sampling for
every exposed miner. Sampling for a
representative fraction of miners is
similar to the SEG concept because both
approaches group miners with similar
exposure characteristics for the purpose
of sampling a smaller subset of the
group.
However, there is likely more room
for error and misclassification using
SEGs in mining, especially among
smaller mines. SEGs rely on the
principle of grouping workers into
exposure profiles and assessing the
health risks to those workers based on
similar exposure conditions.
Accordingly, SEGs are commonly
established by experienced
environmental health and safety (EHS)
professionals using a combination of
exposure characteristics, including
location, job, task, and equipment used.
Small mines may not have EHS
professionals to correctly define SEGs
and validate data using proper statistical
analyses. There is also risk for SEG
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misclassification if, for example,
sampling data is incorrectly grouped,
not representative of all exposures on all
shifts, or not collected for the full shift.
MSHA is also concerned with
variability in silica concentrations in the
ore body in mining (especially in coal).
Mines are constantly changing, which
means that miners’ exposures will also
change. SEGs would need to be
continuously reviewed by EHS
professionals to ensure that they are
correctly defined over time.
The NSSGA, BMC, Pennsylvania Coal
Alliance, and AEMA stated that samples
from miners performing the same task in
the same area but on different shifts
should qualify as representative, with
the Pennsylvania Coal Alliance stating
that MSHA’s limitation of samples to a
single shift is unduly restrictive
(Document ID 1448; 1417; 1378; 1424).
The final rule requires representative
sampling to be restricted to the same
shift, rather than spanning across
multiple shifts. MSHA believes that
where miners are not performing the
same tasks on the same shift and in the
same work area, representative sampling
will not adequately characterize actual
exposures. In the Agency’s experience,
mine operators may schedule high
hazard-generating activities during one
shift and not others, which would create
differences in the environment.
Humidity, changes in geology, and other
environmental conditions that might
impact sampling results could change
across shifts, as well; for example, a
typically warm and sunny day shift
versus a cooler shift where temperatures
approach or move further from the
dewpoint. MSHA finds that rather than
trying to control for potentially
significant and unanticipated variables
across shifts, miner health and safety is
better protected if representative
sampling is confined to the same shift,
where conditions are more likely to be
consistent across miners represented by
the sampling. MSHA notes that OSHA’s
requirements for representative
sampling for general industry and
construction are also applied to
individual shifts. See 29 CFR
1910.1053(d)(3)(i).
Sampling Devices: Incorporation of ISO
7708:1995 by Reference
ISO 7708:1995(E), ‘‘Air quality—
particle size fraction definitions for
health-related sampling,’’ First Edition,
1995–04–01, is an international
consensus standard that defines
sampling conventions for particle size
fractions used in assessing possible
health effects of airborne particles in the
workplace and ambient environment. It
defines conventions for the inhalable,
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thoracic, and respirable fractions. The
ISO standard also provides formulas for
determining the fractions based on the
aerodynamic diameter of the particles
present. MSHA is incorporating by
reference ISO 7708:1995 in § 60.12(e)(4)
to ensure consistent sampling collection
by mine operators through the
utilization of samplers conforming to
ISO 7708:1995.
Under the final rule, MSHA requires
mine operators to use respirableparticle-size-selective samplers that
conform to the ISO 7708:1995 standard
to determine compliance with the PEL.
Mine operators are allowed to use any
type of sampling device for respirable
crystalline silica sampling, as long as
the device is designed to meet the
characteristics for respirable-particlesize-selective samplers that conform to
the ISO 7708:1995 standard and, where
appropriate, meet MSHA permissibility
requirements.
Sampling devices, such as cyclones 74
and elutriators,75 can separate the
respirable fraction of airborne dust from
the non-respirable fraction in a manner
that simulates the size-selective
characteristics of the human respiratory
tract and that meets the ISO standard.
These devices enable collection of dust
samples that contain only particles
small enough to penetrate deep into the
lungs. Size-selective cyclone sampling
devices are typically used in the U.S.
mining industry. These samplers
generally consist of a pump, a cyclone,
and a membrane filter. The cyclone uses
a rapid vortical flow of air inside a
cylindrical or conical chamber to
separate airborne particles according to
their aerodynamic diameter (i.e.,
particle size). As air enters the cyclone,
the larger particles are centrifugally
separated and fall into a grit pot, while
smaller particles pass into a sampling
cassette where they are captured by a
filter membrane that is later analyzed in
a laboratory to determine the mass of
the respirable dust collected. The pump
74 A cyclone is a centrifugal device used for
extracting particulates from carrier gases (e.g., air).
It consists of a conically shaped vessel. The
particulate-containing gas is drawn tangentially into
the base of the cone, takes a helical route toward
the apex, where the gas turns sharply back along the
axis, and is withdrawn axially through the base.
The device is a classifier in which only dust with
terminal velocity less than a given value can pass
through the formed vortex and out with the gas. The
particle cut-off diameter is calculable for given
conditions.
75 An elutriator is a device that separates particles
based on their size, shape, and density, using a
stream of gas or liquid flowing in a direction
usually opposite to the direction of sedimentation.
The smaller or lighter particles rise to the top
(overflow) because their terminal sedimentation
velocities are lower than the velocity of the rising
fluid.
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creates and regulates the flow rate of
incoming air. As the flow rate of air
increases, a greater percentage of larger
and higher-mass particles are removed
from the airstream, and smaller particles
are collected with greater efficiency.
Adjustment of the flow rate changes the
particle collection characteristics of the
sampler and allows calibration to a
specified respirable particle size
sampling definition, such as the ISO
criterion.
A cyclone sampler calibrated to
operate at the manufacturer’s specified
air flow rate that conforms to the ISO
standard can be used to collect
respirable crystalline silica samples
under this final rule. MSHA reviewed
OSHA’s feasibility analysis for its 2016
silica final rule and agrees that there are
commercially available cyclone
samplers that conform to the ISO
standard and allow for the accurate and
precise measurement of respirable
crystalline silica at concentrations
below both the action level and PEL
(OSHA, 2016a). Cyclone samplers
include, but are not limited to, the DorrOliver 10-mm nylon cyclone, as well as
the Higgins-Dewell, GK2.69, SIMPEDS,
and SKC aluminum cyclone. Each of
these cyclones has different operating
specifications, including flow rates, and
performance criteria, but all are
compliant with the ISO criteria for
respirable dust with an acceptable level
of measurement bias. MSHA’s
determination is that cyclone samplers,
when used at the appropriate flow rates,
can collect a sufficient mass of
respirable crystalline silica to quantify
atmospheric concentrations lower than
the action level and meet MSHA’s
crystalline silica sample analysis
specifications for samples collected at
MNM and coal mines.
MNM mine operators who currently
use a Dorr-Oliver 10 mm nylon cyclone
can continue to use it at a flow rate of
1.7 L/min, which conforms to the ISO
standard, to comply with the
requirements. For coal mine operators,
the gravimetric samplers previously
used to sample RCMD (i.e., coal mine
dust personal sampling units
(CMDPSUs)) were operated at a 2.0 L/
min flow rate. Those CMDPSUs can be
adjusted to operate at a flow rate of 1.7
L/min to conform to the ISO standard.
The NMA, AEMA, and SKC Inc.,
noted that samplers other than cyclones
and elutriators should be considered
acceptable under the final rule
(Document ID 1428; 1424; 1366). A
miner health advocate stated that when
conducting sampling under OSHA
requirements, they currently use a type
of sampler called a ‘‘parallel particle
impactor,’’ or PPI sampler, that meets
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the ISO 7708:1995 standard (Document
ID 1375). This commenter stated that
there is a disconnect between the
cyclone samplers mentioned in the
proposed rule and the use of PPI
samplers as an acceptable sampling
device, implying that PPI samplers are
not acceptable because they were not
included in the list of example samplers
that meet the ISO 7708:1995 standard in
the Sampling Methods section of the
proposed rule. This commenter also
suggested that the PPI sampling device
be considered acceptable under this
final rule. Similarly, the NMA, AEMA
and SKC stated that MSHA’s proposal
implies that only cyclone and elutriator
type samplers meet the specifications
for acceptable sampling devices.
MSHA clarifies that cyclone and
elutriator type samplers are not the only
acceptable sampling devices that can be
used to conduct sampling for respirable
crystalline silica under this rule. In the
Sampling Methods section of the
proposed rule, MSHA included a list of
example samplers that conform to the
ISO 7708:1995 standard. This list was
not meant to be all-inclusive, but rather
provide several examples of samplers
currently available in the marketplace
that conform to the ISO 7708:1995
standard (88 FR 44921). As stated above,
mine operators can use any type of
sampling device, as long as it is
designed to meet the characteristics for
respirable-particle-size-selective
samplers that conform to the ISO
7708:1995 standard and, where
appropriate, meet MSHA permissibility
requirements. MSHA clarifies that
under this final rule, any sampling
device that meets the ISO 7708:1995
particle size selective criteria for
respirable dust samplers are acceptable
for respirable crystalline silica
sampling, even if the sampler is not
specifically mentioned in the list of
examples. Under the final rule, the PPI
sampler would be acceptable.
Several commenters, including labor
organizations and a federal elected
official, noted the need for sampling
devices with real-time or near real-time
sample analysis capabilities for
respirable crystalline silica (Document
ID 1449; 1447; 1398; 1412; 1399; 1439).
The AFL–CIO stated that one of the
most significant items not included in
the proposal (that was included in the
2014 Coal Dust Rule) was personal dust
monitoring devices with real-time
analysis (Document ID 1449). The
commenter recommended the adoption
of new technology used by the domestic
or international mining community to
better protect miners. An individual
stated that MSHA should consider and
incorporate continuous and rapid quartz
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monitoring systems to more
appropriately characterize exposures
(Document ID 1412).
MSHA is aware of NIOSH’s rapid
field-based quartz monitoring (RQM)
approach as an emerging technology. It
provides a field-based method for
providing respirable crystalline silica
exposure measurements at the end of a
miner’s shift. With such an end-of-shift
analysis, mine operators can identify
overexposures and mitigate hazards
more quickly. NIOSH Information
Circular 9533, ‘‘Direct-on-filter Analysis
for Respirable Crystalline Silica Using a
Portable FTIR Instrument’’ provides
detailed guidance on how to implement
a field-based end-of-shift respirable
crystalline silica monitoring program.76
The current RQM monitor, however,
was designed as an engineering tool
specifically for quartz in coal mines and
has not been used for measurements of
cristobalite and tridymite. MSHA has
determined that the RQM monitor lacks
tamper-proof components and is
susceptible to interferences (e.g., in
MNM mines) which can affect its
accuracy. Thus, the RQM may not be
used for compliance with the sampling
requirements of the final rule. MSHA
continues to support NIOSH efforts to
develop the RQM monitor.
While the current RQM cannot be
used for compliance with the sampling
requirements under this final rule,
MSHA encourages mine operators to use
the RQM as an engineering tool as the
Agency believes it could assist operators
in identifying areas of concern,
including samples that would be most
appropriate for further laboratory
analysis. MSHA notes that samples
taken by operators using the RQM with
results above the PEL are not subject to
the requirements of the final rule (i.e.,
the mine operator need not report them
to MSHA, take corrective actions, or
conduct additional sampling, etc.).
MSHA continues to support NIOSH
76 National Institute for Occupational Safety and
Health (NIOSH). 2022b. Direct-on-filter analysis for
respirable crystalline silica using a portable FTIR
instrument. By Chubb LG, Cauda EG. Pittsburgh PA:
U.S. Department of Health and Human Services,
Centers for Disease Control and Prevention,
National Institute for Occupational Safety and
Health, DHHS (NIOSH) Publication No. 2022–108,
IC 9533. https://doi.org/10.26616/
NIOSHPUB2022108 (last accessed Jan. 10, 2024).
The document is intended for industrial hygienists
and other health and safety mining professionals
who are familiar with respirable crystalline silica
exposure assessment techniques, but who are not
necessarily trained in analytical techniques. It gives
general instructions for setting up the field-based
monitoring equipment and software. It also
provides case studies and examples of different
types of samplers that can be used for respirable
crystalline silica monitoring. Guidance on the use,
storage, and maintenance of portable IR instruments
is also provided in the document.
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efforts to develop the RQM monitor to
be used in mines.
MSHA maintains that analysis of
samples using accredited laboratories is
an accurate and reliable method of
determining respirable crystalline silica
exposures. Accurate laboratory analysis
is needed as a reference measurement at
the beginning and again at the end of an
initial exposure assessment as well as
when completing follow-up assessments
to validate compliance. However, endof-shift monitoring can reduce the
number of samples taken and provide
quick results that can be used to reduce
the expense of more frequent sampling
and laboratory analysis, during
implementation of corrective actions, to
validate the effectiveness of corrective
actions between collection of
gravimetric samples, and to increase
awareness of potential overexposures in
a timely manner.
Seasonal and Intermittent Mines
Seasonal and intermittent mines may
have less time to conduct 3-month
sampling. Under the rule, all operators,
including seasonal and intermittent,
must conduct initial sampling when
commencing operations after the listed
compliance dates. If that initial
sampling is below the action level,
MSHA believes that, although the
operator may wait up to 3 months to
conduct the next sample, most operators
would have an incentive to take another
sample as soon as practicable under
§ 60.12(a) in order to be relieved from
the continuing 3-month sampling
requirements if a second consecutive
sample result is below the action level.
In that situation, the operator would
need only to conduct its periodic
evaluation every six months or when
circumstances change pursuant to
§ 60.12(c). If the initial sample is at or
above the action level and at or below
the PEL, all operators would need to
take a second sample within 3 months,
and within every three months after that
unless they meet the criteria to
discontinue sampling. Operators that
are active during the 3-month period
would need to meet these sampling
deadlines, even if the operator is not
active full-time during the 3-month
period. Once operators have closed for
the season, or for an extended period
(more than 3 months), they would not
be expected to continue sampling every
3 months. However, when they re-open,
if they have not met the requirements
for discontinuing sampling, they would
need to start sampling immediately and
every three months. MSHA encourages
operators to work with their District
Managers to develop a workable
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sampling schedule that protects miners
as this rule intends.
e. Section 60.12 (f)—Methods of Sample
Analysis
The final rule, like the proposal,
specifies the methods to be used for
analysis of respirable crystalline silica
samples, including details regarding the
specific analytical methods to be used
and the qualifications of the laboratories
where the samples are to be analyzed.
ISO/IEC 17025 Accreditation
Mine operators are required to use
laboratories that are accredited to the
International Organization for
Standardization (ISO) or International
Electrotechnical Commission (IEC)
(ISO/IEC) 17025, ‘‘General requirements
for the competence of testing and
calibration laboratories’’ with respect to
respirable crystalline silica analyses,
where the accreditation has been issued
by a body that is compliant with ISO/
IEC 17011 ‘‘Conformity assessment—
Requirements for accreditation bodies
accrediting conformity assessment
bodies.’’ Accredited laboratories are
held to internationally recognized
laboratory standards and must
participate in quarterly proficiency
testing for all analyses within the scope
of the accreditation.
The ISO/IEC 17025 standard is a
consensus standard developed by ISO/
IEC and approved by ASTM
International (formerly the American
Society for Testing and Materials). This
standard establishes criteria by which
laboratories can demonstrate
proficiency in conducting laboratory
analysis through the implementation of
quality control measures. To
demonstrate competence, laboratories
must implement a quality control
program that evaluates analytical
uncertainty and provides estimates of
sampling and analytical error when
reporting samples. The ISO/IEC 17011
standard establishes criteria for
organizations that accredit laboratories
under the ISO/IEC 17025 standard. For
example, the American Industrial
Hygiene Association (AIHA) accredits
laboratories for proficiency in the
analysis of respirable crystalline silica
using criteria based on the ISO/IEC
17025 and other criteria appropriate for
the scope of the accreditation.
MSHA received a few comments
regarding the proposed requirement for
mine operators to use laboratories
accredited to ISO/IEC 17025 where the
accreditation has been issued by a body
that is compliant with ISO/IEC 17011
from AIHA, NVMA, BMC, and A2LA
(Document ID 1351; 1441; 1417; 1388).
AIHA and A2LA stated that they agree
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with MSHA’s proposed requirement and
BMC stated that they have no objection
to the proposal. A2LA further stated that
relying on accreditation for the approval
of testing laboratories assures quality,
technical competence, accuracy,
compliance, and international
recognition. A2LA stated that it
provides confidence in the reliability of
measurement results and supports
regulatory compliance.
Under the final rule, all mine
operators will have to use third-party
laboratories accredited to ISO/IEC 17025
to have respirable dust samples
analyzed for respirable crystalline silica.
Many MNM mine operators already use
third-party laboratories to perform
respirable crystalline silica sample
analyses. For most coal mine operators,
using a third-party laboratory to analyze
respirable crystalline silica samples is a
new requirement because respirable
coal mine quartz samples are currently
analyzed by MSHA. Under the final
rule, coal mine operators are responsible
for directly monitoring crystalline silica
(quartz) exposures in addition to coal
dust. Requiring all mines to use thirdparty laboratories ensures that sample
analysis requirements and MSHA
enforcement efforts are consistent across
all mines.
Analytical Methods for Sampling
The final rule requires mine operators
to ensure that laboratories evaluate all
samples using analytical methods for
respirable crystalline silica that are
specified by MSHA, NIOSH, or OSHA.
These are validated methods currently
being used by third party accredited
laboratories for measuring respirable
crystalline silica in mine dust matrices.
MSHA expects that samples collected in
MNM mines will be analyzed by X-ray
diffraction (XRD) and samples collected
in coal mines will be analyzed by
Fourier transform infrared spectroscopy
(FTIR).
MNM samples are currently analyzed
by XRD because the XRD method can
distinguish and isolate respirable
crystalline silica for measurement,
thereby avoiding interference or
confounding of respirable crystalline
silica analysis results. For MNM
samples, the methods used for
respirable crystalline silica sample
analysis using XRD include MSHA P–2,
NIOSH 7500, and OSHA ID–142. All
three methods can distinguish between
the three silica polymorphs.
MSHA and NIOSH have specific FTIR
methods for analyzing quartz in coal
mine dust. The NIOSH 7603 method is
based on the MSHA P–7 method which
was collaboratively tested and
specifically addresses the interference
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from kaolinite clay. Current FTIR
methods, however, cannot quantify
quartz if either of the other two forms
of crystalline silica (cristobalite and
tridymite) are present in the sample.
Additional steps such as acid treatment
can be taken to remove respirable
crystalline silica interferences from
other minerals that can be found in
mine dust sample matrices. For coal
samples, the methods used for
respirable crystalline silica sample
analysis using FTIR include MSHA P–
7, NIOSH 7602, and NIOSH 7603.
MSHA received some comments from
mining trade associations, a MNM mine
operator, and a labor union regarding
the proposed requirements for specified
analytical methods (Document ID 1398;
1424; 1417; 1428; 1443). BMC stated
that they have no objection to MSHA’s
proposed provisions and UMWA stated
that they are supportive of MSHA’s
proposed requirements. The AEMA,
NMA and WVCA cautioned that many
minerals interfere with the laboratory’s
analysis of silica and cited a list
produced by OSHA of 18 mineral types
that might interfere. Some of these
commenters expressed concern that
interference could erroneously elevate
silica sample levels and cause mine
operators to spend resources on
corrective actions that are not needed.
As discussed above, MSHA expects
that samples collected in MNM mines
will be analyzed by XRD and samples
collected in coal mines will be analyzed
by FTIR. In response to the commenters’
concern about mineral types that could
erroneously elevate silica sample levels,
MSHA disagrees with the commenters
and notes that the OSHA method cited
by the commenters (i.e., OSHA ID–142)
addresses mineral interference and is
one of the XRD methods that can be
used for respirable crystalline silica
sample analysis under the final rule.
f. Section 60.12 (g)—Sampling Records
Under the final rule, the mine
operator is required to create a record
for each sample taken that includes the
sample date, the occupations sampled,
and the concentrations of respirable
crystalline silica and respirable dust.
The mine operator is also required to
post the record and the laboratory report
on the mine bulletin board and, if
applicable, by electronic means, for the
next 31 days, upon receipt.
MSHA received a few comments on
the proposed sampling records
provision. The APHA recommended
that MSHA update § 60.12(h) to require
mine operators to provide a description
or data that shows the sample was taken
during typical mining activities
(Document ID 1416). The same
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commenter also recommended that
MSHA require the person collecting the
samples and recording the data to
certify the accuracy of the records in
writing. The Hon. Robert C. ‘‘Bobby’’
Scott, The American Thoracic Society et
al. and AFL–CIO supported greater
accessibility of records (Document ID
1439; 1421; 1449). Two of these
commenters also recommended that
sampling records be sent to the miners’
representatives (Document ID 1439;
1449).
In MSHA’s experience, commercial
laboratories that produce reports for
respirable crystalline silica exposures
include information on sample locations
and/or activities being performed. In
some cases, the name of the person that
was sampled is also included. The final
rule only requires the sampling record
to include the date, occupations
sampled, and concentrations of
respirable crystalline silica and
respirable dust since the laboratory
report may contain additional
information. MSHA believes the
elements it requires as part of the
sampling record provide mine operators
and miners with the most important
pieces of information while balancing
concerns about recordkeeping burden.
As required in § 60.16(b), any sampling
record that is created may be requested
at any time by, and must promptly be
made available to, miners, authorized
representatives of miners, or an
authorized representative of the
Secretary.
6. Section 60.13—Corrective Actions
The final rule establishes the
requirements for corrective actions in
§ 60.13. Section 60.13 paragraph (a)
requires mine operators to take certain
actions when any sampling result
indicates that a miner’s exposure to
respirable crystalline silica exceeds the
PEL. Paragraph (a) has three
subparagraphs—(1), (2), and (3).
Paragraph (a)(1) requires mine operators
to make NIOSH-approved respirators
available to affected miners before the
start of the next work shift. In a change
from the proposal, paragraph (a)(1)
specifies that this requirement must be
made in accordance with § 60.14 (b) and
(c). Paragraph (a)(2), unchanged from
the proposal, requires mine operators to
ensure that affected miners wear
respirators properly for the full shift or
during the period of overexposure until
miner exposures are at or below the
PEL. Paragraph (a)(3), unchanged from
the proposal, requires mine operators to
immediately take corrective actions to
lower the concentration of respirable
crystalline silica to at or below the PEL.
Paragraph (b) mirrors language from the
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proposal and specifies the mine
operator’s responsibility to conduct
sampling and implement additional or
new corrective actions until a
subsequent sampling result indicates
miner exposures are at or below the PEL
once corrective actions have been taken.
Paragraph (c), unchanged from the
proposal, requires the mine operator to
make a record of corrective actions and
the dates of those actions. Below is a
detailed discussion of the comments
received on this section and
modifications made in response to the
comments.
MSHA received several comments
including an individual who is a
director at a pulmonary rehab center,
advocacy organizations, and a miner
health advocate, recommending that
mine operators stop all production work
and withdraw miners if samples are
above the PEL (Document ID 1445;
1395; 1396; 1425; 1394; 1399). Some
commenters (e.g., AFL–CIO and an
individual) suggested MSHA should
include an upper exposure limit, above
which operators would be required to
withdraw miners, with ACLC suggesting
miners be withdrawn at 100 mg/m3
(Document ID 1449; 1367; 1445). Some
commenters expressed concern that
allowing miners to continue working in
hazardous dust levels violates the Mine
Act, with one stating that conditions
above the PEL should be considered an
‘‘imminent danger’’ under section 107(a)
of the Mine Act.
MSHA’s existing health standards do
not require the withdrawal of miners
when sampling is over the PEL and
mine operators are taking corrective
actions, except in certain circumstances
based on the risk and exposure to the
miner according to section 104(b) of the
Mine Act. Accordingly, under § 60.13,
mine operators must ensure that
affected miners wear respirators
properly for the full shift or during the
period of overexposure while the mine
operators are taking immediate
corrective actions to lower miner
exposures to at or below the PEL.
MSHA received several comments on
the use of respirators while corrective
actions are being taken by the operator.
A law firm said respirators should be
used permanently as a corrective action
(Document ID 1353). UMWA and Rep.
Robert ‘‘Bobby’’ Scott opposed the
mandatory use of respirators and stated
that mandating respirator use is
inconsistent with the Mine Act; UMWA
instead supported the voluntary usage
of respirators as a supplement to
engineering controls (Document ID
1353; 1398; 1439). USW cautioned that
the provision could allow mine
operators to justify respirator usage on
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more than a temporary basis (Document
ID 1447). The UMWA was also
concerned that using respirators as a
mandatory temporary solution might
lead to reduced use of engineering and
environmental methods as the primary
means of controlling exposures
(Document ID 1398). ACLC stated that
the language is vague and unclear on
how long miners will be required to rely
on respirators while corrective actions
are being taken (Document ID 1445).
Further, commenters including
advocacy organizations, labor
organizations, MNM operators, an
industry trade association, and a
medical professional association stated
that the final rule needs to clarify how
long miners are allowed to wear
respirators when their exposure is over
the PEL (Document ID 1404; 1421; 1425;
1432; 1439; 1440; 1445; 1447; 1449;
1393; 1395; 1396). AFL–CIO stated that
corrective actions should be
strengthened to include actions other
than respirator use and if sampling
shows that there is continued noncompliance with the PEL there needs to
be more significant corrective actions
taken to ensure that dust concentrations
are reduced permanently (Document ID
1449; 1353).
As explained earlier, respirator use is
not allowed for compliance. Under
§ 60.13, if sampling shows exposure
above the PEL, mine operators are
required to provide miners with
approved respirators before the next
shift begins, and affected miners must
wear respirators properly for the full
shift or during the period of
overexposure until miner exposures are
at or below the PEL. This provides
miners with protection from respirable
crystalline silica dust and thereby limits
the serious health effects associated
with respirable crystalline silica
exposures until engineering controls are
in place. Mine operators must also
immediately take corrective actions to
lower the concentration of respirable
crystalline silica to at or below the PEL.
This approach is consistent with the
NIOSH 1995 Criteria Document in
which NIOSH recommends the use of
respirators as an interim measure when
engineering controls and work practices
are not effective in maintaining worker
exposures at or below the PEL. Under
this section, MSHA emphasizes that
respirators are to be used only while
mine operators take corrective actions to
lower the concentration of respirable
crystalline silica to at or below the PEL.
MSHA clarifies that whenever
exposures are over the PEL, corrective
actions must be taken and MSHA must
be notified immediately.
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Further, MSHA emphasizes that
section 202(h) of the Mine Act, an
interim standard applicable to
underground coal mine operators,
specifically prohibits operators from
using respirators as a substitute for
engineering controls in the active
workings. Section 202(h) of the Mine
Act provides that ‘‘Respiratory
equipment approved by the Secretary
and the Secretary of Health and Human
Services shall be made available to all
persons whenever exposed to
concentrations of respirable dust in
excess of the levels required to be
maintained under this chapter. Use of
respirators shall not be substituted for
environmental control measures in the
active workings.’’ 30 U.S.C. 842(h). The
final rule is consistent with the Mine
Act, MSHA’s existing standards, and
case law. See, e.g., Nat’l Min. Ass’n v.
Sec’y, U.S. Dep’t of Lab., 812 F.3d 843,
884 (11th Cir. 2016) (upholding MSHA’s
Lowering Miners’ Exposure to
Respirable Coal Mine Dust, Including
Continuous Personal Dust Monitors rule
and noting ‘‘MSHA has interpreted the
statutory command correctly, however,
in requiring that mine air quality meet
the regulatory standard without resort to
a personal control’’). MSHA clarifies
that the final rule does not permit the
use of respirators in lieu of feasible
engineering and administrative controls.
MSHA believes the corrective actions
provisions are appropriate and requires
mine operators to make changes to
reduce miners’ exposures to respirable
crystalline silica when exposures are
above the PEL. MSHA clarifies that
respirator use is not a corrective action;
the corrective actions are those
actions—such as watering roadways,
repairing or installing new water sprays,
or repairing or installing a new dust
collection system—that reduce the
respirable crystalline silica
concentration to at or below the PEL.
MSHA will determine, on a case-by-case
basis, the adequacy of the corrective
action that must be taken immediately
and the appropriate timeframe within
which it must occur. Although each
engineering control employed as a
corrective action is different, mine
operators are expected to minimize the
time spent performing corrective actions
and, as a result, the time affected miners
spend using respirators. Any exposures
over the PEL are a violation of the
standard. Additionally, when
engineering controls are being
developed and implemented as a part of
corrective actions, mine operators are to
continue corrective action sampling.
Any operator samples over the PEL,
including corrective action sampling,
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are to be reported to the District
Manager. If sampling continues to be
over the PEL, the District Manager will
take appropriate enforcement actions
and may provide assistance, depending
on the circumstances.
Once corrective actions have been
taken, the mine operator shall conduct
sampling pursuant to paragraph
60.12(b). The operator will need to take
additional or new corrective actions
until sampling indicates miner
exposures are at or below the PEL.
Further corrective action sampling is
discussed in Section VIII.B.5. Exposure
Monitoring. Once corrective actions
have been implemented, the mine
operator is expected to make a record of
the corrective actions promptly
including the dates of the corrective
actions. Record keeping is further
discussed in Section VIII.B.9.
Recordkeeping Requirements.
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7. Section 60.14—Respiratory Protection
Section 60.14 expands on the
requirements for the use of respiratory
protection for respirable crystalline
silica. Section 60.14 paragraph (a)
addresses MNM mines only. This
paragraph requires the temporary use of
respirators at MNM mines when
concentrations of respirable crystalline
silica are above the PEL. In a change
from the proposal, the final rule
specifies that the requirements in
paragraph (a) only apply to MNM
mines; coal mines are not covered under
this paragraph—coal mines are
addressed under section 60.13
paragraph (a). The Agency also removed
the term ‘‘non-routine’’ from proposed
paragraph (a).
Paragraph (b), unchanged from the
proposal, applies to all mines and
addresses circumstances where miners
are medically unable to wear
respirators. Paragraph (c) also applies to
all mines and addresses the respiratory
protection requirements. Paragraph
(c)(1), which requires mine operators to
provide NIOSH-approved respirators to
affected miners, is unchanged from the
proposed rule. Paragraph (c)(2) is
changed from the proposal and specifies
that where approved respirators are
used mine operators must have a
written respiratory protection program
in accordance with ASTM F3387–19
and lists the mandatory ASTM program
elements.
MSHA received many comments
regarding the respiratory protection
provisions, with some commenters
supporting the proposal and some
opposing it. After reviewing all the
comments, MSHA concludes that the
proposed respiratory protection
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provisions should be retained, with
some modifications.
a. Section 60.14(a)—Temporary Use of
Respirators at Metal and Nonmetal
Mines
Final 60.14(a) states that when MNM
miners must work in concentrations of
respirable crystalline silica above the
PEL while engineering controls are
being developed and implemented or it
is necessary by nature of the work
involved, the mine operator shall use
respiratory protection as a temporary
measure. In a change from the proposal,
MSHA removed the term ‘‘non-routine’’
from the paragraph heading and
clarified that the requirement for
temporary use of respirators is
applicable only to MNM mines.
MSHA received several comments on
the proposed temporary non-routine use
of respirators, with many commenters
opposing the proposed mandatory use
requirement for coal mines.
Commenters identified difficulties in
wearing respirators and stated that coal
mine operators must comply with
existing standards for ventilation and
dust control plans, which have to be
submitted to and approved by MSHA.
Other commenters expressed concern
that there was an absence of a time limit
for which silica levels over the PEL are
permitted.
Some advocacy organizations and a
miner health advocate asked that MSHA
require mine operators to withdraw
miners when sampling indicated
exposures above the PEL (Document ID
1445; 1395; 1367; 1396; 1425). A
medical professional also requested that
MSHA require operators to withdraw
miners from hazardous conditions when
sampling indicates they are exposed to
respirable silica above the PEL
(Document ID 1394).
An individual stated that mine
construction and coal production, in
particular, should be excluded from the
circumstances in which temporary and
non-routine use of respirators are
allowed (Document ID 1412). Many
commenters including advocacy
organizations, black lung clinics, miner
health advocates, and labor
organizations suggested that coal miners
should be prohibited from working in
overexposures while using respirators,
stating that the working conditions,
especially in underground coal mines,
make it very difficult for miners to
communicate and work safely while
wearing respirators (Document ID 1372;
1399; 1398; 1447; 1449; 1421; 1393;
1395; 1396; 1402; 1425; 1445; 1410;
1342; 1363; 1391; 1394). One of the
labor organizations noted that
respirators do nothing to address
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bystander exposures (Document ID
1449).
After considering the comments,
MSHA agrees, and clarifies that
paragraph (a) does not apply to coal
mine operators. MSHA determined that
coal mine operators control silica and
coal mine dust through their approved
ventilation and dust control plans.
Underground coal mine operators are
required to have ventilation plans,
which include a respirable dust control
plan, which must be submitted to and
approved by MSHA. See 30 CFR
75.370(a)(1). These plans must be
revised to address any overexposures to
airborne contaminants. Surface coal
mines that have had a dust
overexposure are required to develop
and implement respirable dust control
plans that are approved by MSHA. See
30 CFR 71.300. For those areas of a
surface coal mine where methane
accumulation is a hazard, such as
tunnels and other enclosed working
areas, mine operators are required to
dilute airborne contaminants with
ventilation controls.
In MSHA’s experience, if there are
overexposures to respirable crystalline
silica or coal mine dust, coal mine
operators will adjust their ventilation
and dust controls to address these
overexposures. MSHA’s experience has
shown that these adjustments have
generally been successful in protecting
miners from silica and dust exposures
without the need for respirators and that
most conditions can be corrected within
a day. Additionally, as is currently the
case when a respirable coal dust
overexposure occurs, under the final
rule, citations for respirable crystalline
silica overexposures will require
abatement through immediate corrective
actions before the citation is terminated.
MSHA sets any citation abatement
deadline with the protection of the
miners as the primary consideration.
Also, the proposal was a departure
from existing standards for coal mine
operators. Under the existing standards,
coal mine operators have to provide
respiratory protection, but miners did
not have to wear respirators. Therefore,
MSHA has changed this requirement in
the final rule to apply to MNM mines
only for paragraph (a). MSHA reiterates
under § 60.13(a) that coal mine
operators must use respirators when
sampling indicates that a miner’s
respirable crystalline silica exposure
exceeds the PEL.
Commenters including advocacy
organizations, labor organizations,
MNM operators, an industry trade
association, and a medical professional
association requested that MSHA clarify
the meaning of ‘‘temporary non-routine’’
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to specify circumstances and time
limitations (Document ID 1393; 1395;
1396; 1425; 1445; 1447; 1449; 1432;
1440; 1404; 1421; 1409; 1439; 1364).
Some advocacy organizations and a
labor organization asked that MSHA
define ‘‘temporary’’ use for coal mines
(Document ID 1393; 1395; 1449). One of
the labor organizations noted that,
without defined time limits, operators
could require miners to wear respirators
for weeks or months (Document ID
1449).
MSHA agrees with the commenters
who stated that the meaning of
‘‘temporary non-routine’’ needed to be
clarified. MSHA removed ‘‘non-routine’’
from the paragraph heading for clarity
and to be more consistent with the
existing requirements for MNM mine
operators in §§ 56.5005 and 57.5005.
Final paragraph (a) applies only to
MNM operators, is consistent with the
existing requirements for controlling
exposure to airborne contaminants in
§§ 56.5005 and 57.5005 and is
responsive to comments.
Final paragraph (a)(1) requires
respirator use as a temporary measure
while MNM miners must work in
concentrations of respirable crystalline
silica above the PEL while engineering
control measures are being developed
and implemented. Final paragraph (a)(2)
includes a clarifying change from the
proposal to include an example in the
existing MNM standard that requires
MNM mine operators to use respirators
in temporary situations when it is
necessary by the nature of work
involved (for example, occasional entry
into hazardous atmospheres to perform
maintenance or investigation) when
miners are working in concentrations of
respirable crystalline silica above the
PEL. Several existing MSHA standards
use the term ‘‘temporary’’ although the
Agency does not specify a time limit.
The mining industry is familiar with
these standards. MSHA expects
‘‘temporary’’ to have the same meaning
as in existing standards—a short period
of time.
Under existing standards, MNM
miners can work for reasonable periods
of time in concentrations of airborne
contaminants exceeding permissible
levels if they are protected by approved
respirators when developing and
implementing engineering control
measures or when necessary by the
nature of work involved. Under these
existing MNM standards, mine
operators who have overexposures and
are required to provide respiratory
protection to miners are issued a
citation for the overexposure. Generally,
if MNM mine operators have a written
respiratory protection program in place,
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the citation would be non-Significant
and Substantial.
MSHA has always intended for
miners to work in these conditions
temporarily and the agency has enforced
it as such. The final rule thus does not
make any substantive changes from the
existing standard in MNM. The update
in language from ‘‘reasonable periods of
time’’ to ‘‘temporary’’ in the final rule is
an update in line with MSHA’s original
intent and as previously noted, with
other existing MSHA standards. Husch
Blackwell (on behalf of the SSC),
NSSGA, U.S. Silica, and IAAP stated
that respirators are the only feasible
means of protection for certain tasks in
mining environments, such as
housekeeping, working on dust
collectors, and bagging operations
(Document ID 1432; 1448; 1455; 1456).
MSHA emphasizes that respiratory
protection under § 60.14 (a) is required
to be temporary. The Agency intends for
temporary to mean that miners wear
respiratory protection only for short
periods of time; for example, the time
necessary to conduct maintenance and
repair of engineering controls. Similar to
existing MNM standards, the Agency,
under this final rule, does not intend
that miners will wear respirators for
extended periods of time. As an
example, when a crusher needs
maintenance or repair after an
overexposure resulting from a defective
water spray bar, miners must wear
respiratory protection when performing
maintenance or conducting repairs to
the spray bar. Another example includes
when miners change defective dust bags
that can cause overexposures to
respirable crystalline silica; when
replacing the dust bags, miners must
wear respiratory protection.
After reviewing these comments,
MSHA revised paragraph (a)(2) to
provide a clarifying example on when
MNM mine operators would
temporarily use respirators due to the
nature of the work involved. Under the
final rule, the Agency prohibits use of
respirator to achieve compliance with
the PEL. In response to the comment
that respirators are the only means to
achieve compliance for certain mining
tasks, MSHA has reviewed its sample
data and has determined that mine
operators are generally able to achieve
compliance with existing engineering
controls, supplemented by
administrative controls. MSHA is aware
that certain mining tasks related to
maintenance and repair of engineering
controls will require respiratory
protection. However, MSHA anticipates
that respirator use will be temporary,
until controls are repaired and effective,
and respirator use will not be
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considered as a means to achieve
compliance. This clarifying change on
the use of respirators for certain tasks
such as the occasional entry into
hazardous atmospheres to perform
maintenance or investigation, is
consistent with the Agency’s existing
standards.
A joint comment by The American
Thoracic Society et al. suggested that
temporary reliance on respirator use be
limited to miners actively working at
the time it is noted that silica exceeds
the PEL, and only for as long as it takes
to safely shut down operations
(Document ID 1421). The AFL–CIO
suggested that MSHA treat respirator
use as a variance from normal activity,
requiring operators to prove when
respirator use is necessary (Document
ID 1449).
MSHA understands that respirator use
under paragraphs (a)(1) and (a)(2) will
be different depending on the facts and
circumstances in the MNM mines and
that the temporary nature of respirator
use will depend on the time needed to
correct an overexposure. MSHA will
determine the time required for
temporary respirator use on a case-bycase basis. MSHA emphasizes that the
District Manager will be informed of all
overexposures under 60.12(b). MSHA
can take enforcement action, including
issuing a withdrawal order under 104(b)
of the Mine Act, if the facts and
circumstances at the mine require it.
An individual stated that the
proposed rule rejected respirator use as
a method of compliance in the preamble
to § 60.11 but proposed § 60.14
appeared to contradict the prohibition
(Document ID 1412). The Black Lung
Clinics stated there is no real-time
feedback for determining whether a
respirator is effectively reducing
exposure levels (Document ID 1410)
which may provide a false sense of
security that the miner is protected from
cumulative exposures to respirable
crystalline silica.
In response, MSHA clarifies that there
is not a contradiction between § 60.11
and § 60.14. Final rule § 60.11 requires
engineering controls supplemented by
administrative controls to reduce
exposures. In MSHA’s experience,
miners who use respirators under a
respiratory protection program that is in
accordance with MSHA’s standards are
protected from cumulative exposures to
airborne hazards. Final § 60.14(a)
additionally requires the use of
respirators in MNM mines in case of an
overexposure; however, MNM mine
operators will be cited for the
overexposure. This is consistent with
MSHA’s existing standards and
enforcement practice for MNM mines.
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Comments from MNM mining
operators, mining trade associations,
and state mining associations suggested
that, consistent with the OSHA rule,
MSHA should allow operators to use
respirators as a method of compliance
where engineering and administrative
controls are unable to reduce silica
levels below the PEL (Document ID
1368; 1424; 1428; 1441; 1448; 1455).
The NMA stated that respirators,
including PAPRs, should be allowed to
be used whenever miners are working in
exposures above the PEL (Document ID
1428). The Pennsylvania Coal Alliance
and Vanderbilt Minerals, LLC stated
that PAPRs are comfortable to wear for
long periods and do not restrict
breathing (Document ID 1378; 1419). In
contrast, three labor organizations
opposed the use of respirators
(Document ID 1398; 1447; 1449). These
commenters stated that the Mine Act
forbids respirator use as a mandatory
administrative control or as a substitute
for environmental controls and noted
that the proposed rule allowed for
continued production with respirators
in hazardous silica dust levels. A
medical professional stated that miners
should always use respirators, to ensure
complete protection from respirable
crystalline silica exposures (Document
ID 1375).
MSHA disagrees with these
commenters that respirators should be
used as a method of compliance or that
miners should always use respirators.
MSHA has determined that respirators
cannot be used as a method of
compliance. Respirators do not provide
effective protection from overexposures
for various reasons that include: (1)
without a proper fit, dust particles enter
the miner’s breathing zone; (2)
inconsistent or incorrect use can
compromise the effectiveness of the
respirator; and (3) respirators can hinder
effective communication among miners.
MSHA has decided that respirators must
not be used for compliance because they
do not address the dust generation at the
source. Engineering controls are
reliable, provide consistent levels of
protection to many miners, allow for
predictable performance levels, can be
monitored continually, and can remove
harmful levels of airborne contaminants,
including respirable crystalline silica,
from the miner’s environment.
However, MSHA recognizes that
respirators must be used, on a
temporary basis, for certain mining
tasks.
MSHA has provided greater health
protection for miners by requiring (as
opposed to making available) use of
respirators for coal miners when
exposed to respirable crystalline silica
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above the PEL, while continuing
necessary protection for MNM miners.
Also, in Section VII.A. Technological
Feasibility, MSHA has determined that
it is technologically feasible for mine
operators to achieve the PEL using
commercially available engineering
controls.
Engineering controls are reliable,
provide consistent levels of protection
to many miners, allow for predictable
performance levels, can be monitored
continually, and can remove harmful
levels of airborne contaminants,
including respirable crystalline silica,
from the miner’s environment.
The AFL–CIO stated that mine
operators should be required to submit
scenarios where respirators are
necessary under limited circumstances
and if MSHA does not have evidence
respirators are needed for a particular
task, they should not be permitted
(Document ID 1449). After considering
this comment, MSHA has decided not to
require MNM mine operators to submit
scenarios, or plans, for the temporary
use of respirators because MSHA
approval takes time and, in the Agency’s
experience, there are unforeseen
circumstances in a mine that may
require the immediate implementation
of engineering controls. When
overexposures to respirable crystalline
silica occur, paragraph 60.13(a)(3)
requires the mine operator to take
immediate corrective actions to lower
concentrations of respirable crystalline
silica to at or below the PEL. Therefore,
requiring mine operators to submit a
plan and receive MSHA approval before
implementing changes would allow
respirable crystalline silica exposures
above the PEL to remain uncorrected for
longer than necessary, and put miners’
health at risk.
b. Section 60.14(b)—Miners Unable To
Wear Respirators at All Mines
The final rule is changed from
proposed paragraph 60.14(b). MSHA has
revised the heading for paragraph (b) to
include ‘‘at all mines’’ so that it is clear
that paragraph (b) is applicable to
miners unable to wear respirators at
MNM and coal mines. Paragraph (b)(2)
is also changed from the proposal to
remove ‘‘non-routine.’’ This change is
made to be consistent with the change
discussed in paragraph (a). The rest of
paragraph (b) is unchanged from the
proposal. Paragraph (b) requires that,
upon written determination by a PLHCP
that an affected miner is unable to wear
a respirator, the miner be temporarily
transferred to work in a separate area of
the same mine or to an occupation at the
same mine where respiratory protection
is not required. Paragraph (b)(1) states
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28337
that the affected miner shall continue to
receive compensation at no less than the
regular rate of pay in the occupation
held by that miner immediately prior to
the transfer. Paragraph (b)(2) states the
affected miner may be transferred back
to the miner’s initial work area or
occupation when temporary use of
respirators is no longer required.
The USW supported the temporary
transfer of miners unable to wear
respirators (Document ID 1447) while
the Arizona Mining Association stated
that it would be challenging to transfer
miners who cannot wear respirators to
another location or occupation where
respirators are not needed (Document ID
1368).
After reviewing the comments, MSHA
has determined that no change to the
proposal is necessary. MSHA believes
that it should not be difficult for a mine
operator to temporarily transfer miners
to a separate area or occupation to
ensure their health and safety. Under
the rule, the concentration of respirable
crystalline silica to which the miner is
exposed must be controlled through
feasible engineering and administrative
controls; therefore, instances in which a
miner is transferred because of an
inability to wear a respirator should be
infrequent. Miners may be able to work
in other areas of the mine where
respirable crystalline silica
concentrations are under the PEL.
Furthermore, under paragraph (b)(2) the
miner may be transferred back to the
initial work area or occupation when
the limited use of respirators is no
longer required.
c. Section 60.14(c)—Respiratory
Protection Requirements at All Mines
The final rule is changed from
proposed paragraph (c). MSHA has
revised the heading for paragraph (c) to
include ‘‘at all mines’’ so that it is clear
that paragraph (c) is applicable to MNM
and coal mines. Paragraph (c)(1) is
adopted as proposed and requires mine
operators to provide affected miners
with a NIOSH-approved atmospheresupplying respirator or NIOSHapproved air-purifying respirator
equipped with particulate protection
classified as 100 series under 42 CFR
part 84 or particulate protection
classified as High Efficiency ‘‘HE’’
under 42 CFR part 84.
Some commenters, including mining
and industry trade associations, stated
that the NIOSH Pocket Guide to
Chemical Hazards recommends the use
of N–, R–, or P–95 and 99 series
respirators to lower miners’ exposures
to respirable crystalline silica and
suggested MSHA revise the final rule to
also allow for these respirators
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(Document ID 1407; 1419; 1424; 1428;
1442; 1448). Some mining trade
associations and MNM mine operators
recommended that MSHA specifically
allow the use of PAPRs, (Document ID
1424; 1428; 1378; 1419; 1452).
After reviewing comments, MSHA has
decided to maintain paragraph (c)(1) in
the final rule, as proposed. N–, R–, or
P–95 and 99 respirators may provide an
appropriate level of filtration when
properly fitted, worn, and maintained;
however, MSHA has observed that the
structural integrity of these respirators is
very easily compromised in the harsh
mining environment. N–, R–, or P–95
and 99 respirators are not as durable as
other types of air-purifying respirators.
N–, R–, or P–95 and 99 respirators are
easily contaminated, damaged, and
deformed and must be routinely
replaced to maintain effectiveness. Also,
the N–, R–, or P–95 and 99 respirators
do not hold their shape or maintain an
effective seal when they become wet. N–
, R–, or P–95 and 99 respirators that are
damaged or deformed provide little, if
any, protection and may offer a false
sense of security to miners. MSHA
recognizes that PAPRs may be more
comfortable to wear than full-face or
half-face, tight-fitting air purifying
respirators; however, PAPRs are still not
as reliable or effective as engineering
controls and are not a permanent
solution. PAPRs add noise from the fan
and the full-face covering making it
difficult for the miner to hear or
communicate effectively, which could
subject the miner to hazards while
working. They may also reduce the
miner’s peripheral vision and decrease
the wearer’s situational awareness
around equipment or other mining
hazards. PAPRs, like full-face or halfface, tight-fitting air purifying
respirators, must be worn only as a
temporary measure in accordance with
paragraph 60.14(b).
MSHA believes that air-purifying
respirators classified as 100 series or
High Efficiency under the NIOSH
classifications for particulate protection
will provide the maximum level of
protection when miners are wearing
respirators and are most suitable in
protecting the health and safety of
miners from occupational exposure to
respirable crystalline silica when
exposures are above the PEL.
Paragraph (c)(2) is modified from the
proposal and requires that when
approved respirators are used, the mine
operator must have a written respiratory
protection program that meets the
following requirements in accordance
with ASTM F3387–19: program
administration; written standard
operating procedures; medical
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evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage. The proposal did not specify
the requirement for a written respiratory
protection program or list the
mandatory program elements. The
language in the final rule is consistent
with the requirements of ASTM F3387–
19, Standard Practice for Respiratory
Protection, which is incorporated by
reference.
MSHA received comments on the
incorporation by reference of ASTM
F3387–19, with some commenters
supporting the proposal and some
commenters opposing it. An industrial
hygiene professional association, labor
organization and a mining related
business supported the proposal to
update the existing respirator protection
standard (Document ID 1351; 1398;
1392). The AIHA and UMWA stated that
the proposed incorporation by reference
of ASTM F3387–19 to amend the
Agency’s respiratory protection program
to current and comprehensive
requirements was appropriate
(Document ID 1351; 1398). The AEMA
and NMA, who opposed the proposal,
stated that MSHA should not reference
the ASTM F3387–19 requirements if the
Agency does not allow the use of
respirators for compliance purposes
(Document ID 1424; 1428). Vanderbilt
Minerals, LLC asserted that
incorporating ASTM F3387–19 is
beyond MSHA’s statutory authority and
conflicts with the intent of the Mine Act
(Document ID 1419).
As discussed in Section II Pertinent
Legal Authority, the Mine Act requires
the Secretary to develop and promulgate
improved mandatory health or safety
standards to prevent hazardous and
unhealthy conditions and protect the
health and safety of the nation’s miners.
30 U.S.C. 811(a). Section 101(a) of the
Mine Act gives the Secretary the
authority to develop, promulgate, and
revise mandatory health standards to
address toxic materials or harmful
physical agents. Under Section 101(a), a
standard must protect lives and prevent
injuries in mines and be ‘‘improved’’
over any standard that it replaces or
revises. MSHA believes the
incorporation by reference of ASTM
F3387–19 is an improvement over the
ANSI 1969 standard which it replaces.
MSHA’s incorporation by reference of
ASTM F3387–19 is consistent with the
Mine Act and OMB Circular A–119,
‘‘Federal Participation in the
Development and Use of Voluntary
Consensus Standards and in Conformity
with Assessment Activities’’ (81 FR
4673). The OMB Circular directs
agencies to use voluntary consensus
standards in lieu of government-unique
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standards, except where inconsistent
with law or otherwise impractical.
The AIHA, NMA, and EMA stated
that the proposed ASTM F3387–19
standard’s requirements were too
prescriptive and asked that MSHA give
operators the flexibility to select the
elements of that standard that are most
applicable to their own needs and the
hazards at their mines (Document ID
1451; 1441; 1442). The AFL–CIO
expressed concern that mine operators
would be allowed to determine which
parts of the respiratory standard they
will follow and urged MSHA to require
certain components (Document ID
1449). The AEMA stated that the final
rule should clarify whether a specific
written respiratory protection program
is required and under what standards
(Document ID 1424). The AEMA also
asked for more clarity from MSHA on
what elements of ASTM F3387–19 will
be required when respiratory protection
for miners is needed.
The CISC, MSHA Safety Services,
Inc., and Tata Chemicals Soda Ash
Partners, LLC recommended that MSHA
align the respiratory protection
requirements with OSHA’s
requirements (Document ID 1430; 1392;
1452). Draeger Inc. asked that MSHA
include in the rule additional specific
provisions of ASTMF3387–19, such as
the breathing gas requirements in
section 13 of the ASTM F3387–19
standard and wearer seal checks, and
also suggested that MSHA add
requirements to the fit testing
procedures to include physical
movements that are more relevant to
low-seam coal mines (Document ID
1409).
The Agency agrees with commenters
who expressed that the requirements of
the respiratory protection program are
appropriate, and the Agency makes
clarifying changes to the requirements
in the final rule. The Agency has
clarified paragraph (c)(2) to state the
specific respiratory protection program
requirements. In paragraph (c)(2),
MSHA has deleted ‘‘as applicable’’ and
added that, when respirators are used, a
mine operator must have a written
respiratory protection program that
meets the following requirements in
accordance with ASTM F3387–19:
program administration; written
standard operating procedures; medical
evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage. MSHA has the authority, both
under the Mine Act and Federal
regulatory guidelines, to include the
incorporation by reference of consensus
standards such as ASTM F3387–19. The
Mine Act specifically requires MSHA to
issue improved mandatory safety and
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health standards. The incorporation by
reference of ASTM F3387–19 is an
improved standard.
MSHA received a comment from the
MCPA asserting that the medical
evaluation and fit testing requirements
for respirators in ASTM F3387–19 were
too rigorous because there may be
situations where a miner fails a medical
evaluation or fit test simply due to
personal desires, such as having a beard
(Document ID 1406).
MSHA believes that the medical
evaluation and fit testing requirements
for use of respirators are appropriate
because they are critical to ensuring
proper protection and safe respirator use
for respirator wearers who are exposed
to airborne contaminants. In addition,
medical evaluations and fit tests are
required under MSHA’s current
respiratory protection standard (ANSI
Z88.2–1969). Therefore, mine operators
who have used respirators previously
should be familiar with these
requirements.
MSHA incorporates by reference this
consensus standard for two reasons.
ASTM F3387–19 reflects current
respirator technology and accepted
effective respiratory protection
practices. For example, ASTM F3387–
19 provides detailed information on
respirator selection that is based on
NIOSH’s research and long-standing
experience of testing and approving
respirators for occupational use and
OSHA’s respiratory protection
standards. The ASTM F3387–19
standard is prepared and maintained by
subject matter experts, using a rigorous
and well-defined process. The standard
is reviewed by internationally
recognized experts and is approved for
use only if the appropriate procedures
are followed. In addition, adopting
voluntary consensus standards is
consistent with OMB Circular A–119.
MSHA has observed that many
operators, especially larger mine
operators, have already implemented
respiratory protection programs that
meet many of the OSHA requirements,
which are substantially similar to many
requirements in ASTM F3387–19. In
response to commenters who suggested
that MSHA adopt the OSHA respiratory
protection standards, ASTM F3387–19
references OSHA’s respiratory standards
that include assigned protection factors
and maximum use concentrations, and
fit testing. MSHA believes that the
mining industry is familiar with many
provisions in ASTM F3387–19. MSHA
anticipates that for many large mine
operators, few changes to their
respiratory protection program may be
warranted, whereas small mines may
need to revise their respiratory
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protection programs in accordance with
the requirements in ASTM F3387–19.
The program requirements are discussed
in more detail in Section VIII.D.
Updating MSHA Respiratory Protection
Standards: Incorporation of ASTM
F3387–19 by Reference.
Other Comments
The AIHA stated that respirators
should be used only under a
comprehensive respiratory protection
program and under the supervision of
an industrial hygienist (Document ID
1351). AIHA suggested that MSHA
should refer to the most recent edition
of ASTM’s respiratory protection
standard and not the 2019 edition,
which may become obsolete by the time
the silica standard is adopted.
According to the Office of the Federal
Register, MSHA is required to inform
the public of the standard to be
incorporated and the specific edition
that the Agency intends to require. In
the proposed rule, MSHA proposed to
incorporate the 2019 edition of ASTM
F3387, which is the most recent
respiratory protection standard. MSHA
is incorporating by refence ASTM
F3387–19 in this final rule. MSHA is
aware that larger mines may have an
industrial hygienist or safety specialist
administer their respiratory protection
program; this practice is consistent
with, but not required by, the ASTM
F3387–19 standard’s requirements for
program administration. ASTM F3387–
19 specifies that responsibility and
authority for the respirator program
should be assigned to a single qualified
person with sufficient knowledge of
respiratory protection. Qualifications
could be gained through training or
experience; however, the qualifications
of a program administrator must be
commensurate with the respiratory
hazards at the mine site.
The program administrator should
have access to and direct
communication with the site manager
about matters impacting worker safety
and health. ASTM F3387–19 notes a
preference that the administrator be in
the company’s industrial hygiene,
environmental, health physics, or safety
engineering department; however, a
third-party entity that meets the
standard’s requirements may also
provide this service. ASTM F3387–19
outlines the respiratory protection
program administrator’s responsibilities,
specifying that they should include:
measuring, estimating, or reviewing
information on the concentration of
airborne contaminants; ensuring that
medical evaluations, training, and fit
testing are performed; selecting the
appropriate type or class of respirator
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that will provide adequate protection for
each contaminant; maintaining records;
evaluating the respirator program’s
effectiveness; and revising the program,
as necessary.
8. Section 60.15—Medical Surveillance
for Metal and Nonmetal Mines
The final rule establishes
requirements for medical surveillance
for MNM mines in § 60.15. Paragraph (a)
requires MNM mine operators to
provide each miner periodic medical
examinations performed by a PLHCP or
specialist, at no cost to the miner. In a
change from the proposal, under
paragraph (a)(2)(iv), MSHA adds that
the pulmonary function test may also be
administered by a pulmonary function
technologist with a current credential
from the National Board for Respiratory
Care. The rest of paragraph (a) remains
unchanged from the proposal.
Paragraph (b) establishes the
requirements for each MNM mine
operator to provide voluntary medical
examinations every 5 years to all miners
employed at the mine or who have
already worked in the mining industry.
In a change from the proposal, new
paragraph (b)(1) specifies that the
voluntary medical examinations must
be offered during an initial 12-month
period. New paragraph (b)(2), the same
as proposed paragraph (b), requires
mine operators to continue to offer
voluntary medical examinations after
the period in paragraph (b)(1) at least
every 5 years during a 6-month period
that begins no less than 3.5 years and
not more than 4.5 years from the end of
the last 6-month period.
Paragraph (c) specifies that each mine
operator is required to provide the
medical examinations specified in
paragraph (a) to each miner who begins
work in the mining industry for the first
time. In a change from the proposal,
paragraph (c)(1) requires the initial
medical examination to take place no
later than 60 days after beginning
employment (instead of 30 days).
Paragraphs (c)(2) and (c)(3) remain
unchanged from the proposal.
Paragraph (d) specifies the
requirements for medical examination
results. In a change from the proposal,
paragraph (d)(1) specifies that the
medical examination results must be
provided from the PLHCP or specialist
within 30 days of the medical
examination. Like the proposal, the
medical examination results must be
provided to the miner, and at the
request of the miner, to the miner’s
designated physician. In a change from
the proposal, the medical examination
results may also be provided, at the
request of the miner, to another
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designee identified by the miner. In a
change from the proposal, paragraph
(d)(2) specifies that within 30 days of
the medical examination, the mine
operator must ensure that the PLHCP or
specialist also provide the results of
chest X-ray classifications to NIOSH,
once NIOSH establishes a reporting
system. Paragraph (e) specifies the
requirements for the written medical
opinion and is unchanged from the
proposal. Paragraph (f) requires mine
operators to maintain a record of the
written medical opinions received from
the PLHCP or specialist under
paragraph (e) and is unchanged from the
proposal.
MSHA received several comments
regarding the medical surveillance
provisions for MNM mines, offering
both support and opposition. The
PACA, IAAP, and CalCIMA opposed the
proposal, stated that the requirements
were too prescriptive, and asked that
MSHA give operators more flexibility in
implementing medical surveillance
programs (Document ID 1413; 1456;
1433). A mining-related business owner
asserted that medical surveillance
requirements are not needed, stating
that there is a lack of silicosis cases in
MNM miners (Document ID 1392).
Three commenters—an elected federal
official, a miner health clinic, and a
medical association—supported the
proposal and asserted that the medical
surveillance requirements would help
MNM miners track their respiratory
health and mitigate risks for silicarelated chronic diseases (Document ID
1439; 1418; 1373). Two unions, the
AFL–CIO and the USW, stated that both
MNM and coal miners should be
provided with the same level of
protection and care through their
medical surveillance programs
(Document ID 1449; 1447).
After reviewing the comments, MSHA
concludes that the proposed medical
surveillance provisions for MNM mines
should be retained, with some
modifications. As discussed in Section
V. Health Effects Summary and Section
VI. Final Risk Analysis Summary of this
preamble, many MNM mining activities
generate silica dust and could lead to
respirable crystalline silica exposures
that result in adverse health effects such
as silicosis. MSHA agrees with
commenters who stated that the medical
surveillance requirements will provide
MNM miners with health information
that could prevent silica-related
diseases and believes it is necessary to
include the medical surveillance
requirements in the final rule. The
Agency has determined that all MNM
miners receive the same medical
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examination protections under the final
rule.
Some commenters requested that the
Agency use a risk-based approach for
medical surveillance. The NMA,
NSSGA, AEMA, and SSC urged MSHA
to adopt OSHA’s risk-based medical
surveillance framework, which requires
medical monitoring only for those
miners exposed to respirable silica
above the action level for more than 30
days per year (Document ID 1428; 1448;
1424; 1432).
The Agency disagrees with this
approach. Unlike OSHA’s silica
standard, the final rule does not include
an exposure trigger provision because
the Agency believes it is important to
maintain consistency between the
medical surveillance requirements for
MNM and coal mines to ensure all
miners have the information necessary
for the early detection of silica-related
disease. The purpose of medical
surveillance is to provide MNM miners
necessary information to determine if
their health may be adversely affected
by exposure to respirable crystalline
silica and enable miners to take
appropriate action to stop further
disease progression.
Below is a detailed discussion of the
comments received on this section and
modifications made in response to the
comments.
a. 60.15(a)—Medical Surveillance
Paragraph § 60.15(a) requires that
each MNM mine operator make medical
examinations, performed by a PLHCP or
specialist, available to each MNM
miner, at no cost to the miner. Mine
operators must ensure that medical
examinations follow the requirements
under § 60.15(a)(2)(i)–(iv). In a change
from the proposed rule, under
paragraph (a)(2)(iv), MSHA adds that
the pulmonary function test may be
administered by a pulmonary function
technologist with a current credential
from the National Board for Respiratory
Care.
MSHA received several comments on
proposed paragraph 60.15(a). The AIHA,
AANP, and CertainTeed, LLC supported
MSHA’s proposal to require MNM mine
operators to provide MNM miners with
medical examinations performed by a
PLHCP or specialist and agreed with
MSHA’s broad definition of PLHCP
(Document ID 1351; 1400; 1423). The
BIA and the Arizona Mining
Association expressed concerns with
this requirement and asserted that many
MNM mines may experience issues with
getting access to a PLHCP or specialist
qualified to perform the examinations
(Document ID 1422; 1368). The APHA
and AOEC advocated for medical
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surveillance to be performed only by
physicians who are board-certified in
occupational medicine or pulmonary
medicine, or who have experience in
silica medical surveillance (Document
ID 1416; 1373). Two commenters
recommended that MNM miners should
be able to choose their own health care
provider (Document ID 1439; 1412). The
Arizona Mining Association inquired
about whether medical examinations
may be incorporated within the mine
operator’s health care plans (Document
ID 1368).
After reviewing the comments, MSHA
adds under paragraph (a)(2)(iv) that the
pulmonary function test may be
administered by a pulmonary function
technologist with a current credential
from the National Board for Respiratory
Care. This option will provide a larger
pool of qualified respiratory care
professionals who may administer
pulmonary function tests.
MSHA believes that MNM mine
operators should not encounter any
significant issues with identifying and
hiring a qualified PLHCP or specialist to
conduct medical examinations. The
final rule provides flexibility in the
selection of health care professionals.
As discussed in § 60.1, the final rule
allows MNM mine operators more time
to comply; MNM mine operators will
have 24 months after the publication of
the final rule, rather than 4 months after
the publication of the final rule as
specified in the proposed rule. This
additional time addresses commenters’
concerns about time needed for
establishing a medical surveillance
program.
The Agency also clarifies that mine
operators may give miners the option to
choose their own health care provider,
if the provider meets the requirements
of this section. As stated in the
proposal, a qualified PLHCP is an
individual whose legally permitted
scope of practice (i.e., license,
registration, or certification) allows that
individual to independently provide or
be delegated the responsibility to
provide the required health services
(i.e., chest X-rays, spirometry, symptom
assessment, and occupational history).
‘‘Specialist’’ is defined in § 60.2 as an
American Board-Certified Specialist in
Pulmonary Disease or an American
Board-Certified Specialist in
Occupational Medicine.
MSHA does not require medical
examinations in the final rule to be
performed only by physicians who are
board-certified in occupational
medicine or pulmonary medicine,
because PLHCPs may have the
knowledge and skills to conduct these
examinations independently or under
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the supervision of board-certified
specialists. MSHA believes this will
provide mine operators more provider
choices and improve accessibility to
PLHCPs for miners. MSHA also clarifies
that medical examinations may be
integrated into mine operators’ health
care plans; while noting that in such
cases, mine operators must ensure that
the examinations are conducted in
accordance with the requirements in
§ 60.15. The final rule ensures that
medical examinations are
comprehensive and tailored to identify
and mitigate potential health risks
associated with miners’ occupational
exposures to respirable crystalline
silica. The final rule will ensure that the
medical examinations provide MNM
miners with health surveillance
information so that they are aware of the
early development and advancement of
any silica-related disease.
The Agency received comments
regarding the use of NIOSH facilities
and NIOSH B Readers. The American
Industrial Hygiene Association and
National Coalition of Black Lung and
Respiratory Disease Clinics stated that
MSHA should require MNM operators
to use NIOSH-approved facilities
(Document ID 1351; 1410). However,
several commenters, including the
ACOEM, NLA, NVMA, and NSSGA,
expressed concerns about the limited
availability and geographic distribution
of these facilities (Document ID 1405;
1408; 1441; 1448). The NMA, Portland
Cement Association, and AEMA noted
that there are only a limited number of
B Readers available (Document ID 1428;
1407; 1424). The Black Lung Clinics
supported MSHA’s assertion that the
availability of digital radiography allows
for the electronic transmission of chest
radiographs to remotely located B
Readers (Document ID 1410).
MSHA agrees with commenters who
expressed concerns about the
accessibility of NIOSH-approved
facilities, and, like the proposal, the
final rule does not include a
requirement to use such facilities.
MSHA believes that requiring a NIOSHcertified B Reader to classify chest Xrays and requiring either a spirometry
technician with a current certificate
from a NIOSH-approved Spirometry
Program Sponsor or a pulmonary
function technologist with a current
credential from the National Board for
Respiratory Care to perform pulmonary
function tests, will ensure that miners
receive the necessary standard of care to
protect their health while providing
broader access to PLHCPs. As did OSHA
in its 2016 silica final rule (81 FR 16286,
16821), MSHA has determined that the
number of B Readers in the United
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States is adequate to classify the
additional chest X-rays that will be
required under this rule. In addition,
digital X-rays can be transmitted
electronically to B Readers anywhere in
the United States, so this requirement
will provide operators greater access to
B Readers. Further, as discussed more
below, under § 60.15(d)(2), mine
operators are required to ensure that,
within 30 days of the medical
examination, the PLHCP or specialist
provides the results of chest X-ray
classifications to NIOSH, once NIOSH
establishes a reporting system.
In the proposed rule, MSHA solicited
comment on whether other diagnostic
technology, such as high-resolution
computed technology (CT), should be
included in the final rule. The AOEC,
APHA, USW, and a medical
professional urged MSHA to include a
low-dose CT scan, either as a primary
test or if recommended by the
examining clinician, because such scans
are more sensitive than conventional
chest radiographs and would facilitate
earlier detection of disease or
dysfunction (Document ID 1373; 1416;
1447; 1437). The UMWA cautioned
against requiring CT scans because they
are not as readily available and are more
costly (Document ID 1409). The
American Thoracic Society et al.
commented and acknowledged the
benefits of low-dose chest CT scans for
individual disease detection but noted
that such a requirement might limit
population-level disease surveillance
because of a lack of standardization for
interpreting CT scans for diagnosing
pneumoconiosis (Document ID 1421).
The AFL–CIO highlighted other
initiatives such as the Worker Health
Protection Program and the Building
Trades National Medical Screening
Program that provide low-dose CT scans
through a mobile van to serve smaller
population centers and suggested that
similar programs could be created for
MNM miners (Document ID 1449).
MSHA agrees with commenters
regarding the cost concerns and limited
availability of low-dose chest CT scans.
MSHA is aware that there are increased
health risks from higher radiation
exposures from screening with low dose
chest CT scans. MSHA is also aware that
‘‘ultra-low-dose’’ methods for CT scans
are available that would subject the
miner to lower radiation doses than
other screening chest CT scans;
however, this method is not widely
available and is therefore not a practical
resource for mine operators at this time.
Also, as a medical professional
association acknowledged, low-dose
chest CT scans do not have a standard
for the classification of the results,
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unlike classification standards for chest
X-rays (Document ID 1421). For the
reasons above, the final rule does not
add CT scans to the medical
examination requirements in § 60.15(a).
The Agency received some comments
recommending adding testing
requirements. The Miners Clinic of
Colorado and the Black Lung Clinics
suggested requiring diffusion capacity
testing as a pulmonary function test
(Document ID 1418; 1410). MSHA
considered these comments and
determined that diffusion capacity
testing is not as widely available as
forced vital capacity (FVC) and forced
expiratory volume tests (i.e., spirometry
tests). Spirometry is the most common
and widely used lung function test. The
final rule does not add diffusion
capacity testing to the medical
examination requirements in § 60.15(a).
MSHA also received comments on
tuberculosis testing requirements.
Commenters—the AOEC, APHA, and
the NSSGA—recommended that a test
for latent tuberculosis be required as an
initial test or if recommended by the
examining PLHCP, noting that it is
included in OSHA’s silica standard
(Document ID 1373; 1416; 1448).
However, the Portland Cement
Association argued that testing for
tuberculosis is unnecessary (Document
ID 1407). After considering these
comments, MSHA has decided not to
include a tuberculosis test requirement
because it would be duplicative of the
information provided in the medical
and work history examination, which
requires an assessment of the miner’s
history of tuberculosis under § 60.15(a).
The Agency determined that the
information gathered through the
medical and work history examination
will effectively screen for tuberculosis.
In MSHA’s experience, tuberculosis is
not a significant health concern in the
MNM mining industry.
b. 60.15(b)—Voluntary Medical
Examinations
Final 60.15(b) requires mine operators
to provide the opportunity to all miners
employed at the mine to have the
medical examinations under 60.15(a).
Based on its review of the comments,
MSHA has modified the language to
clarify the timing of medical
examinations. Under final paragraph (b),
MNM mine operators must provide the
opportunity for miners to receive
medical examinations as specified
under (b)(1) and (b)(2). This applies to
all MNM miners who are not new to the
mining industry. Miners who are new to
the industry are required to receive
medical examinations as specified
under paragraph (c).
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Paragraph (b)(1) requires mine
operators to provide medical
examinations during an initial 12-month
period. This change ensures that
examinations are offered to miners
during a 12-month period that begins by
the compliance date or during a 12month period that begins whenever a
new mine commences operation.
Under paragraph (b)(2), mine
operators must provide subsequent
medical examinations to miners not
new to the mining industry at least
every 5 years after the period in
paragraph (b)(1). The medical
examinations must be available during a
6-month period that begins no less than
3.5 years and not more than 4.5 years
from the end of the last 6-month period.
As discussed in Section VII.A.
Technological Feasibility, MSHA has
determined that it is technologically
feasible for MNM mine operators to
provide periodic examinations. Miner
participation would be voluntary, as is
the case for coal miners in 30 CFR
72.100(b). In the proposal, MSHA
solicited comments on possible
alternative surveillance strategies or
schedules, including whether each
voluntary examination should be
mandatory.
MSHA received many comments
about proposed § 60.15(b). Several
commenters, including the AEMA,
NVMA, NSSGA, SSC, and USW, urged
that the medical examinations remain
voluntary in the final rule (Document ID
1424; 1441; 1448; 1432; 1447;
1437;1412). The NSSGA asked MSHA to
clarify that while operators are required
to offer workers the option of
participating in medical surveillance,
workers can decline if they wish, unless
employers require it as a condition of
employment. (Document ID 1448).
In response to comments, MSHA
emphasizes that while MNM mine
operators are required to make the
medical examinations available, miner
participation is voluntary. However,
MSHA believes mine operators should
encourage miner participation because
medical surveillance is crucial for early
detection and prevention of silicarelated diseases to ensure miners’ wellbeing and safety. MSHA expects mine
operators to include information on
medical surveillance in their parts 46
and 48 training plans. MSHA will
provide guidance to mine operators on
how medical surveillance, as well as
other silica requirements in this final
rule, can best be integrated in their
existing training plans.
MSHA also considered comments
supporting different timelines for
medical surveillance frequency for
medical examinations. The American
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Thoracic Society et al. and an industry
expert recommended the adoption of a
3-year surveillance frequency
(Document ID 1421; 1437). ACOEM also
supported a 3-year frequency and
suggested a more frequent timeline
based on the discretion of the physician
(Document ID 1405). The AFL–CIO
stated that the examination frequency
should be more than every 5 years but
did not specify an alternative frequency
(Document ID 1449). The APHA stated
that medical examinations every 5 years
may not be sufficient for all miners,
particularly those with health issues or
early evidence of silica-related diseases
and recommended that MSHA revise
this provision to allow for more frequent
examinations if recommended by a
PLHCP or specialist (Document ID
1416). Arizona Mining Association
asked MSHA to clarify the required
timing for medical surveillance
examinations (Document ID 1368).
Some commenters referenced the
OSHA standard as a rationale for more
frequent medical examinations. The
AOEC, a medical professional, NSSGA,
and USW said that all miners should
have the same medical examination
frequency and should follow OSHA’s
standard of making medical
examinations available every 3 years
(Document ID 1373; 1437; 1448; 1447).
The Portland Cement Association
expressed support for using OSHA’s
exposure-based approach if medical
surveillance is in the final rule, but with
a frequency of every 5 years as in
MSHA’s proposal (Document ID 1407).
After considering the comments,
MSHA has determined that the 5-year
period for voluntary medical
examinations is appropriate, after an
initial examination within a 12-month
period starting no later than the
compliance date or within an initial 12month period of a new mine
commencing operations after the
compliance date. The 5-year period
along with the initial examination will
provide miners with information
needed for the timely detection of silicarelated diseases. Miners should use the
information obtained from medical
surveillance to establish a baseline and
make informed decisions regarding their
health. MSHA does not believe a
schedule requiring more frequent
periodic examinations is necessary. . In
the Agency’s experience with the coal
miners’ medical surveillance program,
5-year periodic examinations are
appropriate to provide miners with
information needed for early detection
of silica-related disease. MSHA intends
to provide miners and mine operators
with information and education to help
them recognize the signs and symptoms
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of silica related diseases. MSHA expects
miners will use this information to help
inform their decisions regarding their
medical care. The Agency believes the
medical examinations under the final
rule are comprehensive and will
promote miners’ health and safety.
The Agency received comments on
the timeline in proposed paragraph
60.15(b). NSSGA and IAAP stated that
that prescribing a 6-month period when
examinations must be offered creates
logistical challenges for scheduling
resources and accounting for miners’
work schedules, and they urged MSHA
not to specify when examinations
should be scheduled (Document ID
1448; 1456). However, BMC offered
support for this language, stating that
they supported MSHA’s provision that
mine operators must provide medical
surveillance to miners no later than a
specified number of years, but within a
certain range (Document ID 1417).
MSHA agrees that operators must
provide medical surveillance to miners
employed at the mine on a consistent
schedule. However, in response to
comments, MSHA has modified the
language in this paragraph to clarify the
timing of the voluntary medical
examinations. Paragraph (b)(1), changed
from the proposed rule, requires mine
operators to provide medical
examinations during an initial 12-month
period. Under paragraph (b)(2), the mine
operators must provide medical
examinations at least every 5 years after
the period in paragraph (b)(1). The final
rule specifies that medical examinations
must be available during a 6-month
period that begins no less than 3.5 years
and not more than 4.5 years from the
end of the last 6-month period. The
Agency believes the change in
paragraph (b)(1) will provide miners
necessary health information earlier
than under the proposed rule. The final
rule will ensure miners have early
detection of adverse health effects from
silica exposure. MSHA believes the final
rule safeguards miners’ health, while
fostering enhanced preventative and
protective measures within the mining
industry.
MSHA received comments asking the
Agency to clarify how to verify whether
miners have had previous medical
evaluations. NVMA asked for
clarification about how operators should
verify whether a miner new to the
operator but experienced in the industry
has already completed a medical
examination (Document ID 1441). Other
commenters, including the USW,
recommended that more efforts should
be made to encourage participation and
educate workers (Document ID 1447;
1437). The USW further stated that
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MSHA should encourage participation,
by reducing barriers such as lack of
awareness, privacy and medical
confidentiality concerns, and the fear of
retaliation, job loss, loss of potential job
advancement, and future employment
(Document ID 1447).
In response to the commenter
regarding verification of medical
examinations of newly hired
experienced miners, MSHA encourages
mine operators to work together to
determine the completion of prior
medical examinations without
compromising the confidentiality and
privacy of the miners’ health
information. MSHA clarifies that, under
the final rule, mine operators have no
obligation to verify whether a newlyhired experienced miner had a medical
examination.
MSHA believes that the rule is
designed to prioritize the health and
safety of miners by making medical
examinations available to them. MSHA
requires operators offer medical
examinations, ensuring that miners are
aware, through training, of their
availability, purpose, and health
benefits. MSHA agrees with commenters
that fostering an informed environment
where miners are made aware of the risk
of silica exposure will encourage miners
to take advantage of the availability of
medical examinations. The final rule is
designed to help miners become more
aware of how medical surveillance can
protect them against silica risks. In
response to commenters’ concern about
discrimination and retaliation, MSHA
investigates, in accordance with its
responsibility under the Mine Act,
discrimination complaints to encourage
miners to exercise their rights under the
Mine Act, including the right to medical
evaluations. 30 U.S.C. 815(c).
c. 60.15(c)—Mandatory Medical
Examinations
Final paragraph (c) requires MNM
mine operators to provide a mandatory
initial medical examination for each
MNM miner who is new to the mining
industry. Under paragraph (c)(1), the
mandatory initial medical examination
must occur no later than 60 days after
a miner new to the industry begins
employment. This is a change from the
proposed rule, which required the
initial medical examination within 30
days. Final paragraphs (c)(2) and (3) are
unchanged from the proposed rule.
Under paragraph (c)(2), mine operators
are required to provide a mandatory
follow-up medical examination to the
miner no later than 3 years after the
miner’s initial medical examination.
Final paragraph (c)(3) requires that, if a
miner’s 3-year follow-up medical
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examination shows evidence of
pneumoconiosis or decreased lung
function, the operator provide the miner
with another mandatory follow-up
medical examination with a specialist,
as defined in § 60.2, within 2 years.
MSHA determined that a 3-year
follow-up is appropriate because there
are some individuals who respond
adversely to respirable coal mine dust
exposure relatively quickly, and it is
important to identify those individuals
early. A 3-year interval at the start of a
miner’s career will provide necessary
information for evaluating the results of
subsequent spirometry tests and final
paragraph (c)(1) requires a mandatory
follow-up examination be given 3 years
after the miner’s initial examination.
This is consistent with the 2014 RCMD
Standard. See 30 CFR 72.100.
MSHA received comments on
mandatory medical examinations. A
couple of commenters, including BMC
and AOEC, offered support for
mandatory medical examinations, with
some stating that medical examinations
should be a mandatory requirement for
both new and existing miners
(Document ID 1417; 1373). MCPA
opposed mandatory examinations even
for new miners, stating that
participation in medical surveillance is
a personal choice that should be left up
to each miner (Document ID 1406). NLA
stated that making medical
examinations mandatory for new miners
would make it difficult to retain new
hires (Document ID 1408).
NSSGA, IAAP, and BMC stated that
MSHA should not prohibit operators
from making participation in medical
surveillance a mandatory condition of
employment, if the mine operator
believes mandatory participation is
warranted (Document ID 1448; 1456;
1417). Some commenters, including
USW, were opposed to mine operators
mandating medical examinations as a
condition of employment (Document ID
1447; 1437; 1412). One commenter
emphasized that miners could be
terminated for declining to visit an
operator’s selected PLHCP (Document
ID 1412). The Brick Industry
Association stated that if participation
in a medical surveillance program is a
condition of employment, companies
will not be able to staff their operations
(Document ID 1422).
Arizona Mining Association requested
clarification on whether medical
surveillance services are mandatory or
are just required to be made available to
the miners upon request. (Document ID
1368). PACA, IAAP, and NSSGA asked
MSHA to clarify whether operators can
make medical surveillance mandatory,
and whether operators may conduct
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more extensive medical surveillance
than required under the proposed rule
(Document ID 1413; 1456; 1448). BMC
asked if operators can make medical
examinations mandatory as long as they
meet MSHA’s minimum medical
surveillance requirements (Document ID
1417).
In response to these comments,
MSHA notes that it is aware that some
mine operators already have mandatory
health screening as part of their
employment policies. MSHA is also
aware that some operators require
periodic health examinations as part of
their industrial hygiene practices. As a
result, mandatory medical examinations
may not be new for some mine
operators. Many operators make
participation in medical surveillance a
mandatory condition of employment as
a part of their overall safety and health
program for their workforce. In response
to comments, operators can conduct
more extensive medical surveillance
and can make medical examinations
mandatory as long as they meet MSHA’s
minimum medical surveillance
requirements. The Agency does not
intend for the final rule’s requirements
to interfere with the operator’s decisionmaking process with respect to
managing its operation and miners.
The Agency has weighed USW and
other commenters’ concerns about the
final rule making medical examinations
mandatory and determined that it is
critical to administer medical
examinations when MNM miners first
enter the profession. Mandatory
examinations provided in close
proximity to when miners are first hired
and first exposed to respirable coal mine
dust are necessary in order to establish
an accurate baseline of each miner’s
health. Miners may not recognize early
symptoms of silica-related disease;
therefore, they might not be likely to
seek medical assistance.
MSHA received comments requesting
a longer period for initial medical
examinations. The NSSGA, PACA,
CalCIMA, and IAAP suggested that
many miners new to the industry will
not continue employment beyond an
initial probation period due to the
physical demands of the work
(Document ID1448; 1413; 1433; 1456).
During the Denver, Colorado public
hearing, one commenter suggested
making the period for medical
examinations for new miners longer, so
that mine operators would be providing
medical examinations for those new
miners who are more likely to remain
employed (Document ID 1375). MSHA
agrees with the commenter and has
changed final paragraph (c)(1) to require
an initial medical examination no later
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than 60 days after beginning
employment. This is a change from the
proposed rule, which would have
required mine operators to ensure
miners had a medical examination
within 30 days after beginning
employment. This will help mine
operators use their resources to provide
medical examinations for new miners
who are more likely to continue
employment.
The NSSGA and Vanderbilt Minerals,
LLC suggested eliminating the mandate
for a follow-up examination after an
observed decrease in lung function, as
that requirement is too broad, and the
decrease could be due to nonoccupational contaminants (Document
ID 1448; 1419). In response to
comments, the Agency has not included
this change in the final rule. MSHA
acknowledges the complex nature of
lung function decrease; the final rule
includes a medically sound approach
that aligns examinations and subsequent
actions with individual miner’s health
statuses and occupational exposure
profiles. Evaluating lung function and
changes in lung burden is a normal
function of assessing the development
of lung diseases. This provision will
allow for a uniform approach to medical
surveillance that is already
implemented in the coal industry.
Some mining trade associations
suggested that mandatory examinations
be triggered by a specific level of
exposure, instead of being required for
all miners new to the industry
(Document ID 1408; 1428; 1448; 1424).
The final rule does not include a
‘‘trigger provisions because the Agency
believes it is necessary to maintain
consistency between the final rule’s
requirements for MNM mines and
existing medical surveillance standards
for coal mines. In MSHA’s experience,
medical surveillance requirements
benefit coal miners, and the Agency has
implemented outreach initiatives to
expand coal miners’ participation.
MSHA believes that aligning the MNM
medical surveillance requirements with
the requirements for coal mines will
effectively protect the health and safety
of MNM miners.
d. 60.15(d)—Medical Examinations
Results
Proposed paragraph (d) would have
required that the results of any medical
examination performed under this
section be provided by the PLHCP or
specialist only to the miner and, at the
request of the miner, to the miner’s
designated physician. In response to
comments, MSHA added language
under paragraph (d)(1) to require the
PLHCP or specialist to provide test
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results within 30 days of the medical
examination and added a requirement
that the PLHCP provide test results to
another designee identified by the
miner. Under paragraph (d)(2), the
proposed provision was changed to
require mine operators to ensure, within
30 days of the medical examination, that
the PLHCP provide results of the chest
x-ray classifications to NIOSH, once
NIOSH establishes a reporting system.
MSHA received comments regarding
the sharing of the medical examination
results. Several commenters from MNM
operators and mining industry
organizations stated the medical
examination results should be shared
with the operator (Document ID 1424;
1417; 1456; 1441; 1448). The NSSGA
suggested medical providers be required
to send a written medical opinion to the
operator if the operator requires the
miner to sign a medical release form
stating what information can be shared
with the operator (Document ID 1448).
This commenter also stated that
examination results need to be shared
with the operator as soon as possible, so
that the operator can take actions to
protect miners’ health (Document ID
1448). Other commenters, including
BMC, AEMA, and NVMA, suggested
that medical examination results should
be shared with mine operators
(Document ID 1417; 1424; 1441). AEMA
stated that the failure to communicate a
confirmed diagnosis to the mine
operator may inadvertently adversely
hamper the miner’s ability to receive
compensation under workers’
compensation program (Document ID
1424). However, commenters from labor
organizations and medical professional
associations stated that the proposed
standard ensures that miners’ medical
confidentiality is protected when those
miners undergo medical surveillance
(Document ID 1398; 1447; 1449; 1410;
1373).
MSHA agrees with the commenters
who expressed concerns regarding the
confidentiality and timeliness of
medical examination results. Under
final paragraph (d)(1), MSHA modified
the language of the proposal to clarify
that the final rule requires the mine
operator to ensure the PLHCP or
specialist provide the medical
examination results only to the miner,
or to the miner’s designated physician
or another designee identified by the
miner, and that this be done within 30
days of the examination. Paragraph
(d)(1) ensures that the mine operator
does not receive the miner’s medical
examination results. MSHA also added
a provision to paragraph (d)(1)
specifying that the miner can add a
designee to receive the examination
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results in addition to the miner’s
physician, in case the miner needs to
provide the examination results to other
persons, such as family members or a
health care professional who is not a
physician. MSHA believes the timely
receipt of medical examination results is
important to allow the miner to make
informed decisions regarding their
health. Therefore, the Agency adds the
requirement that the mine operator must
ensure that the PLHCP or specialist
provide the miner with their medical
examination results within 30 days.
Under paragraph (e), the mine
operator will obtain a written medical
opinion from the PLHCP or specialist
within 30 days of the medical
examination. The written opinion must
contain only the following: the date of
the medical examination, a statement
that the examination has met the
requirements of this section, and any
recommended limitations on the
miner’s use of respirators. No other
information from the miner’s medical
examination may be obtained by the
mine operator. Based on MSHA’s
experience with medical surveillance
for coal miners, the Agency believes that
confidentiality regarding medical
conditions is essential, because it
encourages miners to take advantage of
the opportunity to detect early adverse
health effects caused by respirable
crystalline silica. (79 FR 24813, 24928).
The AIHA and the Black Lung Clinics
expressed support for a requirement that
operators submit medical surveillance
plans to NIOSH for approval (Document
ID 1351; 1410). ACOEM stated that if
submitting for NIOSH approval creates
administrative bottlenecks, employers
should instead be allowed to contract
with qualified physicians for these
examinations, with the requirement that
the supervising physician be boardcertified in pulmonary disease or
occupational medicine or another
American Board of Medical Specialties
(ABMS) (Document ID 1405). Two
commenters, the NVMA and AEMA,
stated that NIOSH is not a regulatory
agency, and thus should not oversee
medical surveillance plans (Document
ID 1441; 1424).
The Black Lung Clinics suggested that
medical examination results should be
reported to NIOSH so that MSHA can
monitor the effectiveness of dust
controls (Document 1410). This
commenter further suggested that
MSHA create a repository for all
screening results accessible to health
care providers that can help detect early
disease (Document ID 1410). The
UMWA recommended that MSHA work
with NIOSH to expand the Coal Workers
Health Surveillance Program’s mobile
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units to screen MNM miners as well or,
alternatively, create new Health
Surveillance Program mobile units
targeting MNM miners (Document ID
1398).
After considering the comments,
MSHA agrees with commenters that
medical examination results should be
submitted to NIOSH. MSHA has added
a new final paragraph (d)(2) that
requires the mine operator to ensure
that, within 30 days of a miner’s
medical examination, the PLHCP or
specialist provides the results of chest
X-ray classifications to NIOSH, once
NIOSH establishes a reporting system.
The final rule does not require medical
surveillance plans or NIOSH approval of
them. MSHA agrees with commenters’
concerns that having MNM mine
operators develop and submit a medical
surveillance plan for approval could
cause administrative delays and
adversely affect miners’ health. The new
requirement to submit chest X-ray
classifications to NIOSH for
occupational health research will
provide the public important health
information related to respirable
crystalline silica disease and MSHA
expects this information will provide a
public health benefit.
This requirement is important
because NIOSH intends to work with
MSHA and the MNM mining
community to create a reporting system
to help mine operators ensure that
PLHCPs or specialists may easily submit
the required information. MSHA and
NIOSH will inform mine operators and
other stakeholders in a timely manner
when the reporting system is available.
When NIOSH establishes the system,
NIOSH and MSHA will issue a joint
notice to the mining community. In this
notice, NIOSH and MSHA will include
the logistics of the reporting system,
information on how operators can
ensure that the PLHCPs provide the
required information to NIOSH, and
information on how miners and medical
professionals can effectively use the
system. This information will be posted
on both Agencies’ websites. MSHA
enforcement and Educational Field and
Small Mine Services (EFSMS) staff will
work with operators to facilitate
compliance.
e. 60.15(e)—Written Medical Opinion
As discussed above, final paragraph
(e), unchanged from the proposed rule,
requires MNM mine operators to obtain
a written medical opinion from a
PLHCP or specialist within 30 days of
the medical examination, and requires
that this opinion include only the date
of a miner’s medical examination, a
statement that the examination has met
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the requirements of this section, and
any recommended limitations on the
miner’s use of respirators. The purpose
of the opinion is to enable the mine
operator to verify the examination has
occurred and to provide the operator
with information on miners’ ability to
use respirators.
The Agency received several
comments regarding proposed
paragraph (e). One commenter, the
CalCIMA, was concerned about whether
the medical opinion would be available
in a timely manner (Document ID 1433).
MSHA understands the commenter’s
concern. The Agency believes that the
30-day requirement to provide the
medical opinion regarding the
recommended limitation on the miner’s
use of respirators should provide the
mine operator sufficient notice to
address any issues.
The AOEC suggested that MSHA
should follow OSHA in requiring
clinicians to prepare a written report to
the worker and provide a written
medical opinion to the employer
(Document ID 1373). That commenter
stated that under OSHA’s rule, the
report remains confidential, the
clinician discusses the examination
results with the worker, and the worker
signs a medical release form that
clarifies what information the employer
has received (Document ID 1373).
MSHA notes that its final rule includes
requirements similar to OSHA’s
reporting requirements in that the
operator receives very limited
information and will not be apprised of
the results of the examination. Because
the mine operator is receiving very
limited information, MSHA determined
that a medical release form signed by
the miner is not necessary.
f. 60.15(f)—Written Medical Opinion
Records
Final paragraph (f), unchanged from
the proposed rule, requires the mine
operator to maintain a record of the
written medical opinion obtained from
the PLHCP or specialist under
paragraph (e). This requirement
provides a record to ensure compliance
with the standard. MSHA received
comments on the record retention
requirements for written medical
opinion records that are discussed
further in Section VIII.B.9.a. Records
retention periods.
g. Compliance Assistance
The NSSGA highlighted the
importance of compliance assistance for
mines, especially small mines that do
not have experience with medical
surveillance programs (Document ID
1448). MSHA agrees with the
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commenter that compliance assistance
is needed and will develop compliance
materials to assist mine operators in
implementing the final rule, including
the medical surveillance requirements.
MSHA will work with the mining
community to ensure the final rule is
implemented consistently and in a
manner that adds to existing protections
for miners. See the more complete
discussion on MSHA’s compliance
assistance for this rulemaking under
Section VIII.A. General Issues.
9. Section 60.16—Recordkeeping
Requirements
Section 60.16 identifies recordkeeping
retention requirements for records
created in part 60. The final rule
requires mine operators to retain
evaluation, sampling, and corrective
actions records for at least 5 years. The
final rule requires mine operators to
retain written determination records
and written medical opinion records for
the duration of a miner’s employment
plus 6 months. It also requires mine
operators, upon request from an
authorized representative of the
Secretary, from an authorized
representative of miners, or from
miners, to promptly provide access to
any record listed in § 60.16.
In the proposal, MSHA sought
comment on the utility of the
recordkeeping requirements in this
section. MSHA received several
comments on the proposed
recordkeeping requirements, including
from an industrial hygiene professional
association and mining trade
association, supporting the Agency’s
proposed recordkeeping provisions
(Document ID 1351; 1424). A MNM
operator and mining trade association
opposed the recordkeeping
requirements, stating that the
requirements were duplicative and
should be more flexible (Document ID
1419; 1448). Below is a detailed
discussion of the comments received on
this section.
a. Records Retention Periods
MSHA received comments from labor
unions, advocacy organizations, one
MNM operator, and a federal elected
official requesting an increase in the
retention periods for sampling records
(Document ID 1398; 1416; 1417; 1425;
1439; 1447; 1449). Records that were to
be retained by the mine operator under
this section include evaluation,
sampling, and corrective actions
records, as described in proposed
paragraphs 60.16(a)(1) to (3).
USW and AFL–CIO stated that
increased record retention is
particularly important for MNM mines,
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which are typically surface mines and
are inspected less frequently than
underground coal mines (Document ID
1447; 1449). The UMWA recommended
that, for MNM miners, operators should
be required to keep records specified
under paragraphs (a)(1) to (3) for 30
years and to provide those records to the
miner on termination of employment;
operators be required to transfer records
to a successor employer; and when an
employer is ceasing operations and
there is no successor employer to
receive the record, the employer notify
affected employees of their rights of
access to records at least 3 months prior
to the cessation of the employer’s
business (Document ID 1398). BMC
stated that the sampling and corrective
actions records proposed to be retained
for at least 2 years should be required
to be preserved indefinitely (Document
ID 1417). Appalachian Voices
recommended that all records regarding
sampling be retained for longer than the
life of the mine operation (Document ID
1425).
USW and AFL–CIO expressed
concern that retaining records for 2
years would be insufficient to establish
a pattern of exposure or provide other
critical information such as the
evaluation of corrective actions. Labor
unions, advocacy organizations, a MNM
operator, and an individual suggested
that MSHA should align its
recordkeeping requirements with the
OSHA silica standard recordkeeping
requirements (29 CFR 1910.1020)
(Document ID 1398; 1412; 1416; 1417;
1425; 1447).
In response to comments requesting
an increase in the record retention
period, the final rule increases the
record retention period for evaluation,
sampling, and corrective actions records
in paragraphs (a)(1) to (3) to at least 5
years. Increasing to the 5-year record
retention period for evaluation,
sampling, and corrective actions records
will help mine operators, miners, and
MSHA better evaluate and monitor
changes in exposures, understand
health hazards, and ensure the
implementation and maintenance of
proper controls to protect miners from
health hazards associated with
respirable crystalline silica.
Under final (a)(1) and (2), evaluation
and sampling records confirm that
sampling results accurately represent
current exposure conditions. The 5-year
recordkeeping requirement for
evaluation and sampling records will
provide mine operators with robust
information to enable them to
understand a history of occupational
exposures at the mines and to take
appropriate actions to protect miners,
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such as implementing engineering and
administrative controls. Evaluation and
sampling records can identify
overexposures due to changes in
production, processes, controls, or
geological conditions. These records
help mine operators develop,
implement, and adjust controls and
other measures that protect miners from
overexposures. In addition, these
expanded records will provide miners
and their representatives with
information about exposure patterns
over time to understand health hazards
at their mines and to make informed
decisions about their health care. As
some commenters noted, this
information can be invaluable to miners
who have already been diagnosed with
an illness or experienced negative
health effects and help them to make
decisions about their health and future
employment. The 5-year records of
evaluation and sampling will also
enable MSHA staff in Technical Support
and Educational Field and Small Mine
Services to provide needed compliance
assistance.
The 5-year recordkeeping requirement
for corrective actions records in final
paragraph (a)(3) will help mine
operators and MSHA enforcement staff
determine if existing controls are
effective, or if maintenance or
additional controls are needed. In
MSHA’s experience, the cumulative
record provides MSHA and mine
operators with information to identify
trends in exposures and operational
changes. Mine operators can use trend
information to determine the
effectiveness of controls over time and
to take proactive measures to prevent
future overexposures, while miners and
their representatives can use the trend
information to determine health hazards
and protection needs at their mines.
MSHA has determined that the 5-year
retention period in final paragraphs
(a)(1) to (3) balances the operator’s
burden to maintain records and the
need for this information to take
appropriate action to protect miners’
health. The 5-year record retention is
also consistent with MSHA’s record
retention period for operator samples
collected for diesel particulate matter in
underground metal and nonmetal mines
(§ 57.5071(d)(2)) and other injury and
illness reports required for all mines
(§ 50.40). From MSHA’s experience and
observation, informed miners who are
aware of occupational health hazards
around them are more likely to follow
safe work practices and to report these
hazards to their operators or MSHA
when necessary. When miners are aware
of occupational health hazards and
participate in the identification,
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remediation, and control of those
hazards, the overall level of safety and
health at the mine will be improved. In
sum, informed miners are more likely
and better able to play an active role in
safety and health as the Mine Act
envisions and better protect themselves
and other miners.
MSHA notes that minor changes have
been made to final paragraphs (a)(1) to
(3) to change the citation for the records
addressed and to reflect changes
discussed in § 60.12 and 60.13. MSHA
has similarly revised the citations in
Table 1 to Paragraph (a)—
Recordkeeping Requirements.
Like the proposal, final paragraphs
(a)(4) and (5) require that the written
determination by a PLHCP that a miner
is unable to wear a respirator
under § 60.14(b), as well as the medical
surveillance records under§ 60.15(f), be
retained for the duration of the miner’s
employment plus 6 months. MSHA
received several comments regarding
the retention period for medical
surveillance records, with most
commenters supporting a longer
retention period.
UMWA recommended that medical
surveillance records be kept for 30 years
and provided to the miner on
termination of employment; that
operators be required to transfer records
to a successor employer; and that when
an employer is ceasing operations and
there is no successor employers to
receive the record, the employer be
required to notify affected employees of
their rights of access to records at least
3 months prior to the cessation of the
employer’s business Document ID
1398). AOEC, APHA, and USW
suggested that MSHA should align its
recordkeeping requirements for medical
surveillance records with the OSHA
silica standard recordkeeping
requirements (29 CFR 1910.1020)
(Document ID 1373; 1416; 1447). These
same commenters and a black lung
clinic and an individual suggested that,
given the latency periods associated
with health effects from silica exposure,
medical surveillance records are
invaluable for miners who are
diagnosed with silica-related health
conditions (Document ID 1373; 1416;
1447; 1418; 1412).
In response to these comments,
MSHA reiterates that mine operators do
not have access to a miner’s medical
information and therefore, do not
maintain a record of such information.
Only the PLHCP’s written determination
made under paragraph 60.14(b) on
whether a miner is able to wear a
respirator must be provided to mine
operators. Under the final rule, as in the
proposal, the mine operator will retain
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the written determination record for the
duration of miner employment plus six
months.
Under final 60.15(d), medical
examination results must be provided to
the miner, at the request of the miner,
to the miner’s designated physician or
another designee identified by the
miner, and to NIOSH, once NIOSH
establishes a reporting system. MSHA is
not regulating the retention of medical
examination results since they are not
provided to the mine operator. The
medical surveillance information (the
written medical opinion records) that
the mine operator will retain under final
paragraph (a)(5) includes a record of the
date of the medical examination, a
statement that the examination has met
the requirements of this section, and
any recommended limitations on the
miner’s use of respirators. MSHA
believes that retaining these medical
surveillance records for the duration of
the miner’s employment plus 6 months
is appropriate. The requirement to
retain records for an additional 6
months beyond the miner’s employment
gives a miner more time to request
records if the miner is employed at
another mine. For example, a miner
who was determined to be medically
unable to wear a respirator may need
this record for new mine operator. The
final rule does not increase the retention
period because, as described above, the
written medical opinion that the
operator receives contains only basic
information compared to the medical
examination records that are in the
miner’s possession and control.
NVMA asked for clarification on the
medical surveillance recordkeeping
requirements, remarking that the rule
does not include provisions requiring
tracking of miners’ exposure throughout
their careers and noting that miners
often change companies over the course
of their careers (Document ID 1441).
This commenter asked whether it would
be assumed that a miner’s occupational
illness stems from work with their
current employer, even if all samples
and medical surveillance show the
miner was not exposed above the PEL
during their current employment.
MSHA reiterates that each miner’s
medical examination results are
provided to that miner, to the miner’s
physician or other designee at the
request of the miner, and to NIOSH,
once NIOSH establishes a reporting
system. NIOSH’s reporting system, once
established, will provide public health
information on rates of silica-related
disease, tenure, and prevalence in the
MNM industry.
Miners will have access to all medical
examination results obtained under this
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part and will be able to track any
impacts of exposure. The purpose of the
medical surveillance examination
requirements is to help miners seek help
from medical professionals who can
identify early symptoms of respirable
crystalline silica-related diseases and
inform them of their health status, so
that they can take early and necessary
steps to protect their health.
Vanderbilt Minerals, LLC stated that
medical records are required to be
collected under the Health Insurance
Portability and Accountability Act and
that an additional requirement by
MSHA would be duplicative and
unnecessary (Document ID 1419).
MSHA clarifies that the mine operator is
not responsible for obtaining and
preserving the miner’s medical
examination results or records.
Therefore, there is no duplication of
collecting medical records.
b. Access to Records Maintained Under
60.16
Final paragraph 60.16(b), like the
proposal, requires mine operators to
make records in this section available
promptly upon request to miners,
authorized representatives of miners,
and authorized representatives of the
Secretary of Labor. A federal elected
official stated that MSHA should require
sampling records and any other
information required to be posted on the
mine bulletin board to be submitted to
miner representatives (Document ID
1439). This commenter also urged
MSHA to require operators to provide
cumulative exposure records to the
miner upon request, similar to 30 CFR
57.5040. A miner health advocate
suggested that corrective actions records
should be required to be submitted to
MSHA and miner representatives
(Document ID 1372).
After considering the comments,
MSHA determined that no change to
final paragraph (b) is necessary. The
requirement to provide all the listed
records promptly upon request to
miners, authorized representatives of
miners, and authorized representatives
of the Secretary of Labor ensures that
miners and MSHA will have access to
records as needed which facilitates
enforcement and transparency. Miners,
miners’ representatives, and MSHA can
request the records in this section at any
time; therefore, MSHA has determined
that it is not necessary to require
operators submit records to miners,
miners’ representatives, and MSHA
without request.
c. Other Comments
The APHA suggested that all required
records should be made available to
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28347
NIOSH (Document ID 1416). As
discussed in response to comments
under paragraph 60.15(d)(2), MSHA is
requiring that the results of chest X-ray
classifications obtained under medical
surveillance examinations be made
available to NIOSH for its research.
MSHA has determined that it is not
necessary to provide other records
required under part 60 to NIOSH.
The AIHA supported the proposed
recordkeeping requirements and
recommended that operators be required
to develop and maintain exposure
control plans that identify the tasks that
involve miners’ exposures above the
PEL and the methods used to protect
miners, including procedures to restrict
access to work areas where high
exposures may occur (Document ID
1351).
After considering the comment,
MSHA has concluded that an exposure
control plan record is not necessary,
because of the sampling and control
methods required. As required under
part 60, mine operators must use
engineering and administrative controls
to prevent overexposures to respirable
crystalline silica. Under § 60.12(c), mine
operators are required to evaluate these
controls at least every 6 months or
whenever there is a change in
production, processes, installation and
maintenance of engineering controls,
installation and maintenance of
equipment, administrative controls, or
geological conditions to determine if the
change is reasonably expected to result
in new or increased respirable
crystalline silica exposures. The
operator must make a record of the
evaluation, including the evaluated
change, the impact on respirable
crystalline silica exposure, and the date
of the evaluation and post the record on
the mine bulletin board and, if
applicable, by electronic means, for the
next 31 days. Operators are expected to
conduct these evaluations to assess
changing conditions on a regular basis
to ensure miners are not exposed at
levels above the PEL. The evaluation
records provide important information
to mine operators to enable them to
implement effective control methods to
protect miners, to identify occupations
and work areas where there is a risk of
overexposure, and to make necessary
adjustments. MSHA has determined
requiring exposure control plan records
is not necessary.
Under paragraph 60.12(g), when mine
operators sample for respirable
crystalline silica, operators must make a
record of the sample date, the
occupations sampled, and the
concentrations of respirable crystalline
silica and respirable dust, must obtain
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the laboratory report, and must make
the information available to the miners.
This record will enable operators and
miners to identify those tasks where
overexposures may have occurred and
individuals who may be overexposed, as
the commenter suggested. Under
§ 60.13(b), operators must make a record
of any corrective actions. This record
will provide mine operators with
necessary information to determine
which control methods should be
developed, implemented, and
maintained to prevent exposures above
the PEL. Miners can use this
information to take a proactive approach
to their health.
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10. Section 60.17—Severability
The final rule includes a statement of
severability that each section of this
part, as well as sections in 30 CFR parts
56, 57, 70, 71, 72, 75, and 90 that
address respirable crystalline silica or
respiratory protection, is separate and
severable from the other sections and
provisions.
The severability clause under § 60.17
serves two purposes. First, it expresses
MSHA’s intent that if any section or
provision of the Lowering Miners’
Exposure to Respirable Crystalline
Silica and Improving Respiratory
Protection rule—including its
conforming amendments in sections of
30 CFR parts 56, 57, 70, 71, 72, 75, and
90 that address respirable crystalline
silica or respiratory protection—is held
invalid or unenforceable or is stayed or
enjoined by any court of competent
jurisdiction, the remaining sections or
provisions should remain effective and
operative. Second, the severability
clause expresses MSHA’s judgment,
based on its technical and scientific
expertise, that each individual section
and provision of the rule can remain
effective and operative if some sections
or provisions are invalidated, stayed, or
enjoined. Accordingly, MSHA’s
inclusion of this severability clause
addresses the twin concerns of Federal
courts when determining the propriety
of severability: identifying agency intent
and clarifying that any severance will
not undercut the structure or function of
the rule more broadly. Am. Fuel &
Petrochem. Mfrs. v. Env’t Prot. Agency,
3 F.4th 373, 384 (D.C. Cir. 2021)
(‘‘Severability ‘depends on the issuing
agency’s intent,’ and severance ‘is
improper if there is substantial doubt
that the agency would have adopted the
severed portion on its own’’’) (quoting
North Carolina v. FERC, 730 F.2d 790,
796 (D.C. Cir. 1984) and New Jersey v.
Env’t Prot. Agency, 517 F.3d 574, 584
(D.C. Cir. 2008)).
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Under the principle of severability, a
reviewing court will generally presume
that an offending provision of a
regulation is severable from the
remainder of the regulation, so long as
that outcome appears consistent with
the issuing agency’s intent, and the
remainder of the regulation can function
independently without the offending
provision. See K Mart Corp. v. Cartier,
Inc., 486 U.S. 281, 294 (1988)
(invalidating and severing subsection of
a regulation where it would not impair
the function of the statute as a whole
and there was no indication the
regulation would not have been passed
but for inclusion of the invalidated
subsection). Consequently, in the event
that a court of competent jurisdiction
stays, enjoins, or invalidates any
provision, section, or application of this
rule, the remainder of the rule should be
allowed to take effect.
MSHA did not receive any comments
on this section. Final § 60.17 is the same
as proposed.
C. Conforming Amendments
The final rule makes conforming
amendments in 30 CFR parts 56, 57, 70,
71, 72, 75, and 90 based on the new part
60. The compliance dates for the
conforming amendments align with the
compliance dates for part 60.
Compliance with the conforming
amendments to parts 56 and 57 is
required by 24 months after publication,
for MNM operators; and compliance
with the conforming amendments to
parts 70, 71, 72, 75, and 90 is required
by 12 months after publication, for coal
mine operators. The compliance dates
for the conforming amendments assure
that miners are protected under the
existing standards until mine operators
are required to comply with part 60.
In other words, existing sections in
parts 56 and 57 will remain in place for
24 months following publication. For
MNM operators, compliance with the
conforming amendments in parts 56 and
57 is not required until 24 months after
publication. Existing sections in parts
70,71, 72, 75, and 90 will remain in
place for 12 months following
publication. For coal operators,
compliance with the conforming
amendments in these parts is not
required until 12 months after
publication.
For the conforming amendments, a set
of instructions involving the
establishment of temporary sections and
redesignation of those sections are
required for the Federal Register to
maintain existing standards for parts 56,
57, 70, 71, 72, 75, and 90 until their
respective compliance dates. On the
effective date of the final rule (60 days
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after publication), the conforming
amendments will be published to
temporary sections, designated by the
suffix ‘‘T’’ at the end of the section
number (e.g., § 56.5001T). These
temporary sections indicate how the
paragraphs will read on the compliance
dates. On the compliance dates, the
existing sections associated with
conforming amendments will be
removed and the temporary sections
will be redesignated without the ‘‘T’’ to
replace the removed section (e.g.
§ 56.5001T will be redesignated
§ 56.5001). With the redesignation,
compliance with the conforming
amendments will be required.
The conforming amendment changes
to respiratory protection standards are
discussed in Section VIII.D Updating
MSHA Respiratory Protection
Standards: Incorporation of ASTM
F3387–19 by Reference.
1. Part 56—Safety and Health
Standards—Surface Metal and
Nonmetal Mines
a. Section 56.5001—Exposure Limits
For Airborne Contaminants
The final rule, like the proposal,
amends § 56.5001(a) to add respirable
crystalline silica as an exception.
Amended paragraph (a) governs
exposure limits for airborne
contaminants other than respirable
crystalline silica and asbestos for
surface MNM mines. MSHA did not
receive any comments on the proposed
change.
In a change from the proposal, MSHA
makes a non-substantive change to
paragraph (a) to update the terminology
for the name of the MSHA District
Office to the Mine Safety and Health
Enforcement District Office. The Mine
Safety and Health Enforcement District
Office covers both MNM mines and coal
mines since the Agency no longer
maintains separate offices for both types
of mines. The Agency no longer
differentiates between MNM District
Offices and Coal District Offices. This
change was not discussed in the
proposal.
b. Temporary Section Until Compliance
Date
As described above, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 56. Then, 720 days
after publication of the final rule, the
existing section for the conforming
amendments in part 56 will be removed
and the temporary section will be
redesignated without the ‘‘T’’ to replace
the removed section. The result of these
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technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
2. Part 57—Safety and Health
Standards—Underground Metal and
Nonmetal Mines
a. Section 57.5001—Exposure Limits
For Airborne Contaminants
The final rule, like the proposal,
amends § 57.5001(a) to add respirable
crystalline silica as an exception.
Amended paragraph (a) governs
exposure limits for airborne
contaminants other than respirable
crystalline silica and asbestos for
underground MNM mines. MSHA did
not receive any comments on the
proposed change.
In a change from the proposal, MSHA
makes a non-substantive change to
paragraph (a) to update the terminology
for the name of the MSHA district office
to the Mine Safety and Health
Enforcement District Office. The Mine
Safety and Health Enforcement District
Office covers both MNM mines and coal
mines since the Agency no longer
differentiates between MNM District
Offices and Coal District Offices. This
change was not discussed in the
proposal.
b. Temporary Section Until Compliance
Date
As described above, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 57. Then, 720 days
after publication of the final rule, the
existing section for the conforming
amendments in part 57 will be removed
and the temporary section will be
redesignated without the ‘‘T’’ to replace
the removed section. The result of these
technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
3. Part 70—Mandatory Health
Standards—Underground Coal Mines
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a. Section 70.2—Definitions
The final rule, like the proposal,
removes the quartz definition in § 70.2
since the Agency is adopting an
independent respirable crystalline silica
standard in part 60. Therefore, the term
quartz no longer appears in part 70.
MSHA did not receive any comments on
the proposed change.
b. Section 70.101—Respirable Dust
Standard When Quartz Is Present
The final rule, like the proposal,
removes § 70.101 in its entirety and
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reserves the section number. Section
70.101, Respirable dust standard when
quartz is present, is no longer needed
because MSHA is adopting an
independent respirable crystalline silica
standard in part 60.
As discussed in greater detail in
Section VIII.B.3.b PEL in coal mines, of
this preamble, MSHA solicited
comments on whether to eliminate the
reduced standard for total respirable
dust when quartz is present at coal
mines and received feedback from
stakeholders generally agreeing with the
Agency’s proposal to establish a
standard for respirable crystalline silica
that is independent from the respirable
coal mine dust standard. For example,
the NMA, the MCPA and the
Pennsylvania Coal Alliance supported
the removal of the respirable dust
standards when quartz is present (i.e.,
§§ 70.101 and 71.101, and 90.101),
reasoning that they are no longer needed
since the rule proposes a standalone
standard for respirable crystalline silica
(Document ID 1428; 1406; 1378).
In response to commenters, MSHA
has concluded that establishing an
independent and lower PEL for
respirable crystalline silica for coal
mines allows more effective control of
respirable crystalline silica than the
existing reduced standards, because the
separate standard is more transparent
and protective. MSHA clarifies that the
respirable coal mine dust standard is
not eliminated, only the sampling
requirements for when silica is present
under § 70.101. MSHA agrees with the
commenters supporting the removal of
§ 70.101.
c. Section 70.205—Approved Sampling
Devices; Operation; Air Flowrate
The final rule, like the proposal,
amends paragraph 70.205(c) to remove
the reference to the reduced RCMD
standard. References to the RCMD
exposure limit specified in § 70.100
replace references to the applicable
standard. The rest of the section remains
unchanged.
d. Section 70.206—Bimonthly
Sampling; Mechanized Mining Units
The final rule, like the proposal,
removes § 70.206 and reserves the
section number. Section 70.206
included requirements for bimonthly
sampling of mechanized mining units
which were in effect until January 31,
2016, and are no longer applicable.
e. Section 70.207—Bimonthly Sampling;
Designated Areas
The final rule, like the proposal,
removes § 70.207 and reserves the
section number. Section 70.207
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included requirements for bimonthly
sampling of designated areas that were
in effect until January 31, 2016, and are
no longer applicable.
f. Section 70.208—Quarterly Sampling;
Mechanized Mining Units
The final rule, like the proposal,
amends § 70.208 to remove references to
a reduced RCMD standard. Paragraph (c)
in § 70.208 is removed and the
paragraph designation reserved.
References to the respirable dust
standard specified in § 70.100 replace
references to the applicable standard
throughout the section.
A new table 1 is added to § 70.208.
The new table contains the Excessive
Concentration Values (ECV) for the
section based on a single sample, 3
samples, or the average of 5 or 15 fullshift coal mine dust personal sampler
unit (CMDPSU) or continuous personal
dust monitor (CPDM) concentration
measurements. The new table contains
the remaining ECV after the removal of
the reduced standard in § 70.101 and
was generated from data previously
contained in Tables 70–1 and 70–2 in
Subpart C of part 70. Conforming
changes are made to paragraphs (e) and
(f)(1) and (2) to update the name of the
table to table 1. MSHA did not receive
any comments on the proposed changes.
g. Section 70.209—Quarterly Sampling;
Designated Areas
The final rule, like the proposal,
amends § 70.209 to remove references to
a reduced RCMD standard. Paragraph
(b) in § 70.209 is removed and the
paragraph designation reserved.
References to the RCMD exposure limit
specified in § 70.100 replace references
to the applicable standard.
A new table 1 is added to § 70.209.
The new table contains the ECVs for the
section based on a single sample, 2 or
more samples, or the average of 5 or 15
full-shift CMDPSU/CPDM concentration
measurements. This table contains the
remaining ECV after the removal of the
reduced RCMD standard in § 70.101 and
was generated from data previously
contained in Tables 70–1 and 70–2 in
Subpart C of part 70. Conforming
changes are made to paragraphs (c) and
(d)(1) and (2) to update the name of the
table to table 1. MSHA did not receive
any comments on the proposed changes.
h. Subpart C—Table 70–1 and
Table 70–2
The final rule, like the proposal,
removes Table 70–1 to Subpart C of Part
70, Excessive Concentration Values
(ECV) Based on Single, Full-Shift
CMDPSU/CPDM Concentration
Measurements and Table 70–2 to
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Subpart C of Part 70, Excessive
Concentration Values (ECV) Based on
the Average of 5 or 15 Full-Shift
CMDPSU/CPDM Concentration
Measurements because § 70.101 is
removed. These tables are replaced with
new tables in §§ 70.208 and 70.209.
MSHA did not receive any comments on
the proposed change.
i. Temporary Section Until Compliance
Date
As described above, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for most of the
conforming amendments in part 70.
Then, 360 days after publication of the
final rule, the existing section for these
conforming amendments in part 70 will
be removed and the temporary section
will be redesignated without the ‘‘T’’ to
replace the removed section. The result
of these technical changes is that mine
operators must comply with the existing
standards until the compliance dates in
part 60.
4. Part 71—Mandatory Health
Standards—Surface Coal Mines and
Surface Work Areas of Underground
Coal Mines.
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a. Section 71.2—Definitions
The final rule, like the proposal,
removes the Quartz definition in § 71.2
because the Agency is removing the
respirable dust standard when quartz is
present in § 71.101. The term quartz no
longer appears in part 71. MSHA did
not receive any comments on the
proposed change.
b. Section 71.101—Respirable Dust
Standard When Quartz Is Present
MSHA is removing § 71.101 in its
entirety and reserving the section
number. The respirable coal mine dust
standard when quartz is present in
§ 71.101 is no longer needed because
MSHA is adopting an independent
respirable crystalline silica standard in
part 60.
As discussed in greater detail in
Section VIII.B.3.b. PEL in coal mines, of
this preamble, MSHA solicited
comments on whether to eliminate the
reduced standard for total respirable
dust when quartz is present at coal
mines and received feedback from
stakeholders generally agreeing with the
Agency’s proposal to establish a
standard for respirable crystalline silica
that is independent from the respirable
coal mine dust standard. For example,
the NMA, the MCPA and the
Pennsylvania Coal Alliance supported
the removal of the respirable dust
standards when quartz is present (i.e.,
§§ 70.101 and 71.101, and 90.101),
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reasoning that they are no longer needed
since the rule proposes a standalone
standard for respirable crystalline silica
(Document ID 1428; 1406; 1378).
In response to commenters, MSHA
has concluded that establishing an
independent and lower PEL for
respirable crystalline silica for coal
mines allows more effective control of
respirable crystalline silica than the
existing reduced standards, because the
separate standard is more transparent
and protective. MSHA clarifies that the
respirable coal mine dust standard is
not eliminated, only the sampling
requirements for when silica is present
under § 71.101. MSHA agrees with the
commenters supporting the removal of
§§ 71.101.
c. Section 71.205—Approved Sampling
Devices; Operation; Air Flowrate
The final rule, like the proposal,
amends paragraph (c) to remove the
reference to the reduced RCMD
standard. References to the respirable
dust standard specified in § 71.100
replace the reference to the applicable
standard.
d. Section 71.206—Quarterly Sampling;
Designated Work Positions
The final rule, like the proposal,
amends § 71.206 to remove references to
the reduced RCMD standard. Paragraph
(b) in § 71.206 is removed and the
paragraph designation reserved. Other
conforming changes for § 71.206 remove
references to the applicable standard
and replace them, where needed, with
references to the respirable dust
standard specified in § 71.100.
MSHA is also amending paragraph (l)
by removing Table 71–1 Excessive
Concentration Values (ECV) Based on
Single, Full-Shift CMDPSU/CPDM
Concentration Measurements and Table
71–2 Excessive Concentration Values
(ECV) Based on the Average of 5 FullShift CMDPSU/CPDM Concentration
Measurements since reference to a
reduced RCMD standard in § 71.101 is
removed. A new table has been added
to § 71.206.
Final paragraph (m), like the proposal,
removes the language, ‘‘in effect at the
time the sample is taken, or a
concentration of respirable dust
exceeding 50 percent of the standard
established in accordance with
§ 71.101,’’ because the reduced standard
in § 71.101 is removed.
A new table 1 is added to § 71.206.
This table contains the ECV for the
section based on a single sample, two or
more samples, or the average of five fullshift CMDPSU/CPDM concentration
measurements. This table contains the
remaining ECV after the removal of the
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reduced standard in § 71.101. It was
generated from data contained in
existing Tables 71–1 and 71–2 to
Subpart C of part 71. Conforming
changes are made to paragraphs (h) and
(i)(1) and (2) to update the name of the
table to table 1. MSHA did not receive
any comments on the proposed changes.
e. Section 71.300—Respirable Dust
Control Plan; Filing Requirements
Final § 71.300, like the proposal,
removes references to the reduced
RCMD standard. The respirable dust
standard specified in § 71.100 replaces
references to the applicable standard.
MSHA did not receive any comments on
the proposed change.
f. Section 71.301—Respirable Dust
Control Plan; Approval by District
Manager and Posting
Final § 71.301, like the proposal,
removes references to the reduced
RCMD standard. The respirable dust
standard specified in § 71.100 replaces
references to the applicable standard.
MSHA did not receive any comments on
the proposed change.
g. Temporary Section Until Compliance
Date
As described above, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for most of the
conforming amendments in part 71.
Then, 360 days after publication of the
final rule, the existing section for these
conforming amendments in part 71 will
be removed and the temporary section
will be redesignated without the ‘‘T’’ to
replace the removed section. The result
of these technical changes is that mine
operators must comply with the existing
standards until the compliance dates in
part 60.
5. Part 72—Health Standards for Coal
Mines
a. Section 72.800—Single, Full-Shift
Measurement of Respirable Coal Mine
Dust
Final § 72.800, like the proposal,
removes references to the reduced
RCMD standard. The section also
replaces references to Tables 70–1, 71–
1, and 90–1 with references to the new
tables in §§ 70.208, 70.209, 71.206, and
90.207. MSHA did not receive any
comments on the proposed changes.
b. Temporary Section Until Compliance
Date
As described above, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 72. Then, 360 days
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after publication of the final rule, the
existing section for the conforming
amendments in part 72 will be removed
and the temporary section will be
redesignated without the ‘‘T’’ to replace
the removed section. The result of these
technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
6. Part 75—Mandatory Safety
Standards—Underground Coal Mines
a. Section 75.350(b)(3)(i) and (ii)—Belt
Air Course Ventilation
The final rule, like the proposal,
updates § 75.350 by revising paragraph
(b)(3)(i) and removing paragraphs
(b)(3)(i)(A) and (B) and (b)(3)(ii).
Paragraph (b)(3)(i) is revised to ‘‘[T]he
average concentration of respirable dust
in the belt air course, when used as a
section intake air course, shall be
maintained at or below 0.5 mg/m3.’’
Paragraph (b)(3)(i)(A) is removed
because its provision has not been in
effect since August 1, 2016. Paragraph
(b)(3)(i)(B) is removed because the
language has been incorporated in
revised paragraph (b)(3)(i), making
(b)(3)(i)(B) redundant. Existing
paragraph (b)(3)(ii) is removed since it
refers to a reduced RCMD standard
under § 70.101 that is also removed.
Existing paragraph (b)(3)(iii) is
redesignated to (b)(3)(ii). MSHA did not
receive any comments on the proposed
changes.
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b. Temporary Section Until Compliance
Date
As described above, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 75. Then, 360 days
after publication of the final rule, the
existing section for the conforming
amendments in part 75 will be removed
and the temporary section will be
redesignated without the ‘‘T’’ to replace
the removed section. The result of these
technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
7. Part 90—Mandatory Health
Standards—Coal Miners Who Have
Evidence of the Development of
Pneumoconiosis.
a. Section 90.2—Definitions
The final rule, like the proposal,
removes the Quartz definition in § 90.2
because the Agency is removing the
respirable dust standard when quartz is
present in § 90.101. The term quartz no
longer appears in part 90.
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In addition, MSHA is revising the
definition of Part 90 miner to remove
‘‘the applicable standard’’ (which
referred to the reduced RCMD standard).
The revised definition just includes ‘‘the
standard’’ (which refers to the respirable
dust standard specified in § 90.100).
MSHA did not receive any comments on
the proposed change.
b. Section 90.3—Part 90 Option; Notice
of Eligibility; Exercise of Option
The final rule, like the proposal,
revises paragraph (a) in § 90.3 to remove
‘‘the applicable standard’’ (which
referred to the reduced RCMD standard)
and just include ‘‘the standard’’ (which
refers to the respirable dust standard
specified in § 90.100). MSHA did not
receive any comments on the proposed
change.
c. Section 90.100—Respirable Dust
Standard
In a change from the proposal, MSHA
updates § 90.100 by removing
paragraphs (a) and (b) and revising the
section to, ‘‘After the 20th calendar day
following receipt of notification from
MSHA that a part 90 miner is employed
at the mine, the operator shall
continuously maintain the average
concentration of respirable dust in the
mine atmosphere during each shift to
which the part 90 miner in the active
workings of the mine is exposed, as
measured with an approved sampling
device and expressed in terms of an
equivalent concentration, at or below
0.5 mg/m3.’’ Paragraph (a) is removed
because its provision has not been in
effect since August 1, 2016. Paragraph
(b) is removed because the language has
been incorporated in the revised
language above, making it redundant.
MSHA makes this change in the final
rule to match the change made in
§ 75.350(b)(3)(i).
d. Section 90.101—Respirable Dust
Standard When Quartz Is Present
The final rule, like the proposal,
removes § 90.101 in its entirety and
reserves the section number. The
respirable coal mine dust standard
when quartz is present in § 90.101 is no
longer needed because MSHA is
adopting an independent respirable
crystalline silica standard in part 60.
As discussed in greater detail in
Section VIII.B.3.b PEL in coal mines, of
this preamble, MSHA solicited
comments on whether to eliminate the
reduced standard for total respirable
dust when quartz is present at coal
mines and received feedback from
stakeholders generally agreeing with the
Agency’s proposal to establish a
standard for respirable crystalline silica
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that is independent from the respirable
coal mine dust standard. For example,
the NMA, the Metallurgical Coal
Producers Association (MCPA) and the
Pennsylvania Coal Alliance supported
the removal of the respirable dust
standards when quartz is present (i.e.,
§§ 70.101 and 71.101, and 90.101),
reasoning that they are no longer needed
since the rule proposes a standalone
standard for respirable crystalline silica
(Document ID 1428; 1406; 1378).
In response to commenters, MSHA
has concluded that establishing an
independent PEL of 50 mg/m3 for a fullshift exposure, calculated as an 8-hour
TWA for respirable crystalline silica
allows more effective control of
respirable crystalline silica than the
existing reduced standards, because the
separate standard is more transparent
and protective. MSHA clarifies that the
respirable coal mine dust standard is
not eliminated, only the sampling
requirements for when silica is present
under §§ 90.101. MSHA agrees with the
commenters supporting the removal of
§§ 90.101.
e. Section 90.102—Transfer; Notice
The final rule, like the proposal,
amends § 90.102 to remove ‘‘the
applicable standard’’ (which referred to
the reduced RCMD standard) and just
include ‘‘the standard’’ (which refers to
the respirable dust standard specified in
§ 90.100). MSHA did not receive any
comments on the proposed change.
f. Section 90.104—Waiver of Rights; ReExercise of Option
The final rule, like the proposal,
amends § 90.104 to remove ‘‘the
applicable standard’’ (which referred to
the reduced RCMD standard) and just
include ‘‘the standard’’ (which refers to
the respirable dust standard specified in
§ 90.100). MSHA did not receive any
comments on the proposed change.
g. Section 90.205—Approved Sampling
Devices; Operation; Air Flowrate
The final rule, like the proposal,
amends § 90.205 to remove ‘‘the
applicable standard’’ (which referred to
the reduced RCMD standard) and just
include ‘‘the standard’’ (which refers to
the respirable dust standard specified in
§ 90.100). MSHA did not receive any
comments on the proposed change.
h. Section 90.206—Exercise of Option or
Transfer Sampling
The final rule, like the proposal,
amends § 90.206 to remove ‘‘the
applicable standard’’ (which referred to
the reduced RCMD standard) and just
include ‘‘the standard’’ (which refers to
the respirable dust standard specified in
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§ 90.100). MSHA did not receive any
comments on the proposed change.
i. Section 90.207—Quarterly Sampling
The final rule, like the proposal,
amends § 90.207 to remove ‘‘the
applicable standard’’ (which referred to
the reduced RCMD standard) and just
include ‘‘the standard’’ (which refers to
the respirable dust standard specified in
§ 90.100).
Paragraph (b) in § 90.207 is removed
and the paragraph designation reserved.
Conforming changes are made to
paragraphs (c) and (d)(1) and (2) to
update the name of the table to table 1.
MSHA is amending paragraph (g) by
removing Table 90–1 Excessive
Concentration Values (ECV) Based on
Single, Full-Shift CMDPSU/CPDM
Concentration Measurements and Table
90–2 Excessive Concentration Values
(ECV) Based on the Average of 5 FullShift CMDPSU/CPDM Concentration
Measurements because § 90.101 is
removed. A new table 1 is added to
paragraph (g) to replace the tables
removed. The new table contains the
ECV for the section based on a single
sample, two or more samples, or the
average of 5 full-shift CMDPSU/CPDM
concentration measurements. This table
contains the remaining ECV after the
removal of the reduced standard in
§ 90.101 and was generated from data
contained in Tables 90–1 and 90–2.
MSHA did not receive any comments on
the proposed changes.
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j. Section 90.300—Respirable Dust
Control Plan; Filing Requirements
The final rule, like the proposal,
amends § 90.300 to remove ‘‘the
applicable standard’’ (which referred to
the reduced RCMD standard) and just
include ‘‘the standard’’ (which refers to
the respirable dust standard specified in
§ 90.100). MSHA did not receive any
comments on the proposed change.
k. Section 90.301—Respirable Dust
Control Plan; Approval by District
Manager; Copy to Part 90 Miner
The final rule, like the proposal,
amends § 90.301 to remove ‘‘the
applicable standard’’ (which referred to
the reduced RCMD standard) and just
include ‘‘the standard’’ (which refers to
the respirable dust standard specified in
§ 90.100). MSHA did not receive any
comments on the proposed change.
l. Temporary Section Until Compliance
Date
As described above, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 90. Then, 360 days
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after publication of the final rule, the
existing section for the conforming
amendments in part 90 will be removed
and the temporary section will be
redesignated without the ‘‘T’’ to replace
the removed section. The result of these
technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
D. Updating MSHA Respiratory
Protection Standards: Incorporation of
ASTM F3387–19 by Reference
MSHA is updating the Agency’s
existing respiratory protection standard
to help safeguard the life and health of
all miners exposed to respirable
airborne contaminants at MNM and coal
mines. The final rule amends the
Agency’s existing respiratory protection
standards to incorporate by reference
ASTM F3387–19, ‘‘Standard Practice
for Respiratory Protection’’, in
§§ 56.5005T and 57.5005T for MNM
mines and § 72.710T for coal mines
(which will become permanent
§§ 56.5005 and 57.5005 720 days after
publication and permanent § 72.710 360
days after publication). This change is
consistent with the incorporation by
reference of ASTM F3387–19 in final
§ 60.14(c)(2) making the standard’s
requirements applicable to respirable
crystalline silica, and other airborne
hazards encountered by miners. The
ASTM F3387–19 standard includes
provisions for selection, fitting, use, and
care of respirators used to remove
airborne contaminants from the air
using filters, cartridges, or canisters, as
well as respirators that protect in
oxygen-deficient or immediately
dangerous to life or health (IDLH)
atmospheres. ASTM F3387–19 is the
most recent consensus standard
developed by experts in government
and professional associations on the
selection, use, and maintenance for
respiratory equipment. The ASTM
Standard replaces American National
Standards Institute’s ANSI Z88.2–1969,
‘‘Practices for Respiratory Protection’’
(ANSI Z88.2–1969), which was
incorporated in the existing standards.
Incorporating this voluntary
consensus standard complies with the
Federal mandate—as set forth in the
National Technology Transfer and
Advancement Act of 1995 and OMB
Circular A–119—that agencies use
voluntary consensus standards in their
regulatory activities unless doing so
would be legally impermissible or
impractical. This standard also
improves clarity because it is a
consensus standard developed by
stakeholders.
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Under existing standards, whenever
respiratory protective equipment is
used, mine operators are required to
have a respiratory protection program
that is consistent with the provisions of
ANSI Z88.2–1969. At the time of its
publication, ANSI Z88.2–1969 reflected
a consensus of accepted practices for
respiratory protection.
Respirator technology and knowledge
on respiratory protection have since
advanced, and as a result, changes in
respiratory protection standards have
occurred. For example, in 2006, OSHA
revised its respiratory protection
standard to add definitions and
requirements for Assigned Protection
Factors (APF) and Maximum Use
Concentrations (MUCs) (71 FR 50122,
50123). In addition to this rulemaking,
OSHA updated Appendix A to
§ 1910.134: Fit Testing Procedures (69
FR 46986, 46993, Aug. 4, 2004).
After withdrawing the 1992 version of
Z–88.2 in 2002, ANSI published the
American National Standard, ANSI/
AIHA Z88.10–2010, ‘‘Respirator Fit
Testing Methods,’’ approved in 2010.
These rules and standards addressed the
topics of APFs and fit testing. APFs
provide employers with critical
information to use when selecting
respirators for employees exposed to
atmospheric contaminants found in
industry. Finally, in 2015, ANSI
published ANSI/ASSE Z88.2–2015,
‘‘Practices for Respiratory Protection,’’
which referenced OSHA regulations.
These updates included requirements
for classification of considerations for
selection and use of respirators,
establishment of cartridge/canister
change schedules, use of fit factor value
for respirator fit testing, calculation of
effective protection factors, and
compliance with compressed air dew
requirements, compressed breathing air
equipment, and systems and
designation of positive pressure
respirators. In July 2017, ANSI/ASSE
transferred the responsibilities for
developing respiratory consensus
standards to ASTM International.
The ASTM standard contains detailed
guidance and provisions on respirator
selection that are based on NIOSH’s
extensive experience with testing and
approving respirators for occupational
use and OSHA’s research and
rulemaking on respiratory protection.
ASTM F3387–19 also addresses all
aspects of establishing, implementing,
and evaluating respiratory protection
programs and establishes minimum
acceptable respiratory protection
program requirements in the areas of
program administration, standard
operating procedures, medical
evaluation, respirator selection, training,
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fit testing, respirator maintenance,
inspection, and storage. ASTM F3387–
19 comprehensively covers numerous
aspects of respiratory protection and
provides the most up-to-date provisions
for current respirator technology and
effective respiratory protection.
Therefore, MSHA believes that ASTM
F3387–19 will provide mine operators
with information and guidance on the
proper selection, use, and maintenance
of respirators, which will protect the
health and safety of miners.
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1. Respiratory Protection Program
Requirements
Under the final rule, MSHA requires
that the respiratory protection program
be in writing and be consistent with the
requirements of ASTM 3387–19,
including program administration,
standard operating procedures, medical
evaluation, respirator selection, training,
fit testing; and maintenance, inspection,
and storage. The following subsections
discuss some of the requirements listed
in ASTM F3387–19.
a. Program Administration
ASTM F3387–19 specifies several
practices related to respiratory
protection program administration,
including the qualifications and
responsibilities of a program
administrator. For example, ASTM
F3387–19 provides that responsibility
and authority for the respirator program
be assigned to a single qualified person
with sufficient knowledge of respiratory
protection. Qualifications may have
been gained through training or
experience; however, the qualifications
of a program administrator must be
commensurate with the respiratory
hazards present at a worksite.
This individual administering the
program should have access to and
direct communication with the site
manager about matters impacting
worker safety and health. ASTM F3387–
19 notes a preference that the
administrator be in the company’s
industrial hygiene, environmental,
health physics, or safety engineering
department; however, a third-party
entity meeting the provisions may also
provide this service. ASTM F3387–19
outlines the respiratory protection
program administrator’s responsibilities,
specifying that they should include:
measuring, estimating, or reviewing
information on the concentration of
airborne contaminants; ensuring that
medical evaluations, training, and fit
testing are performed; selecting the
appropriate type or class of respirator
that will provide adequate protection for
each contaminant; maintaining records;
evaluating the respirator program’s
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effectiveness; and revising the program,
as necessary.
b. Standard Operating Procedures (SOP)
Written SOPs shall be established by
the employer and shall cover a complete
respirator program for routine and
emergency. ASTM F3387–19 also states
that written SOPs for respirator
programs are necessary when respirators
are used routinely or sporadically.
Written SOPs should cover hazard
assessment; respirator selection;
medical evaluation; training; fit testing;
issuance, maintenance, inspection, and
storage of respirators; schedule of airpurifying elements; hazard reevaluation; employer policies; and
program evaluation and audit. ASTM
F3387–19 also provides that wearers of
respirators be provided with copies of
the SOP and that written SOPs include
special consideration for respirators
used for emergency situations. The
procedures are reviewed in conjunction
with the annual respirator program
audit and are revised by the program
administrator, as necessary.
c. Medical Evaluation
Medical evaluations determine
whether an employee has any medical
conditions that would preclude the use
of respirators, limitation on use, or other
restrictions. ASTM F3387–19 provides
that a program administrator advise the
PLHCP of the following conditions to
aid in determining the need for a
medical evaluation: type and weight of
the respirator to be used; duration and
frequency of respirator use (including
use for rescue and escape); typical work
activities; environmental conditions
(e.g., temperature); hazards for which
the respirator will be worn, including
potential exposure to reduced-oxygen
environments; and additional protective
clothing and equipment to be worn.
ASTM F3387–19 also incorporates ANSI
Z88.6 Respiratory Protection—
Respirator Use—Physical Qualifications
for Personnel.
d. Respirator Selection
Proper respirator selection is an
important component of an effective
respiratory protection program. ASTM
F3387–19 provides that proper
respirator selection consider the
following: the nature of the hazard,
worker activity and workplace factors,
respirator use duration, respirator
limitations, and use of approved
respirators. ASTM F3387–19 states that
the respirator selection process for both
routine and emergency use should
include hazard assessment, selection of
respirator type or class that can offer
adequate protection, and maintenance
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of written records of hazard assessment
and respirator selection.
ASTM F3387–19 provides specific
steps to establish the nature of
inhalation hazards, including
determining the following: the types of
contaminants present in the workplace;
the physical state and chemical
properties of airborne contaminants; the
likely airborne concentration of the
contaminants (by measurement or by
estimation); potential for an oxygendeficient environment; an occupational
exposure limit for each contaminant;
existence of an IDLH atmosphere; and
compliance with applicable health
standards for the contaminants.
ASTM F3387–19 includes other
information to support the respirator
selection process, including information
on operational characteristics,
capabilities, and performance
limitations of various types of
respirators. These limitations must be
considered during the selection process.
ASTM F3387–19 also describes types of
respirators and considerations for their
use, including service life, worker
mobility, compatibility with other
protective equipment, durability,
comfort factors, compatibility with the
environment, and compatibility with job
and workforce performance. Finally,
ASTM F3387–19 provides other
information that is essential for
respirator selection, including degree of
oxygen deficiency, ambient noise, and
need for communication.
e. Training
Employee training is essential for
correct respirator use. ASTM F3387–19
provides that all users be trained in
their area of responsibility by a qualified
person to ensure the proper use of
respirators. A respirator trainer must be
knowledgeable about the application
and use of the respirators and must
understand the site’s work practices,
respirator program, and applicable
regulations. Employees who should
receive training under ASTM F3387–19
include the workplace supervisor, the
person issuing and maintaining
respirators, respirator wearers, and
emergency teams. To ensure the proper
and safe use of a respirator, the standard
also provides that the training for each
respirator wearer should cover, at a
minimum: the need for respiratory
protection; the nature, extent, and
effects of respiratory hazards in the
workplace; reasons for particular
respirator selections; reasons for
engineering controls not being applied
or reasons why they are not adequate;
types of efforts made to reduce or
eliminate the need for respirators;
operation, capabilities, and limitations
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of the respirators selected; instructions
for inspecting, donning, and doffing the
respirator; the importance of proper
respirator fit and use; and maintenance
and storage of respirators. The standard
provides for each respirator wearer to
receive initial and annual training.
Workplace supervisors and persons
issuing respirators are retrained as
determined by the program
administrator. Training records for each
respirator wearer are maintained and
include the date, type of training
received, performance results (as
appropriate), and instructor’s name.
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f. Respirator Fit Testing
A serious hazard may occur if a
respirator, even though properly
selected, is not properly fitted. For
example, if a proper face seal is not
achieved, the respirator will provide a
lower level of protection than it is
designed to provide because the
respirator could allow contaminants to
leak into the breathing area. Proper fit
testing verifies that the selected make,
model, and size of a respirator fits
adequately and ensures that the
expected level of protection is provided.
ASTM F3387–19 includes provisions for
qualitative and quantitative fit testing to
determine the ability of a respirator
wearer to obtain a satisfactory fit with
a tight-fitting respirator and
incorporates ANSI/AIHA Z88.10,
Respirator Fit Testing Methods, for
guidance on how to conduct fit testing
of tight-fitting respirators and on
appropriate methods to be used. This
includes information on the application
of fit factors and assigned protection
factors, and how these factors are used
to ensure that a wearer is receiving the
necessary protection. ASTM F3387–19
provides for each respirator wearer to be
fit tested before being assigned a
respirator; this fit testing should happen
at least once every 12 months or when
a wearer expresses concern about
respirator fit or comfort or has a
condition that may interfere with the
face piece seal.
g. Maintenance, Inspection, and Storage
Proper maintenance and storage of
respirators are important in a respiratory
protection program. ASTM F3387–19
includes specific provisions for
decontaminating, cleaning, and
sanitizing respirators, inspecting
respirators, replacing, and repairing
parts, and storing and disposing of
respirators. For example, the
decontamination provisions state that
respirators must be decontaminated
after each use and cleaned and sanitized
regularly per manufacturer instructions.
Following cleaning and disinfection,
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reassembled respirators are inspected to
verify proper working condition. ASTM
F3387–19 states that employers consult
manufacturer instructions to determine
component expiration dates or end-ofservice life, inspect the rubber or other
elastomeric components of respirators
for signs of deterioration that would
affect respirator performance, and repair
or replace respirators failing inspection.
ASTM F3387–19 also provides that
respirators are stored according to
manufacturer recommendations and in a
manner that will protect against hazards
(e.g., physical, biological, chemical,
vibration, shock, temperature extremes,
moisture). It also provides that
respirators are stored in a way that
prevents distortion of rubber or other
parts.
2. Section-by-Section Analysis of
Incorporation by Reference—ASTM
F3387–19
a. Part 56—Safety and Health
Standards—Surface Metal and
Nonmetal Mines
Section 56.5005—Control of Exposure to
Airborne Contaminants
Final § 56.5005 is changed from the
proposal. The final rule requires a
written respiratory protection program
consistent with the requirements of
ASTM F3387–19. In the NPRM, MSHA
proposed to revise paragraph (b) to
remove the incorporation by reference
to ANSI Z88.2—1969 and incorporate
by reference ASTM F3387–19 to state
that approved respirators must be
selected, fitted, cleaned, used, and
maintained in accordance with the
requirements of ASTM F3387–19 ‘‘as
applicable.’’ MSHA proposed to update
the Agency’s existing respiratory
protection standard to help safeguard
the life and health of all miners when
exposed to respirable airborne
contaminants at MNM mines while
wearing respirators. The ASTM F3387–
19 standard includes, for example,
provisions for selection, fitting, use, and
care of respirators used to remove
airborne contaminants from the air
using filters, cartridges, or canisters, as
well as respirators that protect in
oxygen-deficient or immediately
dangerous to life or health (IDLH)
atmospheres. MSHA proposed to
incorporate by reference ASTM F3387–
19 because it is the most recent
consensus standard developed by
experts in government and professional
associations on the selection, use, and
maintenance for respiratory equipment.
AEMA stated that the final rule
should clarify whether a specific written
respiratory protection program is
required and under what standards
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(Document ID 1424. MSHA’s response
to these comments is discussed in detail
in Section VIII.B.7. Section 60.14—
Respiratory protection. Also, the Agency
provides a detailed description of some
requirements for the respiratory
protection program in Section VIII.D.1.
Respiratory Protection Program
Requirements.
In response to comments, MSHA has
modified the language in paragraph (b)
in the final rule compared to the
proposal. The modifications include:
the removal of ‘‘as applicable’’;
clarification that a respiratory protection
program must be in writing, and one
non-substantive edit in the introductory
clause. These changes clarify what the
requirements are for MNM mine
operators’ respiratory protection
programs.
MNM mine operators do not have to
create a separate written respiratory
protection program under each of 30
CFR parts 56, 57, and 60 where ASTM
F3387–19 is incorporated by reference.
Operators may create one single
program that is applicable to respirable
crystalline silica hazards (part 60) and
other airborne contaminants (parts 56
and 57). However, as required by ASTM
F3387–19 and MSHA standards, the
respiratory protection program must
assess the potential respiratory hazard
or hazards and the mine operator must
then select approved respirators which
are appropriate for the airborne
hazard(s) encountered. MSHA believes
the final rule provides MNM mine
operators with additional time which
should be sufficient to allow them to
prepare and develop written respiratory
protection programs, if necessary, that
are based on the finalrule’s
requirements.
Consistent with the proposal, MSHA
is changing paragraph (c) to require the
presence of at least one other person
with backup equipment and rescue
capability when respiratory protection
is used in atmospheres that are IDLH.
This change is needed to conform to
language in the incorporation by
reference of ASTM F3387–19, which
defines IDLH as ‘‘any atmosphere that
poses an immediate hazard to life or
immediate irreversible debilitating
effects on health’’ (ASTM International,
2019).
As described above in Section VIII.C.
Conforming Amendments, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 56. Then, 720 days
after publication of the final rule, the
existing section for the conforming
amendments in part 56 will be removed
and the temporary section will be
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redesignated without the ‘‘T’’ to replace
the removed section. The result of these
technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
b. Part 57—Safety and Health
Standards—Underground Metal and
Nonmetal Mines
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Section 57.5005—Control of Exposure to
Airborne Contaminants
Final § 57.5005 is changed from the
proposal for the same reasons discussed
in § 56.5005. The final rule requires a
written respiratory protection program
consistent with the requirements of
ASTM F3387–19. In the NPRM, MSHA
proposed to revise paragraph (b) to
remove the incorporation by reference
to ANSI Z88.2—1969 and incorporate
by reference ASTM F3387–19 to state
that approved respirators must be
selected, fitted, cleaned, used, and
maintained in accordance with the
requirements of ASTM F3387–19 ‘‘as
applicable.’’ MSHA proposed to update
the Agency’s existing respiratory
protection standard to help safeguard
the life and health of all miners when
exposed to respirable airborne
contaminants at MNM mines while
wearing respirators. The ASTM F3387–
19 standard, for example, includes
provisions for selection, fitting, use, and
care of respirators used to remove
airborne contaminants from the air
using filters, cartridges, or canisters, as
well as respirators that protect in
oxygen-deficient or immediately
dangerous to life or health (IDLH)
atmospheres. MSHA proposed to
incorporate by reference ASTM F3387–
19 because it is the most recent
consensus standard developed by
experts in government and professional
associations on the selection, use, and
maintenance for respiratory equipment.
AEMA stated that the final rule
should clarify whether a specific written
respiratory protection program is
required and under what standards
(Document ID 1424). MSHA’s response
to these comments is discussed in detail
in Section VIII.B.7. Section 60.14—
Respiratory protection. Also, the Agency
provides a detailed description of each
of the requirements for the respiratory
protection program in Section VIII.D.1.
Respiratory Protection Program
Requirements.
In response to comments, MSHA has
modified the language in paragraph (b)
in the final rule compared to the
proposal. The modifications include:
the removal of ‘‘as applicable’’;
clarification that a respiratory protection
program must be in writing, and one
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04:45 Apr 18, 2024
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non-substantive edit in the introductory
clause. These changes clarify what the
requirements are for MNM mine
operators’ respiratory protection
programs.
MNM mine operators do not have to
create a written respiratory protection
program under each of 30 CFR parts 56,
57, and 60 where ASTM F3387–19 is
incorporated by reference. Operators
may create one single program that is
applicable to respirable crystalline silica
hazards (part 60) and other airborne
contaminants (parts 56 and 57).
However, as required by ASTM F3387–
19 and MSHA standards, the respiratory
protection program must assess the
potential respiratory hazard or hazards
and the mine operator must then select
approved respirators which are
appropriate for the airborne hazard(s)
encountered. The final rule provides
MNM mine operators additional time
for compliance, which MSHA believes
should give them sufficient time to
prepare and develop written respiratory
protection programs, if necessary, that
are based on the final rule’s
requirements.
Consistent with the proposal, MSHA
is changing paragraph (c) to require the
presence of at least one other person
with backup equipment and rescue
capability when respiratory protection
is used in atmospheres that are IDLH.
This change is needed to conform to
language in the proposed incorporation
by reference of ASTM F3387–19, which
defines the term IDLH as ‘‘any
atmosphere that poses an immediate
hazard to life or immediate irreversible
debilitating effects on health’’ (ASTM
International, 2019).
As described above in Section VIII.C.
Conforming Amendments, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 57. Then, 720 days
after publication of the final rule, the
existing section for the conforming
amendments in part 57 will be removed
and the temporary section will be
redesignated without the ‘‘T’’ to replace
the removed section. The result of these
technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
c. Part 72—Health Standards for Coal
Mines
Section 72.710—Selection, Fit, Use, and
Maintenance of Approved Respirators
Final § 72.710 includes two changes
from the proposal. The final rule
requires that approved respirators be
selected, fitted, used, and maintained in
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28355
accordance with the provisions of a
written respiratory protection program
consistent with the requirements of
ASTM F3387–19. In the NPRM, MSHA
proposed an editorial change to the
introductory statement to § 72.710 and
that approved respirators must be
selected, fitted, used, and maintained in
accordance with the requirements of
ASTM F3387–19 ‘‘as applicable.’’
MSHA proposed to update the
Agency’s existing respiratory protection
standard to help safeguard the life and
health of coal miners when exposed to
respirable airborne contaminants such
as respirable coal dust while wearing
respirators. The ASTM F3387–19
standard includes provisions for
selection, fitting, use, and care of
respirators used to remove airborne
contaminants from the air using filters,
cartridges, or canisters, as well as
respirators that protect in oxygendeficient or immediately dangerous to
life or health (IDLH) atmospheres.
MSHA proposed to incorporate by
reference ASTM F3387–19 because it is
the most recent consensus standard
developed by experts in government
and professional associations on the
selection, use, and maintenance for
respiratory equipment.
AEMA stated that the final rule
should clarify whether a specific written
respiratory protection program is
required and under what standards
(Document ID 1424).
MSHA’s response to these comments
is discussed in detail in Section VIII.B.7.
Section 60.14—Respiratory protection.
Also, the Agency provides a detailed
description of each of the requirements
for the respiratory protection program in
Section VIII.D.1. Respiratory Protection
Program Requirements.
In response to comments, MSHA has
modified the language to remove as ‘‘as
applicable’’ and to clarify that the
respiratory protection program must be
in writing and must be consistent with
ASTM F3387–19. This change clarifies
what the requirements are for coal mine
operators’ respiratory protection
programs.
Coal mine operators do not have to
create a separate written respiratory
protection program under 30 CFR parts
60 and 72 part where ASTM F3387–19
is incorporated by reference. Operators
may create a single program that is
applicable to respirable crystalline silica
hazards (part 60) and other airborne
contaminants (part 72). However, as
required by ASTM F3387–19 and
MSHA standards, the respiratory
protection program must assess the
potential respiratory hazard or hazards
and the mine operator must select
approved respirators which are
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
appropriate for the airborne hazard(s)
encountered. MSHA believes the final
rule provides coal mine operators with
sufficient time to prepare and develop
written respiratory protection programs
that are based on the rule’s
requirements.
As described above in Section VIII.C.
Conforming Amendments, 60 days after
publication of the final rule, a new
temporary section with the suffix ‘‘T’’
will be added for the conforming
amendments in part 72. Then, 360 days
after publication of the final rule, the
existing section for the conforming
amendments in part 72 will be removed
and the temporary section will be
redesignated without the ‘‘T’’ to replace
the removed section. The result of these
technical changes is that mine operators
must comply with the existing
standards until the compliance dates in
part 60.
IX. Summary of Final Regulatory
Impact Analysis and Regulatory
Alternatives
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A. Introduction
Executive Order (E.O.) 12866, as
amended by E.O. 14094, and E.O. 13563
direct agencies to assess all costs and
benefits of available regulatory
alternatives and, if regulation is
necessary, to select regulatory
approaches that maximize net benefits
(including potential economic,
environmental, public health and safety
effects, distributive impacts, and
equity).77 E.O. 13563 emphasizes the
importance of quantifying both costs
and benefits, of reducing costs, of
harmonizing rules, and of promoting
flexibility. E.O.s 12866 and 13563
require that regulatory agencies assess
both the costs and benefits of
regulations.
Under E.O. 12866 (as amended by
E.O. 14094), the Office of Management
and Budget (OMB)’s Office of
Information and Regulatory Affairs
(OIRA) determines whether a regulatory
action is significant and, therefore,
subject to the requirements of the E.O.
and review by OMB. 58 FR 51735,
51741 (1993). As amended by E.O.
77 Executive Order 12866 of September 30, 1993:
Regulatory Planning and Review. 58 FR 51735.
October 4, 1993. https://www.archives.gov/files/
federal-register/executive-orders/pdf/12866.pdf
(last accessed Jan. 10, 2024).
Executive Order 14094 of April 6, 2023:
Modernizing Regulatory Review. 88 FR 21879.
April 11, 2023. https://www.federalregister.gov/
documents/2023/04/11/2023-07760/modernizingregulatory-review (last accessed Jan. 10, 2024).
Executive Order 13563 of January 18, 2011:
Improving Regulation and Regulatory Review.
January 18, 2011. https://www.regulations.gov/
document/EPA-HQ-OA-2018-0259-0005 (last
accessed Jan. 10, 2024).
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14094, section 3(f) of E.O. 12866 defines
a ‘‘significant regulatory action’’ as a
regulatory action that is likely to result
in a rule that may: (1) have an annual
effect on the economy of $200 million
or more; or adversely affect in a material
way the economy, a sector of the
economy, productivity, competition,
jobs, the environment, public health or
safety, or state, local, territorial, or tribal
governments or communities; (2) create
a serious inconsistency or otherwise
interfere with an action taken or
planned by another agency; (3)
materially alter the budgetary impact of
entitlements, grants, user fees or loan
programs or the rights and obligations of
recipients thereof; or (4) raise legal or
policy issues for which centralized
review would meaningfully further the
President’s priorities or the principles
set forth in the E.O. OIRA has
determined that this final rule is a
significant regulatory action under
section 3(f)(1) of E.O. 12866, and
accordingly it has been reviewed by
OMB. Pursuant to Subtitle E of the
Small Business Regulatory Enforcement
Fairness Act of 1996, also known as the
Congressional Review Act (5 U.S.C. 801
et seq.), OIRA has determined that this
rule meets the criteria set forth in 5
U.S.C. 804(2).
E.O. 13563 directs agencies to propose
or adopt a regulation only upon a
reasoned determination that its benefits
justify its costs; the regulation is tailored
to impose the least burden on society,
consistent with achieving the regulatory
objectives; and in choosing among
alternative regulatory approaches, the
agency has selected those approaches
that maximize net benefits. E.O. 13563
recognizes that some benefits are
difficult to quantify and provides that,
where appropriate and permitted by
law, agencies may consider and discuss
qualitative values that are difficult or
impossible to quantify, including
equity, human dignity, fairness, and
distributive impacts.
To comply with E.O.s 12866 and
13563, MSHA has prepared a final
regulatory impact analysis (FRIA) for
the final rule. The purpose of the FRIA
is to:
• Profile the mining industry
impacted by the final rule;
• Estimate the monetized societal
benefits attributable to the new PEL
resulting from reductions in fatal cases
of lung cancer, non-malignant
respiratory disease, end-stage renal
disease, and both fatal and non-fatal
cases of silicosis;
• Identify additional non-quantified
benefits expected from the final rule;
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• Estimate the costs that the mining
industry will incur to achieve
compliance with the final rule;
• Assess the economic feasibility of
the final rule for the mining industry;
and
• Evaluate the principal regulatory
alternatives to the final rule that MSHA
has considered.
MSHA estimates the final rule will
have an annualized cost of $90.3 million
in 2022 dollars at a discount rate of 3
percent. The breakdown of this total
cost value by compliance cost for each
provision is as follows: approximately
59 percent is attributable to exposure
monitoring; 21 percent to medical
surveillance; 15 percent to exposure
controls (engineering, improved
maintenance and repair, and
administrative controls); 5 percent to
respiratory protection and incorporating
ASTM F3387–19. Of the annualized
compliance cost of $90.3 million, the
MNM sector will incur $82.1 million
(approximately 91 percent) and the coal
sector will incur $8.2 million
(approximately 9 percent).
Under a discount rate of 3 percent, the
total monetized benefits of the new
respirable crystalline silica final rule
from avoided deaths and morbidity
cases, including the benefits of avoided
morbidity preceding mortality, are
$246.9 million per year in 2022 dollars.
The net quantified benefits of the final
rule are calculated as the difference
between the estimated benefits and
costs. MSHA estimates that the net
annualized benefits of the final rule,
using a discount rate of 3 percent, is
$156.6 million.
In addition to these quantified
benefits, there are unquantified benefits.
MSHA believes that the medical
surveillance program will help miners
to detect silica-related diseases early.
Early detection of illness often leads to
early intervention and treatment, which
may slow disease progression and/or
improve health outcomes. However,
MSHA lacks data to quantify these
additional benefits. Furthermore, MSHA
expects that there will be additional
benefits from replacing ANSI Z88.2–
1969 with ASTM F3387–19. The ASTM
standard reflects developments in
respiratory protection since the time in
which MSHA issued its existing
standards. The updated standard will
play a critical role in safeguarding the
health of miners, reducing their
exposures to respirable crystalline silica
and other airborne contaminants. Again,
due to a lack of data, MSHA did not
quantify the expected additional
benefits that would be realized by
requiring respiratory protection
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
programs consistent with the ASTM
F3387–19 standard.
The standalone FRIA contains
detailed supporting data and
discussions for the summary materials
presented here, including the profile of
the mining industry, estimated costs
and benefits attributable to the final
rule, the assessment of the economic
feasibility of the final rule for the
mining industry, and the evaluation of
regulatory alternatives. The standalone
FRIA is placed in the rulemaking docket
at www.regulations.gov, docket number
MSHA–2023–0001. The summary of the
standalone FRIA is presented below.
The FRIA includes several revisions
made since the PRIA. In response to
public comments on the proposed rule
and PRIA, MSHA revised its cost and
benefit estimates. The revisions
increased both the estimated costs and
benefits.
Four types of changes were made to
the cost and benefit estimates. First, the
final rule includes several changes from
the proposed rule, and these changes
affected estimated costs. The changes
include: additional time provided by
MSHA for mine operator compliance;
revisions to exposure monitoring
requirements including removal of the
use of objective data and historical
sample data to discontinue sampling;
the requirement for mine operators to
immediately report all exposures above
the PEL from operator sampling to the
MSHA District Manager or other
designated office; revisions to the
requirement for periodic evaluations to
include additional evaluations
whenever changes are made; the
requirement of respiratory protection for
MNM mines when engineering controls
are being developed and implemented,
or it is necessary by the nature of the
work performed; and changes to the
medical surveillance requirements for
MNM operators related to the
compliance date and a new requirement
for reporting miners’ chest X-ray results
to NIOSH.
Second, MSHA revised the FRIA
methodology to annualize compliance
costs over 60 years, which is the
regulatory time horizon for this analysis.
The 60-year analysis period starts with
the first day of compliance for the coal
sector (12 months after publication of
the final rule). Coal mine operators
incur compliance costs beginning 12
months after publication of the final
rule. MNM mine operators incur
compliance costs beginning 24 months
after publication of the final rule. The
analysis period ends 60 years after the
first day of compliance for the coal
sector, thus 60 years of compliance costs
for coal mine operators and 59 years of
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compliance costs for MNM mine
operators are included in the analysis.
MSHA also updated both compliance
costs and benefits to reflect 2022 dollars
using the GDP implicit price deflator.
Third, MSHA made several changes to
the PRIA cost estimation methodology;
for example, the Agency modified its
assumption about the proportion of the
miner workforce that would be sampled
in larger mines, as well as its
assumption about the number of
corrective actions, to account for
circumstances in which multiple
corrective actions may be necessary to
reduce miners’ exposure to below the
PEL. MSHA also revised estimates of
maintenance and repair and
administrative control costs each year.
Lastly, MSHA made some changes to
the PRIA benefit estimation
methodology. Changes were also made
to the benefit estimates. As discussed in
Section VI. Final Risk Analysis
Summary, the PRA underestimated
benefits from the proposed rule by
excluding future retired miners from the
number who would benefit. Both the
FRA and the FRIA are updated to
account for benefits for working miners
and future retired miners. It is important
to note that the FRIA only monetizes
benefits to future retired miners—i.e.,
retired individuals who were employed
as miners at least one year after the start
of implementation. The FRIA
methodology does not attribute any
health benefits to individuals who
retired before the start of
implementation of the final rule. The
FRIA reflects the fact that the number of
future retired miners increases gradually
after the start of implementation. For
example, in the first year after the start
of implementation, there will be no
retired miners who benefit from the
rule. In the second year after the start of
implementation, there will be one
cohort of retired miners who benefit
from the rule (i.e., those in their final
year of mining when implementation
began). In this way, the FRIA monetizes
benefits to future retired miners while
accounting for the fact that future
retired miners who benefit from the rule
increase in size gradually during the 60year analysis period.
B. Miners and Mining Industry
This section provides information on
the characteristics of the MNM and coal
mining sectors, including their
estimated revenues, number of mines in
each sector, commodities the industry
produces, and employment sizes. In
addition, this section provides the
respirable crystalline silica exposure
profiles for miners across different
occupational categories in the MNM and
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coal sectors. These data come from the
U.S. Department of the Interior (DOI),
U.S. Geological Survey (USGS); U.S.
Department of Labor (DOL), Mine Safety
and Health Administration (MSHA),
Educational Policy and Development
and Program Evaluation and
Information Resources; DOL, Bureau of
Labor Statistics (BLS), Occupational
Employment and Wage Statistics
(OEWS); U.S. Census Bureau, Statistics
of U.S. Businesses (SUSB); and the
Energy Information Administration
(EIA).
In general, economic profiles were
developed using 2019 data because this
was the most recent year available that
was not impacted by temporary changes
resulting from the COVID–19 pandemic.
To estimate the current number of
miners, MSHA used the 2019 Quarterly
Employment Production Industry
Profile (MSHA, 2019a) and the 2019
Quarterly Contractor Employment
Production Report (MSHA, 2019b).
MSHA estimated the number of and
type of mines using 2019 data from the
Mine Data Retrieval System, including
the Mines database, (MSHA, 2022d) and
the 2019 employment data (MSHA,
2019a,b).
The size of the mining industry is
difficult to forecast given the
uncertainties in future demand for
various mined commodities, as well as
uncertainties about technological
changes. MSHA assumed the current
mining workforce and the current
number of mines would not change
during the 60 years following
implementation of the final rule. If the
industry were to contract or expand in
the future, the relative ratio of benefits
to costs would remain roughly the same
because both the benefits and costs of
the final rule are in proportion to the
size of the industry.
1. Structure of the Mining Industry
The mining industry can be divided
into two major sectors: (1) MNM mines
and (2) coal mines, with further
distinction made regarding type of
operation (i.e., underground mines or
surface mines) and commodity. The
MNM mining sector is made up of metal
mines (e.g., copper, iron ore, gold,
silver, etc.) and nonmetal mines.
Nonmetal mines can be further
categorized into four commodity groups:
(1) nonmetal (mineral) materials such as
clays, potash, soda ash, salt, talc, and
pyrophyllite; (2) stone, including
granite, limestone, dolomite, sandstone,
slate, and marble; (3) crushed limestone;
and (4) sand and gravel, including
industrial sands.
MSHA categorizes mines by size
based on employment. For purposes of
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this industry profile and the FRIA
analyses, MSHA categorized mines into
the following four size groups: 78 (1) 1 to
20 miners; (2) 21 to 100 miners; (3) 101
to 500 miners; and (4) 501 or more
miners.
MSHA tracks mine characteristics and
maintains a database containing the
number of mines by mine type and size,
number of employees, and employee
hours worked. MSHA also collects data
on the number of independent
contractor firms who provide miners to
the industry, the number of contract
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78 Miner employment is based on the information
submitted quarterly through the MSHA Form 7000–
2, excluding Subunit 99—Office (professional and
clerical employees at the mine or plant working in
an office); https://www.msha.gov/sites/default/files/
Support_Resources/Forms/7000-2_0.pdf (last
accessed Jan. 10, 2024).
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miners they employ, and their
employed contract miners’ hours
worked. Contract miners may work at
any mine.
Table IX–1 presents an overview of
the mining industry, including the
number of MNM and coal mines, their
employment (excluding contract
miners), and their estimated revenues
by commodity and size. As mentioned
above, all data regarding the number of
miners and mines are current in
reference to the year 2019 and are
assumed to remain constant during the
60 years following the implementation
of the final rule. Estimated revenues are
also based on 2019 data but have been
inflated to 2022 dollars using the GDP
implicit price deflator (U.S. Bureau of
Economic Analysis, 2023).
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The MNM mining sector is comprised
of an estimated 11,525 mines which
employ an estimated 169,070
individuals, of which 150,928 are
miners (excluding contract miners) and
18,142 are office workers. In addition,
contract miners work an estimated 71.3
million hours in MNM mines each year.
The coal mining sector is comprised
of an estimated 1,106 mines that employ
an estimated 52,966 individuals, of
which 51,573 are miners (excluding
contract miners) and 1,393 are office
workers. In addition, contract miners
work an estimated 28.0 million hours in
coal mines each year.
A further breakdown of MNM mines
and coal mines by mine commodity and
mine size is provided below.
BILLING CODE 4520–43–P
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Table IX-1: Profile ofMNM and Coal Mines, by Mine Size
Estimated
Revenues 1
Millions
in 2022
Percent
dollars
Mine
Commodity
Mine Size by
Miner
Employment
Metal
Metal
Metal
Metal
Emp<=20
20 < Emp <= 100
100 < Emp <= 500
500>Emp
$572.6
$1,566.1
$12,817.5
$15,561.6
Metal
Non-Metal
Non-Metal
Total
Emp<=20
20 < Emp <= 100
Non-Metal
Non-Metal
Non-Metal
Stone
100 < Emp <= 500
500>Emp
Total
$30,517.8
$3,651.5
$10,162.4
$9,412.6
$2,124.2
$25,350.6
Stone
Stone
Stone
Stone
Crushed Limestone
Crushed Limestone
Crushed Limestone
Crushed Limestone
Crushed Limestone
Sand and Gravel
Sand and Gravel
Sand and Gravel
Sand and Gravel
Sand and Gravel
MNMTotal
Emp<=20
20 < Emp <= 100
100 < Emp <= 500
500>Emp
Total
Emp<=20
20 < Emp <= 100
100 < Emp <= 500
500>Emp
Total
Emp<=20
20 < Emp <= 100
100 < Emp <= 500
$4,144.7
$6,380.2
$3,808.7
$227.3
$14,560.9
$6,621.2
$6,569.2
$1,250.7
$0.0
$14,441.1
$7,110.5
$2,591.5
Number of
Mines2
No.
Percent
40.7%
51.8%
280
645
100.0%
71.9%
37,026
3,694
100.0%
16.3%
76,414.7
6,397.5
207
42
23.1%
39.3%
36.2%
8.4%
100.0%
28.5%
3
897
2,002
0.3%
100.0%
83.1%
8,921
8,220
1,845
22,680
17,805.0
16,491.4
3,721.6
44,415.4
43.8%
26.2%
339
67
1
2,409
1,555
293
14
0
1,862
5,879
188
14.1%
2.8%
100.0%
14.4%
40.1%
37.1%
1.6%
100.0%
45.8%
45.5%
8.7%
0.0%
100.0%
69.7%
25.4%
4.7%
0.0%
100.0%
83.5%
15.7%
0.8%
0.0%
100.0%
96.7%
3.1%
Emp<=20
MNMTotal
MNMTotal
MNMTotal
20 < Emp <= 100
100 < Emp <= 500
500>Emp
$27,269.4
$27,787.4
$17,913.1
28.7%
29.2%
18.8%
1,066
195
26
88.8%
9.2%
1.7%
0.2%
MNMTotal
Coal
Coal
Coal
Coal
Total
$95,070.2
$1,143.0
$3,659.4
$16,353.5
$7,943.3
$29,099.2
100.0%
11,525
100.0%
3.9%
12.6%
707
271
116
12
1,106
63.9%
24.5%
Total
Emp<=20
20 < Emp <= 100
100 < Emp <= 500
500>Emp
Coal
Total
No.
22.1%
7.9%
$497.8
$0.0
$10,199.8
$22,100.4
500>Emp
Percent
1,433.8
3,921.3
32,094.2
38,965.3
42.0%
51.0%
56.1%
13.9%
No.
Production Hours
(thousands) 2
851
1,947
15,060
19,168
1.9%
5.1%
157
39
62
22
Miners Excluding
Contract Miners2
4.9%
10
0
0.0%
100.0%
23.2%
6,077
10,238
56.2%
27.3%
100.0%
0.2%
0.0%
100.0%
10.5%
1.1%
100.0%
11,198
14,779
8,762
539
35,278
11,771
10,480
1,856
0
24,107
23,887
6,703
2.3%
5.3%
8.1%
100.0%
31.7%
41.9%
24.8%
1.5%
100.0%
48.8%
43.5%
7.7%
0.0%
100.0%
75.0%
21.1%
20,035.5
30,842.4
18,411.6
1,098.8
70,388.3
22,834.9
22,655.5
4,313.4
0.0
49,803.8
39,673.3
14,459.5
1,247
0
31,837
51,401
100.0%
34.1%
2,777.6
0.0
56,910.5
90,375.0
42,830
35,145
21,552
28.4%
23.3%
14.3%
89,683.7
74,088.3
43,785.7
150,928
4,358
11,814
26,145
9,256
51,573
100.0%
297,932.6
9,077.4
27,591.7
59,897.7
20,962.2
117,529.0
3.9%
0.0%
8.5%
22.9%
50.7%
17.9%
100.0%
Percent
1.9%
5.1%
42.0%
51.0%
100.0%
14.4%
40.1%
37.1%
8.4%
100.0%
28.5%
43.8%
26.2%
1.6%
100.0%
45.8%
45.5%
8.7%
0.0%
100.0%
69.7%
25.4%
4.9%
0.0%
100.0%
30.3%
30.1%
24.9%
14.7%
100.0%
7.7%
23.5%
51.0%
17.8%
100.0%
Total
Employment2
No.
999
2,251
16,508
20,771
40,529
4,237
10,065
9,163
2,134
25,599
12,563
16,824
9,896
602
39,885
13,495
11,641
2,002
0
27,138
27,262
7,320
1,337
0
35,919
58,556
48,101
38,906
23,507
169,070
4,611
12,145
26,818
9,392
52,966
Percent
2.5%
5.6%
40.7%
51.2%
100.0%
16.6%
39.3%
35.8%
8.3%
100.0%
31.5%
42.2%
24.8%
1.5%
100.0%
49.7%
42.9%
7.4%
0.0%
100.0%
75.9%
20.4%
3.7%
0.0%
100.0%
34.6%
28.5%
23.0%
13.9%
100.0%
8.7%
22.9%
50.6%
17.7%
100.0%
BILLING CODE 4520–43–C
a. Metal Mining
There are 24 groups of metal
commodities mined in the U.S. Metal
mines represent an estimated 2.4
percent (280/11,525) of all MNM mines
and employ an estimated 24.5 percent of
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all MNM miners (excluding contract
miners). Of these 280 estimated mines,
157 (56.1 percent) employ 20 or fewer
miners and 22 (7.9 percent) employ
greater than 500 miners. Additionally,
MSHA data show that there is an
estimated total of 13,792 contract
miners in the metal mining industry
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with an estimated 18.9 million reported
production hours in a year.
b. Non-Metal (Mineral) Mining
There are 35 non-metal commodities
mined in the U.S., not including stone
and sand and gravel. Non-metal mines
represent an estimated 7.8 percent (897/
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Notes:
1. Coal Revenues were calculated using MSHA Production Figures in Short Tons by Rank: 650.3 million tons
Bituminous Coal, 53.2 million tons Lignite Coal, 2.6 million tons Anthracite Coal; and EIA price's per short ton by
Coal Rank: EIA Annual Coal Report 2019; Table 31 Average Sales Price of Coal by State And Rank, 2019; US
Total: $58.93/ton Bituminous Coal, $19.86/ton Lignite Coal, $102.22/ton Anthracite Coal;
https://www.eia.gov/coal/annual/archive/0584_2019.pdf (last accessed Jan. 11, 2024 ). The revenues for MNM
commodities are calculated by applying the proportion ofrevenues represented by each commodity among all MNM
commodities in the 2017 SUSB data and applying that proportion to the 2019 production value for all industrial
minerals reported by USGS. Revenues were inflated to 2022 dollars using the Bureau of Economic Analysis (BEA)
GDP Implicit Price Deflator, available at: https://fred.stlouisfed.org/series/GDPDEF#0 (last accessed October 26,
2023).
2. The estimated current and future number of mines, miners, and production hours are based on 2019 data and are
assumed to have remained constant through the 60 years following the start of implementation of the rule.
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11,525) of all MNM mines and employ
an estimated 15 percent of all MNM
miners (excluding contract miners). The
majority of non-metal mines (71.9
percent) employ fewer than 20 miners
and less than 1 percent employ more
than 500 miners. According to MSHA
data, there are an estimated 11,346
contract miners in the non-metal mining
industry with an estimated 14.5 million
reported production hours in a year.
c. Stone Mining
The stone mining subsector includes
eight different stone commodities. Of
these eight, seven are further classified
as either dimension stone or crushed
and broken stone. Stone mines make up
an estimated 20.9 percent (2,409/11,525)
of all MNM mines and employ an
estimated 23.4 percent of all MNM
miners (excluding contract miners). The
majority of these mines (83.1 percent)
employ fewer than 20 miners and one
mine employs over 500 miners.
According to MSHA data, there are an
estimated 18,559 contract miners in the
stone mining industry with an estimated
total of 18.8 million reported production
hours in a single year.
d. Crushed Limestone
Crushed limestone mines make up an
estimated 16.2 percent (1,862/11,525) of
all MNM mines and are estimated to
employ about the same percentage (16.0
percent) of all MNM miners (excluding
contract miners). Of the 1,862 crushed
limestone mines, the vast majority (83.5
percent) employ fewer than 20 miners;
none employ over 500 miners.
Additionally, MSHA data show that
there are an estimated 9,065 contract
miners in the crushed limestone mining
industry with an estimated total of 10.2
million reported production hours in a
single year.
e. Sand and Gravel Mining
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Sand and gravel mines account for an
estimated 52.7 percent (6,077/11,525) of
all MNM mines and employ an
estimated 21.1 percent of all MNM
miners (excluding contract miners).
Nearly all (96.7 percent) employ fewer
than 20 employees; none employ over
500 miners. MSHA data show that there
are an estimated 7,512 contract miners
in the sand and gravel mining industry
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with an estimated 8.9 million
production hours in a single year.
f. Coal
Of the estimated 1,106 total coal
mines, an estimated 63.9 percent (707/
1,106) employ fewer than 20 miners and
1.1 percent employ more than 500
miners. Overall coal mine employment
is estimated to be 52,966, of which
51,573 are miners (excluding contract
miners) and the remaining 1,393 are
office workers. Additionally, there are
an estimated total of 22,003 contract
miners in the coal mining industry with
an estimated 28.0 million reported
production hours in a single year.
2. Economic Characteristics of the
Mining Industry
The value of all MNM mining output
in 2022 dollars was estimated at $95.1
billion (U.S. Department of Interior,
2019). Metal mines, which include iron,
gold, copper, silver, nickel, lead, zinc,
uranium, radium, and vanadium mines,
contributed $30.5 billion. In the USGS
Mineral Commodity Summaries,
production values for nonmetals, stone,
sand and gravel, and crushed limestone
are combined into one commodity
group titled ‘‘industrial minerals.’’
Therefore, MSHA estimated the
production value of each individual
commodity by taking the proportion of
revenues for the commodity in question
among all commodities in the 2017
SUSB and applying that proportion to
the 2019 production value for all
industrial minerals reported by USGS.
This approach yields the following
estimates: non-metal production is
valued at an estimated $22.3 billion,
stone mining at $14.6 billion, crushed
limestone at $14.4 billion, and sand and
gravel at $10.2 billion.
The U.S. coal mining sector is made
up of three major commodity groups:
bituminous, anthracite, and lignite.
According to MSHA data, bituminous
operations represent approximately 92.1
percent of total coal production in short
tons and employ 91.9 percent of all coal
miners (excluding contract miners).
Anthracite operations represent 0.4
percent of coal production and employ
1.9 percent of coal miners (excluding
contract miners). Lignite operations
represent roughly 7.5 percent of total
coal production and employ 6.2 percent
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of coal miners (excluding contract
miners).
To estimate coal revenues in 2019,
MSHA combined production estimates
with unit prices. Mine production data
were taken from MSHA quarterly data
and the coal unit prices per ton were
taken from the 2019 EIA Annual Coal
Report. Estimated revenues were then
inflated to 2022 dollar values using the
GDP implicit price deflator. As shown
in Table IX–1, 2019 total coal revenues
expressed in 2022 dollars totaled an
estimated $29.1 billion.
3. Respirable Crystalline Silica Exposure
Profile of Miners
Using the quarterly employment data
submitted by mines and the
Occupational Employment and Wage
Statistics (OEWS) reported by the BLS,
MSHA estimated the distribution of
miners (excluding contract miners)
across different occupational categories.
For contract miners, MSHA lacked
information on occupational categories.
However, based on MSHA’s program
experience, MSHA assumed that the
distribution of contract miners across
the different occupational categories
mirrors that of the miners (excluding
contract miners) in each of the two
sectors. For example, MSHA assumed
that, because 1.9 percent of MNM
production miners are drillers, 1.9
percent of contract miners working in
MNM mines are also drillers.
As discussed in Section VI. Final Risk
Analysis Summary, full-time
equivalents (FTEs) are used to account
for the fact that miners may experience
more or less than 2,000 hours of
exposure to respirable crystalline silica
per year. MSHA calculates the number
of miner FTEs by dividing the estimated
total number of hours worked across all
mines in a given sector by 2,000 hours.
Based on these calculations, MSHA
estimates 184,615 FTEs in the MNM
sector of which 148,966 (81 percent) are
miner FTEs (excluding contract miners)
and the remaining 35,649 (19 percent)
are contract miner FTEs (Table IX–2).
For the coal sector, MSHA estimates
72,768 FTEs of which 58,764 (81
percent) are miner FTEs (excluding
contract miners) and the remaining
14,004 (19 percent) are contract miner
FTEs.
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Table IX-2: Estimated Miner and Contract Miner Full-Time Equivalents (FTEs)
MSHA’s exposure data is described in
Section VI. Final Risk Analysis
Summary. In summary, MSHA used
compliance data from 2005 through
2019 to estimate the current levels of
exposure to respirable crystalline silica
among MNM miners (MSHA, 2022b).
For the coal sector, MSHA used data
from 2016–2021 (MSHA, 2022a). For the
coal sector, MSHA only used exposure
data since 2016, by which time all
provisions of the Coal Mine Dust
Standard had gone into effect. MSHA
did not use earlier data so that the
benefits in this FRIA are clearly
attributable to this final rule and not to
the Coal Mine Dust Standard.
MSHA distributed the respirable dust
samples in its MNM and coal exposure
datasets by occupational category and
exposure interval. Because exposure
data associated with individual miners
are not available, MSHA derived the
imputed exposure profile of miners and
miner FTEs stratified by occupational
category and exposure interval. Based
on this imputation, MSHA found that,
in the MNM sector, an estimated 13,242
miners (6 percent), including contract
miners, currently have respirable
crystalline silica exposures above the
existing PEL of 100 mg/m3, an estimated
37,966 (18 percent) have exposures
above the new PEL of 50 mg/m3, and an
estimated 77,736 (37 percent) have
exposures at or above the action level of
25 mg/m3. On an FTE basis, an estimated
11,579 miner FTEs (6 percent),
including contract miner FTEs, have
respirable crystalline silica exposures
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above the existing PEL of 100 mg/m3, an
estimated 33,146 (18 percent) have
exposures above the new PEL of 50 mg/
m3, and an estimated 67,946 (37
percent) have exposures at or above the
action level of 25 mg/m3.
In the coal sector, an estimated 1,406
miners (2 percent), including contract
miners, currently have respirable
crystalline silica exposures above the
existing PEL of 85.7 mg/m3, an estimated
4,080 (6 percent) have exposures above
the new PEL of 50 mg/m3, and an
estimated 13,971 (19 percent) have
exposures at or above the action level of
25 mg/m3. On an FTE basis, the figures
are similar with an estimated 1,391
miner FTEs (2 percent), including
contract miner FTEs, having respirable
crystalline silica exposures above the
existing PEL of 85.7 mg/m3, an estimated
4,035 (6 percent) having exposures
above the new PEL of 50 mg/m3, and an
estimated 13,818 (19 percent) having
exposures at or above the action level of
25 mg/m3.
C. Cost Analysis
The FRIA assesses the costs in the
MNM and coal sectors of reducing
miners’ exposures to silica to 50 mg/m3
for a full-shift exposure, calculated as an
8-hour TWA and the costs of complying
with the final rule’s other requirements.
Under the final rule, mine operators
are required to: implement exposure
controls (§ 60.11); conduct exposure
monitoring and report all samples over
the PEL to MSHA (§ 60.12); take
immediate corrective actions and
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provide miners with respirators when a
sampling result indicates that miner
exposure exceeds the PEL (§ 60.13);
respiratory protection is required as a
temporary measure for all MNM miners
when MNM miner exposure exceeds the
PEL while engineering controls are
being developed and implemented or
when it is necessary by the nature of
work involved (for example, occasional
entry to hazardous atmospheres to
perform maintenance or investigation)
(§ 60.14)(a); make periodic medical
examinations available to MNM miners
and ensure certain medical results are
reported to NIOSH (§ 60.15); develop or
revise existing respiratory protection
programs and practices in accordance
with the ASTM F3387–19 (§§ 56.5005,
57.5005, and 72.710); and retain records
for the specified durations (§ 60.16).
MSHA estimates the annualized costs
of the final rule range from $88.8
million to $92.4 million, depending on
the discount rate used (Table IX–3). Of
this total, about 91 percent will be
incurred by mine operators in the MNM
sector and 9 percent by mine operators
in the Coal sector. The difference in cost
between the MNM and coal sectors is
driven by the much larger number of
MNM mines, as well as differences in
mine size and the extent to which
current exposures are already below 50
mg/m3. In addition, MNM mine
operators will incur costs to meet the
medical surveillance requirements
which further drives the difference in
total costs between the MNM and coal
sectors.
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Parameter1
MNM
Coal
Total
Number of Contract Miners2
60,275
22,003
82,278
Number of Contract Miner Hours2
71,297,875
28,007,955
99,305,830
Contract Miner FTEs3
35,649
14,004
49,653
Number of Miners (Excluding Contract Miners)4
150,928
51,573
202,501
Number of Miner Hours (Excluding Contract Miners)4
297,932,646
117,528,968
415,461,614
Miner FTEs (Excluding Contract Miners )5
148,966
58,764
207,730
Miner and Contract Miner FTEs Combined6
184,615
72,768
257,383
Notes:
1. The estimated number of current and future miners, miner hours, and miner FTEs are based on 2019 data and are
assumed to have remained constant through the 60 years following the start of implementation (MSHA, 2019a;
MSHA, 2019b).
2. (Mine Safety and Health Administration, 2022a); (Mine Safety and Health Administration, 2022b)
3. The figure is calculated by dividing the total number of contract miner hours by 2,000.
4. From Table IX-1.
5. Similar to the contract miner FTEs, the figure is calculated by dividing the total number of miner hours by 2,000.
6. The figure is the sum of the calculated miner and contract miner FTEs.
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Table IX-3: Summary of Estimated Annualized Compliance Costs by Sector (in millions of
2022 dollars)
Sector
Total, All Mines
Metal/
Nonmetal, Total
Coal, Total
Number
of
Mines 1
0 Percent Discount
Rate
3 Percent Discount
Rate
Percent
12,631
Annualized
Cost
$88.77
Percent
100.0%
Annualized
Cost
$90.28
11,525
$80.75
91.0%
1,106
$8.02
9.0%
7 Percent Discount
Rate
Percent
100.0%
Annualized
Cost
$92.39
$82.06
90.9%
$83.84
90.7%
$8.22
9.1%
$8.55
9.3%
100.0%
For the PRIA, MSHA estimated
annualized costs would range from
$56.2 million (0 percent discount rate)
to $60.0 million (7 percent discount
rate). However, the estimated
compliance costs for the PRIA were
calculated in 2021 dollars. To compare
PRIA and FRIA costs on an equivalent
basis, MSHA inflated estimated PRIA
compliance costs from 2021 dollars to
2022 dollars, which increases PRIA
costs by about 7 percent. In 2022
dollars, estimated PRIA costs range from
$60.1 million (0 percent discount rate)
to $64.2 million (7 percent discount
rate). Annualized estimated FRIA
compliance costs exceed PRIA costs by
about $28.2 to $28.7 million per year.
After accounting for the inflation to
2022 dollars, the remaining difference
in estimated compliance costs between
the PRIA and FRIA are attributable to
several changes to the proposed rule,
including:
• A longer phase-in implementation
is provided for both coal and MNM
mines.
• Objective data and historical
sample data may no longer be used to
demonstrate compliance with exposure
monitoring requirements.
• Sample results exceeding the PEL
must be reported to the MSHA district
manager or other designated office.
• Periodic evaluations must be
conducted at least every 6 months or
whenever there is a change in:
production; processes; installation or
maintenance of engineering controls;
installation or maintenance of
equipment; administrative controls; or
geological conditions.
• Limited temporary use of
respirators is permitted in MNM mines
only.
• For medical surveillance, the first
medical examination offered to all
MNM miners must be within 12 months
of the compliance date. Also, chest Xray results must be reported to NIOSH.
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Under the FRIA, annualized costs are
attributable to the following provisions
of the final rule:
• Exposure Monitoring ($53.2
million, 59 percent of total)
• Exposure Controls ($13.7 million,
15 percent of total)
• Respiratory Protection ($3.3
million, 4 percent of total)
• Medical Surveillance ($18.8
million, 21 percent of total), and
• ASTM Update ($1.2 million, 1
percent of total).
Nearly two-thirds of the increase in
estimated compliance costs ($19.0
million) is attributable to the exposure
monitoring requirements under the final
rule. The remainder is largely
attributable to increased estimates for
exposure controls ($7.5 million) and
respiratory protection ($2.2 million).
MSHA expects that the amount of
sampling performed by mine operators
will increase because the final rule does
not allow mine operators to use
objective data and historical sample
data (operator and MSHA sample data
from prior 12 months) to demonstrate
compliance with exposure monitoring
requirements. Below the estimate of
each cost component is discussed in
more detail.
1. Costs for Exposure Monitoring
There are five types of exposure
monitoring required under the final
rule:
• First-time sampling and secondtime sampling based on a representative
fraction of miners (§ 60.12(a)). First-time
sampling occurs starting by the rule’s
respective compliance dates for coal
mines and MNM mines. Second-time
sampling occurs within three months of
first-time sampling.
• Above-action-level sampling of a
representative fraction of miners. If the
most recent sampling results are at or
above the action level (§ 60.12(a)),
above-action-level sampling starts three
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months after the most recent sampling
and continues until two consecutive
samples demonstrate that miners’
exposures are below the action level.
• Corrective actions must be
performed for samples over the PEL.
The mine operator must take corrective
actions to reduce exposure and conduct
corrective actions sampling until sample
results are at or below the PEL
(§ 60.12(b)). All corrective actions
sample results exceeding the PEL must
be immediately reported to the MSHA
District Manager or other office
designated by the District Manager.
• Periodic evaluations (qualitative
monitoring) must be performed at least
every 6 months, or whenever there is a
change in production, processes,
engineering or administrative controls,
or geological conditions that may
reasonably be expected to result in new
or increased respirable crystalline silica
exposures to ensure that any change
will not have increased miners’
exposures (§ 60.12(c)).
• If the periodic evaluations
conducted under § 60.12(c) determine
that increased exposures are likely,
post-evaluation sampling must be
conducted to ensure exposures remain
at or above the action level (§ 60.12(d)).
For quantitative monitoring, MSHA
estimates total sampling costs as a
function of several factors: the unit cost
of sampling, made up of labor costs
(miners’ and external consultants’ time
and hourly wage), laboratory costs for
analyzing the samples, and clerical costs
for recording the results; the number of
samples that constitutes the required
representative fraction each time the
operator conducts sampling; and the
frequency with which operators are
assumed to carry out different types of
monitoring (samplings and evaluation).
MSHA assumes that regardless of the
type of sampling, the unit cost of
sampling does not vary, since the
process of collecting a dust sample and
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Note: 1. The estimated number of current and future mines are based on 2019 data (MSHA, 2022d) and are assumed
to have remained constant through the following the start of implementation of the final rule.
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analyzing for respirable crystalline silica
is relatively similar at different mines.
For the qualitative monitoring, MSHA
estimates periodic evaluation costs as a
function of labor costs and the
frequency of evaluation. The calculation
of each of these factors is discussed
below.
Labor Costs of Exposure Monitoring
The most important component of
sampling and evaluation cost is the time
required to conduct the activities. For
sampling, this includes the time needed
to prepare for sampling, take the
samples, and perform recordkeeping
tasks on the results. Sampling takes
time, which is valued at the hourly
wage of the person wearing the
sampling equipment and the person
conducting the sampling. To err on the
side of overestimates, MSHA assumed
that in MNM mines, sample preparation
and collection is performed by an
industrial hygienist (IH).79 The IH may
be an in-house specialist or an external
consultant. For coal mines, miners
certified to perform sampling under 30
CFR 70.202, 71.202, and 90.202 can
conduct the sampling required under
the final rule.
In addition, MSHA assumed the
personnel conducting sampling can
collect 2, 3, and 4 samples per day at
small, medium, and large mines,
respectively. This determines the
number labor hours needed to complete
sampling at a mine, and therefore
directly affects labor costs.
Sampling labor costs: For coal mines,
MSHA estimates sampling labor cost at
$398 per sample at mines with 20 or
fewer employes; $264 per sample at
mines with 21 to 500 employees; and
$248 per sample at mines with more
than 500 employees. For metal mines,
MSHA estimates sampling labor cost at
$747 per sample for mines with 20 or
fewer employes; $380 per sample at
mines with 21 to 500 employees; and
$334 per sample for mines with more
than 500 employees. For nonmetal
mines, MSHA estimates sampling labor
cost at $772 per sample at mines with
20 or fewer employees; $366 per sample
at mines with 21 to 500 employees; and
$322 per sample at mines with more
than 500 employees. These figures
include the recordkeeping costs
specified below.
Evaluation labor costs: MSHA
estimates that a periodic evaluation will
typically require two hours of time for
79 In reality, some MNM mines may train their
miners or other in-house employees to conduct
sampling. In such scenarios, an IH would not be
used and the labor cost of sampling would be based
on the loaded hourly wage for the participating
employee.
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an IH. Thus, the cost ranges from $131
to $162 per evaluation.
Laboratory Analysis Costs of Sampling
MSHA estimates that laboratory
analysis will cost the mine operator
$150 per sample. This includes the cost
of packing and shipping the sample to
the lab, the laboratory analysis, and
reporting sample results to the operator.
Recordkeeping Cost of Sampling
The labor time required for recording
results of sampling is estimated at 17
minutes and is valued at the loaded
hourly wage of an industrial hygienist.
Thus, costs for recordkeeping time due
to sampling range from $19 to $23 per
sample.
Number of Samples—Representative
Sampling
While the cost of labor time and
laboratory analysis are the primary
components of cost per sample, a
second major determinant of sampling
cost at any mine is the number of
samples required each time sampling
occurs. Where several miners perform
the same tasks on the same shift and in
the same work area, the mine operator
may sample a representative fraction
(i.e., at least two) of these miners to
meet the sampling requirements. The
final rule requires that mine operators
sample a representative fraction of
miners who are expected to have the
highest exposure to respirable
crystalline silica. MSHA estimated the
number of miners considered a
representative sample based on the size
of the mine. In small mines that employ
20 or fewer miners (including contract
miners), MSHA assumes that a sample
comprising at least 50 percent of miners
will be necessary to collect a
representative sample. In medium-sized
mines with 20 to 100 miners, the
assumption is that a minimum 25
percent of miners will need to be
sampled for the sample to be
representative. In large mines with 100
or more miners, the Agency assumes
that a minimum 15 percent of miners
will need to be sampled for the sample
to be representative.
Frequency of Exposure Monitoring—
Number of Samples and Evaluations
The third component of sampling cost
is the frequency with which it must be
performed. Sampling frequency
depends on sample results, as specified
by MSHA’s exposure monitoring
requirements.
First-time and second-time sampling.
First-time and second-time sampling is
performed by all mine operators. Firsttime sampling occurs by the relevant
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28363
compliance date for existing mines.
Second-time sampling occurs within 3
months following first-time sampling.
First-time and second-time sampling is
representative sampling. The number of
samples taken at a mine will depend on
the size of the mine. After the first-time
sampling is completed, each operator
will determine the next action based on
the first sample result. If that result is
below the action level, the mine
operator will have to conduct the
second sampling. If the results from
both samplings are below the action
level, no further sampling is required,
unless there are changes identified by
periodic evaluations that may
reasonably be expected to result in new
or increased respirable crystalline silica
exposures. (Periodic evaluations are
further discussed below.) The secondtime sampling must be taken after the
operator receives the results of the firsttime sampling but no sooner than 7 days
after the prior sampling was conducted.
Above-action-level sampling.
Sampling above the action level is also
representative. Unlike first- and secondtime sampling, this type of sampling
will not be required of all mines, but
only of those mines showing exposure
levels at or above the action level of 25
mg/m3. This sampling continues as long
as the most recent sample results
demonstrate exposure at a mine is at or
above the action level of 25 mg/m3 but
below the new PEL of 50 mg/m3.
MSHA estimated the percent of
samples exceeding the action level in
Year 1 based on its exposure profile
developed using the Agency’s
compliance sampling data. MSHA
assumed that mine operators will
reduce the percentage of samples
exceeding the action level from their
current level of 31 percent to about 15
percent of samples by Year 7.
Corrective Actions Sampling.
Corrective actions sampling is required
when a sample result exceeds the new
PEL. A sample result above the PEL
requires the mine operator to take
corrective actions and conduct
corrective actions sampling to
determine if the actions reduced
exposures to the PEL. MSHA uses the
estimated number of samples exceeding
50 mg/m3 to estimate the number of
corrective actions taken. Each sample
result above the PEL requires a
corrective action and an additional
sample to ensure that the corrective
action was effective. Not all corrective
actions may be effective in reducing
exposures below the PEL. Therefore,
MSHA increased the number of samples
exceeding the new PEL by 25 percent to
account for situations requiring more
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than one corrective action taken by
mine operators.
Periodic Evaluation. MSHA assumed
that mines operating only two quarters
or less per year will conduct this
evaluation once per year, while mines
operating more than two quarters per
year will perform this evaluation twice
per year.
However, because the rule requires
periodic evaluation whenever factors
change that may affect exposures, some
mines, such as portable mines, will
likely have to conduct evaluations more
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frequently than semi-annually.
Therefore, MSHA increased its estimate
of the number of periodic evaluations by
20 percent (i.e., annual periodic
evaluations are equal to 2.4 times the
number of mines) to account for mines
that will need to perform evaluations
more than twice per year.
Post-Evaluation Sampling. Periodic
evaluation may lead to sampling
performed for purposes of evaluating
whether exposure levels might have
changed or if they remain below the
action level. MSHA assumed that post-
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evaluation sampling comprises 2.5
percent of miners. This percentage is
relatively small because mine operators
are already collecting sample data
which can be used for these purposes.
However, MSHA estimated that some
additional sampling might be needed
and included additional post-evaluation
sampling costs.
Table IX–4 summarizes how the costs
of each type of monitoring measures are
estimated.
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Table IX-4: Exposure Monitoring Calculation
Exposure
Monitoring
Requirement 1
First-time and
second-time
sampling
Above-actionlevel sampling
Determination of Cost
per Sample or
Evaluation 1• 2
Sampling labor cost +
lost work time +
recording time +
laboratory fees
Sampling labor cost +
lost work time +
recording time +
laboratory fees
Number of Samples
or Evaluations 1
Representative sample
of all miners who may
reasonably be
expected to be
exposed to respirable
crystalline silica, by
mine size
Miners that meet
condition for periodic
sampling x percent of
miners needed for
representative sample,
by mine size
Corrective actions
sampling
Sampling labor cost +
lost work time +
recording time +
laboratory fees
Sample results above
the PEL (> 50 µg/m 3)
X 1.25
Post-evaluation
sampling
Sampling labor cost +
lost work time +
recording time +
laboratory fees
Periodic
evaluation
Hours per evaluation x
in-house loaded
industrial hygienist wage
2.5 percent of all
miners x percent of
miners needed for
representative sample,
by mine size
Number of mines x
frequency of
evaluation x 1.2
Condition for Exposure
Monitoring Requirement and
Frequency1
All mines
Twice
Miners at or above the action level
(;:::25 µg/m 3) but at or below the PEL
('.'S 50 µg/m 3)
Number of quarters mine is in
operation.
Three months after sampling results
at or above the action level and
continues until two consecutive
samples demonstrate that miners'
exposures are below the action level
Samples taken because first-time or
second-time samples, above-actionlevel samples, or post-evaluation
samples showed results above the
PEL; multiple samples might be
necessary to demonstrate postcorrective action exposure level is
below the PEL.
If evaluation shows exposure level
may exceed PEL, sampling
performed to determine if exposure
level is above PEL or action level
All mines
Every 6 months, or when there is a
change in production, processes,
engineering or administrative
controls, or other factors that may
reasonably be expected to result in
new or increased respirable
crystalline silica exposures.
Table IX–5 below presents the
estimated number of samples by
sampling type and by commodity sector
in the first 7 years of the analysis
because MSHA expects a long-run
average to be reached in Year 7. MSHA
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projects that in the first 2 years
(following the coal and MNM
compliance dates), 259,059 samples will
be taken compared to 92,663 per year in
Years 7 through 60. This is a result of:
(a) declines in first-time and second-
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time sampling after the first year of
compliance, and (b) declines in aboveaction-level and corrective actions
sampling as mine operators become
more experienced in developing and
implementing new controls.
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Notes:
1. Throughout this table, miners refer to both miners (excluding contract miners) and contract miners.
2. Lost work time, recording time, and laboratory cost fees as presented in FRIA Table 4-3 are constant within
each commodity type (coal, metal, nonmetal) across all mine sizes. Sampling labor cost are constant within each
commodity but vary by mine size because there is a fixed component (e.g., the cost of an IH) that is spread over
more samples as mine size increases.
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First-time and second-time sampling.
Of the 259,059 samples expected to be
taken in the first 2 years following the
coal and MNM compliance dates,
MSHA projects that approximately 60
percent (154,680/259,059) will be from
first-time and second-time sampling.
After Year 1 for Coal, and Year 2 for
MNM, all first-time and second-time
sampling will only be performed by new
mines. MSHA projects that about 2
percent of mines in any given year will
be new entrants to the mining industry,
although the total number of mines in
each year remains roughly constant.
Table IX-5: Estimated Number of Samples and Evaluations Taken by Type and Year
Year 1
Year2
Year3
Year4
All Mines
Year5
Year6
131,783
117,558
103,332
92,663
Years 7 - 60
Sample Totals, All Mines
All Types
41,599
217,460
First-time and second-time
Mines
146,009
sampling 1
1,106
11,547
253
253
253
253
253
Miners
73,576
212,675
5,696
5,696
5,696
5,696
5,696
Samples
29,796
124,884
3,082
3,082
3,082
3,082
3,082
Sampling with results exceeding the action
level2
Mines 3
-
-
-
-
-
-
-
Miners
13,727
92,941
146,671
130,341
114,011
97,681
85,434
5,423
48,275
79,062
69,948
60,834
51,720
44,885
Samples4
Corrective actions sampling
Mines 3
-
-
-
-
-
-
-
Miners
4,031
40,664
67,967
60,816
53,665
46,513
41,246
1,991
27,348
46,912
41,800
36,689
31,577
27,743
1,106
12,631
12,631
12,631
12,631
12,631
12,631
2,449
28,308
28,308
28,308
28,308
28,308
28,308
Samples4
Periodic evaluations
Mines
Evaluations
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Mines 3
-
-
-
-
-
-
-
Miners
3,679
14,239
14,239
14,239
14,239
14,239
14,239
Samples4
4,390
16,953
16,953
16,953
16,953
16,953
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16,953
Metal/Nonmetal
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Post-evaluation sampling
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Sample Subtotals, MNM Mines
-
All Types
197,985
126,983
113,207
99,432
85,656
75,324
231
231
231
231
First-time and second-time sampling'
Mines
-
11,525
Miners
-
211,203
4,224
4,224
4,224
4,224
4,224
Samples
-
124,288
2,486
2,486
2,486
2,486
2,486
231
Sampling with results exceeding the action leveF
-
Mines 3
Miners
Samples4
-
-
-
-
-
-
66,222
120,930
105,578
90,227
74,875
63,361
37,719
68,892
60,165
51,437
42,710
36,165
Corrective actions sampling
Mines 3
-
-
-
-
-
-
-
Miners
-
32,698
60,129
53,106
46,083
39,060
33,792
-
23,414
43,041
37,993
32,944
27,896
24,110
-
11,525
11,525
11,525
11,525
11,525
11,525
-
25,859
25,859
25,859
25,859
25,859
25,859
Samples4
Periodic evaluations
Mines
Evaluations
Post-evaluation sampling
Mines 3
-
-
-
-
-
-
-
Miners
-
10,560
10,560
10,560
10,560
10,560
10,560
Samples4
-
12,564
12,564
12,564
12,564
12,564
12,564
18,126
17,676
17,339
Coal
Sample Subtotals, Coal Mines
All Types
41,599
19,475
19,025
18,576
First-time and second-time sampling'
Mines
1,106
22
22
22
22
22
22
Miners
73,576
1,472
1,472
1,472
1,472
1,472
1,472
29,796
596
596
596
596
596
596
Samples
Sampling with results exceeding the action leveF
Mines 3
-
-
-
-
-
-
-
Miners
13,727
26,719
25,741
24,763
23,785
22,806
22,073
5,423
10,556
10,170
9,783
9,397
9,010
8,720
Samples4
Corrective actions sampling5
Mines 3
-
-
-
-
-
-
-
Miners
4,031
7,966
7,838
7,710
7,582
7,454
7,454
1,991
3,934
3,871
3,807
3,744
3,681
3,633
1,106
1,106
1,106
1,106
1,106
1,106
1,106
2,449
2,449
2,449
2,449
2,449
2,449
2,449
Samples4
Periodic evaluations
Mines
Evaluations
-
-
-
-
-
-
-
Miners
3,679
3,679
3,679
3,679
3,679
3,679
3,679
Sample4
4,390
4,390
4,390
4,390
4,390
4,390
4,390
Notes:
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Post-evaluation sampling
Mines 3
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1. For years 2 - 60 for Coal mines, and years 3 - 60 for MNM mines, MSHA assumes that 2 percent of mines will
be new and therefore undertake first-time and second-time sampling, but with no net growth, the total number of
mines will remain constant.
2. This includes above--action-level sampling (2: 25 µg/m 3 but:::; 50 µg/m 3) and results that exceed new PEL(> 50
µg/m 3) thus requiring corrective actions. Above--action-level sampling is expected to decline linearly from current
exposure levels from year 1 to the start of year 7, after which time the frequency of sampling at or above the action
level will be constant. Sample results exceeding the new PEL are also expected to decline linearly from current
exposure levels in year 1 to the start of year 7, after which time the frequency of sampling will be constant.
3. The calculations for above-action-level, corrective actions, and post-evaluation sampling are based on the number
of miners rather than the number of mines. Because MSHA requires representative sampling, it expects that in
general the number of samples taken will be less than the number of miners.
4. Half a year of sampling above-action-level and corrective actions sampling occurs in Year 1 for Coal mines and
Year 2 for Metal/Nonmetal mines.
5. When the most recent sample results exceed the PEL, corrective actions sampling is performed to ensure that the
post-corrective actions exposure level is below the PEL.
6. If a periodic evaluation shows that the exposure level may be at or above the action level, post-evaluation
sampling is performed to assess if the exposure level is, in fact, at or above the action level.
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after corrective actions, to ensure
exposures have been reduced to below
the new PEL—will be 46,912 in Year 3.
This figure is also projected to decline
over time, to 27,743 by Year 7.
Evaluations. MSHA projects that
starting with Year 2 following
implementation, 12,631 mines will take
about 28,308 evaluations per year.
Post-evaluation sampling. Similarly,
post-evaluation sampling remains
constant at approximately 16,953
samples per year since these samples
are independent of the above-actionlevel sampling.
Total Annualized Exposure Monitoring
Costs
Table IX–6 below presents estimated
total annualized exposure monitoring
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costs by type of monitoring and mining
sector. The five types of exposure
monitoring (samplings and evaluation)
are projected to cost mine operators an
average of about $53.2 million (3
percent discount rate) per year over 60
years. The first-time and second-time
sampling ($4.2 million per year) account
for about 8 percent of exposure
monitoring costs; above-action-level
sampling ($23.5 million) accounts for 44
percent; corrective actions sampling
($14.9 million) accounts for 28 percent;
and periodic evaluations and postevaluation sampling ($10.7 million)
together account for about 20 percent.
Of the total exposure monitoring costs,
about 89 percent are expected to be
incurred by MNM mines and the
remaining 11 percent by coal mines.
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Above-action-level sampling. MSHA
projects that the number of aboveaction-level samples will increase from
5,423 in Year 1 to 48,275 in Year 2 and
to 79,062 in Year 3 as more mines start
their above-action-level sampling. This
type of sampling is projected to decline
starting from Year 4, due to the
implementation of engineering controls,
maintenance and repair of controls, and
implementation of administrative
controls, all of which will result in
fewer miners and contract miners with
exposure levels at or above the action
level. MSHA projects that by Year 7,
about 45,000 samples per year will be
taken.
Corrective actions sampling. MSHA
also projects that the number of
corrective actions samples—those taken
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28369
Table IX-6: Total Annualized Exposure Monitoring Costs by Sector (in millions of 2022
dollars)
Annualized Costs
Cost Type
All Mines
First-time and second-time sampling
Above-action-level sampling
Corrective actions sampling
Post-evaluation sampling
Periodic evaluations
Total
Metal/Nonmetal
First-time and second-time sampling
Above-action-level sampling
Corrective actions sampling
Post-evaluation sampling
Periodic evaluations
Subtotal
Coal
First-time and second-time sampling
Above-action-level sampling
Corrective actions sampling
Post-evaluation sampling
Periodic evaluations
Subtotal
Note: 1. At the 3 percent discount rate.
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BILLING CODE 4520–43–C
Several commenters disagreed with
MSHA’s estimates for sampling costs
(Document ID 1419; 1441; 1442; 1448)
in the PRIA. For example, a mining
trade association NSSGA provided
estimates from several mine operators
that exposure monitoring costs would
be substantially higher than those
reported in MSHA’s PRIA (Document ID
1448). This commenter provided
sampling costs ranging from a low of
$139 to a maximum of $1,800 per
sample, with a median of $650 per
sample, that would increase costs by
$34 million to $162 million for 250,000
MNM miners. This commenter further
stated that sampling costs vary
according to the number of miners
sampled: $2,866 for one miner, but
$3,247 for 3 miners (approximately
$1,082 per miner). A second
commenter, a MNM mine operator/
owner Vanderbilt Minerals, LLC, listed
costs in excess of $11,000 for a single 3day sampling event (Document ID
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0%
Discount
Rate
3%
Discount
Rate
Percent
Annualized
Costs 1
$170.2
$1,390.4
$884.0
$426.3
$225.0
$3,095.9
$2.8
$23.2
$14.7
$7.1
$3.8
$51.6
$4.2
$23.5
$14.9
$7.0
$3.7
$53.2
$6.3
$23.9
$15.0
$6.8
$3.6
$55.6
7.8%
44.2%
27.9%
13.1%
6.9%
100.0%
$151.3
$1,239.1
$821.4
$354.6
$201.2
$2,767.6
$2.5
$20.7
$13.7
$5.9
$3.4
$46.1
$3.7
$21.0
$13.8
$5.8
$3.3
$47.6
$5.6
$21.4
$14.0
$5.6
$3.2
$49.7
6.9%
39.4%
26.0%
10.9%
6.2%
89.4%
$18.8
$151.3
$62.6
$71.7
$23.9
$328.2
$0.3
$2.5
$1.0
$1.2
$0.4
$5.5
$0.5
$2.5
$1.0
$1.2
$0.4
$5.6
$0.7
$2.5
$1.0
$1.2
$0.4
$5.9
0.9%
4.8%
2.0%
2.2%
0.7%
10.6%
1419). A third commenter, an industry
trade association EMA, stated that 400
of its 446 employees would require
1,200 individual samples over the
course of one year to meet the sampling
requirements (Document ID 1442). A
fourth commenter, NVMA, stated that
one of its members estimated sampling
costs would increase by $1.2 million for
its 7,000 employees (Document ID
1441).
MSHA acknowledges that the range of
costs per sample provided by
commenters likely exceeds MSHA’s
own estimates. As explained earlier, and
in greater detail in Section 4 of the
standalone FRIA document, MSHA’s
calculations of the average unit costs of
sampling, sample analysis, and
evaluation take into account the labor
cost of time spent sampling, laboratory
fees for sample analysis, lost work time
due to sampling, recordkeeping time,
plus the cost of performing periodic
evaluations. MSHA assumes that the
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labor cost of sampling varies by
commodity and mine size. MSHA
estimates that mine operators will take
5.76 million samples at a cost of $3.09
billion over the 60-year analysis period.
MSHA estimated the weighted average
(mean) cost at $500 per sample, with
costs ranging from $250 per sample (for
coal mines with more than 500
employees) to $750 per sample (for
metal mines with 20 or fewer
employees). A direct comparison with
the cost estimates provided by the above
commenter (NSSGA) is not possible
because NSSGA presents the median
but not the mean cost per sample from
the organization’s members who
provided data. Because the distribution
of costs provided by this commenter is
skewed towards higher values, the mean
cost is likely to exceed the median
value. Thus, these data suggest the
sampling costs provided by the
commenter are probably falling within
the range of MSHA’s estimates.
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However, MSHA estimates sampling
costs of a ‘‘typical’’ mine for the purpose
of this analysis.80 NSSGA presented
costs of $1,800 per sample, $2,866 for
sampling one miner, and $3,247 for
sampling 3 miners are not necessarily
inconsistent with MSHA’s cost
estimates. For example, the operator
who lists costs exceeding $11,000 for a
3-day sampling episode did not provide
the number of miners sampled or the
number of samples taken in that
sampling episode. Using MSHA’s lowest
estimate of $330 per sample for a mine
with more than 500 miners, this
estimate is equivalent to about 33
samples, which is not unreasonable for
three, 10-hour days of sampling. The
commenter’s cost estimate of $11,000
over 3 days is consistent with MSHA’s
estimate.
MSHA acknowledges that some mine
operators will incur higher sampling
costs than the operator of a ‘‘typical’’
mine. MSHA believes that some small
mine operators may experience higher
sampling costs than MSHA estimates
due to operating in remote areas where
it may be more difficult to procure
sampling services, and to the size of the
mine. MSHA estimates the labor cost
per sample at a small MNM mine will
be nearly twice the cost per sample at
larger MNM mines. Under MSHA
estimates, the percentage of miners
needed to achieve representative
sampling (50 percent) is twice as large
as the percentage at larger mines (25
percent or less).
MSHA was unable to determine from
the information provided by
commenters, how they determined a
representative sample and the frequency
of samples taken. For example, the
range of values provided by the NSSGA
was based on ‘‘more than 20
companies.’’ However, there are more
than 6,000 sand and gravel mines
affected by the rule, and it is unclear
whether this cost data represents the
whole sector.
MSHA’s estimated cost per sample is
largely influenced by a mine’s need to
hire a sampling professional. Some
mines might perform their own
sampling, others may hire a sampling
professional (e.g., industrial hygienist);
and others may use a combination of the
two, based on sample timing, numbers
of samples, and mine location. In
80 Industry-wide, a ‘‘typical’’ mine is considered
as a small surface mine, most likely to produce
MNM commodity. Such a mine: would likely have
a small number of buildings, such as a maintenance
shop, an office, and a couple of storage; might
employ up to 50 miners plus managerial and office
staff; and would likely have a crusher and screening
plant, a conveyor, and several pieces of heavy
equipment and haulage vehicles.
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estimating sampling costs, MSHA
assumed half of the MNM samples
would be collected in house and half
collected by a sampling professional.
MSHA considers that mine operators (or
controllers) will evaluate the costs of
options and make the most costeffective decision. The Agency’s
estimated average cost per sample
collected by a contracted industrial
hygienist is nearly equivalent to the
high-end cost examples provided by
some commenters. Differences are
attributable assumptions made on travel
time and expense, numbers of samples
collected per day, numbers of days per
trip (over which travel time and expense
are averaged). To the extent that more
remote mines are able to coordinate
through a local, state, or national
industry association, insurance carrier,
their common mine controller, or other
affiliation, these costs can be reduced by
coordinating sampling dates. In
addition, organizations and associations
provide training on conducting air
sampling. A trained technician working
under an experienced industrial
hygienist can reduce sampling costs.
Estimated total sampling costs from
some commenters are much higher than
MSHA’s estimates because they assume
more miners would have to be sampled
than MSHA estimated under the
proposed rule. For example, NSSGA
estimated that at a cost per sample of
$139 per sample, industry costs will
increase by $34 million, while its
median cost of $650 per sample will
increase industry cost by $162 million
(Document ID 1448). This commenter
appears to have multiplied the cost per
sample by its estimated number of
affected miners, 250,000. Similarly,
EMA mentioned an operator who
assumes that 400 of 446 employees
would be sampled (Document ID 1442),
while a member mentioned by the
NVMA appears to assume that all, or at
least the vast majority of its 7,000
employees would be sampled
(Document ID 1441).
In response to public comments,
MSHA increased its estimate of the
number of samples operators would
need to take to meet the sampling
requirements of the final rule by
increasing the number of samples that
constitutes the required representative
fraction (or sampling
representativeness) and frequency of
sampling and evaluation. For example,
over the first six years starting from the
start of implementation, MSHA now
estimates 758,000 samples of all types
will be taken (Table IX–5), compared to
499,000 under the proposed rule.
Based on exposure profiles for the
MNM and coal mining industries and
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MSHA’s experience and knowledge of
the mining industry, MSHA expects that
on average the ratio of samples to
miners sampled will be smaller than
estimated by commenters. The final rule
allows mine operators to sample a
representative fraction of miners to meet
the rule requirement. That is, a mine
operator would be required to sample a
minimum of two miners where several
miners perform the same tasks on the
same shift and in the same work area,
so not all miners working in the same
mine need to be sampled. Additionally,
this sampling will stop when sampling
results demonstrate exposure at a mine
is below the action level. In Section
8.2.2 of the standalone FRIA document,
MSHA provides two examples of how
representative sampling will reduce the
number of samples required based on
MSHA experience in exposure sampling
at mines and occupation categories.
MSHA has determined that exposure
monitoring requirements in the final
rule are necessary to maintain exposure
levels at a safe level to ensure miners’
health. The exposure monitoring
requirements are also consistent with
the Mine Act’s statutory purpose to
provide improved health protection for
miners. Section 8.2.2 of the standalone
FRIA document outlines a number of
steps mine operators can take to reduce
their monitoring cost.
2. Costs for Exposure Controls
To estimate the installation cost and
to determine which mines will likely
incur exposure control costs to reach
compliance with the new PEL, MSHA
analyzed the most recent 5 years of data
on silica exposure (2015–2019 for MNM
and August 2016–July 2021 for coal). As
a starting point, it assumed that a mine
will incur costs to meet the new PEL if
it had a single sample result that
exceeded the new PEL from the most
recent day for which sample results
were available. Analysis of the data
yielded an initial estimate that 9.7
percent of all mines would incur costs,
as reported in the PRIA. In response to
public comments, MSHA updated this
estimate to reflect the likelihood that
more mines would incur additional
costs of exposure controls. Based on its
analysis and experience, MSHA projects
in this FRIA that each year, about 20
percent of mines will incur some type
of exposure control costs under the final
rule.
MSHA estimated three types of
exposure control costs, as described in
the following sections:
• Installation costs, consisting of the
costs of purchasing new engineering
control equipment and installing it or
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purchasing new services to clean or
ventilate dust from work areas.
• Maintenance and repair costs, to
ensure proper use of existing
engineering controls with increased
frequency of dust control maintenance
and repair.
• Costs of administrative controls to
reduce dust exposure (for example, the
costs of training or posting signage
regarding new policies).
Breaking down the total by type of
cost, each year 5 percent of mines are
expected to incur additional amortized
installation costs, while 20 percent (that
5 percent plus an additional 15 percent)
are expected to incur additional
maintenance and repair costs and costs
for administrative controls.
Costs for New Engineering Controls
Some affected mines will incur
installation costs because they will need
to implement additional engineering
control measures to reduce exposure
levels. Using historical data and
28371
institutional knowledge, MSHA
estimates the number of mines, by size,
that will require additional engineering
controls to meet the new PEL and the
estimated level of capital investment
(i.e., minimal, moderate, and large)
needed. It projects that 580 mines—or a
little under half of those with exposures
above the new PEL at the time of their
most recent sampling—will require
these additional engineering controls,
with a large majority requiring minimal
capital expenditure. (Table IX–7).
Table IX-7: Affected Mines by Employment Size and Control Category Incurring
Additional Engineering Controls, 2019
Mine Employment Size 1
Medium Mines
Large Mines (>
Small Mines(<= (20 < miners <=
20 miners)
100 miners)
100)
Control Category
Total Mines
Engineering controls- Minimal
399
50
9
458
capital expenditure
Engineering controls- Moderate
50
25
9
84
capital expenditure
Engineering controls- Larger
20
8
9
38
capital expenditure
Total
469
28
83
580
Notes: Due to rounding, some totals do not exactly equal the sum of the corresponding individual entries.
Controls categorized under minimal capital expenditure are relatively simple fixes with initial capital costs less than
$2,000; controls with moderate capital expenditure range from roughly $2,000 to $16,000 in capital costs, while
large capital control expenditures exceed $20,000.
1. Production miners and contract miners.
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heavy haulage and excavating
machinery are assumed to have a 15year service life, and new or
substantially renovated structural
ventilation systems are assumed to have
a 30-year service life. Within each
category of capital expenditures, MSHA
takes an average of the engineering
control costs, inclusive of installation,
maintenance, capital, and replacements
costs over the 60-year analysis period
and annualized the costs. Each affected
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mine is assigned the average value for
its capital expenditure category. At a 3
percent discount rate, annualized costs
range from $556 per mine for the lowest
cost tier of capital equipment to $24,345
per mine for the highest cost tier. The
annualized cost is $2,573 per mine per
year when averaged across all mines.
Table IX–8 presents total annualized
engineering costs calculated at $1.43
million (0 percent) to $1.58 million (7
percent) over 60 years.
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MSHA estimates an average cost for
engineering controls based on NIOSH
evaluation of the dust controls used in
the mining industry. MSHA assumed
operating and maintenance (O&M) costs
to be 35 percent of initial capital
expenditure and assumed that
installation cost, when appropriate, will
be equal to initial capital expenditure.
MSHA assumed most controls will have
a 10-year service life, with exceptions
for some equipment. For example,
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Table IX-8: Estimated Total Annualized Engineering Costs (in thousands of 2022 dollars)
by Control Category, 2022
Annualized Engineering Control Cost
at Specified Discount Rate
Number of
Mines
Control Category
0 Percent
3 Percent
7 Percent
Percentage of
Total Costs 1
All Engineering Controls
Total--All
580
$1,431
$1,492
$1,575
100.0%
Metal/Nonmetal
518
$1,186
$1,231
$1,290
82.5%
62
$246
$262
$285
17.5%
Subtotal -- Minimal
458
$251.2
$254.6
$258.0
100.0%
Metal/Nonmetal
417
$228.6
$231.1
$233.4
90.8%
41
$22.7
$23.5
$24.5
9.2%
Subtotal -- Moderate
84
$308.1
$320.8
$337.2
100.0%
Metal/Nonmetal
71
$258.2
$267.8
$279.9
83.5%
Coal
Larger capital expenditure
14
$49.9
$53.0
$57.3
16.5%
Subtotal -- Larger
38
$872.1
$916.8
$979.6
100.0%
Metal/Nonmetal
30
$699.1
$731.8
$776.3
79.8%
$173.1
$185.1
$203.3
20.2%
Coal
Minimal capital expenditure
Coal
Moderate capital expenditure
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Costs for Maintenance & Repair of
Engineering Controls
Beyond adopting more advanced
engineering control infrastructure, an
integral method of reducing respirable
crystalline silica exposure is by
increasing the frequency of maintenance
and repairs for dust control systems. In
MSHA experience, when there are
overexposures, often engineering
controls are in place but the operator
has neglected maintenance and repair.
MSHA has determined that, when the
appropriate dust control systems are
used, effective and regular maintenance
and repair of such systems can help
reduce respirable crystalline silica
exposure below the new PEL.
Maintenance and repair activities are
usually conducted at the beginning of
each shift (or as frequently as necessary)
and can be a part of existing safety and
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operational checks performed on most
equipment.
MSHA estimates, on average, that
mine operators would spend 16 hours
per quarter on additional inspection and
maintenance (i.e., 64 hours per year). To
account for additional maintenance and
repair costs that would result from using
inspection checklists to cover
maintenance and repair of dust
suppression and control equipment,
MSHA added 25 percent to the costs for
maintenance and repairs. These
maintenance and repair costs will be
incurred every year over a 60-year
analysis period, resulting annual cost of
$3,389 per mine for MNM and $4,789
per mine for coal.
MSHA anticipates that additional
mines will incur increased maintenance
and repair costs each year to reduce
exposure below the action level to avoid
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exposure monitoring costs. MSHA
assumes that in total, these maintenance
and repair costs will be incurred by 19.7
percent of mines, or 2,489 mines (2,249
MNM mines and 241 coal mines). These
mines include the 4.7 percent that will
incur new installation costs, plus an
additional 15 percent that will incur
only maintenance and repair costs and
costs of administrative controls. MSHA
assumes that this is the share of mines
industrywide that will incur costs in
each year, even as the specific mines
incurring those costs may vary from
year to year. Multiplying the average
maintenance and repair cost per mine
by the estimated 2,489 mines that will
incur costs ranging from $8.65 million
(0 percent discount rate) to $8.27
million (7 percent discount rate) for
increased maintenance and repair
(Table IX–9).
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Coal
7
Note: 1. Calculated at the 3 percent discount rate.
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table IX-9: Annualized Increased Maintenance and Repair Control Costs (in thousands of
2022 dollars) by Sector
Total Annualized Cost at Specified Discount Rate
Mine Sector
0 Percent
Total
Metal/Nonmetal
3 Percent
$8,646
$7,493.6
Coal
$1,152.2
Note: 1. Calculated at the 3 percent real discount rate.
Costs for Administrative Controls
Administrative controls comprise a
variety of methods to reduce exposure
to respirable crystalline silica dust. In
general, mine operators evaluate
situations in which exposure can be
reduced through changes in policies and
work practices, and implements those
changes by informing miners through
training, published announcements,
procedures, instructions, and signage.
Examples of administrative controls
include enclosing cabs to work with
doors and windows shut and setting
speed limits and minimum distances for
equipment operated on dusty haul
roads.
While many of these examples are
applications of common-sense policies,
they can be circumvented either
accidently or deliberately.
Administrative controls are not always
effective, or as effective as they could
be, because unlike engineering controls,
administrative controls depend on
7 Percent
Percent by Sector1
$8,506
$8,266
$7,353.3
$7,113.3
100.0%
86.5%
$1,152.2
$1,152.2
13.5%
miners’ adherence to the policies and
work practices. Administrative controls
rank lower than engineering controls in
the hierarchy of effectiveness.
The cost of administrative controls is
composed of labor hours. MSHA
believes that 2,489 mines will spend, on
average, 16 labor hours on
administrative controls starting in Year
1 for coal and Year 2 for MNM of the
60-year analysis period. As with the
estimates of additional maintenance and
repair costs, this figure for number of
affected mines is based on MSHA’s
assumption that, beyond those mines
with exposures currently above the new
PEL, an additional 10 percent of mines
might incur increased administrative
costs each year to reduce exposure to
below the action level.
In addition to the time spent
identifying administrative controls,
mine staff need to prepare and publish
training and instructional materials, and
post signage and/or other informational
materials to implement such controls; to
account for this, MSHA increases the
value of labor hours by a factor of 2.0.
MSHA estimates that the additional
labor costs spent on administrative
controls as an average of the loaded
hourly wage rate weighted by the
relative employment of these
occupations in the mining industry. The
estimated average cost is $1,439 per
affected MNM mine (Year 2—60) and
$2,222 per coal mine (Year 1—60).
Table IX–10 shows the estimated
number of mines and annual costs
expected to be incurred in Year 1 and
Years 2 through 60 for administrative
controls. Additionally, Table IX–11
shows that total annualized costs range
from $3.7 million (0 percent discount
rate) to $3.6 million (7 percent discount
rate) based on the discount rate used.
The higher totals for the MNM sector are
attributable to the much larger number
of affected mines than the coal sector.
Table IX-10: Annual Administrative Control Costs (in thousands of 2022 dollars)
Mines Needing
Administrative
Control
Mine Sector
Annual Cost
Percent by
Sector1
Incremental costs incurred in Year 1
Total
Metal/Nonmetal
Coal
241
$534.7
100.0%
0
241
$0.0
0.0%
$534.7
100.0%
Incremental costs incurred in Year 2-60
$3,770.9
$3,236.2
100.0%
85.8%
241
$534.7
14.2%
ER18AP24.167
Coal
Note: 1. Calculated at the 3 percent discount rate
2,489
2,249
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Total
Metal/Nonmetal
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Table IX-11: Annualized Administrative Control Costs (in thousands of 2022 dollars)
Total
Metal/Nonmetal
$3,717.0
$3,657.4
$3,555.5
100.0%
$3,182.3
$3,122.7
$3,020.8
85.4%
$534.7
$534.7
14.6%
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Coal
$534.7
Note: 1. Calculated at the 3 percent discount rate.
Several commenters did not agree
with MSHA’s exposure control
estimates as applied to their mines,
stating that MSHA underestimated the
costs of implementing exposure controls
(Document ID 1419; 1441; 1448; 1455),
and/or asserted that most mine
operators who meet the current PEL will
need to install significant new
engineering controls to meet the new
PEL. For example, Nevada Mining
Association, stated that estimated
compliance costs for one of their
members was $22.7 million for the first
year and $13.6 million for each
following year to retrofit mobile
equipment with filtered pressurized air
as well as medical surveillance and
exposure sampling costs (Document ID
1441). NSSGA stated that ‘‘[b]ased on
communications with 13 member
companies, costs for exposure controls
will vary widely, but on average are
$920,000 annually, with a median of
$225,000 (Document ID 1448).’’ Neither
the types of controls nor the number of
mines installing the controls was
included with the commenter’s
estimate. One of NSSGA’s members also
stated that its 2023 budget for exposure
controls is approximately equal to the
MSHA annual estimate for all of MNM.
Another commenter, US Silica, stated
that in 2023 alone, it incurred $3.6
million in capital costs on two
automated projects and multiple other
projects exceeding MSHA’s estimate for
the industry (Document ID 1455). A fifth
commenter, Vanderbilt Minerals, LLC
provided expected costs of $7 million
for a list of renovations to existing
facilities and new equipment purchases
(Document ID 1419).
Based on its analysis of the Agency’s
sampling database, MSHA believes
roughly 90 percent of mines will be able
to meet the PEL without incurring
additional costs. In Section 4 of the
standalone FRIA document, MSHA
estimates that about 1,230 mines are
expected to incur exposure control costs
to meet the new PEL. Of these, a little
more than 50 percent (650 mines)
should be able to meet the new PEL
using controls such as additional
maintenance and repair, and
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administrative controls. The remaining
47 percent of mines (580 mines)
expected to incur costs will also
implement engineering controls—in
addition to increased maintenance,
repair, and administrative costs—to
meet the new PEL.81 The distinction
between the two types of mines is
related to sample data that shows
compliance with the existing PEL.
Additionally, MSHA includes an extra
10 percent of total mines (111 coal
mines and 1,153 MNM mines) that will
incur exposure control costs, including
enhanced administrative controls and
frequent maintenance and repair.
MSHA’s analysis is described in more
detail in the standalone FRIA. Twenty
operators commented that MSHA
underestimated exposure control costs.
A couple of these commenters did not
provide specific evidence to support
their position that many operators will
incur substantial engineering control
costs.
MSHA assumes that all mines are
currently in compliance with the
existing PEL when estimating
compliance costs. Costs incurred by
operators are attributed to lowering
exposures from the existing PEL to the
new PEL. Some mine operators have
found it difficult to consistently control
exposures to meet the existing PEL; any
additional costs incurred by them will
be more appropriately attributed to
maintaining compliance with the
existing PEL.
The estimated costs presented in the
standalone FRIA represent the average
estimated compliance costs for a typical
mine. MSHA acknowledges that the
exposure control costs will differ
depending on the size of the mine, the
current level of exposure to respirable
crystalline silica, existing engineering
and administrative controls, the mine
layout, work practices, and other
variables. MSHA’s price and cost
estimations are based on a variety of
sources including market research and
MSHA’s experience and sample data.
81 The maintenance, repair, and administrative
costed for the additional 1,260 mines are not to
meet the new PEL but to reduce exposures below
the action level to reduce monitoring costs.
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The evidence provided by the
commenters was collected from
members of trade organizations. It
appears that at least some of the cost
estimates are from either very large
mines—far larger than the ‘‘typical’’
mine used for MSHA cost estimates—or
may reflect an estimate for all mines
controlled by an operator. For example,
the comment that the ‘‘total amount to
retrofit all underground and surface
mobile equipment with filtered
pressurized air, medical surveys and
increased sampling is $22.7 million for
the first year, and $13.6 million each
year after’’ is from an MNM operator
with 7,000 employees. If this represents
a single mine, only 26 MNM mines (0.2
percent) employed more than 500
miners in 2019 (Table IX–1), if this
represents multiple mines, then the
anticipated compliance costs per mine
would be smaller. Because the number
of mines is unknown, and because the
commenter includes sampling costs
(provided separately as $1.2 million per
year) and medical surveillance costs in
the total, it is impossible to
meaningfully compare this estimate
with MSHA’s estimates.
Similarly, US Silica presented costs
exceeding $3.6 million in capital
expenditures on two automated
projects; totaling all projects, US Silica
states it exceeded MSHA’s estimate for
the entire industry (Document ID 1455).
However, it is unclear how many mines
owned by US Silica incurred the costs.
In addition, US Silica installed two
automated systems. Generally, an
automated bagging operation is more
costly to purchase and install than a
manual bagging system. The higher
capital cost of an automated system also
likely results in offsetting cost savings
(e.g., labor costs), and thus US Silica’s
estimated compliance costs likely
include decisions made for other
business reasons, not just the cost of
reducing worker exposure.
Vanderbilt Minerals LLC provided
expected costs of $7 million for
renovations to existing facilities and
new equipment purchases at a single
site, including ‘‘the purchase/
installation of such items as a new
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Mine Sector
Total Annualized Cost at Specified Discount Rate
0 Percent
3 Percent
7 Percent
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bagging system for 50-pound bags, new
dust collectors for drying/milling
equipment, renovation of a laboratory,
office, break room, mill control office,
and crusher operator booth, purchase of
larger water trucks and an increase in
paved haul roads (Document ID 1419).’’
In this case, the costs by the commenter
are clearly higher than MSHA’s
estimated compliance costs for a single
typical mine. However, the site in
question appears to be highly atypical of
most of MNM mining and therefore not
appropriate for extrapolating industry
costs. More details are provided in
Section 8 of the standalone FRIA
document.
A further difficulty in evaluating
commenters’ estimates of engineering
costs is that MSHA presents annualized
costs; that is, compliance costs with
initial capital and one-time costs
amortized over the service life of the
control. Many commenters provided
first-year costs (without identifying
capital, one-time, or recurring
(operation and maintenance) cost
components) to show that MSHA
underestimated exposure control costs.
The comparison of commenters’ firstyear costs with MSHA’s annualized cost
estimates is inappropriate. For example,
a MNM mine operator provided $3.6
million as the first-year cost estimate
without offering information about the
actual service lives of these automation
projects (Document ID 1455). If those
costs are amortized at a 3 percent
discount rate using an assumed 10-year
service life (implying the system will be
replaced 6 times over the course of the
60-year analysis period), the annualized
capital component of their cost is about
$410,000; if the expected service life is
30 years (replaced twice over 60 years),
the annualized cost is about $178,000.
Similarly, when amortized using a 3
percent rate, a $7 million in initial
capital cost is equivalent to less than
$800,000 annualized cost per year if the
system has a 10-year service life, and
less than $400,000 if the service life is
30 years. Thus, it is difficult to directly
compare MSHA’s annualized costs with
first-year costs provided by commenters
without service life information.
Small mine operators specifically
questioned MSHA’s estimates of the
cost of controlling exposure to
respirable silica crystalline silica dust
(Document ID 1411; 1415; 1427; 1435;
1436). Water based dust suppression,
especially if combined with magnesium
chloride, is likely to be more expensive
at some remote mines in arid regions
due to the cost of obtaining and
transporting water. However, these
commenters did not discuss the
applicability of other methods of
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reducing exposures presented in the
FRIA and Technological Feasibility
discussions. For example, operating
vehicles with windows closed, reduced
vehicle speed, and wider vehicle
spacing have all been shown to decrease
operator exposure to dust. These
commenters provided the cost of cabin
air filters and their preference to not use
air conditioning, but it should be noted
that there may be trade-offs in the
choices mine operators make to reduce
exposure to dust. For example, the use
of air conditioning by vehicle operators
will increase costs (filters, fuel use), but
will decrease exposures. These
increased operating costs should be
offset by reduced sampling costs.
3. Costs for Respiratory Protection
The new PEL may result in an
increased use of respirators by miners
when compared with usage under the
existing PEL. This additional usage will
result from provisions § 60.13:
Corrective actions and § 60.14 (a):
Respiratory protection. Under § 60.13, if
sampling results indicate miners’
exposure exceeds the new PEL, mine
operators must make approved
respirators available to affected miners;
ensure that miners wear respirators
properly during the period of
overexposure; and take corrective
actions to lower the concentration of
respirable crystalline silica to at or
below the PEL. Section 60.14 (a)
requires the temporary use of respirators
by MNM miners when engineering
controls are developed and implement
or when necessary due to the nature of
work involved (e.g., entry into a
hazardous atmosphere to perform
maintenance). MSHA expects that
additional use of respiratory protection
will occur because exposure levels that
were below the existing PEL will now
be above the new PEL. MSHA believes
that most respirator use will occur
during the first few years after
implementation of the rule until mine
operators can consistently control
sources of respirable crystalline silica
dust exposure at the new PEL using
engineering controls, but that the
respirator use will decline as mines
implement and improve additional
controls. However, with little data to
support an assumption concerning how
quickly incremental respirator use
might decline, MSHA chose to model
respirator use as remaining constant
over the 60-year analysis period.
Under § 60.13 MSHA believes that
miners who are most likely to need
incremental respirator use to perform
corrective actions work in the following
occupations:
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28375
• Kiln, Mill, and Concentrator Workers
(MNM mines)
• Mobile Workers & Jackhammer
Operators (MNM mines)
• Miners in Other Occupations (MNM
mines)
• Underground Miners (Coal mines)
• Surface Miners (Coal mines)
To estimate the number of miners
who might be required to use respirators
under § 60.13, MSHA first uses sample
data to estimate the number of miners
in these occupations with respirable
crystalline silica exposures between the
new PEL and the existing standards (50
mg/m3 to 100 mg/m3 range for MNM and
50 mg/m3 to 85.7 mg/m3 for coal) to
identify the miners most likely to
increase their use of respirators as a
result of the rule. MSHA then assumes
that 20 percent of that total, about 2,109
miners would these miners end up
using respirators as a result of the rule.
MSHA thus estimates that mine
operators will incur costs for increased
respiratory protection by 1,984 MNM
miners and 125 coal miners per year to
meet the requirements of § 60.13.
Under § 60.14, MSHA uses sample
data to estimate the number of MNM
miners that might need to increase their
use of respirators due to the rule. MSHA
assumes that MNM mine operators will
need to provide additional respiratory
protection for 20 percent of MNM
miners in all occupations with
exposures between the new PEL and the
existing PEL. MSHA estimates MNM
operators will need to provide
respiratory protection to 4,945 MNM
miners to meet the requirements of
§ 60.14.
Under sections 60.13 and 60.14
together, mine operators are expected to
increase respirator protection for
approximately 7,054 miners and
contract miners (6,928 MNM miners and
125 coal miners).
MSHA estimates two types of
respiratory protection costs: the
purchase of new respirators to be issued
and the incremental cost of additional
temporary respirator use. MSHA
believes that given the existing
respiratory protection standards, most
miners have already been issued
respirators to deal with intermittent,
temporary circumstances where
exposures exceed the existing standards.
However, some mine operators with
miners at low risk of exceeding the
existing standard may need to purchase
respirators to account for possible
temporary exposures in the range
between the new PEL and existing
standards. It is likely that some miners
newly at risk for exposure in this range
will not have respirators. In addition,
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because respirators will be used more
under the new PEL, respirators will
deteriorate more quickly and need
replacement. In addition to miners who
did not need to wear a respirator under
the existing standards but might have
occasional temporary need for
respiratory protection under the new
PEL, some mine operators will need to
replace respirators for miners more
frequently due to a small increase in the
need for temporary respiratory
protection.
MSHA assumes that in Year 1, coal
mine operators will incur costs for new
respirators for 50 percent of their coal
miners who are expected to increase
respirator use (i.e., a total of 63 new
respirators) under § 60.13. In Year 2,
MNM mine operators will similarly
incur costs for new respirators for 50
percent of the total MNM coal miners
who are expected to increase their
respirator use (i.e., 3,464 new
respirators under § 60.13 and § 60.14
combined). In Years 2 through 60 (for
coal) and Years 3 through 60 (for MNM),
mine operators will incur replacement
costs for 50 percent of the total number
respirators for respiratory protection
under the new PEL for miners who did
not require respiratory protection under
the existing PEL. In Year 1 of
compliance for coal mines, 63 coal
miners (including contract miners), who
occasionally perform corrective actions
where they would likely be exposed to
respirable crystalline silica in the range
between the new PEL and the existing
standards are expected to be provided
with new respirators by mine operators
t a cost of $9,821. In Year 1 of
compliance for MNM mines (Year 2
following publication of the final rule),
3,464 MNM miners will also be
provided with new respirators for
corrective actions and temporary use at
a cost to mine operators of $502,282.
New respirator purchase costs in Year 1
of compliance for coal and MNM mine
operators are estimated to total $512,103
across both sectors. In subsequent years
(Years 2 through 60 for coal mines;
Years 3 through 60 for MNM mines),
annual costs are expected to be about
half of first year costs ($256,052).
of new respirators purchased in Year 1
(for coal) and Year 2 (for MNM).
Therefore, in Year 3 and onwards, coal
and MNM mine operators will purchase
a total of 1,763 new respirators per year.
Furthermore, MSHA assumed that all
new respirator purchases in any year
throughout the analysis period will
require fit testing and training.
MSHA assumed that mine operators
will purchase tight-fitting, re-useable
half-mask elastomeric respirators at a
cost of $39.57 each plus $17.29 for
filters.82 In addition, MSHA assumed
respirators are assigned to individuals,
not shared equipment. Furthermore,
miners issued new respirators will
require an additional 2 hours of labor
time for fit testing and training which is
valued at the weighted average loaded
wage of all mine workers in the given
sector ($50.60 for Metal miners, $40.47
for Nonmetal miners, and $49.97 for
coal miners).83 84 The resulting annual
cost per miner requiring a new
respirator is estimated to be $145 for
MNM miners and $157 for coal miners.
Table IX–12 presents the estimated
annual costs of purchasing new
Table IX-12: Estimated Annual Cost of New Respirator Purchases (in 2022 dollars)
Miners Including
Contract Miners
Mine Sector
Year 1
Total
Total Annual
Cost
Percent by
Sector
63
$9,821
100.0%
0
$0
0.0%
63
$9,821
100.0%
3,496
$507,193
100.0%
3,464
$502,282
99.0%
31
$4,911
1.0%
1,763
$256,052
100.0%
1,732
$251,141
98.1%
31
$4,911
1.9%
Metal/Nonmetal
Coal
Year2
Total
Metal/Nonmetal
Coal
Total
Metal/Nonmetal
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Coal
Table IX–13 summarizes the total
annualized cost of new respirator
purchases by sector. Overall, the new
PEL is expected to lead mine operators
to purchase new respirators costing an
average of $256,134 (at a 0 percent
discount rate) to $255,285 (at a 7
percent discount rate) per year over the
60-year analysis period.
82 Based on online (non-discount) prices:
websites for Northern Safety, 2022: $29.14/each
3MSeries 6500 half mask respirator, $10.25/pair for
P100 pancake filters; and Grainger, 2022: $50.00 for
MSA 420 series half mask respirator, $24.32 for
P100 filter cartridges (package of 2). Prices are
higher end of potential range, supplier bulk
discounts available from numerous other sources.
83 OSHA APF rulemaking (update to 29 CFR
1910.134) Unit Costs: 1 hour employee training, 1
hour employee qualitative fit testing. Alternatively,
2 hours for quantitative fit testing (from costs
estimated in 2001–2006; may be reduced due to
efficiency of more modern quantitative fit testing
equipment currently available and widely used).
MSHA assumed that worker fit testing is conducted
in small groups; two to four miners are fit tested
during the hour, but all remain part of the group
for the full hour.
84 MSHA assumed there will be no additional
labor costs for personnel conducting fit testing or
training because current respiratory protection
programs already require these steps.
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28377
Table IX-13: Estimated Annualized Cost of New Respirator Purchases (in 2022 dollars)
Total Annualized Cost at Specified Discount Rate
7 Percent
0 Percent
3 Percent
Mine Sector
Total
$256,134
$251,141
$4,992
Metal/Nonmetal
$255,967
$250,884
$5,083
Coal
Note: 1. Calculated at the 3 percent discount rate.
$255,285
$250,047
$5,238
per year). For estimating costs, if an
elastomeric respirator uses two filters at
a time, and the filters last eight hours
before requiring replacement, then these
miners will need an additional 26 pairs
of filters per year (208 hours per year/
8 hours per filter pair). At an average
price of $17.29 per pair of filters, mine
operators will spend an additional $450
per miner per year ($17.29 × 26 filter
pairs) for respirator filters.
MSHA estimates the cost of additional
respirator use under the new PEL for
miners who did not need it under the
existing standards. MSHA assumes the
cost of additional respirator use starts in
Year 1 (for coal mines) and Year 2 (for
MNM mines) will remain constant over
the 60-year analysis period. On average,
MSHA believes additional respirator use
will be necessary for 4 hours per week
per miner, or an additional 208 hours
per year (4 hours per week × 52 weeks
Percent by Sector1
100.0%
98.0%
2.0%
Table IX–14 and Table IX–15 present
the estimated total annual and
annualized cost of additional respirator
usage by sector. The annual cost of
additional temporary respirator use is
expected to be $450 per miner per year
over the 60-year analysis period (Table
IX–14) and total annualized cost is
expected to range from $3.12 million (0
percent discount rate) to $2.96 million
(7 percent discount rate) per year (Table
IX–15).
Table IX-14: Estimated Annual Cost of Additional Respirator Use by Sector (2022 dollars)
Miners Including
Annual Cost per
Mine Sector
Contract Miners
Miner
Year 1
Total
125
$450
1
Metal/Nonmetal
0
$0
Coal2
125
$450
Years 2 - 60
Total
7,054
$450
1
Metal/Nonmetal
6,928
$450
Coal2
125
$450
Notes:
1. Annual cost for MNM in Year 2 through 60; cost is $0 in Year 1.
2. Annual cost for coal in Year 1 through 60.
Total Annual Cost
$56,312
$0
$56,312
$3,170,895
$3,114,584
$56,312
Table IX-15: Annualized Cost of Additional Temporary Respirator Use by Sector (in
thousands of 2022 dollars)
Total Annualized Cost at Specified Real Discount Rate
$3,119.0
$3,061.6
$2,963.6
100.0%
$3,062.7
$3,005.3
$2,907.2
98.2%
$56.3
$56.3
1.8%
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Coal
$56.3
Note: 1. Calculated at the 3 percent discount rate.
The estimate presented in Table IX–
15 may be an overestimate of the cost
of respirator use. MSHA assumed
respiratory use would remain constant
over the 60-year analysis period, it is
likely that need for additional respirator
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use will decline as mines implement
and improve engineering and
administrative controls. However, with
little data to support an assumption
concerning how quickly the need for
additional respirators might decline,
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MSHA chose to model it as constant.
Second, while most mines operate yearround, some mines may operate for as
little as 3 months per year. This will
also decrease the need for respirators
use.
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Metal/Nonmetal
Percent of Total
Annualized Cost1
7 Percent
3 Percent
ER18AP24.171
0 Percent
ER18AP24.170
Mine Sector
Total
28378
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Some commenters provided unit cost
data for respirators and filters that were
greater than the unit cost estimates that
used in the PRIA (Document ID 1411;
1415; 1427; 1435; 1436). First, based on
their data, the replacement filter
cartridges last much longer than those
costed by MSHA, so that the cost of one
year’s use will be lower than MSHA’s
cost estimate due to the long life span
of replacement filters used by
commenters. Second, the commenters
assumed all employees would require
new respirators and did not account for
baseline use (or availability) of
respirators at the mine. The final rule
requires MNM mine operator to use
respiratory protection as a temporary
measure when miners must work in
concentrations of respirable crystalline
silica above the PEL when engineering
control measures are being developed
and implemented or necessitated by the
nature of work involved. MSHA
determined that its cost assumption is
more comprehensive and likely
overestimates respirator protection
costs.
4. Cost for Medical Surveillance
Under the final rule, MSHA will
require each MNM mine operator to
provide mandatory medical
examinations to miners who are new to
the mining industry and voluntary
periodic examinations to all currently
employed miners. These new medical
surveillance standards extend to MNM
miners the opportunity for medical
surveillance that is already available to
coal miners under the existing rules.
The medical examinations will be
provided by a physician or other
licensed health care professional
(PLHCP), or by a specialist. The medical
examination will include a miner’s
medical and work history, a physical
examination, a chest X-ray, and a
pulmonary function test. For those
miners new to the mining industry, the
first mandatory examination must take
place within 60 days after beginning
employment. This must be followed by
a mandatory follow-up examination at 3
years. Should the follow-up
examination indicate any medical issues
related to lung disease, a second
mandatory follow-up examination must
take place in 2 years. In addition to
these mandatory examinations, mine
operators must also offer voluntary
periodic medical examinations to all
MNM miners at least every 5 years. The
first periodic medical examination for
existing MNM miners must be provided
within 12 months of the final rule’s
MNM compliance date, or if a MNM
mine commences operation after the
compliance date, within 12 months of
the mine beginning operations. All of
the medical examinations must be
provided at no cost to the miner.
Additionally, the MNM mine operator
must ensure that, within 30 days of the
medical examination, the PLHCP or
specialist provides the results of chest
X-ray classifications to NIOSH, once
NIOSH establishes a reporting system.
The cost of the x-ray includes the cost
of preparing the report and transmitting
those results to NIOSH.
To estimate the costs of compliance
with the medical surveillance
requirement, MSHA first estimated the
‘‘unit cost’’ of a single medical
examination. MSHA then estimated
how many examinations would occur in
each year over the 60-year analysis
period and multiplied the numbers of
examinations by the unit cost to
determine total costs in each year.
MSHA summed the costs in each year
to estimate a total cost over the full 60year period.
Unit Costs
MSHA assumed that all examinations
entail the same cost elements (in
decreasing order of cost): the physical
examination, chest X-ray, spirometry
test, lost work time while being
examined, lost travel time, symptom
assessment and occupational history,
transportation cost, and recordkeeping
of the mine operator. Table IX–16
displays estimated components in 2022
dollars, which sum to a unit cost of
$628.58 per examination.
Table IX-16: Estimated Cost Per Medical Examination (in 2022 dollars)
To estimate the number of
examinations expected per year, MSHA
used the estimated number of full-time
equivalent (FTE) employees in MNM
mining, which is 184,615 FTE workers.
MSHA assumed that the MNM
employment will remain constant over
the 60-year analysis period following
compliance of the medical surveillance
requirement.85 MSHA estimates that the
85 MSHA chose to express mine employment in
FTEs for the benefits analysis because health
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average length of employment as an
MNM miner (before leaving the mining
occupation) is 22 years, which is
derived from a NIOSH survey that found
impacts would differ between part-time miners,
who would experience less exposure to respirable
crystalline silica dust and thus would be less likely
to experience the same negative health effects in the
same amount of time as miners who worked fulltime or more. A similar logic applies to miners
deciding whether to accept medical examinations,
thus medical surveillance costs are also estimated
based on FTE miners.
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Cost
$158.69
$119.20
$81.89
$49.90
$87.29
$87.29
$26.76
$17.55
$628.58
the average mining experience of MNM
miners is approximately 11 years.86
86 The 2012 report by NIOSH, entitled, ‘‘National
Survey of the Mining Population: Part 1:
Employees,’’ includes the findings of its 2008
survey on mine operators and miners in the U.S.
https://www.cdc.gov/niosh/mining/works/
coversheet776.html (last accessed Jan. 10, 2024).
Details on the survey methodology and results are
available in the link. The NIOSH survey found the
following mine experiences for different types of
MNM mines, which average to about 11 years
(11.375 to be precise): metal mines, 10.7 years;
nonmetal, 12.0 years; stone, 12.5 years, and sand
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Cost Components
Physical Examination
ChestX-Ray
Spirometry Test
Symptom Assessment and Occupational History
Lost Work Time While Being Examined
Lost Travel Time
Transportation Cost
Recordkeeping of Mine Operator
Total
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Based on this estimate, MSHA assumed
that each year 8,392 miners (i.e., about
1/22, or 4.55 percent, of 184,615 FTE
MNM miners) would leave the industry,
and be replaced by the same number of
new entering workers.
MSHA estimates total medical
surveillance costs over the 60-year
analysis period under two different
scenarios due to the uncertainty of how
many currently employed miners will
participate in voluntary medical
surveillance programs. Assuming a
participation rate of 25 percent
(Scenario 1), annualized costs range
from $14.6 million (with a 0 percent
discount) to $14.0 million (with a 7
percent discount rate) and the
annualized cost per MNM miner ranges
from $79 (with 0 percent discount rate)
to $76 (with a 7 percent discount rate).
In scenario 2, MSHA assumed that the
participation rate is 75 percent.
Annualized costs range from $23.7
million (0 percent discount rate) to
$23.1 million (7 percent discount rate).
The annualized cost per MNM miner
range from $128 (7 percent discount
rate) to $125 (0 percent discount rate).
A summary of estimated medical
surveillance costs under the two
scenarios is presented in Table IX–17.
Table IX-17: Summary of Estimated Medical Surveillance Costs for MNM Miners by
Participation Rate and Discount Rate (in millions of 2022 dollars)
Discount Rate
Cost Type
0 percent
3 percent
7 percent
Total Costs
25 percent participation rate
$875.0
$397.2
$196.0
7 5 percent participation rate
$1,383.2
$645.4
$332.4
Average ofparticipation rates
$1,129.1
$521.3
$264.2
25 percent participation rate
$14.6
$14.4
$14.0
7 5 percent participation rate
$23.1
$23.3
$23.7
Average ofparticipation rates
$18.8
$18.8
$18.8
25 percent participation rate
$78.99
$77.74
$75.61
75 percent participation rate
$124.87
$126.32
$128.25
Annualized Cost
Vanderbilt Minerals LLC stated that
MSHA underestimated the cost of
medical surveillance and stated its
program cost approximately $9,400 per
site per year, plus an additional $4,000
per site per year in employee time at 3
hours per employee (Document ID
1419). Assuming an average loaded
wage of a nonmetal sector extraction
worker at $40.47 per hour, $4,000 in
employee time would cover 33
employees. This suggests that average
medical surveillance costs would be
about $406 per employee by dividing
total costs of $13,400 (= $9,400 +
$4,000) per site by 33 employees.87 This
is significantly lower than MSHA’s
estimated unit cost for medical
surveillance of $629 per examination in
2022 dollars (Table IX–16).
Another commenter, National Mining
Association, stated that the proposed
medical surveillance requirements
would impose significant costs on its
members, due to the expansion to cover
potentially 200,000 MNM miners at
more than 11,000 mines (Document ID
1428). As mentioned above, MSHA
assumes that under the final rule,
operators are required to conduct
medical surveillance on currently
employed miners and new miners
(those who start to work on the mining
industry for the first time). For currently
employed miners, MSHA assumes two
participation rates (25 percent and 75
percent) for medical surveillance and
estimates the number of tests per year as
6,700 under 25 percent participation
rate and 20,200 under 75 percent
participation rate tests per year at an
average cost of $4.24 million to $12.7
million each year (undiscounted).
Average over the two participation rates,
MSHA estimates that operators will
conduct an average of 13,500 tests per
year on the new miners at an average
cost of $8.5 million each year
(undiscounted).
Commenters also shared concerns on
medical surveillance costs for small
mine operators (Document ID 1408;
1411; 1415; 1427; 1435; 1436). The
specific issue raised by these
commenters concerned the cost of
hourly wages and travel expenses from
remote mine locations to obtain medical
examinations. Thus, their costs will be
larger than estimated by MSHA. MSHA
acknowledges these concerns but notes
that commenters provided no specific
data in support of their position.
At least two commenters, NSSGA and
Illinois Association of Aggregate
Producers, stated that, under the
proposed rule, companies would incur
millions of dollars in costs that do not
benefit miners’ health and safety, using
as examples requiring sampling every 3
months indefinitely for exposures
between 25 mg/m3 and 50 mg/m3,
requiring that medical surveillance be
offered to miners with less than 30 days
a year of exposure to respirable silica at
and gravel 10.3 years. For comparison, the same
survey found the average mining experience for
coal miners was 16.0 years. These averages reflected
the average number of years that respondent miners
had worked at mines at the time the survey was
conducted. MSHA considered these average mine
experiences to represent approximately one half of
the mining tenure these miners would have (the
years in mining when they leave). Conversely,
MSHA estimated miners’ total expected tenure to be
twice these average mining experiences.
87 The commenter does not state whether
employee time is valued at a loaded hourly rate
(including benefits and overhead) or the raw hourly
rate. If the latter rate is used ($24.34 per hour), then
the commenter’s program would cover 55
employees at a cost of $244 per employee.
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Annualized Cost per MNM miner
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
or above the action level and requiring
initial sampling even for facilities that
have had exposure monitoring for
decades (Document ID 1448; 1456).
MSHA has determined that on-going
sampling and periodic evaluations are
necessary to ensure that exposures to
respirable crystalline silica meet the
new PEL and that miners’ health is
protected. Exposure monitoring, that
includes an action level, provides mine
operators and miners with necessary
information to take actions to prevent
miners’ overexposures. Allowing mine
operators to cease monitoring once
exposure is maintained below the action
level provides operators with the
incentive to reduce and maintain
exposures below the PEL. For medical
surveillance, MSHA believes it is
important for MNM operators to provide
medical surveillance so that MNM
miners will have information about
their health to take necessary action
early to prevent any further progression
of disease.
5. Cost for ASTM Update
Under the final rule, mine operators
are required to have a written
respiratory protection program in
accordance with the 2019 ASTM
F3387–19 standard. A written
respiratory protection program must
include: program administration;
written standard operating procedures;
medical evaluations; respirator
selection; training; fit testing; and
maintenance, inspection, and storage.
Mine operators will compare the ASTM
standard to their existing respiratory
protection program or practices and
identify the elements of their existing
respiratory protection program or
practices that need to be revised. MSHA
evaluated the components of the 2019
ASTM standard that have the potential
to impose additional costs on mine
operators.
MSHA assumes that 20 percent of
MNM mines will incur costs to meet the
2019 ASTM standard each year. MSHA
assumes that all coal mines are affected
by the update to the 2019 ASTM
standard because 30 CFR 72.700(a)
requires coal mine operators to make
respirators available to their miners.
This should be an overestimate because
it is likely that many coal mines already
meet the 2019 ASTM standard. MSHA
assumes that only a small subset of
miners uses respirators each year.
MSHA assumes about 10 percent of
MNM miners and 3.7 percent of coal
miners are expected to be required to
use respirators each year.
Table X–18 presents the total number
of mines compared to the total number
of mines expected to incur compliance
costs to update their respiratory
protection program and practices. In
Year 1, MSHA assumes that 1,106 coal
mines will incur costs to update their
respiratory protection program and
practices to the 2019 ASTM standard,
and 2,722 coal miners and contract
miners are expected to wear respirators.
Starting in Year 2, MSHA estimates that
3,411 mines (i.e., 20 percent of the
11,525 MNM mines and 100 percent of
the 1,106 coal mines) are expected to
incur costs. In addition, MSHA
estimates 6,946 miners and contract
miners wear respirators each year,
which represents less than 2.5 percent
of all miners including contract miners
(6,946/284,778). Respirators are worn to
protect miners from airborne
contaminants (including respirable
crystalline silica and coal dust) at a
small percentage of mines each year and
only a small fraction of the miners at
those mines wear respirators.
Table IX-18: Mines Incurring Incremental Costs of ASTM Update, 2019
MSHA evaluates the components of
the 2019 ASTM standard that may
impose additional costs on mine
operators, and the assumptions in
estimating those costs.
Approved Respirators. Mine operators
are familiar with MSHA’s existing
requirements for using NIOSH-approved
respirators, and this analysis assumed
that mine operators will not incur
additional costs for these requirements.
MSHA assumed recordkeeping
primarily results in labor costs.
Program Audit. Program costs for an
annual review and written report by the
program administrator are included
with the annual labor time. A program
administrator will perform the review
and prepare the report. A second review
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in the form of an outside audit is
conducted by a person not involved in
the respirator program. The audit is to
be repeated at a frequency determined
by the complexity of the program.
Written Standard Operating
Procedures. MSHA assumes that most
mines have established written
Standard Operating Procedures (SOPs)
that comply with the ASTM standard.
MSHA assumed that 50 percent of
affected mine operators will prepare
new or updated SOPs at the start of
implementation. Following this initial
period, these costs will be incurred only
by new mines.
Medical Evaluations. Under this
provision, mine operators would update
the information provided to the PLHCP
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concerning each miner’s work area, type
and weight of respirator, duration and
frequency of respirator use, work
activities and environmental conditions,
hazards, and other PPE worn. This
information is assumed to be part of the
miner’s job description and personnel
records (e.g., fit-test results) and is likely
available electronically at most mines.
As a result, the cost of this provision is
associated with the requirement to
document this information in the
miner’s records and transmit it to the
PLHCP.
Respirator Selection. The provisions
for respirator selection in the 2019
ASTM standard reflect the current
standard of care for respirator use in the
U.S. In this analysis, MSHA assumed
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Miners Including
Average Miners per
Contract Miners in
Affected Mine
Affected Mines
Total
Affected
Mine Sector
Mines
Mines
Miners
Miners
Total
Wearing
Miners
Wearing
Miners
Respirators
Respirators
All Mines
12,631
3,411
115,817
6,946
34.0
2.0
Metal/Nonmetal
11,525
2,305
42,241
4,224
18.3
1.8
Coal
1,106
1,106
73,576
2,722
66.5
2.5
Note: Due to rounding, some totals do not exactly equal the sum of the corresponding individual entries.
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
that mine operators are already using
these criteria for selecting respiratory
protection. MSHA assumed that mine
operators will not incur additional costs
for this provision.
Mine Operator Responsibilities. The
2019 ASTM standard provides that
mine operators allow miners wearing
respirators to leave a hazardous
atmosphere for any reason related to the
respirator. The mine operator will also
investigate the cause of respirator
failures and communicate with the
respirator manufacturer and government
agencies about defects. Respirator
failures or defects are considered rare
events. To account for the potential time
involved should defective respirators be
encountered, this analysis adds a
minimal amount of labor time.
Training the ‘‘Respirator Trainer’’.
Under the 2019 ASTM standard, the
respirator trainer will provide training
to others with responsibilities for
implementing the mine operator’s
respirator program, and therefore, this
person must have an appropriate
training or experience. For existing
mines, this cost is unlikely to recur
except when a respirator trainer leaves
the mine operator’s employment.
However, it is likely to be incurred by
the 2 percent of new mines entering the
market in any given year.
Training for the Mine Operator/
Supervisor and the Person Issuing
Respirators. The mine operator or
supervisor of any miner who must wear
a respirator must receive training on the
elements of the respiratory protection
program in the SOPs and related topics.
The cost in the first year of compliance
will also be incurred in subsequent
years by—at a minimum—new mines
entering the market.
Miner Training. Miners required to
use respirators already receive training
each year under the 1969 ANSI standard
and under 30 CFR part 46 and Part 48.
Most mines incorporate this into their
existing annual health and training
plan, and therefore MSHA estimates
that there are no incremental costs
attributable to this provision.
Fit Testing Frequency. The 2019
ASTM standard provides for annual
respirator fit testing to ensure that the
make, model, and size of the respirator
issued to the miner are appropriate and
the miner is still able to achieve a good
face seal. MSHA assumed that, on
average, miners receive annual fit
testing under existing training
standards. A provision under the 2019
ASTM standard is that the fit testing
must be overseen by a trained
technician or supervisor. The time of
the trained supervisor is an additional
cost incurred under this provision.
Maintenance, Inspection, and
Storage. The provisions for respirator
selection in the 2019 ASTM standard
reflect the current standard of care for
respirator use in the U.S. In this
analysis, MSHA assumed that mine
operators are already using these criteria
for maintaining, inspecting, and storing
respirators. Therefore, MSHA assumed
that mine operators will not incur
additional costs for this provision.
Table IX–19 presents average
compliance costs per mine by sector. In
28381
Year 1, compliance costs average about
$1,700 for coal mines. In Year 2,
compliance costs average about $1,200
for MNM mines and $500 for coal
mines. In Years 3 and following, average
compliance costs per mine are smaller,
ranging from $262 for MNM mines to
$479 for coal mines, with an overall
average of $332 per mine.
MSHA assumes that all mines are
affected by the requirement to have a
written respiratory protection program
that meets the ASTM standard but not
all mines are expected to incur costs for
this requirement. MSHA estimates, in
Year 1 (for coal mines) and Year 2 (for
MNM mines), only 50 percent of
affected mines are expected to incur
costs under provision 2 (SOPs) because
many mines already have SOPs that
comply with the ASTM. In Years 2
through 60 (for coal) and Years 3
through 60 (for MNM), the number of
affected mines that would incur costs is
smaller than in Years 1 and 2 because
following Year 1 (for coal) and Year 2
(for MNM), additional compliance costs
are expected to be incurred primarily by
new mines entering the industry. For
example, provisions related to written
SOPs, Training for the Respirator
Trainer, and Training for the Mine
Operator and Person Responsible for
Issuing Respirators are initial costs
incurred in the first year of compliance.
In subsequent years, those costs would
generally be incurred only by the 2
percent of new mines entering the
industry.
Table IX-19: Respiratory Protection Practices Costs Related to ASTM Update per Mine (in
2022 dollars)
Incremental Cost in Year 1
Total
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Incremental Cost in Year 2
Total
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Cost per Mine
1,106
$1,911,502
0
$0
--
1,106
$1,911,502
$1,728
Metal/Nonmetal
Coal
Total Cost
$1,728
3,411
$3,237,436
$949
Metal/Nonmetal
2,305
$2,707,811
$1,175
Coal
1,106
$529,625
$479
Incremental Cost in Year 3-60
Total
3,411
$1,132,441
$332
04:45 Apr 18, 2024
Metal/Nonmetal
2,305
$602,816
$262
Coal
1,106
$529,625
$479
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Mine Sector
Number of
Mines
Incurring
Costs
28382
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Below in Table IX–20 are the
annualized costs associated with the
ASTM requirement. The total
annualized cost to the mining industry
ranges from $1.18 million (0 percent
discount rate) to $1.32 million (7
percent discount rate), with 53 percent
of those costs attributable to MNM
mines and 47 percent attributable to
coal mines.
Table IX-20: Respiratory Protection Practices Related to ASTM Update Total Annualized
Costs (in thousands of 2022 dollars) per Year
Total Annualized Costs (thousands
of dollars) per Year at Specified
Discount Rate
Component
Total
Mines Incurring
Costs
3,411
0 Percent
$1,181
3 Percent
$1,231
7 Percent
Percentage
of Total
Costs 1
$1,315
100.0%
2,305
$628
$653
$694
53.1%
$553
$578
$622
46.9%
Metal/Nonmetal
Coal
1,106
Note: 1. Calculated at the 3 percent real discount rate.
6. Cost Summary
exposure monitoring; 20.9 percent to
medical surveillance; 15.1 percent to
engineering, improved maintenance and
repair, and administrative controls; 3.7
percent to additional respiratory
protection (e.g., when miners need
temporary respiratory protection from
MSHA estimates that the annualized
cost of the final rule will range from
$88.8 million to $92.4 million in 2022
dollars. At a discount rate of 3
percent,88 59.0 percent is attributable to
exposure at the new PEL when it would
not have been necessary at the existing
PEL); and 1.4 percent related to the
selection, use, and maintenance of
approved respirators in accordance with
ASTM F3387–19, respiratory protection
practices (see Table IX–21).
Table IX-21: Summary of Estimated Compliance Costs by Provision (in millions of 2022
dollars)
0 Percent
Discount Rate
Annualized
Cost
Provision
7 Percent
Discount Rate
3 Percent
Discount Rate
Percent
Annualized
Cost
Percent
Annualized
Cost
Percent
Exposure Monitoring
$51.60
58.1%
$53.24
59.0%
$55.64
60.2%
Exposure Controls
$13.79
15.5%
$13.66
15.1%
$13.40
14.5%
Respiratory Protection
$3.38
3.8%
$3.32
3.7%
$3.22
3.5%
Medical Surveillance2• 3
$18.82
21.2%
$18.84
20.9%
$18.82
20.4%
Subtotal, Part 60 Costs
$87.59
98.7%
$89.05
98.6%
$91.07
98.6%
ASTM2019
$1.18
1.3%
$1.23
1.4%
$1.32
1.4%
Total, All Mines
$88.77
100.0%
$90.28
100.0%
$92.39
100.0%
attributable to MNM mines (see Table
IX–1 and Table IX–2). Of the $90.3
million total, MSHA estimates that the
MNM sector will incur $82.1 million (91
percent) and the coal sector will incur
$8.2 million (9 percent) in annualized
compliance costs (see Table IX–22).
88 In its analysis, MSHA annualizes all costs using
3 percent and 7 percent real discount rates as
recommended by OMB. Using a 7 percent discount
rate, the annualized cost of the rule is estimated at
$75.4 million in 2022 dollars.
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Given the larger size of the MNM
sector and the higher proportion of
samples in the MNM sector that are
above 50 mg/m3, most costs are
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Note: Due to the uncertainty on how many currently employed miners will participate in voluntary medical
surveillance programs, MSHA considered two rates (25 percent and 75 percent) when estimating medical
surveillance costs. The values presented in this table are the average costs between the assumed participation rates of
25 percent and 75 percent.
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28383
Table IX-22: Summary of Estimated Annualized Compliance Costs by Sector (in millions
of 2022 dollars)
2019
Number
of
Mines 1
12,631
0 Percent Discount
Rate
Annualized
Cost
$88.77
3 Percent Discount
Rate
Annualized
Cost
$90.28
7 Percent Discount
Rate
Annualized
Cost
$92.39
Percent
Percent
Percent
Sector
100.0%
100.0%
100.0%
Total, All Mines
Metal/
11,525
$80.75
91.0%
$82.06
90.9%
$83.84
90.7%
Nonmetal
9.0%
9.1%
9.3%
Coal
1,106
$8.02
$8.22
$8.55
Note: 1. The estimated number of current and future mines are based on 2019 data (MSHA, 2022d) and are assumed
to have remained constant through the 60 years following the start of implementation.
89 Discount rates throughout this section refer to
real discount rates. Real discount rates are distinct
from nominal discount rates because they do not
include inflation.
90 Technically, MNM benefits would not reach
their long-run average values until 61 years
following the compliance date for the coal sector
since the compliance deadline for MNM is 1 year
after the compliance deadline for coal.
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service life of a building ventilation
system is 30 years, MSHA assumes that
a mine operator would purchase the
system in year 1 and again in year 31
to estimate 60 years of capital costs.
This is the major change in costing
methodology for the final rule. Under
the proposed rule, MSHA annualized
costs over shorter periods. Given the
types of controls appropriate for
meeting the requirements of the
proposed rule, this approach was
reasonable. Because MSHA set a 1-year
difference between the compliance
dates for the coal and MNM sectors
under the final rule, that method is no
longer accurate. MSHA’s analysis of this
final rule is based on a timeframe of 60
years (which is enough time to analyze
45 years of working life and 15 years of
retirement for new miners who only
experience exposures under the new
PEL).
For both MNM and coal mines, the
estimated costs to comply with the new
PEL (50 mg/m3) assumes that all mines
are compliant with the existing PEL of
100 mg/m3 for MNM mines (for a full
shift, calculated as an 8-hour TWA) and
85.7 mg/m3 for coal mines (for a full
shift, calculated as an 8-hour TWA).
Two mining trade organizations,
American Exploration and Mining
Association and Nevada Mining
Association, stated that MSHA’s cost
projections were inaccurate because
they predicted fixed costs based on
gross proceeds (instead of net proceeds)
(Document ID 1424; 1441). These
commenters also noted that, because the
cost model for each commodity differs,
compliance costs for each commodity
will differ. MSHA did not estimate
compliance costs based on either gross
or net proceeds. MSHA has determined
that its approach better identifies likely
costs than the approach recommended
by the commenters. The Agency
estimated compliance costs based on a
wide range of quantitative and
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qualitative data including: sampling
data on miner exposure, MSHA program
experience, and MSHA’s knowledge of
typical controls, maintenance, and work
practices at mines of different types and
size. MSHA estimates compliance costs
using mine size, labor cost, and other
factors at commodity level, which is
more flexible and accurate than the
estimation of proceeds.
One commenter, a mining-related
business, stated that MSHA’s cost
estimates were based on flawed
sampling data, that ‘‘used samples taken
by MSHA inspectors and then weighted
these based on the number of samples
plus exposures to the current standard
(Document ID 1392). The commenter
stated that powered haulage operators
account for the bulk of samples, while
conveyor operators account for the
fewest samples, resulting in a ratio of
about 1 conveyor operator to 79
powered haulage operators. The
commenter stated that in its experience,
the ratio is about 1 conveyor operator to
4 haulage operators. Because conveyor
operators are underrepresented in the
analysis, this would affect MSHA’s cost
estimates.
As described in Part B—Miners and
Mining Industry, MSHA used 2019
OEWS data to estimate the number of
miners in each occupational group.91
The OEWS is a nationally representative
dataset and MSHA uses it to examine
labor force in the mining industry.
While BLS reported the number of
workers under powered haulage
operators, it did not report any
employment in the OCC Code 53–7011
(Conveyor Operators and Tenders) due
to an insufficient number of
respondents identified as Conveyor
Operators and Tenders.
The samples taken by MSHA
inspectors were not weighted based on
91 OEWS data available at https://www.bls.gov/
oes/ (last accessed Jan. 10, 2024).
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To estimate compliance costs, MSHA
determined the expected measures
necessary for mines to comply with
each provision of the final rule then
estimated the costs incurred by a typical
mine to comply with each provision.
These include one-time costs, such as
those to purchase and install an
engineering control, provide equipment
expected to last multiple years (e.g.,
respirators), or devise and implement an
administrative control. They also
include recurring costs, such as the
operating and maintenance (O&M) costs
of using an engineering control or the
value of the labor hours and supplies
used to perform periodic exposure
monitoring. To aggregate costs for each
provision, MSHA multiplies the average
cost per mine by the number of mines
expected to incur that cost or the
average cost per miner by the number of
miners expected to be affected by the
given provision. These costs are
summed across all provisions for each
of the two major mining sectors to
estimate total industry costs. For
purposes of the cost analysis, MSHA
assumes employment is constant over
this period.
MSHA annualizes all costs using 3
percent and 7 percent discount rates as
recommended by OMB.89 All costs and
benefits are annualized over a 60-year
analysis period. MSHA annualized
benefits to reach the long-run steady
state values projected in MSHA’s FRA.90
Costs are also estimated and annualized
over a 60-year period. This means that
costs for durable equipment, for
example, are estimated based on their
expected service life. If the expected
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
the ‘‘number of samples plus exposures
to the current standard,’’ as the
commenter suggested, but rather by the
estimated number of workers in each
occupational group (Document ID 1392).
MSHA took this approach because the
samples taken by inspectors are not
representative of all jobs at a mine,
rather they are concentrated in areas
where miners are at the greatest risk for
dust exposure. The FRIA analysis is
based on sample and employment data
to provide an overview of all
occupational groups and their
associated risks for the mining industry.
One commenter, N-Compliance Safety
Services, Inc., stated that large mining
company costs under the proposed rule
would be in the millions of dollars
annually, a figure that does not include
the cost of citations, downtime, and
contesting violations (Document ID
1383). Stating that the proposed rule’s
costs would drive up the costs of
commodities and impact transportation
needs and expenses, the commenter
said that the proposed 25 mg/m3 action
level would place most mines in
violation, as it is four times less than the
current PEL and would require four
times the actions to maintain
compliance below it. Downtime to
maintain controls is included in the cost
of the final rule. In response to the
comment from mine operators that the
action level would place most mines in
violation, MSHA clarifies that mine
operators are not required to maintain
exposures below the action level. The
purpose of the action level is to alert
mine operators and miners when
exposures are approaching the PEL.
Mine operators will be in violation if
exposures exceed the new PEL. Mine
operators who maintain exposures at or
above the action and at or below the
new PEL will incur sampling costs but
will not be in violation of the final rule
and will not be faced with citations,
downtime, or contesting violations.
MSHA notes that the commenter has
provided no data to support their
statement that the rule will cost large
mining companies millions of dollars in
compliance costs.
FRA, MSHA estimated the avoided
cases attributable to the new PEL using
a comparison of a population of miners
exposed only under the new PEL to one
exposed only under the existing
standards throughout their working and
retired lives. These benefits included
reductions to excess cases of fatal
silicosis, fatal non-malignant respiratory
diseases (NMRD), fatal end-stage renal
disease, fatal lung cancer, and non-fatal
silicosis. These five health outcomes
were chosen based on their wellestablished exposure-response
relationships with occupational
respirable crystalline silica exposure.93
In the FRIA, MSHA estimates and
monetizes the excess morbidity and
mortality cases avoided during the same
60-year analysis timeframe as
considered by the cost analysis so that
benefits can be directly compared with
the costs of the final rule. The number
of avoided cases presented in the FRIA
during the 60-year analysis period is
less than the number of lifetime cases
avoided estimated in the FRA, since
miners with exposure under the current
limits are gradually replaced by miners
with exposure under the new PEL
during the 60 years following the start
of implementation.
In the PRA, MSHA underestimated
the number of miners who would
benefit from this rule. Based on the 2019
Quarterly Employment Production
Industry Profile (MSHA, 2019a) and the
2019 Quarterly Contractor Employment
Production Report (MSHA, 2019b), the
current number of working miners fulltime equivalents (FTEs) is assumed to
be 184,615 for MNM and 72,768 for
coal.94 In the PRA, MSHA assumed
excess cases of disease would be
reduced only among these working
miners. However, once the current
mining workforce is replaced with new
entrants to the mining industry so that
the entire workforce has worked only
under the new PEL for their 45-years of
working life (i.e., 60 years after the start
of implementation), the future mining
workforce will experience fewer excess
deaths and illnesses from excess
exposure to respirable crystalline silica.
The PRA’s methodology did not include
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D. Benefit Analysis
In the FRIA, MSHA estimates that,
during the 60 years following the
compliance date for the coal sector (i.e.,
the start of the timeframe for the cost
analysis), annual benefits will gradually
increase, as the share of miners’ working
lives under the new PEL (rather than the
existing standards) increases.92 In the
92 Throughout this document, the term ‘‘longrun’’ refers to the period of time when all surviving
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working and retired miners will have only been
exposed under the new PEL.
93 The standalone Health Effects document and
the FRA discuss the evidence for these
relationships in depth, as well as the exposureresponse models used for analysis in the FRA.
94 The analysis of this FRIA assumes the mining
workforce will not change size during the 60 years
following compliance with the rule to simplify
estimation of health benefits. The current and longterm size of the mining workforce was estimated
using 2019 data, since the COVID–19 pandemic
may have led to temporary changes in the mining
workforce that will be reversed in coming years.
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the number of future retired miners who
experienced lower exposures for their
working lives under the final rule and
will continue to benefit during their
retirement, and therefore, the PRA
underestimated the benefits attributable
to the final rule.
Both the FRA and the FRIA are
updated to account for benefits among
both working miners and future retired
miners. It is important to note that the
FRIA only monetizes benefits to future
retired miners—i.e., retired individuals
who were employed as miners after the
start of implementation. The FRIA
methodology does not attribute any
health benefits to individuals who
retired before the start of
implementation of the final rule. The
FRIA is updated to reflect the number
of future retired miners, which increases
gradually after the start of
implementation. For example, in the
first year after the start of
implementation, there will be no retired
miners who benefit from the rule. In the
second year after the start of
implementation, there will be one
cohort of retired miners (i.e., those in
their final year of mining when
implementation began). In this way, the
FRIA monetizes benefits to future
retired miners while accounting for the
fact that future retired miners who
benefit from the rule increase in size
gradually during the 60-year analysis
period.
MSHA estimates that:
• For a population of working and
retired miners exposed only under the
new PEL, the final respirable crystalline
silica rule will result in a total of 1,067
lifetime avoided deaths (982 in MNM
mines and 85 in coal mines) and 3,746
lifetime avoided morbidity cases (3,421
in MNM mines and 325 in coal mines).
These avoided cases will be achieved
once all miners, working and retired,
have been exposed exclusively under
the new PEL (see Table IX–23).
• Over the first 60 years immediately
following the start of implementation,
fewer cases will be avoided than are
shown in Table IX–23. This is because
the annual number of cases avoided will
increase gradually to the long-run
steady-state values, which ultimately
will be achieved only when all miners
have been exposed only under the new
PEL. Table IX–24 shows that, in the first
60 years following the start of
implementation, the final rule will
result in a total of 531 avoided deaths
(487 in MNM and 44 in coal) and 1,836
avoided morbidity cases (1,673 in MNM
and 162 in coal), which are the benefits
MSHA monetized in its FRIA. In
general, the actual number of cases that
will be avoided in the 60 years
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
following the start of implementation is
approximately half the number of
avoided cases once benefits reach their
long-run average annual values (see
Table IX–24).
• Under a discount rate of 3 percent,
the total benefits of the new respirable
crystalline silica rule from these
avoided deaths and morbidity cases,
including the benefits of avoided
morbidity preceding mortality, are
$246.9 million per year in 2022 dollars
(see Table IX–25).
• Because a higher monetary value is
placed on avoided death as compared to
an avoided morbidity case, the majority
(62.5 percent; $154.3 million) of these
benefits is attributable to avoided
mortality due to non-malignant
respiratory disease (NMRD) ($75.4
million), silicosis ($40.3 million), and
end-stage renal disease (ESRD) ($28.4
million), and lung cancer ($10.2
million) (see Table IX–25).
Æ Benefits from avoided morbidity
due to non-fatal silicosis are $72.8
28385
million per year. Of this, $66.3 million
are due to cases avoided in MNM mines
and $6.5 million are due to cases
avoided in coal mines (see Table IX–25).
Æ Benefits from avoided morbidity
that precedes fatal cases of NMRD,
silicosis, renal disease, and lung cancer,
are $19.8 million. Of this, $18.2 million
are due to cases avoided in MNM mines
and $1.6 million are due to cases
avoided in coal mines (see Table IX–25).
BILLING CODE 4520–43–P
Table IX-23: Estimated Cases of Avoided Lifetime Mortality and Morbidity Attributable
to the New Rule Among a Population Exposed Only to the New PEL
Total Lifetime Avoided Cases 1
Coal
Health Outcome
MNM
Total
Avoided Morbidity
Silicosis
3,421
325
3,746
Avoided Morbidity Total (Net of Silicosis
Deaths)
3,421
325
3,746
Avoided Mortality
NMRD (net of silicosis mortality)
489
47
536
15
248
Silicosis
233
ESRD
185
15
200
Lung Cancer2
75
7
82
Avoided Mortality Total
982
85
1,067
Notes: 1. Avoided cases include all miners (including contract miners). Calculations show the difference between
excess cases when assuming compliance with the existing limits versus assuming compliance with the new PEL.
2. A 15-year lag between exposure and observed health effect was assumed for lung cancer estimates.
Table IX-24: Estimated Cases of Avoided Mortality and Morbidity Attributable to the New
Rule during the 60 Years Immediately Following the Start of Implementation
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Avoided Morbidity
Silicosis
1,673
162
1,836
Avoided Morbidity Total (Net of Silicosis
1,673
162
1,836
Deaths)
Avoided Mortality
NMRD (net of silicosis mortality)
241
22
263
123
11
134
Silicosis
ESRD
90
8
98
Lung Cancer2
33
3
36
Avoided Mortality Total
487
44
531
Notes: Due to rounding, some totals do not exactly equal the sum of corresponding individual entries.
1. Avoided cases include all miners (including contract miners). Calculations show the difference between excess
cases when assuming compliance with the existing limits versus assuming compliance with the new PEL of 50
µg/m 3 . Estimates account for the fact that some miners during the 60-year period will have worked under the
existing standards (and thus may have combination of exposures under the existing standards and the new PEL),
while other new entrants into the mining workforce would be solely exposed under the new PEL.
2. A 15-year lag between exposure and observed health effect was assumed for lung cancer estimates.
ER18AP24.181
Total Avoided Cases During 60 Years Following the Start of
lmplementation 1
MNM
Coal
Total
Health Outcome
28386
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table IX-25: Estimated Monetized Benefits over 60 Years for the New Respirable
Crystalline Silica Rule Annualized at a 3 Percent Discount Rate (in millions of 2022 dollars)
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BILLING CODE 4520–43–C
MSHA acknowledges that its benefit
estimates are influenced by underlying
assumptions and that the long
timeframe of this analysis (i.e., 60 years)
is a source of uncertainty. The main
assumptions underlying these estimates
of avoided mortality and morbidity
include the following:
• Employment is held constant over
the 60 years (i.e., the analysis period of
the final rule).95
• For analyses under the ‘‘Baseline’’
scenario, any exposures to respirable
crystalline silica above the existing
standards (i.e., 100 mg/m3 for MNM
miners and 85.7 mg/m3 for coal miners)
were capped at 100 mg/m3 and 85.7 mg/
m3 for MNM and coal exposures,
respectively.
• For analyses under the ‘‘New PEL
50’’ scenario, any exposures to
respirable crystalline above the new PEL
are capped at the new PEL (i.e., 50 mg/
m3).
• Miners have identical employment
and hence identical exposure tenures
(i.e., 45 years).
In addition to the above-mentioned
quantified health benefits, MSHA
expects that there will be additional
benefits from requiring approved
respirators be selected, fitted, used, and
maintained in accordance with ASTM
F3387–19. The ASTM standard reflects
95 MSHA recognizes that it is very challenging to
predict economic factors over such a long period
with high degrees of confidence. Given known
information and forecast limitations, MSHA
believes assuming constant employment is
reasonable.
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MNM
Coal
$66.3
$6.5
$72.8
$66.3
$6.5
$72.8
$69.1
$37.0
$26.1
$9.4
$141.6
$6.3
$3.3
$2.3
$0.9
$12.7
$75.4
$40.3
$28.4
$I0.2
$154.3
$8.6
$5.0
$3.4
$1.1
$0.8
$0.5
$0.3
$0.1
$9.4
$5.5
$3.6
$1.2
$18.2
$226.0
$1.6
$20.9
$19.8
$246.9
improved developments in respiratory
protection since the time in which
MSHA issued its existing standards.
ASTM F3387–19 also includes
respiratory protection program elements
such as program administration;
standard operating procedures (SOPs);
medical evaluation; respirator selection;
training; fit testing; and respirator
maintenance, inspection, and storage.
This provision of the final rule will
ensure that, in circumstances where
respirator use is required, mine
operators will provide miners with
respiratory protection that incorporates
advances in technology and changes in
respiratory protection practices. This
respiratory protection will play a critical
role in safeguarding the health of miners
and reducing their exposures to
respirable crystalline silica and other
airborne contaminants. As demonstrated
in the FRA, reductions in occupational
exposure to respirable crystalline silica
are expected to reduce adverse health
outcomes. However, given the
uncertainty about the current state of
mine operator respiratory protection
practices, MSHA did not quantify the
expected additional benefits that would
be realized by requiring approved
respirators to be selected, fitted, used,
and maintained in accordance with the
requirements of ASTM F3387–19.
MSHA believes that reductions in
coal miners’ exposure to respirable
crystalline silica may also lead to lower
levels of coal mine dust inhalation.
MSHA expects that adverse health
outcomes attributable to respirable coal
mine dust exposure, such as simple and
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complex coal workers’ pneumoconiosis
(CWP), will also be reduced. MSHA has
not estimated the reduction in risk
associated with CWP among coal miners
because the literature does not contain
an exposure-response model that
quantifies the impact of respirable
crystalline silica on CWP mortality risk,
and because MSHA is not making any
assumptions about whether levels of
coal mine dust will be reduced due to
the final rule. MSHA anticipates that
there will be additional unquantified
benefits from the reduction in CWP
provided by the final rule. Within the
avoided silicosis and NMRD deaths,
however, MSHA includes benefits from
avoided mortality due to progressive
massive fibrosis (PMF)—including
mortality due to complicated CWP and
complicated silicosis.
Finally, MSHA also expects that the
final rule’s medical surveillance
provisions will reduce mortality and
morbidity from respirable crystalline
silica exposure among MNM miners.
The initial mandatory examination that
assesses a new miner’s baseline
pulmonary status, coupled with
periodic examinations, will assist in the
early detection of respirable crystalline
silica-related illnesses. Early detection
of illness often leads to early
intervention and treatment, which may
slow disease progression and/or
improve health outcomes. This may also
result in less miner time-off and less
miner turnover. However, MSHA lacks
data to quantify these additional
benefits.
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Health Outcome
Avoided Morbidity (Not Preceding Mortality)
Silicosis (Net of Silicosis Mortality)
Avoided Morbidity (Not Preceding
Mortality) Total
Avoided Mortality
NMRD (Net of Silicosis Mortality)
Silicosis
ESRD
Lung Cancer
Avoided Mortality Total
Avoided Morbidity (Preceding Mortality)
NMRD (Net of Silicosis Mortality)
Silicosis
ESRD
Lung Cancer
Avoided Morbidity (Preceding Mortality)
Total
Grand Total
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
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National Coalition of Black Lung and
Respiratory Disease Clinics was
concerned that the projected benefits of
the proposed rule for coal miners were
significantly lower than the projected
benefits for MNM miners and suggested
that MSHA correct for this by including
dust samples from coal mines taken
prior to August 1, 2016 (Document ID
1410). Similarly, the Appalachian
Citizens’ Law Center asserted that the
benefits estimated in the PRA are low
and urged MSHA to include a longer
history of coal dust sampling data
(Document ID 1445). MSHA believes
that samples from before August 1,
2016, may not accurately reflect the
current conditions in coal mines and
therefore should not be used in
analyzing the impact of this final rule.
As discussed in Appendix A of the
preamble, on August 1, 2016, Phase III
of the 2014 RCMD Standard went into
effect, and this lowered the PEL for
RCMD in coal mines. The controls put
in place to achieve that new PEL
impacted both RCMD with and without
respirable crystalline silica dust in coal
mines, and as such, these controls likely
lowered concentrations of respirable
crystalline silica. Using data from after
the coal mine dust rule went into effect
helps to ensure that benefits attributable
to that rule are not attributed to this rule
incorrectly. More details about the
respirable crystalline silica sample
dataset, including the time coverage and
brief statistics, are described in
‘‘Description of MSHA Respirable
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Crystalline Silica Samples’’ (Appendix
A of the preamble of Proposed Rule). In
addition to the prior effects of the 2014
RCMD Standard on respirable
crystalline silica exposure in the coal
sector, there will also be greater benefits
to MNM miners owing to the medical
surveillance requirements which are
already existing for coal miners.
However, these benefits are
unquantified in the FRA and FRIA
analyses and therefore, do not
specifically contribute to the
discrepancy mentioned by these
commenters.
Further, the benefits quantified here
may underestimate the true benefits to
coal miners. MSHA believes this final
rule will likely lower not only respirable
crystalline silica concentrations, but
also RCMD levels. As a result, MSHA
believes this final rule will provide
additional reductions in CWP, NMRD,
and PMF beyond those conferred by the
2014 RCMD Standard. In the 2014 Coal
Dust Rule, NIOSH emphasized the
important role respirable crystalline
silica plays in causing these diseases,
stating that, ‘‘in concentrating on this
particular exposure-response
relationship with coal mine dust, we
must not forget that [coal] miners today
are being exposed to excess silica levels,
particularly in thinner seam and small
mines, and that this situation could well
get worse as the thicker seams are
mined out. Hence, since silica is more
toxic than mixed coal dust, tomorrow’s
[coal] miners could well be at greater
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28387
risk, despite a reduction in the mixed
coal mine dust standard.’’ While
additional reductions in total RCMD
would be expected due to this final rule,
these reductions cannot be quantified as
the reductions depend on the particular
control measures that mine operators
implement. Additionally, exposureresponse models for respirable
crystalline silica exposure and resultant
CWP are not available. Thus, the
benefits quantified in this FRIA may
underestimate the true benefits to coal
miners, as MSHA does not account for
expected reductions in CWP or in other
diseases due to reduced RCMD.
E. Benefit-Cost Analysis
The net benefits of the final rule are
the differences between the estimated
benefits and costs. Table IX–26 shows
estimated net benefits using alternative
discount rates of 0, 3, and 7 percent.
The choice of discount rate has an effect
on annualized costs, benefits, and net
benefits. While the net benefits of the
final respirable crystalline silica rule
vary depending on the choice of
discount rate used to annualize costs
and benefits, total benefits exceed total
costs under all discount rate considered.
MSHA’s estimate of the net annualized
benefits of the final rule, using a
discount rate of 3 percent, is $156.6
million a year, with the majority ($143.9
million; 91.9 percent) attributable to the
MNM sector.
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table IX-26: Annualized Costs, Benefits, and Net Benefits of MSHA's Final Respirable
Crystalline Silica Rule (in millions of 2022 dollars)
Quantified Benefits and
Costs
Benefits
MNM
Coal
7%
0%
3%
$141.6
$68.9
$20.5
$12.7
$27.1
$18.2
$10.0
$2.4
$93.1
$66.3
$41.5
$350.7
$226.0
Exposure Monitoring
$46.1
Exposure Controls
3%
$230.4
7%
7%
0%
3%
$6.4
$250.9
$154.3
$75.3
$1.6
$0.9
$29.5
$19.8
$11.0
$9.0
$6.5
$4.2
$102.1
$72.8
$45.7
$120.4
$31.9
$20.9
$11.5
$382.6
$246.9
$131.9
$47.6
$49.7
$5.5
$5.6
$5.9
$51.6
$53.2
$55.6
$11.9
$11.7
$11.4
$1.9
$1.9
$2.0
$13.8
$13.7
$13.4
Respiratory Protection
$3.3
$3.3
$3.2
$0.1
$0.1
$0.1
$3.4
$3.3
$3.2
Medical Surveillance
$18.8
$18.8
$18.8
--
--
--
$18.8
$18.8
$18.8
$0.6
$0.7
$0.7
$0.6
$0.6
$0.6
$1.2
$1.2
$1.3
$80.7
$82.1
$83.8
$8.0
$8.2
$8.5
$88.8
$90.3
$92.4
$270.0
$143.9
$36.6
$23.9
$12.7
$3.0
$293.8
$156.6
$39.5
A voided Mortality
A voided Morbidity Preceding
Mortality
A voided Morbidity Not
Preceding Mortality
Total1
0%
Total
Costs
ASTMUpdate
Total
Net Benefits
F. Sensitivity Analysis on the Tenure of
Miners
As mentioned in Part E. Benefit-Cost
Analysis, in performing the benefit
analysis, MSHA assumed that all miners
have a working tenure of 45 years, from
the start of age 21 to the end of age 65.
MSHA also assumed that each miner’s
level of exposure remains the same in
each day of each year. MSHA also
performed a sensitivity analysis to see
how benefits would differ under three
scenarios with alternative tenures,
though with all three sharing the same
simplifying assumption that exposure
remains constant for each miner across
all of their working years. These
alternative scenarios involved: (1) a
tenure of 35 working years (rather than
45), between the ages of 26 and 60; (2)
a tenure of 25 working years, between
the ages of 31 and 55; and a tenure of
15 years, between the ages of 36 and 50.
These age ranges were selected to
maintain the same midpoint miner age
of 43.
Under the assumption that the same
number of miners (257,383) are working
at any given time the lower the tenure,
the more turnover there would be
among miners, the greater the number of
new miners who would enter each year
to replace those who are retiring or
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changing jobs. For example, when the
scenario changes from a 45-year tenure
(which was used in the benefit analysis)
to a 15-year tenure, the analysis would
require a single miner who would work
for 45 years to be effectively replaced by
three miners who would each be
working for 15 years (one after another)
during those same 45 years. This means
that, in these lower-tenure scenarios,
each miner would have accumulated
less exposure by the time they retire, but
there would be more miners retiring
with that level of exposure.
From analyzing the alternative
scenarios with different tenures, using
its risk model, MSHA found that lower
tenures tended to result in more avoided
cases of mortality. This is because,
while the risk of mortality increases for
any miner who works more years, at
lower tenure rates, many more miners
are exposed and are put at risk of dying
from the disease. According to the
models, the increased number of
exposed miners, when tenure is short,
leads to a greater increase in overall
mortality than does the increased
likelihood of mortality occurring for
each miner, when the tenure is long. As
a result, this sensitivity analysis found
that the rule would have greater
benefits, in terms of reducing mortality,
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under scenarios with shorter tenure
than under the 45-year tenure
assumption used in the benefits
analysis. The assumption of a 45-year
tenure may be seen as effectively
leading to an underestimate the benefits
of the rule in terms of reduced
mortality, relative to assumptions
involving lower tenures.
From the way the risk model is
designed, however, the opposite effect
was observed with regard to morbidity
cases, where there were more cases of
morbidity under longer tenure rates.
Under longer tenure rates, there are
estimated to be more cases of morbidity
overall, and therefore the rule has a
greater estimated effect on reducing
cases of morbidity under the
assumption of a 45-year tenure than
under the alternative scenarios.
Nevertheless, because the benefits of
reduced mortality cases count much
more than the benefits of reduced
morbidity cases, it may be concluded
that under the shorter tenures of the
alternative scenarios, the benefits of the
rule would be greater. In other words, if
the tenures of miners are, in fact, shorter
than 45 years, the assumption of a 45year tenure has the net effect of
underestimating the benefits of the rule.
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Notes: Medical surveillance cost is the average cost under the assumed participation rate of25 percent and 75 percent.
1. For the purpose of simplifying the estimation of the monetized benefits of avoided illness and death, MSHA added
the monetized benefits of morbidity preceding mortality to the monetized benefits of mortality at the time of death, and
both would be discounted at that point.
28389
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G. Regulatory Alternatives
In developing the final rule, MSHA
considered three regulatory alternatives.
The first two alternatives contain less
stringent exposure monitoring
provisions than the final rule, which
comparatively presents a
comprehensive approach for lowering
miners’ exposure to respirable
crystalline silica and improving
respiratory protection for all airborne
contaminants. The first alternative
includes no change to the final rule’s
PEL and action level, whereas the
second alternative includes a more
stringent PEL. The second alternative
combines less stringent exposure
monitoring with a more stringent PEL.
The third alternative examines a
different methodology for calculating
miners’ exposures and assessing
compliance. MSHA discusses the
regulatory options in the sections below.
1. Regulatory Alternative 1: Changes in
Sampling and Evaluation Requirements
Under this alternative, the new PEL
would remain unchanged at 50 mg/m3
and the action level would remain
unchanged at 25 mg/m3. Further, mine
operators would conduct: (1) first-time
and second-time sampling for miners
who may be exposed to respirable
crystalline silica at or above the action
level of 25 mg/m3, (2) above-action-level
sampling twice per year for miners who
are at or above the action level of 25 mg/
m3 but at or below the PEL of 50 mg/m3,
and (3) annual evaluation of changing
mining processes or conditions that
would reasonably be expected to result
in new or increased exposures.
Mine operators would still be
required to conduct sampling under this
Regulatory Alternative and would thus
incur compliance costs. However,
exposure monitoring requirements
under this alternative are less stringent
than the requirements under the final
rule because the frequency of aboveaction-level sampling and periodic
evaluations are set at half the frequency
of the final exposure monitoring
requirements. Therefore, the cost of
compliance would be lower under this
alternative. MSHA estimates that
annualized exposure monitoring costs
would total $29.3 million for this
alternative (at a 3 percent discount rate),
compared to $53.2 million for the final
exposure monitoring requirements,
resulting in an estimated difference of
$24.0 million in compliance costs per
year (Table IX–27).
Although this alternative does not
eliminate exposure monitoring, the
requirements are minimal relative to the
monitoring requirements under the final
rule. However, MSHA believes it is
necessary for mine operators to establish
an initial baseline for any miner who
may be reasonably expected to be
exposed to respirable crystalline silica.
In addition, above-action-level sampling
helps mine operators correlate mine
conditions to miner exposure levels and
see exposure trends more rapidly than
would result from semi-annual or
annual sampling. This will enable mine
operators to take necessary measures to
ensure continued compliance with the
new PEL. Further, more frequent
monitoring will enable mine operators
to ensure the adequacy of controls at
their mines and better protect miners’
health. These benefits cannot be
quantified, but they are nevertheless
material benefits that increase the
likelihood of compliance.
Table IX-27: Summary of Part 60 Annualized Compliance Costs (in millions of 2022
dollars), Regulatory Alternative 1 and Final Requirements: All Mines
0 Percent
Discount Rate
Mine Sector
Percent of
New
Requirements
Annualized
Cost
7 Percent
Discount Rate
3 Percent
Discount Rate
Annualized
Cost
(millions of
dollars)
Percent of
New
Requirements
Annualized
Cost
(millions of
dollars)
Percent of
New
Requirement
Regulatory Alternative 1: Changes in Sampling and Evaluation Requirements
$27.79
$29.27
$31.56
$13.79
$13.66
$13.40
$3.38
$3.32
$3.22
Medical Surveillance
$18.82
$18.84
$18.82
Total, Part 60 Costs
$63.77
Exposure Monitoring
Exposure Controls
Respiratory
Protection
72.8%
$65.08
73.1%
$66.99
73.6%
Final Requirements
$53.24
$55.64
$13.79
$13.66
$13.40
$3.38
$3.32
$3.22
Medical Surveillance
$18.82
$18.84
$18.82
Total, Part 60 Costs
$87.59
ddrumheller on DSK120RN23PROD with RULES3
Exposure Controls
Respiratory
Protection
MSHA also believes that requiring
more frequent above-action-level
sampling will provide mine operators
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100.0%
$89.05
with greater confidence that they are in
compliance with the new PEL. Because
of the variable nature of miner
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100.0%
$91.07
100.0%
exposures to airborne concentrations of
respirable crystalline silica, maintaining
exposures below the action level
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provides mine operators with
reasonable assurance that miners would
not be exposed to respirable crystalline
silica at levels above the PEL on days
when sampling is not conducted. MSHA
believes that the benefits of the final
sampling requirements justify the
additional costs relative to Regulatory
Alternative 1.
Two mining trade associations,
American Exploration and Mining
Association and National Mining
Association, expressed support for
Regulatory Alternative #1 (Changes in
Sampling and Evaluation Requirements)
as a more appropriate approach than the
one in the proposed rule, with one
clarifying that its support for Regulatory
Alternative #1 is only secondary to its
primary recommendation that MSHA
adopt OSHA’s risk-based approach to
sampling and evaluation requirements
(Document ID 1424; 1428). Specifically,
these commenters supported the
Regulatory Alternative #1 requirement
for baseline sampling for miners whose
exposure is at or above the proposed
action level of 25 mg/m3 in lieu of the
requirement for baseline sampling of
each miner who is or may reasonably be
expected to be exposed to respirable
crystalline silica of any level. Further,
these commenters supported the
Regulatory Alternative #1 periodic
sampling requirement of twice per year
for miners between the action level and
the PEL, which they said was more in
line with established industrial hygiene
guidelines and would allow mine
operators to allocate industrial hygiene
resources to those areas where they are
better used, including areas where there
is higher risk of exposure above the PEL.
Finally, these commenters supported
the Regulatory Alternative #1
requirement for annual evaluation of
mine processes or conditions, instead of
the proposed rule’s semi-annual review,
stating that it would provide an equal
amount of protection to miners (given
that mining processes and conditions
are relatively stable and non-changing),
while lowering operator compliance
costs.
MSHA believes it is necessary for
mine operators to establish a solid
baseline for any miner who is
reasonably expected to be exposed to
respirable crystalline silica. In addition,
frequent, regular sampling and
evaluation help mine operators correlate
mine conditions to mine exposure levels
and see exposure trends more rapidly
than would result from semi-annual
sampling and annual evaluation. This
will enable mine operators to take
measures necessary to ensure continued
compliance with the PEL. Further, more
frequent monitoring will enable mine
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operators to ensure the adequacy of
controls at their miners and better
protect miners’ health. These benefits
cannot be quantified, but they are
nevertheless material benefits that
increase the likelihood of compliance.
MSHA believes that the benefits of the
sampling and evaluation requirements
justify the additional costs for the final
rule relative to Regulatory Alternative 1.
Therefore, MSHA did not select
Regulatory Alternative 1.
2. Regulatory Alternative 2: Changes in
Sampling and Evaluation Requirements
and the PEL
Under this Regulatory Alternative, the
PEL would be set at 25 mg/m3, mine
operators would install whatever
controls were necessary to meet the
PEL, and no action level would be
designated. Further, under this
Regulatory Alternative, mine operators
would not be required to conduct firsttime and second time sampling, aboveaction-level sampling, and corrective
actions sampling. However, mine
operators would be required to perform
periodic evaluations of changing
conditions and to sample as frequently
as necessary to determine the adequacy
of controls. Additionally, mine
operators would be required to perform
post-evaluation sampling when the
operators determine as a result of the
periodic evaluation that miners may be
exposed to respirable crystalline silica
at or above the action level of 25 mg/m3.
When estimating the cost of
monitoring requirements under the final
rule, MSHA assumed that the number of
samples for post-evaluation sampling
are relatively small (2.5 percent of
miners) because mine operators are
already collecting information which
can be used for these purposes through
the significant amount of above-actionlevel sampling. Since Regulatory
Alternative 2 does not require aboveaction-level sampling given the lack of
an action level under this alternative,
MSHA increases the share of samples
after each evaluation to 10 percent of
miners to ensure the monitoring
requirements can be met.
In addition, to meet the PEL of 25 mg/
m3, mine operators would incur greater
engineering control costs as compared
to the estimated cost of compliance for
reaching a PEL of 50 mg/m3. To estimate
these additional engineering control
costs, MSHA largely uses the same
methodology as for mines affected at the
new PEL of 50 mg/m3.
a. Number of Mines Affected Under
Regulatory Alternative 2
MSHA first estimated the number of
mines expected to incur the cost of
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implementing engineering controls to
reach the more stringent PEL. After
excluding mines that are affected at the
new PEL of 50 mg/m3 (to avoid doublecounting), MSHA finds that 3,477 mines
(2,991 MNM mines and 486 coal mines)
operating in 2019 had at least one
sample at or above 25 mg/m3 but below
50 mg/m3.96
In addition, MSHA also includes the
1,226 affected mines expected to incur
costs to reach the new PEL of 50 mg/m3.
Based on its experience and knowledge,
MSHA does not expect the mines that
install engineering controls to meet the
PEL of 50 mg/m3 would also be able to
comply with a PEL of 25 mg/m3. For
example, to comply with the PEL of 50
mg/m3, a mine might need to add the
engineering controls necessary to
achieve an additional 10 air changes per
hour over that achieved by existing
controls, which are included in the
costs presented in Table IX–21.
However, such a mine facility would
then need to add an additional 10 air
changes per hour to meet the more
stringent PEL of 25 mg/m3, which is not
included in the costs presented in Table
IX–21. Thus, MSHA expects that the
1,226 affected mines will incur
additional costs to meet the PEL of 25
mg/m3 specified under this alternative.
MSHA estimates a total of 4,703
mines will incur costs to purchase,
install, and operate engineering controls
to meet the more stringent PEL of 25 mg/
m3 under this alternative. MNM mines
account for 4,087 (87 percent) and coal
accounts for the remaining 616 mines
(13 percent).
b. Estimated Engineering Control Costs
Under Regulatory Alternative 2
MSHA identified potential
engineering controls that would enable
mines with respirable crystalline silica
dust exposures at or above 25 mg/m3 but
below 50 mg/m3 categories to meet the
more stringent PEL of 25 mg/m3 for this
alternative. While MSHA assumed that
mine operators will base such decisions
on site-specific conditions such as mine
layout and existing infrastructure,
MSHA cannot make further
assumptions about the specific controls
that might be adopted and instead
assumed the expected value of
purchased technologies should equal
the simple average of the technologies
listed in each control category.
Where more precise information is
unavailable, MSHA assumed operating
and maintenance (O&M) costs to be 35
percent of initial capital expenditure
96 About 8,053 of mines active in 2019 either had
neither a sample >25 mg/m3 nor a sample in the last
5 years.
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and installation cost to be equal to the
initial capital expenditure (Table IX–
28). MSHA also assumed the larger
capital expenditure controls will have a
30-year service life.
Table IX-28: Selected Engineering Controls to Decrease Respirable Crystalline Silica Dust
Exposure by Capital Expenditure Cost Range Under Regulatory Alternative 2 (in 2022
dollars)
Engineering Control
Capital Cost
Minimal capital expenditure
Stone saw enclosure
Lar2er capital expenditure
Increase facility ventilation from 20 to 30 air
changes per hour
Full length of conveyor enclosed and
ventilated
Crusher/grinder: appropriate size ventilation
for air flow
Plumbing for hose installations, floor resloping and trom!hs
Installation
Cost1
Expected
Service Life3
O&MCost2
$0
$0
$1,468
1
$167,263
$167,263
$9,751
30
$960,883
$960,883
$55,386
30
$197,928
$197,928
$11,409
30
$45,892
$45,892
$4,209
30
Averal(e
$274,393
$274,393
$16,445
Notes: 1. Unless otherwise specified, MSHA assumed installation costs are equal to capital cost.
2. Unless otherwise specified, MSHA assumed annual O&M costs are equal to 35 percent of capital cost.
3. Service life assumed to be 10 years if not otherwise specified.
However, the difficulty of meeting a
PEL of 25 mg/m3 is such that MSHA’s
experience suggests a single control
from Table IX–29 would not be
sufficient. For example, respirable
crystalline silica dust exposure at such
a stringent limit is likely to occur in
more than one area of the mine; in
addition to increasing ventilation to a
crusher/grinder, enclosing and
ventilating the belt conveyor would
likely be necessary to reduce
concentrations below a PEL of 25 mg/m3.
Similarly, increasing facility ventilation
from 20 to 30 air changes per hour may
not be adequate to meet the PEL. Rather,
40 air changes per might be necessary.
Therefore, MSHA assumes mine
operators will purchase and install at
least two of the engineering controls
listed in Table IX–28 under this
Regulatory Alternative. This assumption
was made to err on the side of
overestimation.
24.2
Table IX–29 presents the annualized
engineering control costs per mine and
total annualized engineering control
costs by mine sector. At a 3 percent
discount rate, the annualized
engineering control costs are about
$98,124 per mine, resulting in an
additional cost of $461.5 million if the
PEL were set at 25 mg/m3 instead of 50
mg/m3.
Table IX-29: Estimated Annualized Costs as a Simple Average per Mine and Total
Engineering Controls per Mine Under Regulatory Alternative 2 (in 2022 dollars), by Sector
Annualized Cost of Engineering Controls at
Specified Real Discount Rate
0 Percent
3 Percent
7 Percent
Annualized Engineering Control Costs per Mine, Over All Controls
Total
$78,145
$98,124
$128,441
MNM
$78,073
$97,714
$127,269
Coal
$78,621
$100,847
$136,218
$367.5
$461.5
$604.1
MNM
$319.1
$399.4
$520.1
$48.4
$62.1
$83.9
Coal
Note: 1. Based on an estimated 4,087 MNM and 616 Coal mines, for 4,703 total affected mines.
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Total Annualized Engineering Control Costs by Mine Sector
(millions) 1
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table IX–30 summarizes the
estimated annualized cost of this
Regulatory Alternative under
consideration. At a 3 percent discount
rate, exposure monitoring costs less
silica exposure levels below 25 mg/m3.
At an estimated annualized cost of
$520.7 million, this alternative would
cost nearly six times more than the final
requirements.
than it does for the final rule. However,
this lower monitoring cost is more than
offset by the increased control costs
necessitated by the requirement that
mines maintain respirable crystalline
Table IX-30: Summary of Part 60 Annualized Compliance Costs (in millions of 2022 dollars)
Under Regulatory Alternative 2 and New Requirements: All Mines
0 Percent Discount Rate
Mine Sector
Annualized
Cost
3 Percent Discount Rate
Percent of
New
Requirements
Annualized
Cost
7 Percent Discount Rate
Percent of
New
Requirements
Annualized
Cost
Percent of
New
Requirements
Regulatory Alternative 2: Changes in PEL and Sampling and Evaluation Requirements
Exposure Monitoring
Exposure Controls
$32.17
$31.67
$30.80
$367.52
$461.48
$604.06
Respiratory Protection
$8.90
$8.75
$8.50
Medical Surveillance
$18.82
$18.84
$18.82
Total, Part 60 Costs
$427.41
488.0%
$520.73
584.8%
$662.17
727.1%
New Requirements
Exposure Monitoring
$51.60
$53.24
$55.64
Exposure Controls
$13.79
$13.66
$13.40
Respiratory Protection
$3.38
$3.32
$3.22
Medical Surveillance
$18.82
Total, Part 60 Costs
$87.59
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$89.05
benefits. Table IX–31 presents the
avoided morbidity and mortality cases
over the 60-year regulatory analysis time
horizon under this alternative. Under
this alternative, 1,271 mortality cases
are expected to be avoided, which is 2.4
times higher than the 531 mortality
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$18.82
100.0%
$91.07
100.0%
cases expected to be avoided under the
new PEL (50 mg/m3). Additionally, 2,521
morbidity cases are expected to be
avoided under this alternative, which is
1.4 times higher than the 1,836
morbidity cases expected to be avoided
under the new PEL (50 mg/m3).
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c. Avoided Mortality and Morbidity
Under Regulatory Alternative 2
Regulatory Alternative 2 increases
miner protection by establishing the
PEL at 25 mg/m3, resulting in
measurable increases in avoided
mortality cases and other health
$18.84
100.0%
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table IX-31: Estimated Cases of Avoided Mortality and Morbidity over 60 Years
(Regulatory Analysis Time Horizon) Following Compliance with the Rule Under
Regulatory Alternative 2
Total Avoided Cases over 60 Years 1
MNM
Coal
Total
Health Outcome
Avoided Morbidity
Silicosis
Avoided Morbidity Total (Net of Silicosis
Deaths)
Avoided Mortality
NMRD (net of silicosis mortality)
Silicosis
ESRD
Lung Cancer2
Avoided Mortality Total
Notes:
2,239
282
2,521
2,239
282
2,521
527
267
249
70
1,114
77
34
36
IO
158
605
301
286
80
1,271
1. A voided cases include both production and contract miners. Calculations show the difference between excess cases when
assuming compliance with the existing limits versus assuming compliance with the new PEL of 50 µg/m 3 . Estimates account
for the fact that some miners during the 60-year period will have worked under the existing standards (and thus may
have combination of exposures under the existing standards and the new PEL), while other new entrants into the
mining workforce would be solely exposed under the new PEL.
2. A 15-year lag between exposure and observed health effect was assumed for lung cancer estimates.
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Table IX–32 presents the monetized
benefits associated with this avoided
morbidity and mortality. The expected
total benefits, discounted at 3 percent,
are $516.3 million, which is more than
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twice the expected total benefits of
$246.9 million under the new PEL (50
mg/m3).
Under this Regulatory Alternative,
these benefits are made up of $369.0
million due to avoided mortality, $47.3
million due to avoided morbidity
preceding mortality, and $100.0 million
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due to avoided morbidity not preceding
mortality. However, when compared to
the annualized costs of $520.7 million
(3 percent) and $662.2 million (7
percent) for the Part 60 requirements,
the net benefits of this alternative are
negative at a 3 percent and 7 percent
discount rate.
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d. Monetized Benefits Under Regulatory
Alternative 2
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table IX-32: Annualized Monetized Benefits over 60 Years (Regulatory Analysis Time
Horizon) Following the Start of Implementation of the Rule (in millions of 2022 dollars)
Under Regulatory Alternative 2, by Health Outcome and Discount Rate
0%
3%
Avoided Morbidity (Not Precedin2 Mortality)
Silicosis (Excluding Silicosis
$124.6
$88.7
Deaths)
Avoided Morbidity (Not
$124.6
$88.7
Precedin2 Mortality) Total
Avoided Mortality
NMRD (Excluding Silicosis
$252.9 $151.2
Deaths)
Silicosis
$121.5
$80.1
ESRD
$118.8
$72.0
Lung Cancer
$34.5
$19.8
Avoided Mortality Total
$527.7 $323.1
Avoided Morbidity (Precedin1 Mortality)
NMRD (Excluding Silicosis
$29.3
$18.9
Deaths)
Silicosis
$14.8
$10.9
ESRD
$13.9
$9.2
Lung Cancer
$3.9
$2.4
Avoided Morbidity
$62.0
$41.3
(Precedin2 Mortality) Total
Grand Total
$714.2 $453.1
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A professional association, American
Industrial Hygiene Association,
expressed support for Regulatory
Alternative 2 (Changes in Sampling and
Evaluation Requirements and the
Proposed PEL) (Document ID 1351).
However, the commenter recommended
that mine operators be required to (1)
conduct baseline sampling and periodic
sampling, (2) conduct semi-annual or
more frequent evaluations of changing
conditions, and (3) sample as frequently
as necessary to determine the adequacy
of controls. In addition, the commenter
stated that, under this alternative, mine
operators should be required to perform
post-evaluation sampling when the
operators determine from the semiannual evaluation that miners are
exposed at the 95-percent confidence
level to respirable crystalline silica
above the PEL of 50 mg/m3, referencing
a NIOSH Occupational Sampling
Strategy Manual.
e. Net Benefits Under Regulatory
Alternative 2
Although the benefits associated with
this avoided morbidity and mortality
under Regulatory Alternative 2 (Table
IX–31 and Table IX–32) are greater than
those for the final rule, the net benefits
of this alternative are negative at both a
3 percent and 7 percent real discount
rate owing to the much higher
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Coal
7%
0%
3%
$55.5
$15.7
$11.3
$55.5
$15.7
$69.0
0%
3%
7%
$7.2
$140.3
$100.0
$62.7
$11.3
$7.2
$140.3
$100.0
$62.7
$36.9
$22.2
$10.3
$289.8
$173.3
$79.3
$44.8
$34.5
$8.1
$156.4
$15.2
$17.2
$4.8
$74.1
$10.4
$10.6
$2.8
$46.0
$6.1
$5.3
$1.2
$22.8
$136.7
$136.0
$39.3
$601.8
$90.5
$82.6
$22.5
$369.0
$50.9
$39.7
$9.3
$179.2
$9.6
$4.3
$2.8
$1.5
$33.6
$21.7
$11.1
$7.0
$5.0
$1.1
$1.9
$2.0
$0.5
$1.4
$1.4
$0.3
$1.0
$0.8
$0.2
$16.7
$15.9
$4.5
$12.3
$10.5
$2.7
$8.0
$5.8
$1.2
$22.7
$8.8
$5.9
$3.4
$70.7
$47.3
$26.1
$234.7
$98.6
$63.2
$33.4
$812.8
$516.3
$268.0
compliance costs for this alternative as
compared to those for the final rule
(Table IX–31). Further, MSHA
determines that meeting a PEL of 25 mg/
m3 is not achievable for all mines and
therefore, Regulatory Alternative 2 is
not chosen.
3. Regulatory Alternative 3: Changes in
the Calculation of Exposure
Concentrations
Regulatory Alternative 3 calculates
exposure concentrations as an entireshift time-weighted average, called a
‘‘full shift TWA’’. Under this Regulatory
Alternative, a different methodology is
used for calculating exposures and
assessing compliance. Elsewhere in the
final rule, the costs and benefits are
based on calculating exposure for a full
shift, calculated as an 8-hour TWA. In
this Regulatory Alternative, MSHA
calculates exposure as a full shift TWA
and re-analyzes the costs and benefits of
the rule. No other changes, such as
changes to the rule requirements, are
included under this Regulatory
Alternative.
a. Number of Mines Affected Under
Regulatory Alternative 3
MSHA expects a change in the
number of affected mines. MSHA has
estimated the number of mines expected
to incur costs when baseline exposure
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7%
concentrations are re-calculated as full
shift TWAs. Based on the use of a full
shift TWA, MSHA finds that 1,053
mines operating in 2019 would incur
costs to purchase, install, and operate
exposure controls under the final rule.
Of this total, 955 are MNM mines and
98 are coal mines. This total is 173
fewer mines than what would incur new
compliance costs under an 8-hour TWA
(1,226 affected mines).
b. Estimated Costs Under Regulatory
Alternative 3
Aside from the change to the
calculation of exposure concentrations
and the number of affected mines at
those concentrations, MSHA does not
make any additional changes in
assumptions or calculations under this
Regulatory Alternative. Therefore, the
cost estimates of this Regulatory
Alternative are calculated using the
same methodology as described in
Section 4 of the FRIA. The changes in
cost estimates are completely
attributable to changes in the estimated
baseline exposure conditions and the
total number of affected mines, as
described in Section 7.3.1 of the FRIA.
Table IX–33 below presents the
estimated annualized compliance costs
of part 60 if exposure concentrations
were calculated using a full shift TWA
instead of a full shift, 8-hour TWA.
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Health Outcome
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Total part 60 annualized compliance
costs are estimated at $86.4 million (at
a 3 percent discount rate), with 92.3
percent of costs attributable to MNM
mines and 7.7 percent attributable to
coal mines. This is $2.7 million (3.0
percent) less than the total part 60
annualized compliance costs when
using an 8-hour TWA ($89.1 million).
The difference is explained by the
decreased number of mines and miners
who are affected by the rule under this
Regulatory Alternative as compared to
the main analysis.
Table IX-33: Summary of Part 60 Annualized Compliance Costs (in millions of 2022
dollars) Under Regulatory Alternative 3 and New Requirements: All Mines
Annualized Cost
Mine Sector
0 Percent
Discount Rate
3 Percent
Discount Rate
7 Percent
Discount Rate
Alternative Exposure Calculated Using Full Shift TWA
Exposure Monitoring
$50.71
$52.05
$54.02
Exposure Controls
$12.70
$12.57
$12.32
Respiratory Protection
$2.95
$2.90
$2.81
Medical Surveillance
$18.82
$18.84
$18.82
$85.17
$86.35
$87.97
Total, Part 60 Costs
Final Rule: Exposure Calculated Using Full Shift, 8-hour TWA
Exposure Monitoring
$51.60
$53.24
$55.64
Exposure Controls
$13.79
$13.66
$13.40
Respiratory Protection
$3.38
$3.32
$3.22
Medical Surveillance
$18.82
$18.84
$18.82
$87.59
$89.05
$91.07
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c. Avoided Mortality and Morbidity
Under Regulatory Alternative 3
While the compliance costs decrease
when a full shift TWA is used, the
estimated benefits of the rule are also
expected to decrease. When miners
work shifts that are longer than 8 hours
(which commonly occurs, as seen both
in the exposure data and in the
employment data), the full shift, 8-hour
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TWA will result in a higher calculated
exposure level than the full shift TWA.
Table IX–34 presents the estimated
number of avoided deaths and illnesses
during the 60 years following the start
of implementation of the new rule,
under the Regulatory Alternative. The
total number of avoided morbidity cases
over the 60-year analysis period is
1,500, which is 18 percent lower under
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the Regulatory Alternative than the
estimate of 1,836 avoided morbidity
cases in the main analysis (see Table
IX–24). The total number of avoided
mortality cases over the 60-year analysis
period is 434, which is 18 percent lower
under the Regulatory Alternative than
the estimate of 531 avoided mortality
cases in the main analysis (see Table
IX–24).
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Total, Part 60 Costs
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Table IX-34: Estimated Cases of Avoided Mortality and Morbidity over 60 Years
(Regulatory Analysis Time Horizon) Following Compliance with the Rule Under
Regulatory Alternative 3
Total Avoided Cases During 60 Years
Following the Start oflmplementation of the
Rule [a]
MNM
Coal
Total
Health Outcome
Morbidity
Silicosis
1,392
l08
1,500
1,392
108
1,500
NMRD (net of silicosis mortality)
198
15
213
Silicosis
l05
7
112
ESRD
75
5
80
Lung Cancer [b]
28
2
30
405
29
434
Morbidity Total (Net of Silicosis Deaths)
Mortality
Mortality Total
Notes: [a] Avoided cases include both production and contract miners. Calculations show the difference
between excess cases when assuming compliance with the existing limits versus assuming compliance
with the new PEL of 50 µg/m 3 . Estimates account for the fact that some miners during the 60-year
period will have worked under the existing standards (and thus may have combination of exposures
under the existing standards and the new PEL), while all new entrants into the mining workforce would
be solely exposed under the new PEL.
[b] A 15-year lag between exposure and observed health effect was assumed for lung cancer estimates.
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attributable to MNM mines and $21.3
million attributable to coal mines. The
discounted annualized benefits under
the Regulatory Alternative are estimated
at $201.9 million at a 3 percent discount
rate and $107.9 million at a 7 percent
discount rate. At a 3 percent discount
rate, the annualized benefits are $45.0
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million (18 percent) less under the
Regulatory Alternative than when using
an 8-hour TWA ($246.9 million). The
annualized benefits under the
Regulatory Alternative are also 18
percent lower both at the 0 percent
discount and 7 percent discount rates.
BILLING CODE 4520–43–P
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d. Monetized Benefits Under Regulatory
Alternative 3
Table IX–35 presents the annualized
benefits of the final rule under this
Regulatory Alternative. The
undiscounted annualized benefits under
the Regulatory Alternative are estimated
at $312.8 million, with $291.5 million
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Table IX-35: Annualized Monetized Benefits over 60 Years (Regulatory Analysis Time
Horizon) Following the Start of Implementation of the Rule (in millions of 2022 dollars)
Under Regulatory Alternative 3, by Health Outcome and Discount Rate
Silicosis (Net of
Silicosis Mortality)
Avoided Morbidity (Not
Preceding Mortality)
Total
Total
$77.4
$55.2
$34.5
$6.0
$4.3
$2.8
$83.5
$59.5
$37.3
$77.4
$55.2
$34.5
$6.0
$4.3
$2.8
$83.5
$59.5
$37.3
NMRD (Excluding
Silicosis Deaths)
$94.9
$56.6
$25.6
$7.1
$4.3
$1.9
$102.0
$60.9
$27.5
Silicosis
$47.6
$31.6
$18.0
$3.1
$2.1
$1.3
$50.7
$33.7
$19.3
Renal Disease
$35.4
$21.7
$10.6
$2.5
$1.5
$0.8
$37.9
$23.3
$11.4
Lung Cancer
$13.62
$7.8
$3.2
$0.99
$0.6
$0.2
$14.6
$8.4
$3.4
$191.5
$117.7
$57.4
$13.7
$8.5
$4.2
$205.2
$126.2
$61.6
$11.0
$7.1
$3.5
$0.8
$0.5
$0.3
$11.8
$7.6
$3.8
Silicosis
$5.8
$4.3
$2.9
$0.4
$0.3
$0.2
$6.2
$4.6
$3.1
Renal Disease
$4.2
$2.8
$1.5
$0.3
$0.2
$0.1
$4.5
$3.0
$1.7
$1.5
$0.9
$0.4
$0.1
$0.1
$0.0
$1.7
$1.0
$0.4
$22.5
$15.1
$8.4
$1.6
$1.1
$0.6
$24.2
$16.2
$9.0
Avoided Mortality Total
NMRD (Excluding
Silicosis Deaths)
Lung Cancer
Avoided Morbidity
(Preceding Mortality)
Total
BILLING CODE 4520–43–C
e. Net Benefits Under Regulatory
Alternative 3
The net annualized benefits under the
Regulatory Alternative are $226.5
million (undiscounted), $114.3 million
(3 percent discount rate), and $18.6
million (7 percent discount rate). The
net benefits under the Regulatory
Alternative are lower than those in the
main analysis by 23 percent (0 percent
discount rate), 27 percent (3 percent
discount rate), and 53 percent (7 percent
discount rate).97
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Coal
97 There are limitations in how the risk
calculations can be performed because of
limitations in the underlying exposure-response
models from the literature. The exposure-response
models were not designed to detect the impact of
longer work shifts, nor were they based on
longitudinal data that could track individuals’ work
shifts over their careers. These calculations
presented in this Alternative analysis provide new
estimates of avoided cases when calculating
exposure as a full shift TWA and when accounting
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MSHA received comments both in
agreement with the Agency’s proposed
‘‘full-shift, 8-hour TWA’’ calculation
method and against it. Commenters in
favor stated that the proposed
calculation method of collecting a
sample for a full-shift and calculating
the exposure level over an 8-hour period
(i.e., normalizing a longer work shift to
an 8-hour shift) capture the total
cumulative exposure to silica dust
properly. Those against the proposal
preferred the use of the entire duration
of the miner’s extended work shift
without any adjustment, and stated that
normalizing the extended shift sampling
result to an 8-hour period inaccurately
skews the results. For more details on
the comments received, please see
section VIII.B.3 of this preamble.
for the fact that fewer samples would meet the
threshold of the new PEL or the new action level
under a full shift TWA.
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The Agency does not choose
Regulatory Alternative 3, that uses full
shift TWA as an alternate calculation of
exposure concentration. Regulatory
Alternative 3 yields much smaller net
benefits than the final rule. Importantly,
Regulatory Alternative 3 would provide
miners less health protection.
Cumulative exposure to respirable
crystalline silica is an important risk
factor in the development of silicarelated disease, as discussed in the
standalone FRA document and section
VIII.B.3.c of this preamble. However, the
full shift TWA methodology does not
account for the increased health risks
associated with the higher cumulative
exposures that can occur during longer
work shifts. The full shift TWA
calculation does not differentiate
between the impacts of working 8-hour
shifts and working extended shifts.
Regulatory Alternative 3 would provide
less protection for miners working
longer shifts.
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X. Final Regulatory Flexibility Analysis
A. The Regulatory Flexibility Act
The Regulatory Flexibility Act of 1980
as amended by the Small Business
Regulatory Enforcement Fairness Act of
1996, hereafter jointly referred to as the
RFA, requires that an agency consider
the economic impact that a final
rulemaking will have on small entities.
The RFA provides that, ‘‘[w]hen an
agency promulgates a final rule under
section 553 of this title, after being
required by that section or any other law
to publish a general notice of proposed
rulemaking . . . the agency shall
prepare a final regulatory flexibility
analysis.’’ 5 U.S.C. 604(a). However,
under section 605(b), in lieu of an initial
regulatory flexibility analysis (IRFA) or
final regulatory flexibility analysis
(FRFA), the head of an agency may
certify that the final rule ‘‘will not, if
promulgated, have a significant
economic impact on a substantial
number of small entities.’’ 5 U.S.C.
605(b). That certification must be
supported by a factual basis.
As part of its notice of proposed
rulemaking, MSHA prepared an IRFA
that analyzed the potential impact of the
proposed rule on small entities. See 5
U.S.C. 603(a). After considering public
comments on the IRFA, MSHA believes
that the final rule will not have a
significant economic impact on a
substantial number of small entities.
However, in the furtherance of good
governance principles and consistent
with guidance from the Small Business
Administration (SBA), the Agency has
prepared a FRFA. Under section 604(a),
the FRFA analysis must contain:
(1) a statement of the need for, and
objectives of, the rule;
(2) a statement of the significant
issues raised by the public comments in
response to the initial regulatory
flexibility analysis, a statement of the
assessment of the agency of such issues,
and a statement of any changes made in
the proposed rule as a result of such
comments;
(3) the response of the agency to any
comments filed by the Chief Counsel for
Advocacy of the Small Business
Administration in response to the
proposed rule, and a detailed statement
of any change made to the proposed rule
in the final rule as a result of the
comments;
(4) a description of and an estimate of
the number of small entities to which
the rule will apply or an explanation of
why no such estimate is available;
(5) a description of the projected
reporting, recordkeeping and other
compliance requirements of the rule,
including an estimate of the classes of
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small entities which will be subject to
the requirement and the type of
professional skills necessary for
preparation of the report or record; and
(6) a description of the steps the
agency has taken to minimize the
significant economic impact on small
entities consistent with the stated
objectives of applicable statutes,
including a statement of the factual,
policy, and legal reasons for selecting
the alternative adopted in the final rule
and why each one of the other
significant alternatives to the rule
considered by the agency which affect
the impact on small entities was
rejected; and for a covered agency, as
defined in section 609(d)(2), a
description of the steps the agency has
taken to minimize any additional cost of
credit for small entities. 5 U.S.C. 604(a).
While a full understanding of MSHA’s
analysis and conclusions with respect to
costs and economic impacts on small
entities requires a reading of the
standalone FRIA document, this FRFA
summarizes the key aspects of MSHA’s
analysis as they affect small entities.
B. Initial Assessment
As part of the proposed rule, MSHA
published an IRFA. MSHA’s proposed
rule would affect MNM and coal mining
operations. The IRFA identified which
mine controllers were small entities,
estimated the direct compliance costs
for those small entities, and compared
the compliance costs to the revenues of
the small entities. Results from the IRFA
are summarized below.
1. Definition of Small Entities
In its IRFA analysis, MSHA relied on
the Small Business Administration
(SBA)’s 2017 Table of Size Standards to
define the size thresholds for small
entities. MSHA identified small-entity
controllers in each North American
Industry Classification System (NAICS)
code, after determining that a
‘‘controller,’’ the entity that owns and
controls one or more mines, is the
appropriate unit of the IRFA analysis,
based on SBA guidance.98 (SBA,
2017).99 The IRFA detailed how SBA’s
98 Small Business Administration, Office of
Advocacy, How to Comply with the Regulatory
Flexibility Act, August 2017.
99 A controller is a parent company owning or
controlling one or more mines, whereas a mine is
an establishment of a parent company. Small
entities subject to the requirements of the
Regulatory Flexibility Act are entities that are
parent companies only and not establishments. See
Small Business Administration, Office of Advocacy,
How to Comply with the Regulatory Flexibility Act,
August 2017. Sec. 3(d) of the Mine Act defines
‘‘operator’’ as ‘‘any owner, lessee, or other person
who operates, controls, or supervises a coal or other
mine.’’ 30 U.S.C. 802(d). Under 30 CFR part 41, an
operator must file a legal identity report with
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size standards vary by North American
Industry Classification System (NAICS)
code, which NAICS codes were used in
the IRFA, and which controllers were
small entities according to these
standards.
2. Number of Affected Small Entities
MSHA estimated that in 2021, there
were a total of 11,791 mines and a total
of 5,879 controllers. Of the controllers,
5,007 were small-entity controllers;
these small-entity controllers owned
8,240 mines. Many controllers owned
one or two mines, while some
controllers owned hundreds of mines
nationwide (or worldwide).
3. Results of the Initial Regulatory
Flexibility Analysis
MSHA estimated the regulatory
compliance costs and revenues for each
of the 5,007 small-entity controllers
identified in 2021. In estimating
compliance costs for small-entity
controllers, MSHA factored in the types
of commodities that controllers
produced and their employment size,
which were gathered from the MSHA
Standardized Information System
(MSIS). MSHA estimated the revenues
of the small-entity controllers based on
data from the Statistics of U.S.
Businesses published by the U.S.
Census Bureau, using NAICS codes and
each controller’s employment size.100
MSHA then calculated the compliance
costs as a proportion of revenues and
used that as an indicator of the relative
burden of the compliance costs for
small-entity controllers.
From these two sets of estimates,
MSHA generated estimates of the ratios
of regulatory compliance cost to revenue
for each controller. Table X–1 shows the
number of controllers, average annual
regulatory costs, average annual
MSHA, and with this report, MSHA identifies a
controller for each mine. 30 U.S.C. 819(d) (each
operator shall file the name and address of the
‘‘person who controls or operates the mine’’). In the
FRFA, consistent with SBA guidance and the Mine
Act, MSHA determines whether the controller is a
small entity.
100 U.S. Census Bureau, ‘‘Statistics of U.S.
Businesses,’’ released May 2021. https://
www.census.gov/data/tables/2017/econ/susb/2017susb-annual.html (last accessed Jan. 10, 2024). Data
in the report were in reference to the year 2017,
which MSHA adjusted to 2021 dollars. Data on
revenues are presented in the report under the
equivalent term ‘‘receipts.’’ MSHA converted the
2017 revenues to 2021 dollars using the GDP
Implicit Price Deflator published by the Bureau of
Economic Analysis October 26, 2022, Table 1.1.9
Implicit Price Deflators for Gross Domestic Product,
Series A191RD. https://apps.bea.gov/histdata/
fileStructDisplay.cfm?HMI=7&DY=2022&DQ=
Q3&DV=Advance&dNRD=October-28-2022 (last
accessed Jan. 10, 2024). The index was 107.749 for
2017 and 118.895 for 2021, creating an adjustment
factor (from 2017 to 2021 dollars) of 118.895/
107.749 or 1.103.
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revenues, and average cost as a percent
of revenue presented in the IFRA. As
shown in Table X–1, for every $1
million in revenue earned by a smallentity controller, the average
28399
compliance cost was estimated to be
$1,220.
Table X-1: Summary of the IRFA Findings: Annualized Compliance Costs to Revenues for
a Typical Small-Entity Controller
Number of
SmallEntity
Controllers
Average
Annual
Regulatory
Cost Per
Small-Entity
Controller
(in 2021 $)
at a3
Percent
Discount
Rate
235
$3,191
$ 12,816,000
0.025
4,772
$4,250
$ 3,822,000
0.127
5,007
$4,200
$ 4,243,000
0.122
Coal SmallEntity
Controllers
MNM SmallEntity
Controllers
Total
Average
Annual
Revenue
Per SmallEntity
Controller (in
2021 $)
Average of Cost as a
Percent of Revenue
(Unweighted Average of
the Percentages Among
All Small-Entity
Controllers) 1
1. Note that because the column displays the unweighted average of the controller-level percentages
across all controllers, it is not equivalent to the ratio of the average cost among all controllers and the
average revenue among all controllers in the previous two columns.
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1. Outreach and Small Business
Advocacy Review
On July 13, 2023, MSHA published its
notice of proposed rulemaking in the
Federal Register. The proposed rule was
also posted on Regulations.gov and on
MSHA’s website to ensure that members
of the public, including small
businesses, had more than one way to
access the proposal. Prior to
publication, MSHA made an informal
copy of the proposed rule available on
the Agency’s website to provide small
businesses and other stakeholders with
additional time to become familiar with
the proposal. MSHA also reached out to
mining labor and industry stakeholders,
public interest groups, and trade
associations, notifying them of the
upcoming publication of the proposed
rule. Some of these stakeholders
represented small businesses.
During the public comment period,
MSHA held three public hearings
(virtual and in-person)—in Arlington,
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Virginia (on August 3, 2023), Beckley,
West Virginia (on August 10, 2023), and
Denver, Colorado (on August 21,
2023)—to facilitate the participation of
the public, small businesses and
organizations that represent them, and
all other stakeholders.
On August 30, 2023, MSHA attended
a Small Business Labor Safety
Roundtable organized by the SBA’s
Office of Advocacy to discuss the
proposal. The Roundtable was also
attended by the small business
community and representatives from
industry and labor. MSHA provided
education about the NPRM’s content at
this roundtable.101
101 MSHA considered the testimonies from the
public hearings and written comments submitted to
the docket for its development of the final rule, but
not the discussion at the Roundtable. For
transparency, however, MSHA makes the materials
presented at the Roundtable available in the docket
at Regulations.gov.
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2. Final Regulatory Flexibility Analysis
a. Objectives of, and Need for, the Final
Rule
Based on its review of the health
effects literature, MSHA determined
that occupational exposure to respirable
crystalline silica causes silicosis and
other diseases. In its FRA, MSHA also
determined that, under existing
standards, miners face a risk of material
impairment of health or functional
capacity from exposures to respirable
crystalline silica.
Following these determinations,
MSHA is issuing a final rule to better
protect miners against occupational
exposure to respirable crystalline silica,
a carcinogen, and to improve respiratory
protection for airborne contaminants.
The final rule will affect both MNM and
coal mining operations.
The final rule establishes, for mines of
all sizes, a PEL of 50 mg/m3 for a fullshift exposure, calculated as an 8-hour
TWA, and an action level of 25 mg/m3
for a full-shift exposure, calculated as an
8-hour TWA. In addition to the PEL and
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action level, the rule includes
provisions for methods of compliance,
exposure monitoring, corrective actions,
respiratory protection, medical
surveillance for MNM mines, and
recordkeeping. MSHA also amends
existing standards for other airborne
contaminants to replace requirements
for respiratory protection and
incorporates by reference ASTM F3387–
19 Standard Practice for Respiratory
Protection to update existing respiratory
protection standards. The final rule will
significantly improve health protections
for all miners over the course of their
working lives.
b. The Agency’s Response to Public
Comments
MSHA received written comments
from trade associations representing
small businesses or small mines
(Document ID 1406; 1408; 1411; 1413;
1415; 1422; 1424; 1427; 1430; 1435;
1436; 1441; 1448; 1453; 1456; 1300;
1302; 1303; 1349; 1368; 1369; 1378;
1383; 1392; 1398). The Agency also
received a letter from the Deputy Chief
Counsel and Assistant Chief Counsel for
Advocacy of the SBA requesting a 60day extension of the public comment
period to give small businesses more
time to comment and provide small
business representatives time to consult
their membership about their operations
and how the proposed rule would
impact them.
On August 14, 2023, MSHA published
a notice in the Federal Register
extending the comment period by
changing the closing date from August
28, 2023, to September 11, 2023 (88 FR
54961).
Commenters raised concerns about
MSHA’s estimates of the proposed rule’s
costs and impacts. MNM operators,
mining and industry trade associations,
and a mining related business stated
that MSHA had underestimated the
costs of the proposal for small mines
(Document ID 1427; 1430; 1435; 1436
1448; 1456; 1392). Commenters,
including mining related businesses,
MNM operators, and mining trade
associations, also stated that, for some
mines, there would be high costs of
initial compliance or high costs of
annual compliance thereafter
(Document ID 1408; 1411; 1415; 1427;
1430; 1435; 1436; 1448; 1453; 1456;
1383; 1392). Commenters including
mining trade associations and MNM
operators cited the cost of obtaining
equipment and services needed to
establish sampling and medical
surveillance programs, as well as the
cost of implementing engineering
controls (Document ID 1408; 1411;
1415; 1427; 1435; 1436; 1441; 1448;
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1392). MNM operators, mining trade
associations, and other mine
organizations commented on the costs
of lab fees, respirators, and travel to
undergo medical examinations for
medial surveillance (Document ID 1408;
1411; 1415; 1435; 1436; 1448; 1453;
1378; 1392). Several MNM operators
and a mining-related business stated
that compliance with the proposal
would substantially increase their water
costs (Document ID 1411; 1415; 1427;
1435; 1436; 1392). Some commenters
including a mining-related business,
mining trade associations, MNM
operators, and other mine industry
organizations noted that the costs of
compliance would be higher for small
mines operating in remote locations
(Document ID 1408; 1411; 1415; 1422;
1424; 1453; 1378; 1392). A mining trade
association and a mining-related
business stated that MSHA failed to
consider that some small mines might
go out of business due to being unable
to afford to comply with the new rule,
which would result in losses to local
economies (Document ID 1429; 1368;
1392).
Taking these comments into
consideration, MSHA changed its
compliance dates and other
requirements, which resulted in
revisions to some of previous cost
estimates. MSHA’s cost estimates are
detailed in Section 4 of the standalone
FRIA document. MSHA believes its cost
estimates for sampling, exposure
controls, laboratory fees, and medical
surveillance are accurate for smallentity controllers. As explained in
Section 8 of the standalone FRIA
document, MSHA adjusted some
compliance costs upwards in response
to commenters; in particular, sampling
and exposure control costs. MSHA
incorporated these adjusted costs in the
cost estimates for small entities. In the
FRFA methodology, the compliance
costs that were derived in the FRIA, per
mine employee, were estimated for
specific size categories of mines, and for
the type of commodity produced in the
mine.102 Based on these costs, and the
number of employees at mines, MSHA
estimated the average, expected
compliance cost for each small-entity
controller in 2021. These are average
costs, which will vary among smallentity controllers. However, overall,
MSHA believes that these estimates
support the conclusion that the
compliance costs incurred by smallentity controllers, on average, will be a
small fraction of the revenue that small
102 These size categories were mines with 20 or
fewer employees, 21–100 employees, 101–500
employees, and over 500 employees.
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controllers earn from their operations.
MSHA found that, among small-entity
controllers, the compliance costs of the
final rule represent, on average, about
0.318 percent of the revenues that small
entities earn. MSHA concluded that
these compliance costs are generally
unlikely to have significantly negative
economic impacts on small-entity
controllers or on local economies.
MSHA understands that some smallentity controllers might have high initial
capital investments for the installation
of new engineering controls. However,
high initial capital expenses, in general,
are not uncommon in mining
operations, especially with regard to the
purchase of major units of equipment
for engineering controls. Because these
new engineering controls will last for
many years, their purchase is
comparable to any other type of
investment in physical capital, for
mining operations, that will be either
paid directly or financed through
periodic payments. If they are paid
directly, this would be a one-time
payment to cover several years,
resulting in a lower cost per year. If the
payment is financed, the annual (or
monthly) costs will be much lower as
well. Because these costs, on an annual
basis, as determined by the useful life of
the engineering controls, will be much
lower than the initial investment, and
these annual costs will be a small
fraction of the revenues earned in those
years, MSHA believes these new
engineering controls will not, on
average, be significantly burdensome to
small-entity controllers. Moreover,
MSHA expects that many of the mines
that implement new engineering
controls will be able to discontinue
sampling once exposure levels are
reduced below the action level. Thus,
even mines with higher initial
expenditures are unlikely to also have
high annual costs thereafter.
MSHA acknowledges the concerns
from small mine operators in rural and
remote areas. Because of the nature of
mining, many mine operators, including
small-entity operators, operate in rural
and remote areas. MSHA believes that
this final rule will not present major
logistical challenges for small mine
operators. As MSHA has stated in
Section VIII.A. General Issues, once the
final rule is implemented, the Agency
will provide compliance assistance,
including training and best practice
materials, to all mine operators, with an
emphasis on small operators.
A mining-related business noted that
the IRFA included no estimates of
indirect costs of the rule (Document ID
1392). Examples of such costs cited by
the commenter included lost
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production, the expenses of employees
traveling to medical examinations, and
impacts on local communities of
reductions in charitable donations by
operators.
MSHA considered the comment that
the rule might lead to lost production.
MSHA is providing additional
compliance time for mine operators,
including small-entity controllers, to
prepare for the final rule’s requirements.
The extended compliance period under
the final rule (24 months after the
publication date for MNM operators and
12 months after the publication date for
coal operators) provides additional time
for mine operators to comply with the
requirements, such as implementing
engineering controls and finding
appropriate resources (industrial
hygienists, medical facilities,
laboratories, sampling devices, etc.).
This extended compliance period is
intended to provide industry additional
time for planning. For example, a MNM
small entity mine operator could use the
increased time to identify and
implement engineering controls to
reduce miners’ exposures.
As in the IRFA, the FRFA includes
the travel expenses related to miners’
time lost due to travelling to medical
examinations and their transportation
costs. Regarding the costs of travel time
to medical examinations, MSHA
believes its estimates of the average
travel time spent to and from medical
examinations and the related cost are
reliable, though it should be recognized
that these are averages and that travel
times could be different for different
mines.
MSHA considered the comment that
the rule could incur ‘‘costs to
communities’’ by making it harder for
mine operators to make charitable
donations to those communities. MSHA
has not included charitable donations
from operators in its analysis, as
charitable donations are voluntary.
MSHA believes that the final rule will
benefit communities because the health
and safety of miners is greatly
improved. In this regard, MSHA’s final
rule is expected to have a net beneficial
effect on mining communities through
the improved health of miners, which
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should reduce the need for charitable
support. Details on the revised estimates
are provided in Section X.D. Analysis of
Small Business Impacts.
c. Description of the Number of Small
Entities to Which the Final Rule Will
Apply
The final rule, like the proposed rule,
will affect MNM and coal mining
operations. As in its IRFA, MSHA
considered a controller (parent
company) that owns and operates one or
more mines as the appropriate unit of
this FRFA.
To determine the number of small
entities subject to the final rule, MSHA
used SBA’s 2023 Size Standards and
other guidance from the Office of
Advocacy such as how to determine if
a government entity is a small entity,
NAICS codes, and MSIS, which
identifies mines and their numbers of
employees working at mines.
MSHA estimated that the number of
small-entity controllers in 2021 was
5,462 out of the total number of
controllers (5,879). The 5,462 smallentity controllers owned a total of 9,395
mines out of a total of 12,529 mines
owned by all controllers in 2021.103 The
estimated number of small-entity
controllers reflects an increase from
5,007 in the IRFA; this revision is due
to the use of more current NAICS codes
and more current SBA size standards. In
addition, MSHA performed a more
thorough analysis of potential
enterprises that might be small but had
not been estimated as small in the IFRA,
such as small local governments that
owned mines.
In analyzing controllers of mines,
MSHA determined that mining
operations subject to the final rule
would fall under 19 NAICS codes.
These industry categories and their
accompanying six-digit NAICS codes
are shown in Table X–2.104 MSHA then
103 The total number of mines (12,529) was
updated in the FRFA based on additional analysis
of the data.
104 The NAICS classifications used in this
analysis are drawn from the latest version of the
NAICS, which was effective in July 2022. MSHA
also used, in the analysis, an earlier version of
NAICS categories that was effective in August 2019.
MSHA had begun developing this analysis prior to
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matched the NAICS codes with SBA
small-entity size standards (based on the
number of employees) to determine the
number of small entities within each of
the respective NAICS codes. MSHA
then counted the number of small-entity
controllers in each NAICS code, after
determining which controllers owned
which mines. Many controllers owned
one or two mines, while some
controllers owned hundreds of mines
nationwide (or worldwide).105 106 Table
X–2 shows the count of all controllers
and a count of small-entity controllers
in each NAICS code.
Table X–2 presents the distribution of
controllers by the one NAICS code for
which they have the most employees,
because some controllers are in more
than one mining NAICS code.
BILLING CODE 4520–43–P
the most current NAICS being effective. The older
NAICS categories were still used in the part of the
current analysis that estimated revenues. This is
because the older categories were still needed in
order for MSHA to cross-tabulate (or crosswalk) its
data on mines and controllers with Bureau of
Census data on revenues by NAICS codes, where
these Census data were organized by the same
NAICS codes that were in the earlier version. No
comparable revenue data, at this writing, had yet
been revised to the most recent NAICS categories.
105 The number of controllers and mines
examined in this regulatory flexibility analysis are
those specifically known to operate in 2021. The
year 2021 is the most current year for which
complete information was available. Such
information about controllers as parent companies
might include, for example, knowledge of whether
the parent company is a large, multinational
corporation, which would then have bearing on this
regulatory flexibility analysis.
106 Each mine is assigned only one NAICS code,
reflecting the commodity that mine primarily
produces. There are several cases in which more
than one mine, owned by the same controller, have
different NAICS codes, so that there are different
NAICS codes for that one controller. In particular,
of the 5,879 unique controllers identified in 2021,
608 of them each had mines that had different
NAICS codes. In theory, this could present an
ambiguity as to whether a controller with more than
one NAICS code should be considered a small
entity or not. Since NAICS codes vary by their
small-entity thresholds, it is theoretically possible
for a controller with more than one NAICS code to
be a small entity according to the threshold for one
of its NAICS codes, while not being a small entity
according to a lower threshold for a different one
of its NAICS codes. However, this situation was not
found to occur for any of the mine controllers; all
controllers that were determined to be small entities
met the conditions for a small entity for each of
their NAICS codes.
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Table X-2: Small Entities Affected by the Final Rule: Distribution of Controllers by NAICS
Category, with One NAICS Code Per Controller1
NAICS
Code
Industry Description
SBA Size
Standards
in Maximum
Number of
Employees2
Number of
All
Controllers
Number of
SmallEntity
Controllers
1,250
1,250
1,250
1,500
1,400
1,500
1,400
1,250
3
1
246
93
19
98
31
14
3
0
218
75
18
82
25
12
500
415
382
750
716
675
850
133
130
550
617
596
500
750
3,046
120
2,839
113
650
108
101
600
108
95
1,000
1,050
61
48
49
47
1,300
2
2
5,879
5,462
211120 Crude Petroleum Extraction3
211130 Natural Gas Extraction3
212114 Surface Coal Mining
212115 Underground Coal Mining
212210 Iron Ore Mining
212220 Gold Ore and Silver Ore Mining
212230 Copper, Nickel, Lead, and Zinc Mining
212290 Other Metal Ore Mining
212311
212312
212313
212319
212321
212322
212323
212390
327310
327410
331313
Dimension Stone Mining and
Quarrving
Crushed and Broken Limestone Mining
and Quarrving
Crushed and Broken Granite Mining
and Quarrving
Other Crushed and Broken Stone
Mining and Quarrving
Construction Sand and Gravel Mining
Industrial Sand Mining
Kaolin, Clay, and Ceramic and
Refractory Minerals Mining
Other Nonmetallic Mineral Mining and
Quarrying
Cement Manufacturing
Lime Manufacturing
Primary production of alumina and
aluminum
Total
Each controller is assigned the one NAICS code for which it devotes the most employees, based on the
employees at its mines and each of its mines being associated with only one NAICS code.
2. SBA, effective March 17, 2023, https://www.sba.gov/document/support-table-size-standards, last updated
October 25, 2023.
3. These categories are commonly associated with mines with activities involving crude petroleum or natural gas
extraction, but the mines in these categories that are counted here, and included in this analysis, also involve mining
operations that would fall under MSHA's jurisdiction. This analysis does not include crude petroleum or natural gas
extraction (and the mines that perform them exclusively) since MSHA does not regulate these activities.
BILLING CODE 4520–43–C
d. Reporting, Recordkeeping, and Other
Compliance Requirements of the Final
Rule
The final rule not only establishes a
PEL of 50 mg/m3 and an action level of
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25 mg/m3 for respirable crystalline silica,
but also includes provisions for
methods of compliance, exposure
monitoring, corrective actions,
respiratory protection, and medical
surveillance for MNM mines. Under the
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final rule, mine operators are required to
install, use, and maintain feasible
engineering and administrative controls
to keep each miner’s exposure to
respirable crystalline silica at or below
the PEL. Mine operators are required to
conduct sampling to assess miners’
exposure to respirable crystalline silica.
MNM operators are required to provide
to all miners, including those who are
new to the mining industry, periodic
medical examinations performed by a
PLHCP or specialist, at no cost to the
miner. This requirement will ensure
that MNM miners, like coal miners, are
able to monitor their health and detect
early signs of respiratory illness.
In addition, the final rule creates new
information collection requirements for
mine operators. As described in greater
detail in Section XI. Paperwork
Reduction Act, operators are required to
collect information involving: (1)
exposure monitoring, (2) corrective
actions, (3) respiratory protection, and
(4) medical surveillance for MNM
mines. (Table XI–1 in that section
displays an estimate of the annualized
information collection burden for the
whole mining industry.)
e. Steps the Agency Has Taken To
Minimize the Economic Impact on
Small Entities
In response to commenters who
expressed concerns that the rule would
lead to excessive demand and backlogs
for sampling devices, industrial
hygienists, labs, medical facilities, and
NIOSH B Readers, MSHA adjusted the
requirements in the final rule to provide
additional time for small-entity
controllers and other controllers, to
prepare for compliance (24 months after
publication of the final rule for MNM
mines and 12 months after publication
of the final rule for coal mines). MSHA
is allowing this longer period for
compliance because MNM operators,
particularly small-entity controllers,
may have less experience with sampling
and may also need time to prepare for
compliance with medical surveillance.
For coal mines, the delayed compliance
period gives operators sufficient time to
plan and prepare for effective
compliance with the new standards,
while also ensuring that improved
protections for miners from the hazards
of respirable crystalline silica take effect
as soon as practically possible. For
additional details on the compliance
dates, see Section VIII.B. Section-bySection Analysis.
MSHA will also provide compliance
assistance to small-entity controllers
and the mining community overall
(including industry and labor) after
publication of the final rule. This
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assistance will include guidance to
assist mine operators in developing and
implementing appropriate controls;
outreach seminars (onsite and virtual,
dates and locations will be posted on
MSHA’s website); dust control
workshops at the National Mine Health
and Safety Academy; support from the
Educational Field and Small Mine
Services staff; support from MSHA’s
Technical Support staff; silica training
and best practice materials; and
information on MSHA’s enforcement
efforts.
MSHA examined three possible
regulatory alternatives to this final rule
and considered how they could affect
small-entity controllers.
Under Regulatory Alternative 1, the
PEL would remain unchanged at 50 mg/
m3 and the action level would remain
unchanged at 25 mg/m3. Further, mine
operators would conduct: (1) first-time
and second-time sampling for miners
who may be exposed to respirable
crystalline silica at or above the action
level of 25 mg/m3, (2) periodic sampling
twice per year, and (3) an annual
evaluation of changing mining processes
or conditions that would reasonably be
expected to result in new or increased
respirable crystalline silica exposures.
Under Regulatory Alternative 2, the PEL
would be set at 25 mg/m3; mine
operators would install whatever
controls are necessary to meet the PEL;
and there would not be an action level.
Further, mine operators would (1) not
be required to conduct any sampling,
but they would be required to (2)
conduct periodic evaluations of
changing conditions and (3) sample as
frequently as necessary to determine the
adequacy of controls.
MSHA determined that the final rule
will provide improved health
protections for miners and will be
achievable for all mines, including those
that are owned and operated by small
entities. MSHA has made the following
determinations regarding the three
alternatives considered:
• Regulatory Alternative 1, ‘‘Changes
in Sampling and Evaluation
Requirements,’’ would reduce overall
costs to the mining industry by 26.9
percent for costs calculated at a 3
percent, and by 26.4 percent for costs
calculated at a 7 percent discount rate.
These reduced costs would be
proportionally experienced by small
entities. The average costs as a percent
of revenues for small entities would
then be reduced (relative to the final
rule) from 0.318 percent to 0.232
percent based on a 3 percent discount
rate, or to 0.234 percent based on a 7
percent discount rate.
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• Regulatory Alternative 2, ‘‘Changes
in Sampling and Evaluation
Requirements and the Proposed PEL,’’
would increase overall costs to the
mining industry by 484.8 percent for
costs calculated at a 3 percent discount
rate, and by 627.1 percent for costs
calculated at a 7 percent discount rate.
The average costs as a percent of
revenues for small entities would then
rise (relative to the final rule) from 0.318
percent to 1.859 percent based on a 3
percent discount rate, and from 0.318
percent to 2.31 percent based on a 7
percent discount rate.
• Regulatory Alternative 3, ‘‘Changes
in the Calculation of Exposure
Concentrations,’’ would change the
methodology used for calculating
exposures and assessing compliance to
a full shift TWA, rather than a full-shift
exposure, calculated as an 8-hour TWA.
MSHA estimated that this alternative
would decrease overall costs to the
mining industry by 3.02 percent for
costs calculated at a 3 percent discount
rate, and by 3.41 percent for costs
calculated at a 7 percent discount rate.
The average costs as a percent of
revenues for small entities would then
fall from 0.318 percent to 0.308 percent
based on a 3 percent discount rate, and
to 0.307 percent based on a 7 percent
discount rate.
Regulatory Alternative 1 would
reduce the costs to small entities.
However, the final rule will better
protect miners from exposures to
respirable crystalline silica. The final
rule’s exposure monitoring
requirements are necessary to ensure
that miners’ health is adequately
protected. MSHA determined that
Regulatory Alternative 1 would not
protect miners’ health. The final rule’s
exposure monitoring requirements,
including monitoring on a more
frequent basis, will provide mine
operators with greater confidence that
they are in compliance with the final
rule.
Regulatory Alternative 2 would
increase costs to small entities, making
it an unsuitable choice for small mines.
Additionally, this alternative would not
be achievable for all mines because a
PEL of 25 mg/m3, while technically
feasible, is not practical for all mines.
Regulatory Alternative 3 would
reduce the costs to small entities.
However, the final rule will better
protect miners by using an exposure
calculation method that recognizes the
importance of cumulative exposure to
respirable crystalline silica being an
important risk factor in the development
of silica-related disease. Regulatory
Alternative 3 does not take into account
the increased health risks associated
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with the higher cumulative exposures
that can occur during longer work shifts,
and, therefore, is less protective for
those miners who work longer shifts. A
more in-depth discussion of the costs
associated with each regulatory
alternative is presented in Section IX.
Summary of Final Regulatory Impact
Analysis and Regulatory Alternatives
and the standalone FRIA document.
D. Analysis of Small Business Impacts
1. Data and Methodology
a. Average Annual Cost per Small-Entity
Controller
Because the controllers vary in the
scale of their mining operations, MSHA
first estimated regulatory costs on a perminer basis. MSHA anticipated that the
regulatory costs per miner would vary
across the six major commodity
categories: coal, metal, nonmetal, stone,
crushed limestone, and sand and
gravel.107 The differences in regulatory
costs by commodity reflect the varying
levels of expected exposure to silica, as
calculated in the FRIA.
MSHA examined employment data
for each controller. By combining this
information with per-mine compliance
cost information, MSHA derived
estimates of the regulatory costs for each
of the 5,462 small-entity controllers
identified in 2021. See the average
annual regulatory cost per controller in
Table X–3.
The compliance burden on the
controllers, large and small, consists
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107 MSHA also anticipated that regulatory costs
would vary by the size of the mine in terms of the
number of miners, with the size categories of: (1)
20 or fewer miners, (2) 21–100 miners, (3) 101–500
miners, and (4) over 500 miners.
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primarily of the costs of additional dust
control measures, exposure monitoring,
medical surveillance for MNM mines,
and other program activities needed to
comply with the rule. For costs
estimates by component, by commodity,
and by mine size, please see Section 4
of the standalone FRIA document.
b. Average Annual Revenue per SmallEntity Controller
MSHA estimated revenues for each
small-entity controller. The Agency
estimated revenues per employee, by
mine, and by controller, using data
published by the U.S. Bureau of Census
in their report, ‘‘Statistics of U.S.
Businesses’’ (SUSB).108 The SUSB data
provided revenue estimates for
enterprises (mines) in each NAICS code
and for each ‘‘size category’’ (based on
number of employees) within each
NAICS code.109
108 U.S. Census Bureau, ‘‘Statistics of U.S.
Businesses,’’ released May 2021. https://
www.census.gov/data/tables/2017/econ/susb/2017susb-annual.html (last accessed Jan. 10, 2024). Data
in the report were in reference to the year 2017,
which MSHA adjusted to 2021 dollars. Data on
revenues are presented in the report under the
equivalent term ‘‘receipts.’’ MSHA converted the
2017 revenues to 2022 dollars using Price Indexes
for Gross Domestic Product, Bureau of Economic
Analysis, Table 1.1.4. https://apps.bea.gov/iTable/
?reqid=19&step=3&isuri=1&1910=x&0=-99&1921=
survey&1903=4&1904=2009&1905=2018&1906=
a&1911=0 (last accessed Jan. 10, 2024). The index
was 100 for 2017 and 117 for 2021, creating an
adjustment factor (from 2017 to 2022 dollars) of
1.118.
109 In a small number of cases (in terms of NAICS
codes and size categories) the SUSB data were
incomplete. In these cases, MSHA imputed
revenue/employee ratios based on closely related
data for comparable NAICS-size categories. MSHA
then used these imputed revenue/employee ratios
to estimate the revenues of some small-entity
controllers, by the methodology just described.
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Some of the small-entity controllers
have operations in non-mining
industries. Non-mining revenues are not
accounted for in this analysis, as the
data was not available. If non-mining
revenues were accounted for, the ratio
of regulatory costs to revenues shown in
the summary table would be even
smaller.
MSHA calculated the number of
mining employees for each small-entity
controller, and for each NAICS category
(for mining NAICS) within each
controller’s activities. MSHA then
combined these data with SUSB data on
revenues by NAICS category and size
category to generate estimated revenues
for each small-entity controller. See the
estimated average annual revenue per
controller in Table X–3.
c. Average of Cost as a Percent of
Revenue (Among Small-Entity
Controllers)
MSHA estimated the average annual
regulatory cost per small-entity
controller, as well as the average annual
revenue per small-entity controller.
MSHA estimated, for each controller,
the annual compliance cost of the final
rule as a proportion of that controller’s
annual revenue.
2. Economic Analysis Results
Based on the methodology described
above, MSHA generated estimates of the
ratios of regulatory compliance cost to
revenue for each controller. Table X–3
shows the number of controllers,
average annual regulatory costs, average
annual revenues, and average cost as a
percent of revenue.
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Table X-3: Annual Compliance Costs to Revenues for a Typical Small-Entity Controller
Average of
Cost as a
Percent of
Revenue
(Unweighted
Average of
the
Percentages
Among
Small-Entity
Controllers
with 5 or
Fewer
Employees)2
Number of
Controllers
Average
Annual
Regulatory
Cost Per
Small-Entity
Controller
(in 2022 $)
Average
Annual
Revenue
Per SmallEntity
Controller
(in 2022 $)
Average of
Cost as a
Percent of
Revenue
(Unweighted
Average of
the
Percentages
Among All
Small-Entity
Controllers)2
293
$9,542
$26,857,599
0.0710
0.066
5,169
$11,110
$5,461,261
0.332
0.307
5,462
$11,026
$6,609,033
0.318
0.299
Coal
SmallEntity
Controllers 1
MNM
SmallEntity
Controllers 1
Total
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MSHA estimated that the final rule
would have an average cost, per smallentity controller, of $11,026 per year in
2022 dollars. The estimated costs for the
final rule represent the costs necessary
for small-entity mine operators to
achieve full compliance with the final
rule.110
From the cost and revenue estimates
described above, MSHA estimated the
ratio of annual regulatory cost to annual
revenue for each small-entity controller.
As shown in Table X–3, the average of
these proportions (weighting controllers
equally) was 0.318 percent. In other
words, for every $1 million in revenue
110 MSHA estimated the costs of the rule for
small-entity controllers by summing the costs for
each of these controller’s mines. The estimated cost
for each mine was based on the number of miners
and the mine’s industry category. A controller’s
estimated cost was the sum of costs for each of its
mines. Similarly, the estimated revenues of a
controller was the sum of the revenues of each of
its mines.
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earned by a small-entity controller, the
average compliance cost was estimated
to be approximately $3,000. This
compliance cost-to-revenue ratio is
slightly lower for controllers with five
or fewer employees (0.299), implying
that the low compliance cost-to-revenue
ratios are generally applicable for the
smallest of the small-entity controllers.
The low cost-to-revenue ratio of these
controllers with five or fewer employees
is due largely to the estimated annual
revenues of these controllers averaging
above $1 million in 2022 dollars, in
comparison to their estimated
compliance costs averaging
approximately $3,000 per year.
MSHA believes that the Agency could
certify the economic impact of this final
rule on small entities, however, in the
interest of public disclosure and
transparency, the Agency prepared a
full analysis to inform the public of its
decision-making process.
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XI. Paperwork Reduction Act
The Paperwork Reduction Act of 1995
(44 U.S.C. 3501–3521) provides for the
Federal Government’s collection, use,
and dissemination of information. The
goals of the Paperwork Reduction Act
include minimizing paperwork and
reporting burdens and ensuring the
maximum possible utility from the
information that is collected under 5
CFR part 1320. The Paperwork
Reduction Act requires Federal agencies
to obtain approval from the Office of
Management and Budget (OMB) before
requesting or requiring ‘‘a collection of
information’’ from the public.
As part of the Paperwork Reduction
Act process, agencies are generally
required to provide a notice in the
Federal Register concerning each
proposed collection of information to
solicit, among other things, comment on
the necessity of the information
collection and its estimated burden, as
required in 44 U.S.C. 3506(c)(2)(A). To
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1. If a controller has both coal and MNM mines, the controller is categorized based on the NAICS code with the
most employees.
2. Note that because the column displays the unweighted average of the controller-level percentages across all
controllers, it is not equivalent to the ratio of the average cost among all controllers and the average revenue among
all controllers in the previous two columns.
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comply with this requirement, MSHA
published a notice of proposed
collection of information in the
Agency’s notice of proposed rulemaking
on July 13, 2023 (88 FR 44852). MSHA
solicited comment on the proposed
information collection requirements and
provided an opportunity for comments
to be sent directly to OMB. MSHA also
prepared and submitted an information
collection request (ICR) to OMB for the
collection of information requirements
identified in the proposal for OMB’s
review in accordance with 44 U.S.C.
3507(d).
MSHA has made several additions
and changes to the proposed rule and
methodology that have paperwork
burden implications. Key additions
include the immediate reporting of
samples over the PEL to MSHA,
reporting chest X-ray classification
results to NIOSH, as well as a written
respiratory protection program
consistent with the requirements of
ASTM F3387–19. Key changes include
certain compliance dates, sampling
requirements, medical examination
dates for current miners, as well as the
frequency of periodic evaluations and
post-evaluation recordkeeping. Each
addition and change and reasons for
each are discussed in detail in Section
VIII.B. Section-by-Section Analysis. The
Agency has also changed the
compliance dates from the proposed
rule to provide mine operators adequate
preparation time to comply effectively
with the final rule’s requirements.
A. Responses to Comments
MSHA sought comment on the utility
of the recordkeeping requirements in
part 60. MSHA received multiple
comments on the proposed
recordkeeping requirements, with
several commenters supporting MSHA’s
proposed recordkeeping provisions or
recommending that records have a
longer retention period than proposed.
None of the comments addressed the
methodology, assumptions, or
calculations made in the Paperwork
Reduction Act portion of the proposal.
This section presents a summary of
the comments received and the
Agency’s responses. Section VIII.B.9.
Section 60.16—Recordkeeping
Requirements provides a more detailed
summary of the comments related to
recordkeeping and MSHA’s responses.
The NSSGA stated that MSHA should
adopt the same rule as the Occupational
Safety and Health Administration’s
(OSHA) 2016 Silica Rule since some
companies have OSHA and MSHA
regulated facilities (Document ID 1448).
This commenter stated that MSHA’s
silica rule with different requirements
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than OSHA creates excessive,
unnecessary paperwork for these
companies.
The Agency clarifies that the Mine
Act gives MSHA jurisdiction over each
MNM or coal mine and each operator of
such mine. The mining industry is
different from the industries that are
subject to OSHA’s standards. MSHA did
consider and adopt, as appropriate,
some of OSHA’s regulatory approach to
controlling workers’ exposures to
respirable crystalline silica in
developing its final rule. This final rule
will better protect miners against
occupational exposure to respirable
crystalline silica, a carcinogenic hazard,
and improve respiratory protection for
airborne contaminants miners
encounter. Nonetheless, the Agency has
developed the rule’s paperwork
requirements to minimize burden on
mine operators.
For records retained under proposed
paragraphs 60.16(a)(1) through (3)—
evaluation records, sampling records,
and corrective action records,
respectively—many commenters,
including labor organizations, advocacy
organizations, and a MNM mine
operator, recommended that record
retention periods should be extended
beyond the proposed requirements,
especially for MNM mines (Document
ID 1416; 1417; 1425; 1439; 1447; 1449).
A miner health advocate recommended
that sampling records under
§ 60.16(a)(2) be preserved for as long as
the mine is in operation instead of the
2-year proposed requirement (Document
ID 1372). Additionally, Appalachian
Voices recommended that the records
under § 60.16(a)(2) should be retained
for longer than the life of the mine
operation (Document ID 1425).
In response to comments requesting
an increase in the record retention
period, in the final rule, MSHA
increases the record retention period for
evaluation, sampling, and corrective
actions records in paragraphs (a)(1) to
(3) to at least 5 years. The 5-year record
retention period for evaluation,
sampling, and corrective actions records
is consistent with the 5-year record
retention period for operator samples
collected while monitoring for airborne
exposure to diesel particulate matter in
underground metal and nonmetal mines
(§ 57.5071(d)(2)) and other injury and
illness reports required under section
50.40. MSHA concludes in this final
rule that a 5-year retention period for
the records retained under paragraphs
§ 60.16(a)(1) through (3) is effective in
providing information for the protection
of miners. This is because the
evaluation, § 60.16(a)(1), and sampling,
§ 60.16(a)(2), records can identify a
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change in operation that might lead to
increased exposures to respirable
crystalline silica. Similarly, the 5-year
recordkeeping requirement for
corrective action records under
§ 60.16(a)(3) is intended to help the
operator and MSHA identify the
effectiveness of existing controls, or the
need for maintenance or additional
control measures. In MSHA’s
experience, recent records can more
effectively assist MSHA and mine
operators in achieving these goals.
MSHA believes the 5-year retention
period achieves the proper balance
between the operator’s burden to
maintain records and the effective
utility of older records to mine
operators, miners, and MSHA.
For records retained under proposed
paragraphs § 60.16(a)(4) and (5)—
written determination and medical
opinion records, respectively, received
from a PLHCP or specialist—some
commenters such as a medical
professional organization, a public
health advocacy organization, and labor
unions also suggested an increased
retention period to help miners
diagnosed with silica-related health
conditions request workers’
compensation claims (Document ID
1416; 1425; 1373; 1437; 1412; 1398;
1447). A labor union recommended that
medical surveillance data collected by
mine operators should be kept for the
duration of a miner’s employment plus
20 or 30 years and for the records to be
provided to the miner upon termination
of employment (Document ID 1398).
MSHA concludes in this final rule that
it is appropriate to retain determination
and medical opinion records, which
have very limited medical information
only relevant to the miner’s ability to
wear a respirator, for the duration of the
miner’s employment plus 6 months
because the miner may need to wear a
respirator at some point without notice.
The requirement to retain records for an
additional 6 months beyond the miner’s
employment gives miners more time to
request records once they terminate
their employment at the mine.
A commenter (NVMA) asked for
clarification on the medical surveillance
recordkeeping requirements, stating that
the rule does not include provisions
requiring tracking of miners’ silica
exposure throughout their careers and
noting that miners often change
companies over the course of their
careers (Document ID 1441). MSHA
clarifies that mine operators do not have
access to a miner’s medical information
and, therefore, do not maintain a record
of such information. Instead, the mine
operator will retain a record of the date
of the medical examination, a statement
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that the examination has met the
requirements of this section, and any
recommended limitations on the
miner’s use of respirators. Each miner,
or the miner’s physician or other
designee at the request of the miner,
will have access to all medical
examination results.
Two commenters including a labor
union also suggested that corrective
action records and cumulative exposure
records be submitted to MSHA, miner
representatives, or miners (Document ID
1447; 1439). After considering the
comments, MSHA determined that it is
not necessary to change the requirement
of providing all the listed records
promptly upon request to miners,
authorized representatives of miners,
and authorized representatives of the
Secretary of Labor. This is because the
requirement to provide all the listed
records promptly upon request ensures
that miners and MSHA will have access
to records as needed can facilitate
enforcement and transparency. Because
miners, miners’ representatives, and
MSHA can request the records at any
time for their own recordkeeping
purposes, MSHA does not believe it is
necessary to have operators submit the
records to miners and MSHA without
request. However, in response to
comments, the final rule requires mine
operators to immediately report all
exposures above the PEL from operator
sampling to the MSHA District Manager
or to any other MSHA office designated
by the District Manager. This
modification will allow the Agency to
promptly address overexposures as
appropriate. As discussed below, this
change from the proposal presents a
modest increase in the estimated
paperwork burden.
The final rule requires a new
information collection as well as
modifications to existing collections. As
required by the Paperwork Reduction
Act, the Department has submitted
information collections, including a
new information collection and
revisions of two existing collections, to
OMB for review to reflect new burdens
and changes to existing burdens. Once
OMB completes its review, the Agency
will publish a notice on the new
information collection under OMB
Control Number 1219–0156. (The
regulated community is not required to
respond to any collection of information
unless it displays a current, valid, OMB
Control Number.)
B. New Information Collection Under
Part 60, Respirable Crystalline Silica
Under final part 60, certain new
burdens apply to all mine operators, and
other burdens apply to only some mine
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operators. Section 60.16 lists all the
recordkeeping requirements related to
part 60. Each of the requirements are
discussed below:
Section 60.12 requires mine operators
to make a record for each sampling and
each periodic evaluation conducted
pursuant to the section. The samplings
identified in § 60.12(a) include:
sampling by the compliance date
(§ 60.12(a)(1)), an additional sampling
(§ 60.12(a)(2)), above-action-levelsampling (§ 60.12(a)(3)), corrective
actions sampling (§ 60.12(b)), and postevaluation sampling (§ 60.12(d)). The
sampling record consists of the
sampling date, the occupations
sampled, and the concentrations of
respirable crystalline silica and
respirable dust, and the mine operator
must also retain laboratory reports on
sampling results under § 60.12(g).
In a change from the proposal, under
final § 60.12(c), the periodic evaluations
must be conducted at least every 6
months or whenever there is a change
in: production; processes; installation
and maintenance of engineering
controls; installation and maintenance
of equipment; administrative controls;
or geological conditions; mine operators
shall evaluate whether the change may
reasonably be expected to result in new
or increased respirable crystalline silica
exposures. The periodic evaluation
record includes the evaluated change,
the impact on respirable crystalline
silica exposure, and the date of the
evaluation under § 60.12(c)(1). In
addition, the mine operator is required
to post the sampling and evaluation
records and the laboratory report on the
mine bulletin board and, if applicable,
by electronic means, for 31 days, upon
receipt under § 60.12(c)(2).
The mine operator must immediately
report all exposures above the PEL to
the MSHA District Manager or to any
other MSHA office designated by the
District Manager under § 60.12(b). A
corrective action must be taken
immediately to lower the concentration
of respirable crystalline silica to at or
below the PEL, once a sample reporting
exposure above the PEL is recorded. The
corrective actions record must include
the corrective actions taken, including
any related respirator use by affected
miners, and the dates of the corrective
actions under § 60.13(c). All records
must be retained for at least 5 years from
the date of each sampling, evaluation, or
corrective action.
Section 60.14(b) requires mine
operators to temporarily transfer a miner
either to work in a separate area of the
same mine or to an occupation at the
same mine where respiratory protection
is not required if the miner has a written
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determination from the PLHCP that the
miner is unable to wear a respirator.
Section 60.16(a)(4) requires the written
determination record to be retained for
the duration of a miner’s employment
plus 6 months. In a change from the
proposal, final § 60.14(c)(2) requires
mine operators to have a written
respiratory protection program that
meets the following requirements in
accordance with ASTM F3387–19:
program administration; written
standard operating procedures; medical
evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage.
Section 60.15 requires MNM mine
operators to provide miners periodic
medical examinations at no cost to the
miner. Section 60.15(d)(1) requires the
mine operator to ensure that the results
of medical examinations or tests are
provided from the PLHCP or specialist
to the miner within 30 days of the
medical examination, and, at the request
of the miner, to the miner’s designated
physician or another designee identified
by the miner. Section 60.15(d)(2)
requires MNM mine operators to ensure
that, within 30 days of the medical
examination, the PLHCP or specialist
provides the results of chest X-ray
classifications to the National Institute
for Occupational Safety and Health
(NIOSH), once NIOSH establishes a
reporting system. Mine operators are
required to obtain a written medical
opinion from the PLHCP or specialist
within 30 days of a miner’s medical
examination. The written medical
opinion must contain only the date of
the medical examination, a statement
that the examination has met the
requirements of the section, and any
recommended limitations on the
miner’s use of respirators under
§ 60.15(e). The written medical opinion
record must be retained by MNM mine
operators for the duration of a miner’s
employment plus 6 months under
§ 60.15(f).
C. Existing Information Collections
The final rule results in changes to
two existing information collection
packages: a non-substantive change to
information collection package under
OMB Control Number 1219–0011,
Respirable Coal Mine Dust Sampling;
and a substantive change to information
collection package under OMB Control
Number 1219–0048, Respirator Program
Records. This is a change from the
proposal, which only contained nonsubstantive changes to existing
information collections.
Non-substantive changes to OMB
Control Number 1219–0011 involve
references to respirable dust when
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quartz is present in the respirable coal
mine dust standard. OMB Control
Number 1219–0011 involves records for
quarterly sampling of respirable dust in
coal mines. MSHA’s standards require
that coal mine operators sample
respirable coal mine dust quarterly and
submit these samples to MSHA for
analysis to determine if the mine is
complying with the respirable coal mine
dust standards. The supporting
statement references quartz and a
reduced standard for respirable dust
when quartz is present. Since the final
rule eliminates the reduced standard
and establishes a separate standard for
respirable crystalline silica, MSHA will
make a non-substantive change to the
supporting statement by removing such
references. However, there will be no
changes from the proposal in paperwork
burden and costs in this information
collection because the change only
contains non-substantive changes to
existing information collections.
OMB Control Number 1219–0048
involves recordkeeping requirements
under 30 CFR parts 56 and 57 for MNM
mines when respiratory protection is
used. Under the final rule, MSHA
updates the existing respiratory
protection standard and requires a
written respiratory protection program
that meets the following requirements in
accordance with ASTM F3387–19:
program administration; written
standard operating procedures; medical
evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage. This substantive change will
result in an increase in the paperwork
burden and costs associated with
respiratory protection in the existing
information collection.
D. Information Collection Requirements
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1. New Information Collection 1219–
0156
Type of Review: New Collection.
OMB Control Number: 1219–0156.
Title: Respirable Crystalline Silica
Standard.
Description of the ICR: The final rule
on respirable crystalline silica contains
information collection requirements on
sampling, periodic evaluations, medical
examinations, and respirator protection
practices. The collected information
will assist miners and mine operators in
tracking actual and potential miners’
occupational exposure to respirable
crystalline silica, and identifying
possible actions taken to control such
exposure.
There are provisions of this rule that
will take effect at different times after
the date of publication of this rule, and
there are information collection
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provisions that will have different
respondents, responses, burden hours,
and costs in each year. Therefore, this
ICR estimates the first 3 years of
compliance.
There were changes in this ICR
between the proposed and final rule
based on changes in methodology and
the rule text. Based on changes to § 60.1
in the final rule, MNM mines are not
expected to begin implementing the rule
until year 2. This change decreases the
recordkeeping burden for all cost items
in the final rule. In the proposed rule,
operators were allowed to use historical
and objective data instead of a secondtime sampling. In the final rule, every
mine is required to conduct a first-time
and second-time sampling, thereby
increasing the related time burden. The
methodology for calculating corrective
actions samples and post-evaluation
samples was also changed, leading to an
increased time burden for both.
Additionally, based on changes to
§ 60.12(b) in the final rule, operators are
now required to notify MSHA after
every overexposure.
The inclusion of ASTM F3387–19
costs in this ICR was a result of a change
in the rule text between the proposed
rule and final rule. In the proposed rule,
operators could choose which ASTM
F3387–19 elements to adopt. In the final
rule, mine operators must have a written
respiratory protection program that
meets an explicit set of requirements in
accordance with ASTM F3387–19. This
change leads to a substantial increase in
the recordkeeping burden for this ICR.
Lastly, the addition of § 60.15(d)(2) in
the final rule, which requires the mine
operator to ensure that a miner’s PLHCP
or specialist provides the results of
chest X-ray classifications to the
National Institute for Occupational
Safety and Health (NIOSH), created a
new recordkeeper cost.
Summary of the Collection of
Information
Highlighted below are the key
assumptions, by provision, used in the
burden estimates in Table XI–1:
a. Section 60.12—Exposure Monitoring
ICR. Section 60.12 requires mine
operators to make a record for each
sampling, corrective actions sampling,
periodic evaluation, and post-evaluation
sampling. Per § 60.1, the compliance
date for MNM mines begins one year
after the compliance date for coal mines.
Number of respondents. For § 60.12,
the respondents consist of all active
mines, because operators of active
mines are assumed to perform sampling
and conduct periodic evaluations.
MSHA counts the number of active
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mines in 2019, defining an active mine
as one that had at least 520 employment
hours (equivalent to 1 person working
full time for a quarter of a year) in at
least one quarter of 2019. Using this
definition, MSHA estimates that a total
of 12,631 mines (11,525 MNM mines
and 1,106 coal mines) will generate
sampling and evaluation records.
Annual number of responses. Annual
responses are summed from several
separate activities including: all types of
sampling (e.g., the first-time/secondtime sampling, above-action-level
sampling, corrective actions sampling,
and post-evaluation sampling), and
periodic evaluations. The estimated
average annual number of responses is
199,817, including 52,587 first-time and
second-time samples (the first sample is
taken by the compliance date or within
6 months after beginning operations and
the second-time sample is taken within
3 months after the first sample), 44,253
above-action-level samples, 50,834
corrective action samples and MSHA
notifications, 12,766 post-evaluation
samples, and 39,377 periodic evaluation
recordings and postings. Details of each
type of sampling and periodic
evaluations are discussed below.
First-time sampling and second-time
sampling apply to every coal and MNM
mine. However, a certain number of
mines are predicted to be able to
discontinue sampling if the results of
these samples are below the action
level. Furthermore, subsequent to Year
1 for Coal, and Year 2 for MNM, all firsttime and second-time sampling will
only be performed by new mines.
MSHA projects that about 2 percent of
mines in any given year will be new
entrants to the mining industry. MSHA
assumes that all active coal mines (1,106
mines) will conduct first-time and
second-time sampling in year 1 of
compliance (producing 29,796 samples).
In years 2 and 3, an estimated 22 new
coal mines will conduct first-time and
second-time sampling (producing 596
samples each year). Similarly, MSHA
assumes that all 11,525 MNM mines
will conduct first-time and second-time
sampling in year 2 of compliance
(producing 124,288 samples). In year 3,
231 new MNM mines will conduct firsttime and second-time sampling
(producing 2,486 samples). MSHA
estimates that an annual average of
52,587 first-time and second-time
samples will be collected in the first 3
years of compliance.
The estimated number of aboveaction-level sampling is calculated
based on the following factors: the
number of miners with sampling results
at or above the action level (25 mg/m3)
but at or below the permissible exposure
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limit (PEL) (50 mg/m3), the percent of
miners needed for representative
samples, and the number of quarters in
a year that mines will be in operation.
Estimation of above-action-level
sampling does not include costs related
to first-time sampling and second-time
sampling. MSHA has revised its
methodology from the proposal,
increasing the number of corrective
actions samples to account for some
operators needing multiple corrective
actions samples before obtaining a
sample below the PEL. The estimated
number of samples is based only on
previous operator samples, not ones
from MSHA inspectors. MSHA does not
expect above-action-level sampling to
begin until the second half of year 1 for
coal mines. MSHA estimates there will
be 5,423 above-action-level coal samples
in the second half of year 1. Due to the
projected decrease in the share of
samples over the action level for coal
mine compliance due to more mines
engaging in increased administrative
controls and frequent maintenance and
repair, the number of above-action-level
coal samples is projected to decrease to
10,556 in year 2 and 10,170 in year 3.
A more detailed discussion is provided
in Section 4.2 of the standalone FRIA
document. MSHA expects above-actionlevel sampling to begin in the second
half of year 2 for MNM mines, resulting
in the number of above-action-leveling
samples increasing from 37,719 in the
second half of year 2 to 68,892 in all of
year 3. Consequently, MSHA estimates
that an annual average of 44,253 aboveaction-level samples will be collected
from coal and MNM mines in the first
3 years of compliance.
MSHA estimates that an annual
average of 731 active mines (604 MNM
and 127 coal) will carry out an annual
average of 25,417 corrective actions
(22,152 MNM and 3,265 coal) due to
overexposure, and these mines will then
conduct corrective actions sampling for
each corrective action. Miner operators
will have to immediately notify MSHA
about each overexposure. MSHA
estimates that an annual average of
25,417 corrective action notifications
will be sent to MSHA.
Next, MSHA assumes that all 1,106
coal mines will record periodic
evaluation results approximately 2.4
times, on average, per year, and then
post those results on a mine bulletin
board, or if applicable, by electronic
means. In a change from the proposal,
MSHA increased its estimate for the
number of periodic evaluations from
about 2 per year to about 2.4 per year,
a 20 percent increase. This was done for
two reasons. First, § 60.12(c) now
requires periodic evaluations at least
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every 6 months after commencing
sampling or whenever there is a change
in production; processes; installation or
maintenance of engineering controls;
installation or maintenance of
equipment; administrative controls; or
geological conditions. Second, MSHA
now accounts for portable mines, which
move frequently and are therefore more
likely to experience one of the changes
noted in § 60.12(c). A more thorough
explanation for this calculation can be
found in Section 4.2 of the standalone
FRIA document.
The number of records for periodic
evaluation in coal mines is 2,449 each
year. All 11,525 MNM mines will record
periodic evaluation results
approximately 2.4 times, on average, a
year, and then post those results on a
mine bulletin board, or if applicable, by
electronic means, starting in year 2. The
number of records for periodic
evaluation in MNM mines is 0 for year
1, and 25,859 for years 2 and 3. Mine
operators will also post results of each
periodic evaluation on mine bulletin
boards, creating an annual average of
19,688 records (2,449 in year 1, 28,308
in year 2, and 28,308 in year 3).
Additionally, MSHA estimates mines
will conduct post-evaluation sampling
as a result of their periodic evaluations,
resulting in an annual average of 12,766
sampling records (8,376 for MNM mines
and 4,390 for coal mines). MSHA
estimates an annual average of 39,377
periodic evaluation recordings and
postings and 12,766 post-evaluation
samples.
The assumption for calculating
corrective actions samples and postevaluation samples was changed from
the proposal. In the proposed rule, the
number of corrective actions samples
was combined with the number of postevaluation samples and their sum was
assumed to be equivalent to a constant
2.5 percent of all miners per periodic
evaluation. In the final rule, the number
of corrective actions samples is based on
the projected share of samples over the
PEL, increased by 25 percent to account
for some operators needing multiple
samples before obtaining a sample
below the PEL, while the number of
post-evaluation samples alone is now
equivalent to 2.5 percent of miners per
periodic evaluation. The change in
methodology is intended to made
estimates more consistent with existing
sampling data. In year 1 for coal mines
and year 2 for MNM mines, they will
sample for only half a year. See Section
4.2 of the standalone FRIA document for
more details.
Estimated annual burden. The
estimated average annual burden is
41,781 hours, including 13,147 hours
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for first-time and second-time sampling,
11,063 hours for above-action-level
sampling, 8,472 for corrective actions
sampling, 5,907 hours for periodic
evaluations recording and posting, and
3,192 hours for post-evaluation
sampling.
MSHA estimates that it takes 15
minutes to record the sampling results,
15 minutes to record the results of a
periodic evaluation, 5 minutes to notify
MSHA after an overexposure, and 3
minutes to post each of the evaluation
results on the mine bulletin board, and,
if applicable, by electronic means.
b. Section 60.13—Corrective Actions
ICR. Section 60.13 requires mine
operators to make approved respirators
available to affected miners and
immediately take corrective actions to
lower the concentration of respirable
crystalline silica to at or below the PEL
if any sampling indicates overexposure.
Once corrective actions are taken, the
mine operator is expected to make a
record of corrective actions. As per
§ 60.1, the compliance date for MNM
mines begins one year after the
compliance date for coal mines. Based
on changes to MSHA’s methodology,
there is no longer a separate paperwork
burden related to respirator records. In
the proposal, MSHA estimated an
annual average of 5,685 records of
miners who are provided respirator
until corrective actions are complete. In
the final rule, MSHA does not treat the
paperwork burden of respirator records
as a separate cost. Instead, it is assumed
to be part of the corrective action
records. Hence, the paperwork burden
of respirator records is not a separate
cost.
Number of respondents. For § 60.13,
only those mines with at least one miner
exposure above the PEL are assumed to
carry out the requirement. MSHA
estimates that an annual average of 731
active mines (604 MNM mines and 127
coal mines) will require corrective
actions, starting in the second half of
year 1 for coal mines and second half of
year 2 for MNM mines. This change
from the proposed rule is based on
MSHA’s new methodology for
calculating corrective actions samples,
which required updating corrective
actions calculations to be consistent
with that methodology. In the proposal,
corrective actions samples were
combined with post-evaluation samples,
accounting for 2.5 percent of all miners
per periodic evaluation. The number of
respondents was assumed to be onefourth of the number of responses for
each full year of sampling. In the final
rule, the overexposure rate is expected
to decrease linearly in the first several
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years after the start of implementation of
the rule. As a result, the number of
corrective actions respondents is
assumed to start with the current
number of operators with an
overexposure in their last sampling
event from an MSHA inspector (as of
2019 for MNM mines and 2021 for coal
mines) and falls each year based on the
decreasing overexposure rate in each
year. Additionally, some operators are
expected to need multiple corrective
actions before they carry out a sample
below the PEL, thereby increasing the
number of corrective actions by 25
percent.
Annual number of responses. The
estimated average annual number of
responses is 25,417 (22,152 MNM and
3,265 coal). MSHA assumes that each
corrective actions sample, whose
calculations are described above and in
Section 4.2 of the standalone FRIA
document, will be preceded by a
corrective action, resulting in 25,417
corrective action records.
Estimated annual burden. The
estimated average annual burden is
2,118 hours. MSHA estimates that on
average it takes 5 minutes to record a
corrective action and the date.
c. Section 60.14—Respiratory Protection
ICR. Section 60.14(b) requires mine
operators to temporarily transfer a miner
when the miner has a written
determination from the PLHCP that the
miner is unable to wear a respirator.
Section 60.14(a) requires the temporary
use of respirators in MNM mines under
conditions specified in §§ 60.14(a)(1)
and 60.14(a)(2). The written
determination record must be retained
for the duration of a miner’s
employment plus 6 months under
§ 60.16(a)(4). Section 60.14(c)(2)
requires mine operators to have a
written respiratory protection program
that meets the following requirements in
accordance with ASTM F3387–19:
program administration; written
standard operating procedures; medical
evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage, which is incorporated by
reference in the final rule. As per § 60.1,
the compliance date for MNM mines is
one year after the compliance date for
coal mines.
Number of respondents. For
§ 60.14(b), MSHA assumes that each
mine taking a corrective action (an
annual average of 604 MNM mines and
127 coal mines) will have one miner
unable to wear a respirator. MSHA
estimates that an additional 10 percent
of MNM mines, which temporarily use
respirators, will also have one miner
unable to wear a respirator in years 2
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and 3 (an annual average of 769 mines).
Consequently, MSHA estimates that an
annual average of 1,500 (1,373 MNM
and 127 coal) mines will have a miner
unable to wear a respirator.
This is a change from the proposal,
where MSHA assumed that 1⁄3 of mine
operators affected by respiratory
protection requirements would have
their miners wear respiratory protection
in year 1 and 10 percent of the same
mine operators would have their miners
wear respiratory protection in years 2
and 3. This change is a result of MSHA
updating its methodology to be
consistent with the final rule
requirements.
For the ASTM F3387–19
incorporation by reference under
§ 60.14(c)(2), MSHA assumes, to err on
the side of overestimation, that a total of
3,411 mine respondents (2,305 MNM
mines and 1,106 coal mines) would
have respiratory protection programs.
MSHA assumes that a half of the coal
mines (553 mines) would write new
standard operating procedures (SOPs)
relating to the respiratory protection
program and the remaining half (533
mines) would revise existing SOPs in
year 1. New coal mines, estimated at 2
percent (22 mines), are assumed to write
respiratory protection SOPs in years 2
and 3. Similarly, for MNM mines,
MSHA assumes that: a half of them
(1,153 mines) would write new SOPs
relating to the respiratory protection
program; the remaining half (1,152
mines) would revise existing SOPs in
year 2; and approximately 46 new MNM
mines to write respiratory protection
SOPs in year 3.
The inclusion of ASTM F3387–19
costs in this ICR is a result of a change
between the proposed rule and final
rule. In the proposed rule, operators
could choose which ASTM F3387–19
elements to adopt. In the final rule,
mine operators must have a written
respiratory protection program that
meets the following requirements in
accordance with ASTM F3387–19:
program administration; written
standard operating procedures; medical
evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage. MSHA estimates that 3,411
mines will be affected by respiratory
protection requirements, an annual
average of 599 existing mines will have
to write new respiratory protection
SOPs, and an annual average of 569
mines will have to revise existing SOPs
each year.
Annual number of responses. The
estimated average annual number of
responses is 5,310, including 1,500 for
records relating to miners’ inability to
wear respirators (§ 60.14(b)) and 3,810
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for respiratory protection requirements
of writing and updating SOPs (§ 60.14
(c)(2)). MSHA estimates that the annual
average of 1,500 mines that will need
records of miners’ inability to wear
respirators will each have one miner
requiring such record, totaling 1,500
records per year (§ 60.14(b)). The annual
3,810 responses concerning § 60.14
(c)(2) are estimated in the following.
First, MSHA assumes that
approximately half of the 3,411 existing
mine operators affected by respiratory
protection requirements, as well as all
new mines affected by these
requirements, will have to write new
respiratory protection SOPs, resulting
an annual average of 599 new written
SOPs (553 in year 1, 1,175 in year 2, and
68 in year 3). Second, MSHA makes a
similar assumption that the other half of
mines affected by respiratory protection
requirements will have to revise existing
ones, generating an annual average of
569 revised SOPs. Together, there will
be a total of 1,168 records of new (599)
and revised (569) SOPs per year.
Finally, based on ASTM F3387–19
guidelines adopted in § 60.14(c)(2) of
this rule, MSHA determines that
existing and new mine operators will
keep records of the new and revised
SOPs, which results in an annual
average of 2,642 records in total.
Estimated annual burden. The
estimated annual burden is 11,333
hours, including 750 for records relating
to miners’ inability to wear respirators
and 10,583 for the ASTM F3387–19
incorporation by reference. MSHA
assumes it takes 30 minutes to
determine and record where a miner
unable to wear a respirator can be
temporarily transferred either to work in
a separate area of the same mine or to
an occupation at the same mine where
respiratory protection is not required.
This will impact one miner in each of
the 1,500 affected mines. MSHA
estimates that, on average, it takes 4
hours for mine operators to write
respiratory protection program SOPs
and 1 hour to revise existing respiratory
protection program SOPs. For coal
mines, MSHA estimates that it takes 4
hours in year 1 and 2 hours in years 2
and 3 to carry out recordkeeping
relating to the respiratory protection
program SOPs. For MNM mines, MSHA
estimates that it takes 4 hours in year 2
and 2 hours in year 3 to perform the
same tasks.
d. Section 60.15—Medical Surveillance
for Metal and Nonmetal Mines
ICR. Section 60.15 requires MNM
mine operators to ensure that the results
of medical examinations or tests will be
provided from the PLHCP or specialist
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within 30 days of the medical
examination to the miner, and at the
request of the miner, to the miner’s
designated physician or another
designee identified by the miner. MNM
mine operators also must ensure that
within 30 days of the medical
examination, the PLHCP or specialist
provides the results of chest X-ray
classifications to NIOSH, once NIOSH
establishes a reporting system
[§ 60.15(d)(2)].
Also, MNM mine operators must
obtain a written medical opinion from a
PLHCP or specialist regarding any
recommended limitations on a miner’s
use of respirators under § 60.15(e). The
written medical opinion must contain
the date of the medical examination, a
statement that the examination has met
the requirements of the section, and any
recommended limitations on the
miner’s use of respirators. The written
medical opinion record must be
retained by MNM mine operators for the
duration of a miner’s employment plus
6 months under § 60.16(a)(5).
As per § 60.1, the compliance date for
MNM mines begins one year after the
compliance date for coal mines.
Number of respondents. Due to
uncertainty regarding participation of
currently employed miners, including
contract workers, in medical
surveillance programs, MSHA
considered two rates (25 percent and 75
percent) when estimating medical
surveillance costs. To be consistent with
FRIA estimates, the values presented
here are the average number of MNM
miners between the assumed
participation rates of 25 percent and 75
percent. Furthermore, MSHA expects
that 50 percent of current miners will
obtain their voluntary medical
examinations in year 2, as that is when
the compliance period begins for MNM
mines. Given that the examinations for
current miners do not need to be
repeated until 5 years later there is no
cost burden associated with this cost
item in year 3. As a result, an average
of 29,371 current MNM miners are
estimated to receive voluntary medical
examinations per year (0 in year 1,
88,112 in year 2, 0 in year 3).
MSHA further estimates that 8,392
miners each year, including contract
workers, are new miners and contractors
working in MNM mines and receive
mandatory medical examinations.
28411
MSHA estimates that the turnover of
MNM miners will be 8,392 miners per
year, starting from year 2 (1/22 of the
estimated total of 184,615 MNM
workers, with an average number of 22
years on the job before leaving the
mining industry). This results in an
annual average of 5,595 MNM miners
receiving mandatory medical
examinations (0 in year 1, 8,392 in years
2 and 3). The estimated total
respondents per year therefore will be
34,965 (= 29,371 current miners × 5,595
new miners).
Annual number of responses. The
estimated annual number of responses
is 34,965, including 5,595 medical
opinion records for new miners and
29,371 records for current miners.
Estimated annual burden. The
estimated annual burden is 8,741 hours,
including 1,399 hours for new MNM
miners and 7,343 hours for current
MNM miners. MSHA estimates it will
take 15 minutes to record the medical
examination results for each of the
34,965 miners.
Total Recordkeeping Burden for Part 60
Total recordkeeping burden for Part
60 is summarized in Table XI–1.
Table XI-1: Estimated Average Annual Recordkeeping Burden for Part 60
Annual
Number of
Respondents
Rule Provision
§ 60.12 - Exposure Monitoring
§ 60.13 - Corrective Actions
§ 60.14 - Respiratory Protection
§ 60.15 - Medical surveillance for
MNMminers
Annual Recordkeeping Total
Annual
Number of
Responses
Estimated
Annual
Burden
(Hours)
41,781
12,631
731
2,643
199,817
25,417
5,310
2,118
11,333
34,965
34,965
8,741
47,596
265,509
63,972
Note:
The total annual number of
respondents is 47,596; the total annual
number of responses will be 265,509;
and the estimated annual burden will be
63,972 hours.
The following estimates of
information collection burden are
summarized in Table XI–2.
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Affected Public: Businesses or ForProfit.
Estimated Number of Respondents:
1,106 respondents in year 1; 109,135
respondents in the year 2; and 21,023
respondents in year 3.
Frequency: On Occasion.
Estimated Number of Responses:
52,821 responses in year 1; 433,240
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responses in year 2; and 310,467
responses in year 3.
Estimated Number of Burden Hours:
18,720 hours in year 1; 109,983 hours in
year 2; and 63,215 hours in year 3.
Estimated Hour Burden Costs:
$1,260,819 in year 1; $7,704,098 in year
2; and $4,238,135 in year 3.
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ER18AP24.196
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The total number of respondents is not a sum of respondents from each sub-category. The respondents
(mine operators) carrying out corrective actions and adhering to respiratory protection program
requirements are a subset of the respondents carrying out exposure monitoring.
The responses and burden hours column totals might not add up to the sum of the items in each column
due to rounding.
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Estimated Capital Costs to
Respondents: $27,044 in year 1;
$2,093,280 in year 2; and $206,725 in
year 3.
Table XI-2: Summary of Information Collection Burden for Part 60
Year3
Annual Average
1,106
109,135
21,023
47,596
Number of Responses
52,821
433,240
310,467
265,509
Number of Burden
Hours (Rounded)
18,720
109,983
63,215
63,972
$1,260,819
$7,704,098
$4,238,135
$4,401,018
$27,044
$2,093,280
$206,725
$775,683
Hour Burden Costs
(Rounded)
Capital Costs to
Respondents
The number of responses and burden
hours decreased from year 2 to year 3
mainly as a result of decreases in
sampling in current MNM mines. In
year 2, MNM mines will conduct firsttime and second-time sampling, while
only a small number of new mines
starting operations in year 3 are required
to conduct this type of sampling. The
increase in capital costs in year 2 is a
result of all medical examinations for
current miners taking place in that year.
For a detailed summary of the burden
hours and related costs by provision, see
the FRIA accompanying the final rule.
The FRIA includes the estimated costs
and assumptions related to the
paperwork requirements under this final
rule.
Summary of Changes
Description of the ICR
This non-substantive change request
revises the supporting statement for this
information collection request due to
the establishment of a PEL for respirable
crystalline silica separate from coal
mine dust in this final rule. These
revisions remove any reference in the
information collection request to quartz
or the reduction of the respirable coal
mine dust standard due the presence of
quartz. This change does not modify the
authority, affected mine operators, or
paperwork burden in this information
collection request.
Background
2. Existing Information Collection 1219–
0011
The calculated burden including
respondents and responses remain the
same.
Affected Public: Businesses or ForProfit.
Estimated Number of Respondents:
676 (0 from this rule).
Frequency: On occasion.
Estimated Number of Responses:
995,102 (0 from this rule).
Estimated Number of Burden Hours:
58,259 (0 from this rule).
Estimated Hour Burden Costs:
$3,271,611 ($0 from this rule).
Estimated Capital Costs to
Respondents: $29,835 ($0 from this
rule).
Type of Review: Non-substantive
change to currently approved
information collection.
OMB Control Number: 1219–0011.
Title: Respirable Coal Mine Dust
Sampling.
Description of the ICR
Background
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Year2
In October 2022, MSHA received
OMB approval for the reauthorization of
Respirable Coal Mine Dust Sampling
under OMB Control Number 1219–0011.
This information collection request
outlines the legal authority, procedures,
burden, and costs associated with
recordkeeping and reporting
requirements for coal mine operators.
MSHA’s standards require that coal
mine operators sample respirable coal
mine dust quarterly and make records of
such samples.
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Summary of the Collection of
Information
Changes in Burden
3. Existing Information Collection 1219–
0048
Type of Review: Substantive change to
currently approved information
collection.
OMB Control Number: 1219–0048.
Title: Respirator Program Records.
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Title 30 CFR parts 56 and 57
incorporate by reference requirements of
ANSI Z88.2–1969, ‘‘Practices for
Respiratory Protection.’’ Under this
standard, certain records are required to
be kept in connection with respirators
in MNM mines. The final rule
incorporates by reference ASTM F3387–
19, ‘‘Standard Practice for Respiratory
Protection,’’ in 30 CFR parts 56 and 57
to replace the Agency’s existing
respiratory protection standard. The
final rule requires respiratory protection
programs to be in writing and to meet
the following requirements in
accordance with ASTM F3387–19:
program administration; written
standard operating procedures; medical
evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage.
Summary of Changes
This substantive change request is to
revise the supporting statement for this
information collection request due to a
modification of respiratory protection
standard from ANSI Z88.2–1969 to
ASTM F3387–19 in the final rule. These
revisions require mine operators to
update their respiratory protection
standard and increase recordkeeping
costs. The change does not modify the
authority or affected mine operators but
increases the paperwork burden and
costs associated with respiratory
protection in this information collection
request.
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ER18AP24.197
Year 1
Number of
Respondents
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Summary of the Collection of
Information
Changes in Burden
The calculated burden including
respondents and responses increases.
Affected Public: Businesses or ForProfit.
Estimated Number of Respondents:
2,305 (1,955 from this rule).
Frequency: On occasion.
Estimated Number of Responses:
43,795 (37,495 from this rule).
Estimated Number of Burden Hours:
23,626 (20,038 from this rule).
Estimated Hour Burden Costs:
$1,459,309 ($1,175,211 from this rule).
Estimated Capital Costs to
Respondents: $140,000 ($0 from this
rule).
XII. Other Regulatory Considerations
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A. National Environmental Policy Act
The National Environmental Policy
Act (NEPA) of 1969 (42 U.S.C. 4321 et
seq.), requires each Federal agency to
consider the environmental effects of
final actions and to prepare an
Environmental Impact Statement on
major actions significantly affecting the
quality of the environment. MSHA has
reviewed the final standard in
accordance with NEPA requirements,
the regulations of the Council on
Environmental Quality (40 CFR part
1500), and the Department of Labor’s
NEPA procedures (29 CFR part 11). As
a result of this review, MSHA has
determined that this final rule will not
have a significant environmental
impact. Accordingly, MSHA has not
conducted an environmental assessment
nor provided an environmental impact
statement.
B. The Unfunded Mandates Reform Act
of 1995
MSHA reviewed this rule according to
the Unfunded Mandates Reform Act of
1995 (UMRA) (2 U.S.C. 1501 et seq.).
Under section 202(a) of the UMRA, 2
U.S.C. 1532(a), an agency must prepare
a written qualitative and quantitative
assessment of any regulation that may
result in the expenditure by State, local,
or tribal governments, in the aggregate,
or by the private sector, of $100 million
(adjusted annually for inflation) or more
in any one year. That threshold is $196
million as of 2023.
The statutory authority for the final
rule is provided by the Mine Act under
sections 101(a), 103(h), and 508. 30
U.S.C. 811(a), 813(h), and 957. MSHA
implements the provisions of the Mine
Act to prevent death, illness, and injury
from mining and promote safe and
healthful workplaces for miners. The
Mine Act requires the Secretary of Labor
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(Secretary) to develop and promulgate
improved mandatory health and safety
standards to prevent hazardous and
unhealthy conditions and protect the
health and safety of the nation’s miners.
30 U.S.C. 811(a).
MSHA concludes that the final rule
would impose a federal mandate on the
private sector in excess of $196 million
in expenditures in one of the 60-year
implementation years, as documented
in the standalone FRIA document (see
Table C–2, Appendix C). The
expenditure burden on the private
sector will be borne by mine operators.
Such expenditures may include
conducting exposure monitoring;
selecting, improving, and implementing
exposure controls; providing respiratory
protection; updating respiratory
protection practices in accordance with
the 2019 ASTM standard; and, for MNM
mine operators, making specified
medical examinations available for all
their miners. However, the rule will not
require State, local, or tribal
governments to expend, in the
aggregate, $196 million or more in any
one year for their commercial activities.
Accordingly, the rule does not trigger
the requirements of the UMRA based on
its impact on State, local, or tribal
governments.
Section 202(c) of the UMRA, 2 U.S.C.
1532(c), authorizes a Federal agency to
prepare any written statement required
under section 202(a) of the UMRA in
conjunction with or as a part of any
other statement or analysis that
accompanies the final rule. The FRIA
constitutes the written statement
containing a qualitative and quantitative
assessment of these anticipated costs
and benefits required under Section
202(a) of the UMRA.
In addition, section 205(a) of UMRA,
2 U.S.C. 1535(a), requires MSHA to
identify and consider a reasonable
number of regulatory alternatives before
promulgating a rule for which a written
statement under section 202 is required.
MSHA is required to select from those
alternatives the most cost-effective and
least burdensome alternative that
achieves the objectives of the rule
unless the Agency publishes an
explanation for doing otherwise, or the
selection of such an alternative is
inconsistent with law. After considering
three regulatory alternatives, this final
rule presents a comprehensive approach
for lowering miners’ exposure to
respirable crystalline silica and MSHA
has determined the rule is both
technologically feasible and
economically justified as described in
Section VII. Feasibility. A full
discussion of the alternatives
considered is presented in Section IX.
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28413
Summary of the Final Regulatory
Impact Analysis and Regulatory
Alternatives and the standalone FRIA
document.
C. The Treasury and General
Government Appropriations Act of
1999: Assessment of Federal
Regulations and Policies on Families
Section 654 of the Treasury and
General Government Appropriations
Act of 1999 (5 U.S.C. 601 note) requires
agencies to assess the impact of Agency
action on family well-being. MSHA has
determined that the final rule will have
no effect on family stability or safety,
marital commitment, parental rights and
authority, or income or poverty of
families and children, as defined in the
Act. The final rule impacts the mining
industry and does not impose
requirements on states or families.
Accordingly, MSHA certifies that this
final rule will not impact family wellbeing, as defined in the Act.
D. Executive Order 12630: Government
Actions and Interference With
Constitutionally Protected Property
Rights
Section 5 of E.O. 12630 requires
Federal agencies to ‘‘identify the takings
implications of proposed regulatory
actions . . .’’ MSHA has determined
that the final rule does not implement
a taking of private property or otherwise
have takings implications. Accordingly,
E.O. 12630 requires no further Agency
action or analysis.
E. Executive Order 12988: Civil Justice
Reform
The final rule was written to provide
a clear legal standard for affected
conduct and was carefully reviewed to
eliminate drafting errors and
ambiguities to minimize litigation and
avoid undue burden on the Federal
court system. Accordingly, the final rule
meets the applicable standards provided
in section 3 of E.O. 12988, Civil Justice
Reform.
F. Executive Order 13045: Protection of
Children From Environmental Health
Risks and Safety Risks
E.O. 13045 requires Federal agencies
submitting covered regulatory actions to
OMB’s Office of Information and
Regulatory Affairs (OIRA) for review,
pursuant to E.O. 12866, to provide OIRA
with (1) an evaluation of the
environmental health or safety effects
that the planned regulation may have on
children, and (2) an explanation of why
the planned regulation is preferable to
other potentially effective and
reasonably feasible alternatives
considered by the agency. In E.O. 13045,
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‘‘covered regulatory action’’ is defined
as rules that may (1) be significant
under Executive Order 12866 Section
3(f)(1) (i.e., a rulemaking that has an
annual effect on the economy of $200
million or more or would adversely
affect in a material way the economy, a
sector of the economy, productivity,
competition, jobs, the environment,
public health or safety, or State, local,
territorial, or tribal governments or
communities), and (2) concern an
environmental health risk or safety risk
that an agency has reason to believe may
disproportionately affect children.
Environmental health risks and safety
risks refer to risks to health or to safety
that are attributable to products or
substances that the child is likely to
come in to contact with or ingest
through air, food, water, soil, or product
use or exposure.
MSHA has determined that, in
accordance with E.O. 13045, while the
final rule is considered significant
under E.O. 12866 Section 3(f)(1), it does
not concern an environmental health or
safety risk that may have a
disproportionate impact on children.
MSHA’s final rule would lower the
occupational exposure limit to
respirable crystalline silica for all
miners, including pregnant miners, take
other actions to protect miners from
adverse health risks associated with
exposure to respirable crystalline silica,
and require updated respiratory
standards to better protect miners from
airborne contaminants.
MSHA is aware of studies which have
characterized and assessed the risks
posed by ‘‘take-home’’ exposure
pathways for hazardous dust particles.
However, the final rule’s primary
reliance on engineering and
administrative controls to protect
miners from respirable crystalline silica
exposures helps minimize risks
associated with ‘‘take-home’’ exposures
by reducing or eliminating silica that is
in the mine atmosphere or the miner’s
personal breathing zone. The risks of
take-home exposures are further
minimized by MSHA’s existing
standards, mine operators’ policies and
procedures, and mine operators’ use of
clothing cleaning systems.
MSHA’s existing standards limit
miners’ exposures to respirable
crystalline silica. MSHA also requires
coal mine operators to provide miners
with bathing facilities and change
rooms. Miners have access to these
facilities to shower and change their
work clothes at the end of each shift. In
addition, some mine operators provide
miners with clean company clothing for
each shift, have policies and procedures
for cleaning or disposing of
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contaminated clothing, and provide a
boot wash for miners to clean work
boots during and after each shift.
Moreover, some mine operators use
clothing cleaning systems that can
remove dust from a miner’s clothing.
Many of these systems include NIOSHdesigned dust removal booths that use
compressed air to remove dust, which is
then vacuumed through a filter to
remove airborne contaminants. Overall,
the Agency’s standards, mine operators’
policies and procedures, and other
safety and health practices including the
use of clothing cleaning systems help to
reduce or eliminate the amount of takehome exposure, therefore protecting
other persons in a miner’s household or
persons who come into contact with the
miner outside of the mine site.
MSHA identified one epidemiological
study (Onyije et al., 2022) that suggests
a possible association between paternal
exposure to respirable crystalline silica
and childhood leukemia. However, this
study does not provide dose-response
data which would be needed to
establish the dose of respirable
crystalline silica which results in a noadverse-effect-level (NOAEL) for
childhood leukemia. This potential
association has not been independently
confirmed by another study.
MSHA has no evidence that the
environmental health or safety risks
posed by respirable crystalline silica,
including ‘‘take-home’’ exposure to
respirable crystalline silica,
disproportionately affect children.
Therefore, MSHA concludes no further
analysis or action is needed, in
accordance with E.O. 13045.
G. Executive Order 13132: Federalism
MSHA has determined that the final
rule does not have ‘‘federalism
implications’’ because it will not ‘‘have
substantial direct effects on the States,
on the relationship between the national
government and the States, or on the
distribution of power and
responsibilities among the various
levels of government.’’ Accordingly,
under E.O. 13132, no further Agency
action or analysis is required.
H. Executive Order 13175: Consultation
and Coordination With Indian Tribal
Governments
MSHA has determined the final rule
does not have ‘‘tribal implications’’
because it will not ‘‘have substantial
direct effects on one or more Indian
tribes, on the relationship between the
Federal Government and Indian tribes,
or on the distribution of power and
responsibilities between the Federal
Government and Indian tribes.’’
Accordingly, under E.O. 13175, no
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further Agency action or analysis is
required.
I. Executive Order 13211: Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use
E.O. 13211 requires agencies to
publish a Statement of Energy Effects for
‘‘significant energy actions,’’ which are
agency actions that are ‘‘likely to have
a significant adverse effect on the
supply, distribution, or use of energy’’
including a ‘‘shortfall in supply, price
increases, and increased use of foreign
supplies.’’ MSHA has reviewed the final
rule for its impact on the supply,
distribution, and use of energy because
it applies to the mining industry. The
final rule would result in annualized
compliance costs of $8.2 million using
a 3 percent discount rate and $8.6
million using a 7 percent discount rate
for the coal industry relative to annual
revenue of $29.1 billion. The final rule
would also result in annualized
compliance costs of $81.9 million using
a 3 percent discount rate and $83.6
million using a 7 percent discount rate
for the metal/nonmetal mine industry
relative to annual revenue of $95.1
billion. Because it is not ‘‘likely to have
a significant adverse effect on the
supply, distribution, or use of energy’’
including a ‘‘shortfall in supply, price
increases, and increased use of foreign
supplies,’’ it is not a ‘‘significant energy
action.’’ Accordingly, E.O. 13211
requires no further agency action or
analysis.
J. Executive Order 13272: Proper
Consideration of Small Entities in
Agency Rulemaking
MSHA has thoroughly reviewed the
final rule to assess and take appropriate
account of its potential impact on small
businesses, small governmental
jurisdictions, and small organizations.
MSHA’s analysis is presented in Section
X. Final Regulatory Flexibility Analysis.
K. Executive Order 13985: Advancing
Racial Equity and Support for
Underserved Communities Through the
Federal Government
E.O. 13985 provides ‘‘that the Federal
Government should pursue a
comprehensive approach to advancing
equity for all, including people of color
and others who have been historically
underserved, marginalized, and
adversely affected by persistent poverty
and inequality.’’ E.O. 13985 defines
‘‘equity’’ as ‘‘consistent and systematic
fair, just, and impartial treatment of all
individuals, including individuals who
belong to underserved communities that
have been denied such treatment, such
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as Black, Latino, and Indigenous and
Native American persons, Asian
Americans and Pacific Islanders and
other persons of color; members of
religious minorities; lesbian, gay,
bisexual, transgender, and queer
(LGBTQ+) persons; persons with
disabilities; persons who live in rural
areas; and persons otherwise adversely
affected by persistent poverty or
inequality.’’ To assess the impact of the
final rule on equity, MSHA considered
two factors: (1) the racial/ethnic
distribution in mining in NAICS 212
(which does not include oil and gas
extraction) compared to the racial/
ethnic distribution of the U.S. workforce
(Table XII–1), and (2) the extent to
which mining may be concentrated
within general mining communities
(Table XII–2).
In 2008, NIOSH conducted a survey of
mines, which entailed sending a survey
packet to 2,321 mining operations to
collect a wide range of information,
including demographic information on
miners. NIOSH’s 2012 report, entitled
‘‘National Survey of the Mining
Population: Part I: Employees’’ reported
the findings of this survey (NIOSH,
2012a). Race and ethnicity information
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about U.S. mine workers is presented in
Table XII–1. Of all mine workers,
including miners as well as
administrative employees at mines, 93.4
percent of mine workers were white,
compared to 80.6 percent of all U.S
workers.111 There were larger
percentages of American Indian or
Alaska Native and Native Hawaiian or
Other Pacific Islander people in the
mining industry compared to all U.S.
workers, while there were smaller
percentages of Asian, Black or African
American, and Hispanic/Latino people
in the mining industry compared to all
U.S. workers.
Table XII–2 shows that there are 22
mining communities, defined as
counties where at least 2 percent of the
population is working in the mining
industry.112 Although the total
111 National data on workers by race were not
available for the year 2008; comparable data for
2012 are provided for comparison under the
assumption that there would not be major
differences in distributions between these two
years.
112 Although 2 percent may appear to be a small
number for identifying a mining community, one
might consider that if the average household with
one parent working as a miner has five members in
total, then approximately 10 percent of households
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population in this table represents only
0.15 percent of the U.S. population, it
represents 12.0 percent of all mine
workers. The average per capita income
in these communities in 2020,
$47,977,113 was lower than the U.S.
average, $59,510, representing 80.6
percent of the U.S. average. However,
each county’s average per capita income
varies substantially, ranging from 56.4
percent of the U.S. average to 146.8
percent.
The final rule would lower exposure
to respirable crystalline silica and
improve respiratory protection for all
mine workers. MSHA determined that
the final rule is consistent with the goals
of E.O. 13985 and would support the
advancement of equity for all workers at
mines, including those who are
historically underserved and
marginalized.
BILLING CODE 4520–43–P
in the area would be directly associated with
mining. While 10 percent may also appear small,
this refers to the county. There are likely particular
areas that have a heavier concentration of mining
households.
113 This is a simple average rather than a
weighted average by population.
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table XII-1: Racial and Ethnic Distribution of Mine Workers 1 (2012)
Number of
Workers in
Mining
(except oil
and gas)
(NAICS
code 212)
As a Percent of
Total Mine
Workers Who
Self-Identified
in These
Categories
(Latest Data for
2008)
Percent of
All Workers
in the United
States for
Comparison
(Latest Data
2012)4
26,622
192,839
219,461
12.1
87.9
100.0
15.0
85.0
100.0
4,050
183
8,893
634
1.9
0.1
4.3
0.3
0.8
5.4
13.0
0.2
194,016
207,776
93.4
100.0
80.6
100.0
Ethnicity
Hispanic/Latino
Non-Hispanic or Latino
Total
Race2
American Indian or Alaska Native 3
Asian
Black or African American
Native Hawaiian or Other Pacific
Islander
White
Total
1. Mine workers includes miners and other workers at mines such as administrative employees.
2. Does not include mine workers who did not self-report in one of these categories. Some of the surveyed mine
workers may not have self-reported in one of these categories if they are affiliated with more than one race, or if
they chose not to respond to this survey question.
3. Includes mine workers who self-identified as an American Indian or Alaskan Native as a single race, not in
combination with any other races. No other data on mine workers in this racial group were available from this
source. In other employment statistics often reported on American Indians and Alaska Natives, their population is
based on self-reporting as being American Indian or Alaska Native in combination with any other race, which has
resulted in the reporting of much higher employment levels. See BLS, Monthly Labor Review, "Alternative
Measurements of Indian Country: Understanding Their Implications for Economic, Statistical, and Policy Analysis,"
https://www.bls.gov/opub/mlr/2021/article/altemative-measurements-of-indian-country.htm.
4. More recent data from the 2020 Decennial Census were not available in September 2022.
Sources: National Institute for Occupational Safety and Health (NIOSH). 2012a. National Survey of the Mining
Population Mining Publication: Part 1: Employees, DHHS (NIOSH) Pub. No. 2012-152, June 2012; U.S. Census
Bureau, 2012 American Community Survey (ACS).
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28417
Table XII-2: Mining Counties: Counties in the United States with Relatively High
Concentrations of Mine Workers (At Least 2 Percent of the County Population)
#
County
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
White Pine County, Nevada
Pershing County, Nevada
Humboldt County, Nevada
Campbell County, Wyoming
Winkler County, Texas
Mercer County, North Dakota
Chase County, Kansas
Shoshone County, Idaho
Logan County, West Virginia
Sweetwater County, Wyoming
Glasscock County, Texas
Livingston County, Kentucky
Buchanan County, Virginia
McDowell County, West Virginia
Big Hom County, Wyoming
Sevier County, Utah
Boone County, West Virginia
Moffat County, Colorado
Nye County, Nevada
Raleigh County, West Virginia
Wyoming County, West Virginia
Elko County, Nevada
Total
All U.S. Counties
Mine Workers in Mining Counties as a Percent
of All U.S. Mine Workers
Population of Mine Counties as a Percent of
U.S. Population
Number of
Mine
Workers
(First
Quarter
2022)
1,288
771
1,549
3,547
513
555
166
723
1,643
2,050
56
431
946
660
413
601
582
349
1,062
1,647
456
1,090
20,963
174,387
Population of
County
(Latest Data
in 2021)
9,182
6,741
17,648
46,401
7,415
8,323
2,598
13,612
31,909
41,614
1,149
8,959
19,816
18,363
11,632
21,906
21,312
13,185
43,946
73,771
21,051
53,915
494,448
331,893,745
Estimated
Percent of
Population
Who Are
Mine
Workers
14.0
11.4
8.8
7.6
6.9
6.7
6.4
5.3
5.1
4.9
4.9
4.8
4.8
3.6
3.6
2.7
2.7
2.6
2.4
2.2
2.2
2.0
4.2
12.0%
0.15%
L. Incorporation by Reference
The Office of the Federal Register
(OFR) has regulations concerning
incorporation by reference. 5 U.S.C.
552(a); 1 CFR part 51. These regulations
require that information that is
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incorporated by reference in a rule be
‘‘reasonably available’’ to the public.
They also require discussion in the
preamble to the rule of the ways in
which materials are reasonably available
to interested parties or how the Agency
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worked to make those materials
reasonably available to interested
parties. Additionally, the preamble to
the rule must summarize the material. 1
CFR 51.5(b).
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Source: Bureau of Labor Statistics (BLS), Quarterly Employment and Wages First Quarter 2022 (2022); Bureau of
Economic Analysis, Personal Income by County, Metro, and Other Areas 2020 (2020); U.S. Census Bureau,
"Annual Estimates of the Resident Population for Counties: April 1, 2020 to July 1, 2021 (CO-EST2021-POP)."
available at: https://www.census.gov/data/tables/time-series/demo/popest/2020s-counties-total.html (last accessed
Jan. 11, 2024); U.S. Census Bureau, Quick Facts, available at:
https://www .census.gov/quickfacts/fact/table/US/PST04522 l (last accessed Jan. 11, 2024).
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In accordance with the OFR’s
requirements, MSHA provides the
following: (a) summaries of the
materials to be incorporated by
reference and (b) information on the
public availability of the materials and
on how interested parties can access the
materials.
ASTM F3387–19, ‘‘Standard Practice for
Respiratory Protection’’
ASTM F3387–19 is a voluntary
consensus standard that represents upto-date advancements in respiratory
protection technologies, practices, and
techniques. The standard includes
provisions for selection, fitting, use, and
care of respirators designed to remove
airborne contaminants from the air
using filters, cartridges, or canisters, as
well as respirators that protect miners in
oxygen-deficient or immediately
dangerous to life or health atmospheres.
These provisions are based on NIOSH’s
long-standing experience of testing and
approving respirators for occupational
use and OSHA’s respiratory protection
standards on assigned protection factors
and fit testing. This final rule
incorporates by reference ASTM F3387–
19 in §§ 56.5005T, 57.5005T, and
72.710T (which will become permanent
§§ 56.5005 and 57.5005 720 days after
publication and permanent § 72.710 360
days after publication) and in
§ 60.14(c)(2) to better protect all miners
from airborne contaminants. MSHA
believes that incorporating by reference
ASTM F3387–19 provides mine
operators with up-to-date requirements
for respirator technology, reflecting an
improved understanding of effective
respiratory protection and therefore
better protecting the health and safety of
miners. For further details on MSHA’s
update to the Agency’s existing
respiratory protection standard, please
see Section VIII.D. Updating MSHA
Respiratory Protection Standards:
Incorporation of ASTM F3387–19 by
Reference.
A paper copy or printable version of
ASTM F3387–19 may be purchased by
mine operators or any member of the
public at any time from ASTM
International, 100 Barr Harbor Drive,
P.O. Box C700, West Conshohocken, PA
19428–2959; www.astm.org. ASTM
International makes read-only versions
of its standards that have been
referenced or incorporated into Federal
regulation or laws available free of
charge at its online Reading Room,
www.astm.org/products-services/
reading-room.html.
In addition, upon finalization of this
rule, ASTM F3387–19 will be available
for review free of charge at MSHA
headquarters at 201 12th Street South,
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Arlington, VA 22202–5450 (202–693–
9440) and at Mine Safety Health
Enforcement District and Field Offices.
ISO 7708:1995(E): Air quality—Particle
Size Fraction Definitions for HealthRelated Sampling
ISO 7708:1995 is an international
consensus standard that defines
sampling conventions for particle size
fractions used in assessing possible
health effects of airborne particles in the
workplace and ambient environment. It
defines conventions for the inhalable,
thoracic, and respirable fractions. The
final rule incorporates by reference ISO
7708:1995 in § 60.12(e)(4) to ensure
consistent sampling collection by mine
operators through the utilization of
samplers conforming to ISO 7708:1995.
For further details on MSHA’s
incorporation by reference of ISO
7708:1995, please see Section VIII.B.5.d.
Sampling Devices: Incorporation of ISO
7708:1995 by Reference.
A paper copy or printable version of
ISO 7708:1995 may be purchased by
mine operators or any member of the
public at any time from ISO, CP 56, CH–
1211 Geneva 20, Switzerland; phone: +
41 22 749 01 11; fax: + 41 22 733 34 30;
website: www.iso.org/. ISO makes readonly versions of its standards that have
been incorporated by reference in the
CFR available free of charge at its online
Incorporation by Reference Portal,
http://ibr.ansi.org/Default.aspx.
In addition, upon finalization of this
rule, ISO 7708:1995 will be available for
review free of charge at MSHA
headquarters at 201 12th Street South,
Arlington, VA 22202–5450 (202–693–
9440) and at Mine Safety Health
Enforcement District and Field Offices.
TLVs® Threshold Limit Values for
Chemical Substances in Workroom Air
Adopted by ACGIH for 1973
ACGIH’s publication entitled ‘‘TLVs®
Threshold Limit Values for Chemical
Substances in Workroom Air Adopted
by ACGIH for 1973’’ presents Threshold
Limit Value (TLV®) guidelines for
hundreds of chemical substances found
in the work environment (particulates,
gases, and vapors). TLVs® are airborne
concentrations of chemical substances
that represent conditions under which it
is believed that nearly all workers may
be repeatedly exposed, day after day,
over a working lifetime, without adverse
effects. TLVs® generally refer to timeweighted average concentrations
(TWAs) for a 7 or 8-hour workday and
40-hour workweek that are applied as
guidelines in the control of health
hazards.
TLVs®, which appears the
amendatory text of this rule, was
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previously approved for use in
§§ 56.5001 and 57.5001.
Copies of the document may be
purchased from the American
Conference of Governmental Industrial
Hygienists, 3640 Park 42 Drive,
Cincinnati, OH 45241; 513–742–2020;
http://www.acgih.org. This publication
is also available for examination free of
charge at MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5452; 202–693–9440; and at Mine Safety
and Health Enforcement District and
Field Offices.
American National Standards Practices
for Respiratory Protection ANSI Z88.2–
1969.
ANSI Z88.2–1969, which appears the
amendatory text of this rule, was
previously approved for use in § 72.710.
XIII. References
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2017. Misclassification of occupational
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Blackley, D.J, Crum, J.B., Halldin, C.N.,
Storey, E. and Laney, A.S. 2016b.
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mucociliary structure and MUC5B
expression in airways of C57BL/6 mice.
Experimental Lung Research. 46(7):217–
225. doi: 10.1080/
01902148.2020.1762804.
XIV. Appendix
Appendix A—Description of MSHA
Respirable Crystalline Silica Samples
This document describes the respirable
crystalline silica samples used in this rule.
The Mine Safety and Health Administration
(MSHA) collected these samples from metal/
nonmetal (MNM) and coal mines, then
analyzed the data to support this rulemaking.
Technical details are discussed in the
attachments that follow.
MNM Respirable Dust Sample Dataset,
2005–2019
From January 1, 2005, to December 31,
2019, 104,354 valid MNM respirable dust
samples were entered into the MSHA
Technical Support Laboratory Information
Management System (LIMS) database.114 The
dataset includes MNM mine respirable dust
personal exposure samples collected by
MSHA inspectors. A total of 57,824 samples
contained a respirable dust mass of 0.100 mg
or greater (referred as ‘‘sufficient-mass dust
samples’’), while a total of 46,530 samples
contained a respirable dust mass of less than
0.100 mg (referred as ‘‘insufficient-mass dust
samples’’).115
114 Only valid (non-void) MNM respirable dust
samples were included in the LIMS dataset. Voided
samples include any samples with a documented
reason which occurred during the sampling and/or
the MSHA’s laboratory analysis for invalidating the
results.
115 Sufficient-mass dust samples are analyzed for
their quartz content, whereas insufficient-mass dust
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28431
Respirable dust samples collected by
MSHA inspectors are assigned a three-digit
‘‘contaminant code’’ based on the
contaminant in the sample. MSHA’s
contaminant codes group contaminants based
on their health effects 116 and are assigned by
the MSHA Laboratory based on sample type
and analysis results. The codes link
information to the sample, such as
contaminant description, permissible
exposure limit (PEL), and the units of
measure for each contaminant sampled.
The MNM respirable crystalline silica
dataset includes five contaminant codes.
MNM Respirable Dust Sample Contaminant
Codes
• Contaminant code 521—MNM respirable
dust samples that were not analyzed for
respirable crystalline silica.
• Contaminant code 523—MNM respirable
dust samples containing 1 percent or more
quartz.
• Contaminant code 525—MNM respirable
dust samples containing cristobalite.
• Contaminant code 121—MNM respirable
dust samples containing less than 1 percent
quartz where the commodity is listed as a
‘‘nuisance particulate’’ in Appendix E of the
TLVs® Threshold Limit Values for Chemical
Substances in Workroom Air Adopted by
ACGIH for 1973 (reproduced in Table A–1).
• Contaminant code 131—MNM respirable
dust samples containing less than 1 percent
quartz where the commodity is not listed as
a ‘‘nuisance particulate’’ in Appendix E of
the 1973 ACGIH TLV® Handbook
(reproduced below).
samples are not. This is because even if the
insufficient-mass dust samples contained only
quartz they would not have exceeded the
permissible exposure limit (PEL) at that time.
116 For example, contaminant code 523 indicates
that dust from that sample contained 1 percent or
more respirable crystalline silica (quartz). Exposure
to respirable crystalline silica has been linked to the
following health outcomes: silicosis, non-malignant
respiratory disease, lung cancer, and renal disease.
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Table A-1: Reproduction of TLVs® Threshold Limit Values for Chemical Substances in
Workroom Air Adopted by ACGIH for 1973 Appendix E, Threshold Limit Values
Material List: "Some Nuisance Particulates 1; Threshold Limit Value -10 mg/m3"
Alundum (AhQ3)
Calcium Carbonate
Cellulose (paper fiber)
Corundum (Ah03)
Emery
Glass, fibrous 2 or dust
Glycerin Mist
Graphite (synthetic)
Gypsum
Kaolin
Limestone
Magnesite
Marble
Pentaerythritol
Plaster of Paris
Portland Cement
Rouge
Silicon Carbide
Starch
Sucrose
Tin Oxide
Titanium Dioxide
Vegetable oil mists (except castor,
cashew nut, or similar irritant oils)
an incorrect flow rate, had insufficient
sampling time, or were duplicates. This
resulted in a final dataset consisting of
57,769 MNM samples that contained a mass
of at least 0.100 mg of respirable dust. The
dataset containing the analyzed samples that
MSHA retained can be found in the
rulemaking docket MSHA–2023–0001.
MNM Respirable Dust Samples With a Mass
of at Least 0.100 Milligram (mg) (SufficientMass Dust Samples)
The 57,824 samples that contained at least
0.100 mg of respirable dust were analyzed to
quantify their respirable crystalline silica
content—mostly respirable quartz but also
respirable cristobalite. The respirable
crystalline silica concentrations were entered
into the MSHA Standardized Information
System (MSIS) database (internal facing) and
Mine Data Retrieval System (MDRS) database
(public facing). MSIS and MDRS differ from
LIMS in that some of the fields associated
with a sample can be modified or corrected
by the inspector who conducted the
sampling. These correctable fields include
Mine ID, Location Code, and Job Code.
Inspectors cannot access or modify the fields
in the LIMS database.
Fifty-five samples 117 were removed from
the dataset because they were erroneous, had
MNM Respirable Dust Samples With a Mass
of Less Than 0.100 mg (Insufficient-Mass
Dust Samples)
The LIMS database also included 46,530
MNM respirable dust samples that contained
less than 0.100 mg of respirable dust. These
samples did not meet the minimum dust
mass criterion of 0.100 mg and were not
analyzed for respirable crystalline silica by
MSHA’s Laboratory.
From these 46,530 samples, 167
samples 118 were removed because they were
erroneous, had an incorrect flow rate, or had
117 There were 55 samples removed: 7 samples
had no detected mass gain (denoted as ‘‘0 mg’’); 1
sample was a partial shift that was not originally
marked correctly; 1 sample was removed at the
request of the district; 44 samples had flow rates
outside the acceptable range of 1.616–1.785 L/min;
and 2 samples were duplicates of samples that were
already in the dataset. This resulted in the final
sample size of 57,769 = 57,824¥(7 + 1 + 1 + 44
+ 2).
118 There were 167 samples removed: 75 samples
had a cassette mass less than ¥0.03 mg (based on
instrument tolerances, samples that report a cassette
mass between ¥0.03 mg and 0 mg were treated as
having a mass of 0 mg, samples with masses below
that threshold of ¥0.03 mg were excluded); 52
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insufficient sampling time. This resulted in
46,363 remaining MNM samples containing
less than 0.100 mg of respirable dust. These
samples were assigned to contaminant code
521, indicating that the samples were not
analyzed for quartz. The dataset containing
the unanalyzed samples that MSHA retained
can be found in the rulemaking docket
MSHA–2023–0001.
All MNM Respirable Dust Samples
After removing the 222 samples mentioned
above (55 sufficient-mass and 167
insufficient-mass), the dataset consisted of
104,132 MNM respirable dust samples:
57,769 sufficient-mass samples and 46,363
insufficient-mass samples. A breakdown of
the MNM respirable dust samples is included
in Table A–2.
samples had Mine IDs that did not report
employment in any year from 2005–2019; 31
samples had flow rates outside the acceptable range
of 1.615–1.785 L/min ; six samples had sampling
times of less than 30 minutes; and three samples
had invalid Job Codes. This resulted in the final
sample size of 46,363 = 46,530¥(75 + 52 + 31 +
6 + 3).
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Source: American Conference of Governmental Industrial Hygienists (ACGIH). 1973. TL Vs® Threshold Limit
Values for Chemical Substances in Workroom Air Adopted by ACGIH for 1973. Cincinnati, Ohio.
Notes:
1. When toxic impurities are not present, e.g., quartz < 1 percent.
2. <5-7 µm in diameter.
This list contains examples of certain materials that are considered "nuisance" particulates when the material is in
dust form. This list is not intended to be exclusive. If the miner sampled is exposed to one or more of the listed
materials, then the TLV® for "nuisance" dust should be applied.
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28433
Table A-2: Distribution of MNM Respirable Dust Samples
Contaminant
Code
Number of
Samples
Description
523
525
121
131
Total LIMS samples with dust mass ~ 0.100 mg (sufficientmass samvles)
Samples removed with dust mass~ 0.100 mg
Samples retained with dust mass ~ 0.100 mg
Dust respirable fraction,~ 1% quartz
Containing cristobalite
Nuisance dust, listed, respirable fraction, <1 % silica
Unlisted dust, respirable fraction, <1 % silica
521
Total LIMS samples with dust mass < 0.100 mg
(insufficient-mass samples)
Samples removed with dust mass < 0.100 mg
Samples retained with dust mass < 0.100 mg
Respirable dust samples not analyzed for quartz
57,824
55
57,769
39,772
7
9,256
8,734
46,530
167
46,363
46,363
Total Samples
Total Samples Removed
Total Samples Retained
104,354
222
104,132
Coal Respirable Dust Sample Dataset, 2016–
2021
From August 1, 2016, to July 31, 2021,
113,607 valid respirable dust samples from
coal mines were collected by MSHA
inspectors and entered in the LIMS
database.119 For coal mines, the reason the
analysis is based on samples collected by
inspectors beginning on August 1, 2016, is
that this is when Phase III of MSHA’s 2014
RCMD Standard went into effect. Samples
taken prior to implementation of the RCMD
standard would not be representative of
current respirable crystalline silica exposure
levels in coal mines.
Of these samples collected by MSHA
inspectors, 67,963 samples were analyzed for
respirable crystalline silica; 45,644 samples
were not. The record of a respirable dust
sample from coal mines contains a record of
the sample type and the occupation of the
miner sampled. A coal sample’s type is based
on the location within the mine as well as the
occupation of the miner sampled. Below is a
list of coal sample types and descriptions, as
well as the mass of respirable dust required
for that type of sample to be analyzed for
respirable crystalline silica.
• Type 1—Designated occupation (DO).
The occupation on a mechanized mining unit
119 Only valid (non-void) coal respirable dust
samples were included in the LIMS dataset. Voided
samples include any samples with a documented
reason which occurred during the sampling and/or
the MSHA’s Laboratory analysis for invalidating the
results.
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(MMU) that has been determined by results
of respirable dust samples to have the
greatest respirable dust concentration.
Designated occupation samples must contain
at least 0.100 mg of respirable dust to be
analyzed for respirable crystalline silica.
• Type 2—Other designated occupation
(ODO). Occupations other than the DO on an
MMU that are also designated for sampling,
required by 30 CFR part 70. These samples
must contain at least 0.100 mg of respirable
dust to be analyzed for respirable crystalline
silica.
• Type 3—Designated area (DA).
Designated area samples are from specific
locations in the mine identified by the
operator in the mine ventilation plan under
30 CFR 75.371(t), where samples will be
collected to measure respirable dust
generation sources in the active workings.
These samples must contain at least 0.100 mg
of respirable dust to be analyzed for
respirable crystalline silica.
• Type 4—Designated work position
(DWP). A designated work position in a
surface coal mine or surface work area of an
underground coal mine that is designated for
sampling in order to measure respirable dust
generation sources in the active workings.
Designated work position samples must
contain at least 0.200 mg of respirable dust
to be analyzed for respirable crystalline
silica. There are exceptions for certain
occupations: bulldozer operator (MSIS
general occupation code 368), high wall drill
operator (code 384), high wall drill helper
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(code 383), blaster/shotfirer (code 307),
refuse/backfill truck driver (code 386), or
high lift operator/front end loader (code 382).
Samples from these occupations must have at
least 0.100 mg of respirable dust to be
analyzed for respirable crystalline silica.
• Type 5—Part 90 miner. A Part 90 miner
is employed at a coal mine and has exercised
the option under the old section 203(b)
program (36 FR 20601, Oct. 27, 1971) or
under 30 CFR 90.3 to work in an area of a
mine where the average concentration of
respirable dust in the mine atmosphere
during each shift to which a miner is exposed
is continuously maintained at or below the
applicable standard and has not waived these
rights. A sample from a Part 90 miner must
contain at least 0.100 mg of respirable dust
to be analyzed for respirable crystalline
silica.
• Type 6—Non-designated area (NDA).
Non-designated area samples are taken from
locations in the mine that are not identified
by the operator in the mine ventilation plan
under 30 CFR 75.371(t) as areas where
samples will be collected to measure
respirable dust generation sources in the
active workings. These samples are not
analyzed for respirable crystalline silica.
• Type 7—Intake air samples are taken
from air that has not yet ventilated the last
working place on any split of any working
section or any worked-out area, whether
pillared or non-pillared, as per 30 CFR
75.301. These samples are not analyzed for
respirable crystalline silica.
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Sources: MSHA MDRS/MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through
December 31, 2019 (version 20220615); MSHA Personal Health Samples Public Dataset.
28434
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• Type 8—Non-designated work position
(NDWP). A work position in a surface coal
mine or a surface work area of an
underground coal mine that is sampled
during a regular health inspection to measure
respirable dust generation sources in the
active workings but has not been designated
for mandatory sampling. For the analysis of
respirable crystalline silica, these samples
must have at least 0.200 mg of respirable
dust. There are exceptions for certain
occupations: bulldozer operator (MSIS
general occupation code 368), high wall drill
operator (code 384), high wall drill helper
(code 383), blaster/shotfirer (code 307),
refuse/backfill truck driver (code 386), or
high lift operator/front end loader (code 382).
Samples taken from these occupations must
contain at least 0.100 mg respirable dust to
be analyzed for respirable crystalline silica.
Coal Respirable Dust Samples Analyzed for
Respirable Crystalline Silica
There were 67,963 samples from coal
mines collected by MSHA inspectors from
underground and surface coal mining
operations that were analyzed for respirable
crystalline silica. These results were entered
first into LIMS, and then into MSIS and
MDRS. Results from MSIS were used as they
may be updated by the inspectors at later
dates.120 From those 67,963 samples, 4,836
samples were removed as they were
environmental samples, voided in MSIS, or
had other errors.121 This resulted in a dataset
of 63,127 samples from coal mines that were
analyzed for respirable crystalline silica. The
dataset containing the analyzed samples that
MSHA retained can be found in the
rulemaking docket MSHA–2023–0001.
Coal Respirable Dust Samples Not Analyzed
for Respirable Crystalline Silica
Similar to MNM respirable dust samples,
the LIMS database includes 45,644 coal
samples that did not meet the criteria for
analysis and were thus not analyzed for
respirable crystalline silica content.122 After
removing 13,243 123 samples that were
environmental samples, erroneous, or had
voided controls, there were 32,401 samples
that were not analyzed for respirable
crystalline silica. The dataset containing the
unanalyzed samples that MSHA retained can
be found in the rulemaking docket MSHA–
2023–0001.
All Coal Respirable Dust Samples
In total, 18,079 respirable dust samples
from coal mines were removed from the
original datasets: 4,836 samples that were
analyzed for respirable crystalline silica and
13,243 samples that were not. This created a
final dataset of 95,528 samples: 63,127
analyzed samples and 32,401 samples that
were not analyzed.124 A breakdown of
respirable dust samples from coal mines is
included in Table A–3.
Table A-3: Distribution of Coal Respirable Dust Samples
Sample Type
Total LIMS Samples Analyzed for Respirable
Crystalline Silica Content
Analyzed Samples Removed
Analyzed Samples Retained
Type 1
Type2
Type4
Type 5
Type 8
Number of Samples
67,963
4,836
63,127
10,149
42,828
4,788
365
4,997
Total LIMS Samples Not Analyzed for Respirable
Crystalline Silica Content
Unanalyzed samples removed
Unanalyzed samples retained
Total Samvles
Total Samples Removed
Total Samples Retained
45,644
13,243
32,401
113,607
18,079
95,528
120 As mentioned in the section concerning
samples for MNM mines, MSIS and MDRS differ
from LIMS in that some data fields can be modified
or corrected by the inspector. These correctable
fields include market.
121 There were 4,836 samples removed: 4,199
samples were environmental and not personal
samples (see Sample Type explanation for more
detail); 631 samples had been voided after they had
been entered into MSIS; and 6 had invalid Job
Codes. This resulted in the final sample size of
63,127 = 67,963¥(4,199 + 631 + 6).
122 In addition to the criteria listed above,
samples from Shop Welders (code 319) are not
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analyzed for respirable crystalline silica as they are
instead analyzed for welding fumes.
123 There were 13,243 samples removed: 6
samples had typographical errors; 14 samples had
a cassette mass less than ¥0.03 mg (based on
instrument tolerances, samples that report a cassette
mass between ¥0.03 mg and 0 mg were treated as
having a mass of 0 mg); 92 samples had invalid Job
Codes; 12,724 were environmental samples; 44
samples had an occupation code of 000 despite
having a personal sample ‘Sample Type’; 271
samples had controls that were voided; and 92
came from Job Code 319—Welder (see Footnote
119). This resulted in the final sample size of
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32,401 = 50,545¥(6 + 14 + 92 + 12,724 + 44 + 271
+ 92).
124 This dataset did not include any other coal
mine respirable dust sample types collected by
MSHA inspectors—i.e., sample types 3 (designated
area samples), types 6 (Non-face occupations) and
7 (Intake air), samples taken on the surface mine
shop welder (n=319), and all voided samples.
Voided samples are any samples that have a
documented reason which occurred during the
sampling and/or laboratory analysis for invalidating
the results.
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Source: MSHA MDRS/MSIS respirable crystalline silica data for the coal industry, August 1, 2016,
through July 31, 2021 (version 20220617).
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Attachment 1. MNM Samples Analyzed for
Cristobalite
Cristobalite is one of the three polymorphs
of respirable crystalline silica. At the request
of the inspector, MNM 125 respirable dust
samples that contain at least 0.050 mg of
respirable dust are analyzed for cristobalite.
Of the 57,769 retained MNM samples that
28435
contained at least 0.050 mg of respirable
dust, 0.6 percent (or 359 samples) were
analyzed for cristobalite. Coal respirable dust
samples are not analyzed for cristobalite.126
Table Al-1: MNM Respirable Dust Samples Analyzed for Cristobalite
Description
Samples with mass .? 0.100 mg
Samples analyzed for Cristobalite
Samples not analyzed for Cristobalite
Number of Samples
57,769
359
57,410
Percent of Samples
0.6%
99.4%
Sources: MSHA MDRS/MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through
December 31, 2019 (version 20220615); MSHA Personal Health Samples Public Dataset.
While the samples that were analyzed for
cristobalite were assigned to all four
contaminant codes seen in this dataset, the
majority were assigned contaminant code
523.
Table Al-2: Distribution of MNM Respirable Dust Samples Analyzed for Cristobalite, by
Contaminant Code
Code
Contaminant
523
525
121
131
Total Samples Analyzed for Cristobalite
Dust respirable fraction, ~ 1% quartz
Containing cristobalite
Nuisance dust, listed, respirable fraction, <1 % silica
Unlisted dust, respirable fraction, <1 % silica
Number of
Samples
359
215
6
32
106
Percent of
Samples
59.9%
1.7%
8.9%
29.5%
Sources: MSHA MDRS/MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through
December 31, 2019 (version 20220615); MSHA Personal Health Samples Public Dataset.
The distribution of the 359 samples by
cristobalite mass can be seen in Table A1–
3.127
Table Al-3: Distribution of Analyzed Samples by Cristobalite Mass
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Total
Percent of
Samples
93.1%
3.9%
1.9%
0.8%
0.3%
100%
Sources: MSHA MDRS/MSIS respirable crystalline silica data for the
MNM industry, January 1, 2005, through December 31, 2019 (version
20220615); MSHA Personal Health Samples Public Dataset.
125 See Attachment 2. Technical Background
about Measuring Respirable Crystalline Silica, for
more information.
126 See Attachment 2. Technical Background
about Measuring Respirable Crystalline Silica, for
more information.
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127 Of the 369 samples that were analyzed for
cristobalite, 334 had a value for cristobalite mass
that was less than the limit of detection (LOD) for
cristobalite, 10mg. As such these samples were
assigned a value of 5mg of cristobalite, one half the
LOD. See Attachment 2. Technical Background
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about Measuring Respirable Crystalline Silica, for
more information.
E:\FR\FM\18APR3.SGM
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5
11-20
21-30
31-40
>40
Number of
Samples
334
14
7
3
1
359
ER18AP24.203
(µ2:)
ER18AP24.202
Cristobalite Mass
28436
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
The mass of each sample was then used to
calculate a cristobalite concentration by
dividing the mass of cristobalite by the
volume of air sampled (0.816 m3). The
calculated concentrations ranged from 6mg/
m3 to 53mg/m3.128
Table Al-4: Samples Analyzed for Cristobalite by Concentration (µ,g/m 3)
Cristobalite Concentration
(u!!lm 3)
6
12-20
21-30
31-40
41-50
> 50
Total
Number of
Samples
334
12
5
5
2
1
359
Percent of
Samples
93.1%
3.3%
1.4%
1.4%
0.6%
0.3%
100%
Sources: MSHA MDRS/MSIS respirable crystalline silica data for the MNM industry,
January 1, 2005, through December 31, 2019 (version 20220615); MSHA Personal Health
Samples Public Dataset.
ddrumheller on DSK120RN23PROD with RULES3
Limits of Detection and Limits of
Quantification for Silica Sample Data
The Limits of Detection (LOD) and Limits
of Quantification (LOQ) are the two terms
128 One sample had a cristobalite concentration of
53mg/m3. It was sampled in July of 2011 at Mine
ID 4405407 and cassette number 610892. The
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used to describe a method’s capability. The
LOD refers to the smallest amount of the
target analyte (respirable crystalline silica)
that can be detected in the sample and
distinguished from zero with an acceptable
confidence level that the analyte is actually
present. It can also be described as the
instrument signal that is needed to report
with a specified confidence that the analyte
is present. The LOQ refers to the smallest
amount of the target analyte that can be
repeatedly and accurately quantified in the
sample with a specified precision. The LOQ
is higher than the LOD. The values of the
LOD and LOQ are specific to MSHA’s
Laboratory as well as the instrumentation
and analytical method used to perform the
analysis. These values do not change from
one batch to another when samples are
analyzed on the same equipment using the
same method. However, their levels may
change over time due to updated analytical
methods and technological advances. The
values of the LOD and LOQ for the methods
(XRD and FTIR) used in analyzing respirable
crystalline silica samples are explained in
MSHA documents for MNM samples and
coal samples (MSHA Method P–2, 2018a;
MSHA Method P–7, 2018b and 2020b).
MSHA periodically updates these values to
reflect progress in its analytical methods. The
values of LOD and LOQ were last updated in
2022 for MNM samples and in 2020 for coal
samples.
The values of LODs and LOQs for
respirable crystalline silica in samples from
MSHA inspectors depend on several factors,
including the analytical method used (XRD
or FTIR) and the silica polymorph analyzed
(quartz, cristobalite, or tridymite), as
presented in Table A2–1.
For a sample with respirable crystalline
silica content less than the method LOD, the
maximum concentration is calculated as the
respirable crystalline silica mass equivalent
to LOD divided by the volume of air
sampled. For example, the XRD analysis as
performed for a MNM sample, as a method
LOD of 5mg. If a such a sample is analyzed
using that method and no quartz is detected
and that sample is collected at 1.7 L/min air
flow rate for 480 minutes (i.e., 8 hours), the
air sample volume would be 816 L (= 1.7 L/
min * 480 minutes), or 0.816 m3. The
calculated maximum concentration
associated with such sample having
respirable crystalline silica mass below the
method LOD would be 6mg/m3 (= 5mg/0.816
m3). The ‘‘half maximum concentration’’ is
the midpoint between 0 and the calculated
maximum respirable crystalline silica
concentration, which is 3mg/m3 (= 1⁄2 * 6mg/
m3) in this example.
commodity being mined was Stone: Crushed,
Broken Quartzite. The occupation of the miner
being sampled was Miners in Other Occupations:
Job Code 513—Building and Maintenance.
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BILLING CODE 4520–43–P
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Attachment 2. Technical Background About
Measuring Respirable Crystalline Silica
In the proposed rule, respirable crystalline
silica refers to three polymorphs: quartz,
cristobalite, and tridymite. MSHA’s
Laboratory uses two methods to analyze
respirable crystalline silica content in
respirable dust samples. The first method, Xray diffraction (XRD), separately analyzes
quartz, cristobalite, and tridymite contents in
respirable dust samples that mine inspectors
obtain at MNM mine sites (MSHA Method P–
2, 2018a). The second method, Fourier
transform infrared spectroscopy (FTIR), is
used to analyze quartz in respirable dust
samples obtained at coal mines (MSHA
Method P–7, 2018b and 2020b). Although the
XRD method can be expanded from MNM to
coal dust samples, MSHA chooses to use the
FTIR method for coal dust samples because
it is a faster and less expensive method.
However, the current MSHA P–7 FTIR
method cannot quantify quartz if cristobalite
and/or tridymite are present in the sample.
The method also corrects the quartz result for
the presence of kaolinite, an interfering
mineral for quartz analysis when found in
coal dust.
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28437
Table A2-1: Calculated Maximum Concentration for Samples Below LOD, by Analytical
Method and Respirable Crystalline Silica Polymorph
Sample
Dates
MSHA
Analytical
Method
(Method
Name 1)
MNMMines
01/01/2005 XRD
(P-2-2018)
12/31/2019
01/01/2005 XRD
(P-2-2018)
12/31/2019
Coal Mines
08/01/2016 FTIR
(P-7-2018)
08/31/2020
09/01/2020
-
FTIR
(P-7-2020)
Respirable
Crystalline
Silica
Analysis Type
(polymorph)
Quartz
Cristobalite
Quartz
Quartz
07/31/2021
Calculated
Maximum
Concentration
("Half
maximum
concentration)
Limit of
Quantification
(µg per filter)
Limit of
Detection
(µg per
filter)
816 L=0.816
m3 in 8 hours
(1.7 L/min)
816 L=0.816
m3 in 8 hours
(1.7 L/min)
20 µg
5 µg
6 µg/m 3
(half= 3 µg/m 3)
40 µg
10 µg
12 µg/m 3
(half= 6 µg/m 3)
XL= Sampling
time (min) x
2.0 L/min/
1000 m3
XL= Sampling
time (min) x
2.0 L/min/
1000 m3
20 µg
4 µg
Air Volume
for Sample
(flow rate)
12 µg
3 µg
Value is
variable based
on sampling
time (min)
BILLING CODE 4520–43–C
The air volume is treated differently for
MNM and coal samples under the existing
standards. In the case of MNM samples, 8hour equivalent time weighted averages
(TWAs) are calculated using 480 minutes (8
hours) and a flow rate of 1.7 L/min, even if
samples are collected for a longer duration.
In contrast, coal TWAs are calculated using
the full duration of the shift and a flow rate
of 2.0 L/min and converted to an MRE
equivalent concentration under existing
standards.
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Assumptions for Analyzed Samples
Samples from MNM mines that contain at
least 0.100 mg of dust mass are analyzed for
the presence of quartz and/or cristobalite. For
samples from coal mines, the minimum
129 In its Final Regulatory Economic Analysis
(FREA) for its 2016 silica rule, OSHA observed: ‘‘
. . . that XRD analysis of quartz from samples
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amount of respirable dust for a sample to be
analyzed for respirable crystalline silica is
determined by sample type and the
occupation of the miner sampled. For Sample
Types 1, 2, and 5, the sample must contain
at least 0.100 mg of respirable dust. For
Sample Types 4 and 8, the sample must
contain at least 0.200 mg of respirable dust
unless it comes from one of the following
occupations: bulldozer operator (MSIS
general occupation code 368), high wall drill
operator (code 384), high wall drill helper
(code 383), blaster/shotfirer (code 307),
refuse/backfill truck driver (code 386), and
high lift operator/front end loader (code 382).
Samples taken from these occupations must
contain at least 0.100 mg respirable dust to
be analyzed for respirable crystalline silica.
MSHA makes separate assumptions based
on the mass of respirable crystalline silica for
a sample, whether it is above or below the
method LOD. For all samples reporting a
mass of respirable crystalline silica greater or
equal to the method LOD, MSHA used the
reported values to calculate the respirable
crystalline silica concentration for the
sample. For samples with values below the
method LOD, including samples reported as
containing 0 mg of silica, MSHA used 1⁄2 of
the LOD to calculate the respirable
crystalline silica concentration of the sample.
MSHA understands that its assumptions
regarding samples with respirable crystalline
silica mass below the method LOD will have
a minimal impact on the assessment.129
prepared from reference materials can achieve
LODs and LOQs between 5 and 10 mg was not
disputed in the [rulemaking] record.’’ (OSHA,
2016).
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ER18AP24.206
Notes:
1. Samples in the designated sampling years are collected and analyzed using the corresponding analytical methods.
The values ofLOQ and LOD are determined by the analytical method, polymorph, and air volume for each sample.
The analytical methods used are P-2-2018 for MNM, and P-7-2018 or P-7-2020 for coal, respectively. For example,
method P-2-2018 is used in measuring both quartz and cristobalite for MNM samples taken from January 1, 2015, to
December 31, 2019. The values of LOQ are different for quartz and cristobalite in MNM samples. MSHA updated
its methods for coal in 2020 (Method P-7-2020) and MNM in 2022 (method P-2-2022).
2. As of the 2018 SOP the LOQ for cristobalite was 40 µg based on the instrumentation and software in use at the
time. The current LOQ as updated in the 2022 SOP is 20 µg, as based on the instrumentation and software currently
in use.
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table A2-2: MSHA's Assumptions of Values Used to Calculate Concentration of Quartz
and Cristobalite
Value Used to
Calculate RCS
Concentration
Measured Mass
Quartz
2:LOQ
Measured Value
2:LOD and 0 µg/m 3 and 0 µg/m 3 and 2014
04:45 Apr 18, 2024
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concentration of silica could be up to the
calculated maximum concentration based on
the method LOD. For example, consider a
sample from an MNM mine that was
analyzed for quartz and had a reported quartz
mass of 4 mg. This falls below the LOD of 5
mg but above 0 mg, and as such the sample
could actually contain anywhere from 0 mg of
quartz up to the LOD value of 5 mg of quartz.
In these cases, MSHA used 1⁄2 the LOD
value to calculate respirable crystalline silica
concentration. MSHA explored other options
to treat these samples such as treating the
reported silica mass as 0 mg/m3 (lower
bound) as well as assuming the sample silica
mass is just below the LOD and assigning
each sample a value of the method LOD
(upper bound). The use of the 1⁄2 LOD value
is considered a reasonable assumption since
using either the lower bound of 0 mg/m3 or
the upper bound of the associated method’s
LOD could under or overestimate exposures,
respectively. The assumption is not expected
to impact the assessment of silica
concentration because any sample results
with respirable crystalline silica mass below
the method LODs (between 3–10 mg/m3)
would also have been well below the lowest
exposure profile range (<25 mg/m3).
Quartz Mass of 0 mg
A portion of the MNM and coal samples
below the LOD are listed as having respirable
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Sfmt 4700
crystalline silica (specifically quartz) mass
levels of 0 mg. For these samples, instead of
treating the mass of silica in the sample as
a true zero, MSHA replaced the value with
1⁄2 the LOD of the associated method.
Although the respirable crystalline silica
mass of these samples is less than the LOD,
it is likely that the sample still contains a
small amount of respirable crystalline silica.
Hence, MSHA assumes a value of 1⁄2 LOD in
its calculation of respirable crystalline silica
concentration for these samples. This
assumption is considered to be reasonable
because using the lower bound of 0 mg/m3 for
these samples could underestimate the
respirable crystalline silica concentration
while using the upper bound of method
LODs could overestimate the respirable
crystalline silica concentration.
Table A2–3 presents an example for quartz,
one of the respirable crystalline silica
polymorphs. This table shows the LOD of
quartz mass and the possible range of quartz
concentrations for samples reporting a quartz
mass of 0 mg. These adjusted concentrations
are expected to have a limited impact of the
assessment of respirable crystalline silica
concentration, as supported by MSHA’s
sensitivity analyses.
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18APR3
ER18AP24.207
The reported value of respirable crystalline
silica mass from an MNM or coal sample can
fall under one of four groups: (1) at or above
the method LOQ, (2) at or above the method
LOD but below the LOQ, (3) greater than 0
mg but less than the method LOD, or (4) equal
to 0 mg. MSHA treats these samples
differently based on their respirable
crystalline silica mass.
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28439
Table A2-3: Recast Concentration of Samples with O µ,g/m 3 Quartz
Sample
Dates
Quartz Mass
LOD (Value Less
than LOD listed)
01/01/2005 12/31/2019
01/01/2005 12/31/2019
5 µg
Range of
Concentrations
(µg/m3)
Recast Concentration
MNM
(0 ue:)
5 µg
(1 to <5 ug)
0 µg/m 3
Recast using ½ LOD
1 to <6 µg/m 3
Recast using ½ LOD
Coal
08/01/2016 3 µg
0 µg/m 3
Recast using ½ LOD
(0 ue:)
08/31/2020
08/01/2016 3 µg
1 to 2 µg/m 3
Recast using ½ LOD
(1 to <3 ug)
08/31/2020
09/01/2020 3 µg
0 µg/m 3
Recast using ½ LOD
(0 µg)
07/31/2021
09/01/2020 3 µg
1 to 2 µg/m 3
Recast using ½ LOD
(1 to<3 ue:)
07/31/2021
Sources: MSHA MDRS/MSIS respirable crystalline silica database January 1, 2005, through
December 31, 2019, for MNM, August 1, 2016 - July 31, 2021, for Coal.
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cristobalite are summed to generate the total
respirable crystalline silica. If only one of
these polymorphs is detected, the sample
concentration is based on the detected
polymorph. If the concentrations of both
polymorphs (quartz and cristobalite) are
reported as 0 mg/m3, 1⁄2 the LOD mass is
assumed in calculating the concentrations
and the resulting concentrations are summed.
Unanalyzed Samples
There are also samples whose dust mass
fell below their associated mass threshold,
and as such, they were not analyzed for the
presence of quartz and/or cristobalite. The
respirable dust mass for a sample was
considered to be 0 mg when the net mass gain
of dust was 0 mg or less.
References
MSHA. 2018. P–2: X-Ray Diffraction
Determination of Quartz and Cristobalite
in Respirable Metal/Nonmetal Mine
Dust.
MSHA. 2018a. P–7: Infrared Determination of
Quartz in Respirable Coal Mine Dust.
MSHA. 2020b. P–7: Determination of Quartz
in Respirable Coal Mine Dust by Fourier
Transform Infrared Spectroscopy.
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OSHA, 2016. Final Regulatory Economic
Analysis (FEA) for OSHA’s Final Rule on
Respirable Crystalline Silica, Chapter
IV.3.2.3—Sensitivity of Sampling and
Analytical Methods.
Appendix B—Mining Commodity
Groups
For this final rule, the mining industries
are grouped into six commodities—Coal,
Metal, Nonmetal, Stone, Crushed Limestone,
and Sand and Gravel. The table below shows
the six commodity groupings based on the
Standard Industrial Classification (SIC) codes
and the 2022 North American Industry
Classification System (NAICS) codes. The
SIC system is a predecessor of NAICS using
industry titles to standardize industry
classification. The NAICS is widely used by
Federal statistical agencies, including the
Small Business Administration (SBA), for
classifying business establishments for the
purpose of collecting, analyzing, and
publishing statistical data related to the U.S.
business economy.
BILLING CODE 4520–43–P
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Cristobalite Measurement
Respirable dust samples from MNM mines
are rarely analyzed for cristobalite by MSHA,
and respirable coal dust samples are not
analyzed for the presence of cristobalite.
MNM samples are analyzed for the presence
of cristobalite only when requested by MSHA
inspectors because the geological or work
conditions indicate this specific polymorph
may be present. The LIMS database includes
samples for which cristobalite was analyzed,
either with or without quartz analysis. MSHA
uses similar assumptions for cristobalite and
quartz.
The cristobalite LOD for these samples is
10 mg. The MSHA Laboratory-reported values
are used for analyzed dust samples with
cristobalite mass values equal to or above the
method LODs. Samples that were analyzed
for cristobalite and had a cristobalite mass
value below the method LOD were assigned
values of 1⁄2 LOD, or 5 mg. For example, 267
samples, or 74.4 percent of the 359 samples
that were analyzed for cristobalite, reported
a value of 0 mg of cristobalite; these were
assigned a value of 5 mg.
When a sample is analyzed for two
polymorphs (i.e., both quartz and
cristobalite), detectable quartz and
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Mining
Commodity
Group
SIC Code Industry
2022
NAICS
Code
2022 NAICS Code Industry
PO 00000
Frm 00224
Fmt 4701
Crude Petroleum and Natural Gas
Extraction
Natural Gas Extraction
Surface Coal Mining
Underground Coal Mining
Iron Ore Mining
Gold Ore and Silver Ore Mining
Copper, Nickel, Lead, and Zinc Mining
(partial: Cooner and Nickel only)
Sfmt 4725
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18APR3
Nonmetal
Oil Shale, Oil Sand, Oil Mining
211120
Nonmetal
Coal
Coal
Metal
Metal
Natural Gas
Bituminous Coal, Lignite, and Anthracite Coal
Bituminous and Anthracite Coal
Iron Ore, Magnetite
Gold Ore, Silver Ore
211130
212114
212115
212210
212220
Metal
Copper Ore NEC, Nickel, Lead-Zinc Ore, Zinc
212230
Metal
Chromite Chromium Ore, Cobalt Ore, Columbium Tantalum Ore, Manganese Ore,
Molybdenum Ore, Tungsten Ore, Miscellaneous Metal Ore NEC, Aluminum Ore-Bauxite,
Antimony Ore, Beryl-Beryllium Ore, Mercury Ore, Platinum Group Ore, Rare Earths Ore,
Tin Ore, Titanium Ore, Zirconium Ore, Uranium-Vanadium Ore, Uranium Ore,
Vanadium Ore
212290
Other Metal Ore Mining
Stone
Dimension Stone NEC, Dimension Granite, Dimension Limestone, Dimension Marble,
Dimension Sandstone, Dimension Slate, Dimension Traprock, Dimension Basalt,
Dimension Mica, Dimension Quartzite
212311
Dimension Stone Mining and Quarrying
Crushed
Limestone
Crushed, Broken Limestone NEC
212312
Stone
Crushed, Broken Granite
212313
Stone
Crushed, Broken Stone NEC; Crushed, Broken Marble; Crushed, Broken Sandstone;
Crushed, Broken Slate; Crushed, Broken Traprock; Crushed, Broken Basalt; Crushed,
Broken Mica; Crushed, Broken Quartzite
212319
Other Crushed and Broken Stone
Mining and Quarrying
Sand and
Gravel
Construction Sand and Gravel, Common Sand
212321
Construction Sand and Gravel Mining
Crushed and Broken Limestone Mining
and Quarrying
Crushed and Broken Granite Mining
and Quarrying
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
04:45 Apr 18, 2024
ER18AP24.209
Table B-1: SIC Code Industry and 2022 NAICS Code Industry in Mining Sector
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SIC Code Industry
2022
NAICS
Code
2022 NAICS Code Industry
Frm 00225
212322
Industrial Sand Mining
Nonmetal
Kaolin and Ball Clay, Clay, Ceramic, and Refractory Minerals, Aplite, Bentonite, Brucite,
Common Clays NEC, Feldspar, Fire Clay, Fullers Earth, Kyanite, Magnesite, Common
Shale
212323
Kaolin, Clay, and Ceramic and
Refractory Minerals Mining
Nonmetal
Miscellaneous Nonmetallic Mineral NEC, Asbestos, Cryolite, Diatomaceous Earth
(Diatomite), Gilsonite, Graphite, Gypsum, Leonardite, Mica, Perlite, Pumice,
Pyrophyllite, Shell, Crushed Dimension Soapstone, Talc, Tripoli, Vermiculite, Zeolites,
Wollastonite, Gemstones, Agate, Amethyst, Emerald, Garnet, Olivine, Crystal Quartz,
Sapphire, Turquoise, Potash, Soda, and Borate Minerals NEC, Boron Minerals, Potash,
Sodium Compounds, Trona, Potassium Compounds, Phosphate Rock, Colloidal
Phosphates, Chemical and Fertilizer Mineral NEC, Barite Barium Ore, Fluorspar, Lithium
Minerals, Pigment Minerals, Pyrites, Salt, Sulfur, Brine Evaporated Salt
212390
All Other Nonmetallic Mineral Mining
Cement Manufacturing
Fmt 4701
Industrial Sand NEC, Ground Silica, Ground Cristobalite, Ground Quartz
Sfmt 4700
E:\FR\FM\18APR3.SGM
Stone
Cement
Stone
Lime
327310
327410
Metal
Alumina
331313
Agricultural Lime Manufacturing
Alumina Refining and Primary
Aluminum Production
18APR3
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04:45 Apr 18, 2024
Mining
Commodity
Group
Sand and
Gravel
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BILLING CODE 4520–43–C
Appendix C—Occupational Categories
for Respirable Crystalline Silica
Sample Collection
This Appendix explains how MSHA
categorized MNM and coal samples in
constructing respirable crystalline silica
exposure profile tables for the final rule.
MSHA developed respirable crystalline silica
exposure profile tables using its inspectors’
sampling results. One set of exposure profile
tables displays the analysis of 15 years of
respirable crystalline silica sampling data
collected from MNM mines (Attachment 1),
and the other set displays the analysis of 5
years of respirable crystalline silica samples
collected from coal mines (Attachment 2).130
In the MNM tables, the respirable crystalline
silica concentration information is broken
out by 5 commodities (e.g., ‘‘Metal,’’
‘‘Crushed Limestone,’’ etc.) and then by 11
occupational categories (e.g., ‘‘Drillers,’’
‘‘Stone Cutting Operators,’’ etc.). The data for
coal mining is disaggregated by 2 locations
(‘‘Underground’’ and ‘‘Surface’’) and then by
9 occupational categories (e.g., ‘‘Crusher
Operators,’’ ‘‘Continuous Mining Machine
Operators,’’ etc.).
Job Codes and Respirable Dust Sampling
MSHA inspectors use job codes to label
samples of respirable dust when they
conduct health inspections.131 Following the
sampling strategy outlined in the most recent
MSHA Health Inspection Procedures
Handbook (December 2020; PH20–V–4), the
inspectors determine potential airborne
contaminants to which miners may be
exposed, including respirable dust, and then
take samples from the appropriate miners or
working areas at a mine. Using gravimetric
samplers, the inspectors collect respirable
dust samples at MNM and coal mines. When
submitting the collected samples to MSHA’s
Laboratory for analysis, the inspectors label
their samples with the three-digit job code
that best describes the duties that each miner
was performing during the sampling period.
The three-digit job codes are taken from
MSHA’s Inspection Application System
(IAS), which includes 220 job codes for coal
mines and 121 job codes for MNM mines.
Attachments 3 and 4 list the complete list of
IAS job codes for coal and MNM operations,
respectively.
Coal Job Codes: The coal job codes have
generally been consistent over time, with
new codes added when needed. In the threedigit coal job code, the first digit generally
identifies where the work is taking place in
the mine: 0 (Underground Section Workers—
Face); 1 (General Underground—Non-Face); 2
(Underground Transportation—Non-Face); 3
(Surface); 4 (Supervisory and Staff); 5
(MSHA—State); and 6 (Shaft and Slope
Sinking). The coal codes starting with 6 were
added in 2020 to better delineate the samples
for miners conducting shaft and slope
sinking activities. An example is presented
below in Table C–1. IAS has the same job
code for the duties of a coal ‘‘supervisor/
foreman’’ as two predecessor documents—
the ‘‘Job Code Pocket Cards’’ for coal mining,
used by MSHA’s predecessor, the Mining
Enforcement and Safety Administration
(MESA) (see Attachment 5), and a Fall 1983
Mine Safety and Health publication.
Table C-1: Example of Consistent Coal Job Classifications - Occupations Classified as
"Supervisor/Foreman"
Occupation / Activity
Section Foreman
Bullgang Foreman/Labor Foreman
Maintenance Foreman
Assist Mine Foreman/Assist Mine
Manager
Mine Foreman/Mine Manager
Fire Boss Pre-Shift Examiner
Superintendent
Outside Foreman
Preparation Plant Foreman
MESA Pocket
Card
Job Code
1983
Publication 1
Job Code
2022 IAS
Job Code
049
149
418
049
149
418
049
149
418
430
430
430
449
462
481
489
494
449
462
481
489
494
449
462
481
489
494
MNM Job Codes: Many of the 121 MNM job
codes are similar to the coal job codes, as
noted in Attachment 4. One major difference
is that unlike the coal job codes, MNM job
codes are not based on the location of the
work/job. The first digit of the three-digit
MNM job code does not indicate whether a
job is located at an underground or surface
area of the mine. For example, a ‘‘MNM
Diamond Drill Operator’’ (Job Code 034)
could be working on the surface or
underground, whereas a ‘‘Coal Drill
Operator’’ would have a different job code
based on the miner’s location within a mine
(Job Code 034—underground at the face; Job
Code 334—at the surface).
130 For coal mines, the analysis is based on
samples collected by inspectors beginning on
August 1, 2016, when Phase III of MSHA’s 2014
RCMD standard went into effect. Samples taken
prior to implementation of the RCMD standard
would not be representative of current respirable
crystalline silica exposure levels in coal mines.
131 The job codes have been referred to as both
job codes and occupation codes by MSHA. For
example, in the Mine Data Retrieval System, they
are called job codes; in other materials, including
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Occupational Categories for the Respirable
Crystalline Silica Rulemaking
Some of the original work to group the
MNM job codes into occupational categories
was completed in 2010 in support of earlier
rulemaking efforts. The MNM occupational
categories were developed first and were
later updated with additional sampling data
as it became available. The coal occupational
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categories were developed several years later
and were generally modeled after the MNM
tables; however, coal occupational categories
are first divided based on surface and
underground locations because occupational
activities at different locations of a mine can
have differing impacts on coal miners’
exposures to respirable crystalline silica.
Originally, MSHA used 9 coal and 14 MNM
occupational categories for its respirable
crystalline silica data analyses.
For the respirable crystalline silica
exposure profile tables in the proposed
MSHA’s Inspection Application System (IAS), they
are called occupational codes. For the purposes of
this document, the term job code has been used to
clearly differentiate the job codes from the
occupational categories.
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Source: Fall 1983 Mine Safety and Health publication (page 6).
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
respirable crystalline silica rule, MSHA made
no change to the 9 coal occupational
categories, but condensed the 14 MNM
occupational categories to 11. These
occupational categories are meant to
reasonably group multiple job codes with
similar occupational activities/tasks and
engineering controls. The grouping of job
codes into occupational categories purposely
focused on the occupational activities/tasks
and exposure risk of the miner performing a
particular job rather than the type of mining
equipment utilized by the miner. The
creation of occupational categories based on
the types of equipment utilized by miners
would have failed to accurately characterize
the risk of individual miners.
Coal Occupational Categories
There are 220 job codes for coal miners in
IAS.132 Overall, 209 job codes are included
in the 9 occupational categories. Some job
codes were excluded, primarily because
sampling data were not available for those
job codes. The codes that have been excluded
are:
• Job code 0 ‘‘Area,’’ because area samples
are not specific to any one occupation.
• Job code 398 ‘‘Groundman,’’ because
there were no sample data for this code in
the respirable crystalline silica sampling
dataset.
• Job codes 590 ‘‘Education Specialist,’’
591 ‘‘Mineral Industrial Safety Officer,’’ 592
‘‘Mine Safety Instructor,’’ and 594 ‘‘Training
Specialist,’’ because there were no coal
respirable crystalline silica (quartz) data for
these codes for the timeframe selected.
• Job codes 602 ‘‘Electrician,’’ 604
‘‘Mechanic,’’ 609 ‘‘Supply Person,’’ 632
‘‘Ventilation Worker,’’ and 635 ‘‘Continuous
Miner Operator Helper,’’ because there were
no sample data for these codes in the
respirable crystalline silica sampling dataset.
The remaining 209 coal job codes are first
divided by the job location—underground or
surface—because potential respirable
crystalline silica exposures at coal mines can
28443
vary depending on where a miner works at
a given mine. (Three job codes are used in
both underground and surface locations: job
codes 402 ‘‘Master Electrician,’’ 404 ‘‘Master
Mechanic,’’ and 497 ‘‘Clerk/Timekeeper.’’)
The underground and surface job codes are
further grouped on the basis of the types of
tasks and typical engineering controls. For
example, as shown in Figure C–1, the
underground ‘‘Continuous Mining Machine
Operators’’ occupational category includes 14
different occupations that involve drilling
activities—occupations such as ‘‘Coal Drill
Helper,’’ ‘‘Coal Drill Operator,’’ and ‘‘Rock
Driller.’’ The underground ‘‘Operators of
Large Powered Haulage Equipment’’
occupational category has 12 similar
occupations including ‘‘Loading Machine
Operator,’’ ‘‘Shuttle Car Operator,’’ and
‘‘Motorman.’’
Figure C–1: Examples of the Grouping of
Coal Job Codes Into Coal Occupational
Categories
Coal Occupational Categories
Developed by OSRV for Proposed Rule
There are five categories of underground
occupations and four categories of surface
occupations.
The five underground occupational
categories include:
(1) Continuous Mining Machine Operators
(e.g., Coal Drill Helper and Coal Drill
Operator);
(2) Operators of Large Powered Haulage
Equipment (e.g., Shuttle Car, Tractor, Scoop
Car);
(3) Longwall Workers (e.g., Headgate
Operator and Jack Setter (Longwall));
(4) Roof Bolters (e.g., Roof Bolter and Roof
Bolter Helper); and
(5) Underground Miners (e.g., Electrician,
Mechanic, Belt Man/Conveyor Man, and
Laborer, etc.).
The four surface occupational categories
include:
(1) Drillers (e.g., Coal Drill Operator, Coal
Drill Helper, and Auger Operator);
(2) Operators of Large Powered Haulage
Equipment (e.g., Backhoe, Forklift, and
Shuttle Car);
(3) Crusher Operators (e.g., Crusher
Attendant, Washer Operator, and ScalperScreen Operator); and
(4) Mobile Workers (e.g., Electrician,
Mechanic, Blaster, Cleanup Man, Mine
Foreman, etc.).
Attachments 1 and 3 provide the full lists
of occupational categories and coal job codes.
132 IAS also contains 272 coal job codes that are
used to fill out a Mine Accident, Injury and Illness
Report (MSHA Form 7000–1). These codes were not
included in the respirable crystalline silica
VerDate Sep<11>2014
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MNM Occupational Categories
From the 121 MNM job codes in IAS, 120
job codes are included in the occupational
categories and 1 job code is excluded. The
code that has been excluded is:
• Job code 413 ‘‘Janitor,’’ because there
were no sample data for this code in the
respirable crystalline silica sampling dataset.
Of the 120 job codes included, 1 job code
was listed in both the ‘‘Crushing Equipment
and Plant Operators’’ occupational category
and the ‘‘Kiln, Mill and Concentrator
Workers’’ category. The code that was used
twice is:
• Job Code 388 ‘‘Screen/Scalper
Operators,’’ because MNM job codes do not
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indicate the location where the work is
taking place and this work can be conducted
either in a plant or on the surface of the
mine.
The final 121 MNM job codes (with job
code 388 included twice) were first grouped
into 14 occupational categories based on the
types of tasks and typical engineering
controls used. For example, as seen in Figure
C–2, the ‘‘Drillers’’ occupational category
includes the 20 different occupations that
involve drilling activities, such as ‘‘Diamond
Drill Operator,’’ ‘‘Drill Operator Churn,’’ and
‘‘Continuous Miner Operator.’’ ‘‘Belt
Cleaner,’’ ‘‘Belt Crew,’’ and ‘‘Belt Vulcanizer’’
are included in the occupational category,
‘‘Conveyor Operators.’’ Similar tasks were
grouped together because the work activities
and respirable crystalline silica exposures
were anticipated to be comparable.
Figure C–2: Examples of the Grouping of
MNM Job Codes Into MNM Occupational
Categories
exposure profile tables and are not discussed
further in this document.
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
MNM 1ob Codes Used by
MNM Occupational Categories
Developed by OSRV for Proposed Rule
The 14 occupational categories were:
(1) Bagging Machines;
(2) Stone Saws;
(3) Stone Trimmers, Splitters;
(4) Truck Loading Stations;
(5) Mobile Workers (e.g., Laborers,
Electricians, Mechanics, and Supervisors);
(6) Conveyors;
(7) Crushers;
(8) Dry Screening Plants;
(9) Kilns/Dryers, Rotary Mills, Ball Mills,
and Flotation/Concentrators;
(10) Large Powered Haulage Equipment
(e.g., Trucks, FELs, Bulldozers, and Scalers);
(11) Small Powered Haulage Equipment
(e.g., Bobcats and Forklifts);
(12) Jackhammers;
(13) Drills; and
(14) Other Occupations.
After additional consideration, it was
determined that the original 14 categories
could be further condensed into the final 11
categories since some of the occupational
categories contained job codes where the
types of tasks and engineering and
administrative controls were similar enough
to be combined.
The final 11 occupational categories
include:
(1) Drillers (e.g., Diamond Drill Operator,
Wagon Drill Operator, and Drill Helper);
(2) Stone Cutting Operators (e.g.,
Jackhammer Operator, Cutting Machine
Operator, and Cutting Machine Helper);
(3) Operators of Large Powered Haulage
Equipment (e.g., Trucks, Bulldozers, and
Scalers);
(4) Conveyor Operators (e.g., Belt Cleaner,
Belt Crew, and Belt Vulcanizer);
(5) Crushing Equipment and Plant
Operators (Crusher Operator/Worker, Scalper
Screen Operator, and Dry Screen Plant
Operator);
(6) Kiln, Mill, and Concentrator Workers
(e.g., Ball Mill Operator, Leaching Operator,
and Pelletizer Operator);
(7) Operators of Small Powered Haulage
Equipment (e.g., Bobcats, Shuttle Car, and
Forklifts);
(8) Packaging Equipment Operators (e.g.,
Bagging Operator and Packaging Operations
Worker);
(9) Truck Loading Station Tenders (e.g.,
Dump Operator and Truck Loader);
(10) Mobile Workers (Laborers,
Electricians, Mechanics, and Supervisors,
etc.); and
(11) Miners in Other Occupations (Welder,
Dragline Operator, Shotcrete/Gunite Man,
and Dredge/Barge Operator, etc.).
The sampling data for each of the 11
occupational categories were then
summarized by commodity group (‘‘Metal,’’
‘‘Nonmetal,’’ ‘‘Stone,’’ ‘‘Crushed Limestone,’’
and ‘‘Sand and Gravel’’) based on the
material being extracted.133 The available
sampling data were then collated for each
occupation and commodity and summarized
by concentration ranges in the exposure
profile tables for MNM mines.
133 Crushed Limestone and Sand and Gravel were
considered separately because these commodities
make up a large percentage of inspection samples.
Watts et al. (2012). Respirable crystalline silica
[Quartz] Concentration Trends in Metal and
Nonmetal Mining, J Occ Environ Hyg 9:12, 720–
732.
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BILLING CODE 4520–43–P
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ER18AP24.086
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28445
Attachment 1: Tables for MNM Respirable Crystalline Silica Samples
Table Cl-1: Summary Statistics ofRespirable Crystalline Silica in Metal/Nonmetal (MNM)
Sector from 2005 to 2019, by Commodity and Occupational Category
Metal
Number
of
Samples
Occupation
Drillers
352
31.0
16.0
549
10
92.0
81.5
195
Operators of Large Powered Haulage Equipment
673
28.5
17.0
426
Conveyor Operators
29
57.4
29.0
382
Crushing Equipment and Plant Operators
628
79.3
50.0
1,263
Kiln, Mill, and Concentrator Workers
467
35.4
20.0
588
Operators of Small Powered Haulage Equipment
38
104.4
7.0
3,361
Packaging Equipment Operators
88
36.4
9.0
371
Truck Loading Station Tenders
21
31.2
15.0
179
1,004
52.0
26.0
3,588
189
67.5
25.0
1,690
3,499
49.1
25.0
3,588
Drillers
194
22.0
6.0
353
Stone Cutting Operators
81
39.1
7.0
566
Operators of Large Powered Haulage Equipment
922
16.9
7.0
449
Conveyor Operators
31
10.2
6.0
37
Crushing Equipment and Plant Operators
586
27.8
13.0
613
Kiln, Mill, and Concentrator Workers
423
24.0
13.0
384
Operators of Small Powered Haulage Equipment
237
25.4
10.0
190
Packaging Equipment Operators
1,390
36.2
18.0
2,124
Truck Loading Station Tenders
42
15.1
3.0
134
1,053
25.3
10.0
574
206
14.4
3.0
191
5,165
26.4
11.0
2,124
707
35.3
16.0
1,148
Stone Cutting Operators
1,969
73.7
48.0
999
Operators of Large Powered Haulage Equipment
3,223
20.2
9.0
559
44
41.1
23.0
309
2,764
35.8
20.0
613
Kiln, Mill, and Concentrator Workers
308
29.0
10.0
675
Operators of Small Powered Haulage Equipment
404
34.3
20.0
315
Stone Cutting Operators
Mobile Workers
Miners in Other Occupations
Metal OVERALL
(All Occupations)
Nonmetal
Mobile Workers
Miners in Other Occupations
Nonmetal OVERALL
(All Occupations)
Stone
Drillers
Conveyor Operators
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Crushing Equipment and Plant Operators
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ISO Concentration, µg/m 3
Mean
Median
Max
(µg/m3)
(µg/m3)
(µg/m3)
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Number
of
Samples
Occupation
7.0
1,130
Truck Loading Station Tenders
113
19.9
3.0
190
4,778
36.2
17.0
1,548
597
24.7
12.0
347
15,415
36.6
17.0
1,548
Drillers
670
25.5
7.0
1,306
Stone Cutting Operators
143
75.8
38.0
574
5,522
15.8
7.0
567
24
27.7
12.0
164
3,593
23.2
11.0
613
Kiln, Mill, and Concentrator Workers
162
11.0
3.0
81
Operators of Small Powered Haulage Equipment
162
25.7
10.0
342
Packaging Equipment Operators
270
11.9
3.0
113
Truck Loading Station Tenders
122
11.7
3.0
112
3,931
27.8
11.0
4,289
585
17.3
6.0
613
15,184
21.7
10.0
4,289
Drillers
169
46.6
20.0
959
Stone Cutting Operators
243
94.3
55.0
1,095
6,676
22.3
12.0
613
87
69.9
28.0
1,605
3,994
42.9
25.0
613
Kiln, Mill, and Concentrator Workers
442
81.5
44.0
1,800
Operators of Small Powered Haulage Equipment
269
61.4
29.0
580
Packaging Equipment Operators
724
75.1
51.0
652
Truck Loading Station Tenders
155
59.3
37.0
613
Mobile Workers
4,450
46.4
23.0
3,676
Miners in Other Occupations
1,297
28.0
11.0
613
Sand and Gravel OVERALL
(All Occuoations)
18,506
38.7
20.0
3,676
MNMOVERALL
57,769
33.2
15.0
4,289
Operators of Large Powered Haulage Equipment
Conveyor Operators
Crushing Equipment and Plant Operators
Mobile Workers
Miners in Other Occupations
Crushed Limestone OVERALL
(All Occuoations)
Operators of Large Powered Haulage Equipment
Conveyor Operators
Crushing Equipment and Plant Operators
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Max
(µg/m3)
30.0
Stone OVERALL
(All Occuoations)
VerDate Sep<11>2014
Median
(µg/m3)
508
Miners in Other Occupations
Sand and
Gravel
Mean
(µg/m3)
Packaging Equipment Operators
Mobile Workers
Crushed
Limestone
ISO Concentration, µg/m 3
04:45 Apr 18, 2024
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18APR3
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28447
Source: MSHA MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through December 31, 2019
(version 20220812). All samples were of sufficient mass to be analyzed for respirable crystalline silica.
Notes:
Summary of personal samples presented as ISO 8-hour TWA concentrations. The proposed permissible exposure limit (PEL) for
all mines is 50 µg/m 3 as an 8-hour time-weighted average (8-hour TWA) sample collected according to the ISO standard
7708: 1995: Air Quality-Particle Size Fraction Definitions for Health-Related Sampling.
1. The compliance samples summarized in this table were collected by MSHA inspectors as 8-hour TWAs using ISOcompliant sampling equipment with an air flow rate of 1.7 L/min, with results comparable to the proposed PEL.
2. When the mass of respirable crystalline silica collected was too small to be reliably detected by the laboratory, a mass of 2.5
µg for quartz and 5 µg for cristobalite (1/2 the respective limits of detection for these two forms of crystalline silica) were
assumed and used to calculate sample results.
3. The procedure to calculate the ISO 8-hour TWA concentration (µg/m 3) is:
8-hour TWA=
quartz mass
X 1000 ..!::....
(480 minutes) x (air flow rate)
m3
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where: quartz mass is in micrograms (µg); normalized sampling time is 8 hours (480 minutes); flow rate= 1.7 L/min;
1000 Liters (L) per cubic meter (m3)
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Number
of
Samples
Sample Counts in ISO Concentration Ranges, µg/m 3
::;25
>25 to
<50
>50to
< 100
> 100 to
<250
> 250 to
<500
>500
352
220
74
42
13
2
1
10
1
2
3
4
0
0
Operators of Large Powered Haulage Equipment
673
423
142
80
26
2
0
Conveyor Operators
29
12
8
4
4
1
0
Crushing Equipment and Plant Operators
628
173
143
165
115
26
6
Kiln, Mill, and Concentrator Workers
467
276
99
68
18
5
1
Operators of Small Powered Haulage Equipment
38
30
5
1
1
0
1
Fmt 4701
Packaging Equipment Operators
88
60
8
11
8
1
0
Truck Loading Station Tenders
21
13
5
1
2
0
0
1,004
500
227
164
82
24
7
189
98
33
32
18
4
4
3,499
1,806
746
571
291
65
20
Drillers
194
144
29
13
7
1
0
Stone Cutting Operators
81
58
8
6
6
2
1
Operators of Large Powered Haulage Equipment
922
768
94
38
19
3
0
Conveyor Operators
31
27
4
0
0
0
0
Crushing Equipment and Plant Operators
586
384
108
68
22
3
1
Kiln, Mill, and Concentrator Workers
423
292
81
40
9
1
0
Operators of Small Powered Haulage Equipment
237
166
30
31
10
0
0
Packaging Equipment Operators
1,390
808
276
210
83
9
4
Truck Loading Station Tenders
42
35
4
2
1
0
0
Metal
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18APR3
ER18AP24.090
Drillers
Mobile Workers
Miners in Other Occupations
Metal SUBTOTAL
(All Occupations)
Nonmetal
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Occupation
Frm 00232
04:45 Apr 18, 2024
Commodity
28448
VerDate Sep<11>2014
Table Cl-2: Sample Count Distribution of Respirable Crystalline Silica Exposure in Metal/Nonmetal (MNM) Sector from
2005 to 2019, by Commodity and Occupational Category
ddrumheller on DSK120RN23PROD with RULES3
VerDate Sep<11>2014
Commodity
Occupation
Sample Counts in ISO Concentration Ranges, µg/m 3
::;25
> 100 to
<250
> 250 to
<500
>500
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1
206
176
17
12
1
0
0
5,165
3,640
780
513
196
29
7
707
423
149
90
35
8
2
Stone Cutting Operators
1,969
618
423
548
280
77
23
Operators of Large Powered Haulage Equipment
3,223
2,443
456
243
75
5
1
44
23
10
8
2
1
0
2,764
1,582
606
386
164
22
4
Kiln, Mill, and Concentrator Workers
308
219
42
31
11
3
2
Operators of Small Powered Haulage Equipment
404
228
87
67
18
4
0
Packaging Equipment Operators
508
393
57
25
22
6
5
Truck Loading Station Tenders
113
85
11
14
3
0
0
4,778
2,860
946
635
285
38
14
597
419
100
54
23
1
0
15,415
9,293
2,887
2,101
918
165
51
Drillers
670
535
64
46
16
5
4
Stone Cutting Operators
143
50
30
34
19
8
2
5,522
4,613
564
254
82
7
2
24
17
3
2
2
0
0
3,593
2,650
537
304
80
17
5
Kiln, Mill, and Concentrator Workers
162
146
10
6
0
0
0
Operators of Small Powered Haulage Equipment
162
114
24
16
7
1
0
Packaging Equipment Operators
270
240
17
11
2
0
0
Drillers
Sfmt 4725
Mobile Workers
Miners in Other Occupations
Stone SUBTOTAL
(All Occupations)
Operators of Large Powered Haulage Equipment
Crushing Equipment and Plant Operators
28449
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Crushing Equipment and Plant Operators
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38
Conveyor Operators
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93
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04:45 Apr 18, 2024
129
Nonmetal SUBTOTAL
(All Occupations)
Crushed
Limestone
>50to
< 100
782
Miners in Other Occupations
Stone
>25 to
<50
1,053
Mobile Workers
Conveyor Operators
ER18AP24.091
Number
of
Samples
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28450
VerDate Sep<11>2014
Occupation
Number
of
Samples
Sample Counts in ISO Concentration Ranges, µg/m 3
::;25
Truck Loading Station Tenders
> 50 to
<100
> 100 to
<250
> 250 to
<500
>500
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18APR3
122
110
6
5
1
0
0
3,931
2,831
593
344
128
21
14
585
502
46
26
6
4
1
15,184
11,808
1,894
1,048
343
63
28
Drillers
169
99
35
22
8
3
2
Stone Cutting Operators
243
64
48
79
32
12
8
6,676
4,891
1,127
502
133
20
3
87
41
25
7
11
2
1
3,994
2,004
1,014
625
288
53
10
Kiln, Mill, and Concentrator Workers
442
132
117
118
45
20
10
Operators of Small Powered Haulage Equipment
269
114
69
51
24
6
5
Packaging Equipment Operators
724
169
188
229
107
22
9
Truck Loading Station Tenders
155
59
32
39
22
2
1
Mobile Workers
4,450
2,341
988
675
343
75
28
Miners in Other Occupations
1,297
936
198
105
37
16
5
Sand and Gravel SUBTOTAL
(All Occupations)
18,506
10,850
3,841
2,452
1,050
231
82
MNMOVERALL
57,769
37,397
10,148
6,685
2,798
553
188
Mobile Workers
Miners in Other Occupations
Crushed Limestone SUBTOTAL
(All Occupations)
Sand and Gravel
>25 to
<50
Operators of Large Powered Haulage Equipment
Conveyor Operators
Crushing Equipment and Plant Operators
Source: MSHA MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through December 31, 2019 (version 20220812). All samples were of sufficient
mass to be analyzed for respirable crystalline silica.
Note:
1. Personal samples were collected using ISO-compliant sampling equipment and calculated as an 8-hour time-weighted average (8-hour TWA). Samples were collected using an
air flow rate of 1. 7 L/min and reported as 8-hour TW As. See notes in Summary table C2-1 for additional details.
ER18AP24.092
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04:45 Apr 18, 2024
Commodity
ddrumheller on DSK120RN23PROD with RULES3
VerDate Sep<11>2014
Table Cl-3: Percentage Distribution of Respirable Crystalline Silica Exposure in Metal/Nonmetal (MNM) Sector from 2005 to
2019, by Commodity and Occupational Category
Metal
Occupation
Drillers
Total
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18APR3
21.0%
11.9%
3.7%
0.6%
0.3%
100%
10
10.0%
20.0%
30.0%
40.0%
0.0%
0.0%
100%
Operators of Large Powered Haulage
Equipment
673
62.9%
21.1%
11.9%
3.9%
0.3%
0.0%
100%
Conveyor Operators
29
41.4%
27.6%
13.8%
13.8%
3.4%
0.0%
100%
Crushing Equipment and Plant Operators
628
27.5%
22.8%
26.3%
18.3%
4.1%
1.0%
100%
Kiln, Mill, and Concentrator Workers
467
59.1%
21.2%
14.6%
3.9%
1.1%
0.2%
100%
Operators of Small Powered Haulage
Equipment
38
78.9%
13.2%
2.6%
2.6%
0.0%
2.6%
100%
Packaging Equipment Operators
88
68.2%
9.1%
12.5%
9.1%
1.1%
0.0%
100%
Truck Loading Station Tenders
21
61.9%
23.8%
4.8%
9.5%
0.0%
0.0%
100%
1,004
49.8%
22.6%
16.3%
8.2%
2.4%
0.7%
100%
189
51.9%
17.5%
16.9%
9.5%
2.1%
2.1%
100%
3,499
51.6%
21.3%
16.3%
8.3%
1.9%
0.6%
100%
Drillers
194
74.2%
14.9%
6.7%
3.6%
0.5%
0.0%
100%
Stone Cutting Operators
81
71.6%
9.9%
7.4%
7.4%
2.5%
1.2%
100%
Operators of Large Powered Haulage
Equipment
922
83.3%
10.2%
4.1%
2.1%
0.3%
0.0%
100%
Conveyor Operators
31
87.1%
12.9%
0.0%
0.0%
0.0%
0.0%
100%
Crushing Equipment and Plant Operators
586
65.5%
18.4%
11.6%
3.8%
0.5%
0.2%
100%
Kiln, Mill, and Concentrator Workers
423
69.0%
19.1%
9.5%
2.1%
0.2%
0.0%
100%
Operators of Small Powered Haulage
Equipment
237
70.0%
12.7%
13.1%
4.2%
0.0%
0.0%
100%
1,390
58.1%
19.9%
15.1%
6.0%
0.6%
0.3%
100%
Mobile Workers
Miners in Other Occupations
Metal SUBTOTAL
(All Occupations)
28451
62.5%
Packaging Equipment Operators
ER18AP24.093
::;25
Percentage (%) of Samples in ISO Concentration Ranges, µg/m 3
> 250 to
>25to
>50to
> 100 to
>500
::; 100
::;250
::;500
::;50
352
Stone Cutting Operators
Nonmetal
Number
of
Samples
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
04:45 Apr 18, 2024
Commodity
ddrumheller on DSK120RN23PROD with RULES3
Occupation
Jkt 262001
9.5%
4.8%
2.4%
0.0%
0.0%
100%
1,053
74.3%
12.3%
8.8%
3.6%
0.9%
0.1%
100%
206
85.4%
8.3%
5.8%
0.5%
0.0%
0.0%
100%
5,165
70.5%
15.1%
9.9%
3.8%
0.6%
0.1%
100%
707
59.8%
21.1%
12.7%
5.0%
1.1%
0.3%
100%
Stone Cutting Operators
1,969
31.4%
21.5%
27.8%
14.2%
3.9%
1.2%
100%
Operators of Large Powered Haulage
Equipment
3,223
75.8%
14.1%
7.5%
2.3%
0.2%
0.0%
100%
44
52.3%
22.7%
18.2%
4.5%
2.3%
0.0%
100%
2,764
57.2%
21.9%
14.0%
5.9%
0.8%
0.1%
100%
Kiln, Mill, and Concentrator Workers
308
71.1%
13.6%
10.1%
3.6%
1.0%
0.6%
100%
Operators of Small Powered Haulage
Equipment
404
56.4%
21.5%
16.6%
4.5%
1.0%
0.0%
100%
Packaging Equipment Operators
508
77.4%
11.2%
4.9%
4.3%
1.2%
1.0%
100%
Truck Loading Station Tenders
113
75.2%
9.7%
12.4%
2.7%
0.0%
0.0%
100%
4,778
59.9%
19.8%
13.3%
6.0%
0.8%
0.3%
100%
597
70.2%
16.8%
9.0%
3.9%
0.2%
0.0%
100%
15,415
60.3%
18.7%
13.6%
6.0%
1.1%
0.3%
100%
Drillers
670
79.9%
9.6%
6.9%
2.4%
0.7%
0.6%
100%
Stone Cutting Operators
143
35.0%
21.0%
23.8%
13.3%
5.6%
1.4%
100%
5,522
83.5%
I0.2%
4.6%
1.5%
0.1%
0.0%
100%
24
70.8%
12.5%
8.3%
8.3%
0.0%
0.0%
100%
3,593
73.8%
14.9%
8.5%
2.2%
0.5%
0.1%
100%
162
90.1%
6.2%
3.7%
0.0%
0.0%
0.0%
100%
Nonmetal SUBTOTAL
(All Occupations)
PO 00000
Frm 00236
Drillers
Conveyor Operators
Crushing Equipment and Plant Operators
Fmt 4701
Sfmt 4725
E:\FR\FM\18APR3.SGM
18APR3
83.3%
Miners in Other Occupations
Mobile Workers
Miners in Other Occupations
Stone SUBTOTAL
(All Occupations)
Crushed
Limestone
Operators of Large Powered Haulage
Equipment
Conveyor Operators
Crushing Equipment and Plant Operators
Kiln, Mill, and Concentrator Workers
ER18AP24.094
Total
42
Mobile Workers
Stone
::,25
Percentage (%) of Samples in ISO Concentration Ranges, µg/m 3
>25to
>50to
> 100 to
> 250 to
>500
<50
<500
< 100
< 250
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
04:45 Apr 18, 2024
Truck Loading Station Tenders
Number
of
Samples
28452
VerDate Sep<11>2014
Commodity
ddrumheller on DSK120RN23PROD with RULES3
VerDate Sep<11>2014
Commodity
Occupation
::,25
Percentage (%) of Samples in ISO Concentration Ranges, µg/m 3
>25to
>50to
> 100 to
> 250 to
>500
<50
<500
< 100
< 250
Total
14.8%
9.9%
4.3%
0.6%
0.0%
100%
Packaging Equipment Operators
270
88.9%
6.3%
4.1%
0.7%
0.0%
0.0%
100%
Truck Loading Station Tenders
122
90.2%
4.9%
4.1%
0.8%
0.0%
0.0%
100%
3,931
72.0%
15.1%
8.8%
3.3%
0.5%
0.4%
100%
585
85.8%
7.9%
4.4%
1.0%
0.7%
0.2%
100%
15,184
77.8%
12.5%
6.9%
2.3%
0.4%
0.2%
100%
Drillers
169
58.6%
20.7%
13.0%
4.7%
1.8%
1.2%
100%
Stone Cutting Operators
243
26.3%
19.8%
32.5%
13.2%
4.9%
3.3%
100%
6,676
73.3%
16.9%
7.5%
2.0%
0.3%
0.0%
100%
87
47.1%
28.7%
8.0%
12.6%
2.3%
1.1%
100%
3,994
50.2%
25.4%
15.6%
7.2%
1.3%
0.3%
100%
Kiln, Mill, and Concentrator Workers
442
29.9%
26.5%
26.7%
10.2%
4.5%
2.3%
100%
Operators of Small Powered Haulage
Equipment
269
42.4%
25.7%
19.0%
8.9%
2.2%
1.9%
100%
Packaging Equipment Operators
724
23.3%
26.0%
31.6%
14.8%
3.0%
1.2%
100%
Truck Loading Station Tenders
155
38.1%
20.6%
25.2%
14.2%
1.3%
0.6%
100%
Mobile Workers
4,450
52.6%
22.2%
15.2%
7.7%
1.7%
0.6%
100%
Miners in Other Occupations
1,297
72.2%
15.3%
8.1%
2.9%
1.2%
0.4%
100%
Sand and Gravel SUBTOTAL
(All Occupations)
18,506
58.6%
20.8%
13.2%
5.7%
1.2%
0.4%
100%
MNMOVERALL
57,769
64.7%
17.6%
11.6%
4.8%
1.0%
0.3%
100%
PO 00000
70.4%
Jkt 262001
162
Crushed Limestone SUBTOTAL
(All Occupations)
Miners in Other Occupations
Frm 00237
Fmt 4701
Operators of Large Powered Haulage
Equipment
Conveyor Operators
Sfmt 4725
Crushing Equipment and Plant Operators
E:\FR\FM\18APR3.SGM
18APR3
ER18AP24.095
28453
Source: MSHA MSIS respirable crystalline silica data for the MNM industry, January 1, 2005, through December 31, 2019 (version 20220812). All samples were of sufficient
mass to be analyzed for respirable crystalline silica.
Note:
1. Personal samples were collected using ISO-compliant sampling equipment and calculated as an 8-hour time-weighted average (8-hour TWA). Samples were collected using an
air flow rate of 1.7 L/min and reported as 8-hour TWAs. See notes in Summary table C2-1 for additional details.
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
04:45 Apr 18, 2024
Operators of Small Powered Haulage
Equipment
Mobile Workers
Sand and Gravel
Number
of
Samples
ddrumheller on DSK120RN23PROD with RULES3
28454
VerDate Sep<11>2014
Attachment 2: Tables for Coal Respirable Crystalline Silica Samples
Table C2-1: Summary Statistics ofRespirable Crystalline Silica Exposure in Coal Sector from 2016 to 2021, by Location and Occupational
Category
Underground
Jkt 262001
PO 00000
Frm 00238
Fmt 4701
Surface
Number of
Samples
Occupation
ISO Concentration
(8-hour TWA u11/m 3)
Mean
Median
Max
Sfmt 4725
E:\FR\FM\18APR3.SGM
Continuous Mining Machine Operators (Underground)
9,910
24.6
18.5
390.5
Operators of Large Powered Haulage Equipment
(Underground)
21,777
17.7
13.6
476.8
Longwall Workers (Underground)
3,176
32.9
22.2
453.4
RoofBolters (Underground)
14,306
26.5
20.9
778.6
Underground Miners (Underground)
3,926
15.7
11.l
324.0
Underground OVERALL
(All Occupations)
53,095
22.1
16.0
778.6
Drillers (Surface)
1,762
36.5
20.9
747.8
Operators of Large Powered Haulage Equipment
(Surface)
5,313
19.9
9.9
721.9
631
9.6
6.2
117.0
Mobile Workers (Surface)
2,326
12.6
8.6
288.3
Surface OVERALL
(All Occupations)
10,032
20.5
11.1
747.8
COAL OVERALL
63,127
21.9
16.0
778.6
Crusher Operators (Surface)
18APR3
Source: MSHA MSIS respirable crystalline silica data for the Coal Industry, August 1, 2016, through July 31, 2021 (version 20220617). All samples were of
sufficient mass to be analyzed for respirable crystalline silica.
Notes: Summary of personal samples presented as ISO 8-hour TWA concentrations. The proposed permissible exposure limit (PEL) for all mines is 50 µg/m 3
as an 8-hour time-weighted average (8-hour TWA) sample collected according to the ISO standard 7708: 1995: Air Quality-Particle Size Fraction
Definitions for Health-Related Sampling.
1. The compliance samples summarized in this table were collected by MSHA inspectors for the entire duration of each miner's work shift using sampling
equipment with an air flow rate of 2 L/min, with results reported as MRE TWA concentrations. For this rulemaking analysis, MSHA recalculated the samples
as ISO-equivalent 8-hour TWA concentrations, comparable to the proposed PEL (since samples were not collected using an ISO-compliant sampling
method). The procedure to calculate an ISO-equivalent concentration from an MRE TWA sample concentration involves normalizing the sample
concentration to an 8-hour TWA and applying the empirically derived conversion factor of 0.857 recommended by NIOSH (1995a) using the following
equation:
.
.
2. ISO 8-hour TWA concentrat10n = (MRE TWA m µg/m 3 ) x
(original sampling time)
(
.
4B0mmutes
)
x 0.857
where: both concentrations (ISO 8-hour TWA and MRE TWA) are concentrations presented as µg/m3; sampling time in minutes.
3. When the mass ofrespirable crystalline silica collected was too small to be reliably detected by the laboratory, a mass of 1.5 µg (1/2 the limit of detection)
was assumed and used to calculate sample results.
ER18AP24.096
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
04:45 Apr 18, 2024
Location
ddrumheller on DSK120RN23PROD with RULES3
VerDate Sep<11>2014
> 100 to
::S250
111>"/m 3
111>"/m 3
>500
111>"/m 3
6,750
2,366
572
67
144
11
0
21,777
17,938
3,110
576
51
95
7
0
3,176
1,767
857
356
62
125
9
0
14,306
8,768
4,194
1,093
106
141
3
1
3,926
3,396
398
96
11
22
3
0
53,095
38,619
10,925
2,693
297
527
33
1
Drillers (Surface)
1,762
1,019
422
180
30
90
17
4
Operators of Large Powered Haulage
Equipment (Surface)
5,313
4,268
627
219
45
132
18
4
588
28
13
1
1
0
0
2,326
2,102
164
45
3
11
1
0
18APR3
Surface OVERALL
(All Occupations)
10,032
7,977
1,241
457
79
234
36
8
COAL OVERALL
63,127
46,596
12,166
3,150
376
761
69
9
Jkt 262001
> 85.7 to
::S 100
111>"/m 3
> 250 to
111>"/m 3
> 50 to
::S 85.7
111>"/m 3
Location
Underground
Occupation
Continuous Mining Machine Operators
(Underground)
PO 00000
Operators of Large Powered Haulage
Equipment (Underground)
Frm 00239
Longwall Workers (Underground)
RoofBolters (Underground)
Fmt 4701
Underground Miners (Underground)
Sfmt 4725
Underground OVERALL
(All Occupations)
Surface
Crusher Operators (Surface)
Mobile Workers (Surface)
>25to
Number
of
Samples
::S25
111>"/m 3
9,910
631
:::;so
:::;soo
Source: MSHA MSIS respirable crystalline silica data for the coal industry, August 1, 2016, through July 31, 2021 (version 20220617). All samples were of
sufficient mass to be analyzed for respirable crystalline silica.
Note:
1. Personal samples presented in terms ofISO concentrations, normalized to 8-hour time-weighted averages (TWAs). The samples were originally collected for
the entire duration of each miner's work shift, using an air flow rate of 2 L/min. See notes in Summary table C 1-1 for additional details.
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Sample Counts in ISO Concentration Ranges, 8-hour TWA, µg/m 3
E:\FR\FM\18APR3.SGM
04:45 Apr 18, 2024
Table C2-2: Sample Count Distribution of Respirable Crystalline Silica Exposure in Coal Sector from 2016 to 2021, by
Location and Occupational Category
28455
ER18AP24.097
ddrumheller on DSK120RN23PROD with RULES3
28456
VerDate Sep<11>2014
Location
Jkt 262001
PO 00000
Underground
Occupation
Percentage(%) of Samples in ISO Concentration Ranges, 8-hour TWA, µg/m 3
Frm 00240
E:\FR\FM\18APR3.SGM
18APR3
>50to
:5 85.7
>85.7 to
:5100
> 100 to
:5 250
>250to
:5 500
>500
9,910
68.1%
23.9%
5.8%
0.7%
1.5%
0.1%
0%
100%
21,777
82.4%
14.3%
2.6%
0.2%
0.4%
<0.1%
0%
100%
3,176
55.6%
27%
11.2%
2%
3.9%
0.3%
0%
100%
14,306
61.3%
29.3%
7.6%
0.7%
1%
<0.1%
<0.1%
100%
3,926
86.5%
10.1%
2.4%
0.3%
0.6%
0.1%
0%
100%
53,095
72.7%
20.6%
5.1%
0.6%
1%
0.1%
<0.1%
100%
Drillers (Surface)
1,762
57.8%
24%
10.2%
1.7%
5.1%
1%
0.2%
100%
Operators of Large Powered Haulage
Equipment (Surface)
5,313
80.3%
11.8%
4.1%
0.8%
2.5%
0.3%
0.1%
100%
631
93.2%
4.4%
2.1%
0.2%
0.2%
0%
0%
100%
2,326
90.4%
7.1%
1.9%
0.1%
0.5%
<0.1%
0%
100%
Surface OVERALL
(All Occupations)
10,032
79.5%
12.4%
4.6%
0.8%
2.3%
0.4%
0.1%
100%
COAL OVERALL
63,127
73.8%
19.3%
5%
0.6%
1.2%
0.1%
<0.1%
100%
Continuous Mining Machine Operators
(Underground)
Longwall Workers (Underground)
Roof Bolters (Underground)
Fmt 4701
Sfmt 4725
>25to
:5 50
Underground Miners (Underground)
Underground OVERALL
(All Occupations)
Crusher Operators (Surface)
Mobile Workers (Surface)
Source: MSHA MSIS respirable crystalline silica data for the coal industry, August 1, 2016, through July 31, 2021 (version 20220617). All samples were of
sufficient mass to be analyzed for respirable crystalline silica.
Note:
1. Personal samples presented in terms ofISO concentrations, normalized to 8-hour time-weighted averages (TWAs). The samples were originally collected for
the entire duration of each miner's work shift, using an air flow rate of 2 L/min. See notes in Summary table C 1-1 for additional details.
ER18AP24.098
Total
:5 25
Operators of Large Powered Haulage
Equipment (Underground)
Surface
Number
of
Samples
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
04:45 Apr 18, 2024
Table C2-3: Percentage Distribution of Respirable Crystalline Silica Exposure in Coal Sector from 2016 to 2021, by Location
and Occupational Category
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28457
Attachment 3: Coal Job Codes
The complete list of job codes that are found in IAS, as of March 11, 2022, are included
below, with Table C3-1 listingjob codes for coal miners. For coal, the first digit of the job code
identifies where the work is taking place. For example, codes starting with 0 represent jobs that
occur at the underground face of the mine. Job codes that start with 6 were added in 2020.
0- Underground Section Workers (Face)
1 - General Underground (Non-Face)
2- Underground Transportation (Non-Face)
3 -Surface
4 - Supervisory and Staff
5 - MSHA - State
6- Shaft and Slope Sinking
Table C3-1: Coal Job Codes
Table C3-1: Coal Job Codes
Occupation / Activity
Job Code
Mechanic
038
039
040
041
042
043
Mechanic Helper
044
Underground Section Workers (Face)
000
001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
ddrumheller on DSK120RN23PROD with RULES3
019
031
032
033
034
035
036
037
VerDate Sep<11>2014
04:45 Apr 18, 2024
Area
Belt Man/Conveyor Man
Electrician
Electrician Helper
Rock Duster
045
046
047
Blaster/Shooter/Shotfirer
Stopping BuilderNentilation
Man/Mason
Supply Man
048
Auger (Jack Setter) (Intake Side)
049
Wireman
Roof Bolter (Twin Head) (Intake
Side)
Shuttle Car Operator (Off
Standard Side)
Roof Bolter (Twin Head) (Return
Side)
050
051
052
053
054
055
Fan Attendant
Laborer
060
Auger (Timberman) (Return Side)
061
Auger (Timberman) (Intake Side)
Roof Bolter (Mounted) (Intake
Side)
064
Coal Drill Helper
070
071
072
Coal Drill Operator
073
Shotfirer Helper
Brattice Man
Continuous Miner Helper
Frm 00241
Headgate Operator
Jack Setter (Longwall)
Loading Machine Helper
Loading Machine Operator
Longwall Operator (Tailgate
Side)
Rockman
Roof Bolter (Single Head)
Roof Bolter Helper (Single Head)
Roof Bolter (Mounted) (Return
Side)
Section Foreman
Shuttle Car Operator (Standard
Side)
Stall Driver
Tailgate Operator
Utility Man
Scoop Car Onerator
Auger (Jack Setter) (Return Side)
Longwall (Return-Side Face
Worker)
Longwall (Return-Side Fixed)
Longwall Operator (Headgate
Side)
Auger Operator
Auger Helper
Mobile Bridge Operator
Shuttle Car Operator (Off
Standard)
Tractor Operator/Motorman
General Underground (Non-Face)
Cutting Machine Helper
PO 00000
Cutting Machine Operator
Hand Loaders
074
Continuous Miner Operator
Jkt 262001
Occupation / Activity
101
Fmt 4701
Sfmt 4725
Belt Man/Conveyor Man
E:\FR\FM\18APR3.SGM
18APR3
ER18AP24.099
Job Code
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table C3-1: Coal Job Codes
Job Code
102
103
104
105
106
108
109
110
111
112
113
114
115
116
117
118
119
122
123
146
149
154
155
156
157
158
159
160
Table C3-1: Coal Job Codes
Occupation / Activity
Job Code
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
333
334
340
341
342
343
344
345
347
348
349
350
351
Electrician
Electrician Helper
Mechanic
Mechanic Helper
Rock Duster
Stopping BuilderNentilation
Man/Mason
SunnlvMan
Timberman
Wireman
Belt V ulcanizer
Cleanup Man
Coal Sampler
Fan Attendant
Laborer
Rodman
Oiler/Greaser
Welder
Coal Dump Operator
Transit Man
Roof Bolter
Bullgang Foreman/Labor
Foreman
Belt Cleaner
Chainman
Rock Driller
Pumper
Rock Machine Operator
Water Line Man
ddrumheller on DSK120RN23PROD with RULES3
Shonman
Underground Transportation (Non-Face)
201
216
220
221
240
250
261
262
263
265
269
276
277
VerDate Sep<11>2014
04:45 Apr 18, 2024
Belt Man/Convevor Man
Trackrnan
Cager
Hoistrnan
Loader Head/Roscoe Operator
Shuttle Car Operator
Batterv Station Operator
Brakeman/Roperider
Track Foreman
Dispatcher
Motorman
Driver
BugQV Pusher
Surface
Jkt 262001
PO 00000
Frm 00242
Fmt 4701
Sfmt 4725
Occupation / Activity
Convevor Operator
Electrician
Electrician Helper
Mechanic
Mechanic Helner
Welder (Non-Shop)
Blaster/Shooter/Shotfirer
Mason
SuPnlvMan
Scranner Operator
Wireman
Belt Vulcanizer
Cleanup Man
Coal Samnler
Fan Attendant
Laborer/Blacksmith
Rodman
Oiler/Greaser
Welder (Shon)
Cage Attendant/Cager
Hoist Engineer/Onerator
Coal Strip Operator
Transit Man
Backhoe Operator
Diester Table Operator
Forklift Onerator
Pumper
Utilitv Man
Vacuum Filter Operator
Face Worker-Shaft/Slope Sinking
Clam Ooerator
Coal Drill Helper
Coal Drill Ooerator
Boom Operator
Belt Man/Convevor Man
Bit Sharoener
Car Trimmer/Car Loader
Car Shake-Out Operator
Crusher Attendant
Froth Cell Operator
Machinist
Rot"rv Dumn Onerator
Shuttle Car Onerator
Scoon Onerator
E:\FR\FM\18APR3.SGM
18APR3
ER18AP24.100
28458
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table C3-1: Coal Job Codes
352
354
355
356
357
358
359
360
362
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
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387
388
390
391
392
393
394
395
396
397
398
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Table C3-1: Coal Job Codes
Occupation / Activity
Job Code
Supervisory And Staff
Steel Worker
402
404
414
418
423
Sweeper Operator
Chainman
Rock Driller
Washer Operator
Water Circuit Operator
Self-Propelled Compactor
Operator
430
Shopman Repair Cars
449
Brakeman
456
Dispatcher
462
464
481
489
494
495
496
497
Waterbov
Coal Shovel Operator
Bulldozer Operator
Motorman/Locomotive Operator
Auger Operator
Auger Helper
Barge Attendant
Car Dropper
Cleaning Plant Operator
590
591
592
593
594
Road Grader Operator
Coal Truck Driver
Road Roller Operator
Crane Operator/Dragline
Operator
Dryer Operator
602
604
607
609
612
614
616
631
632
Fine Coal Plant Operator
Hoist Onerator Helper
Highlift Operator/Front End
Loader
Hicliwall Drill Helper
Hi2:hwall Drill Operator
Lampman
Refuse Truck Driver/Backfill
Truck Drive
Rotary Bucket Excavator
Operator
635
Scalper-Screen Operator
Weighman
636
646
647
649
Camenter
650
Water Truck Operator
654
656
Silo Operator
Striooing Shovel Operator
Tipple Operator
Watchman
Yard Engine Operator
673
Groundman
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Master Electrician
Master Mechanic
Dust Sampler
Maintenance Foreman
Surveyor
Assist Mine Foreman/Assist Mine
Manager
Mine Foreman/Mine Manager
Engineers
(ElectricityN entilation/Minin
Fire Boss Pre-Shift Examiner
Inspector
Superintendent
Outside Foreman
Preparation Plant Foreman
Safety Director
Union Representative
Clerk/Timekeeper
MSHA-State
Education Specialist
Mineral Industrial Safety Officer
Mine Safety Instructor
Safety Representative
Training Specialist
Shaft and Slope Sinking
Electrician
Mechanic
Blaster/Shooter/Shot Firer
Supply Person
(Intake) Twin Head Roof Bolter
(Return) Twin Head Roof Bolter
Laborer
Blaster/Shooter/Shot Firer Helper
Ventilation Worker
Continuous Miner Operator
Helper
Continuous Miner Operator
Single Head Roof Bolter
Single Head Roof Bolter Helper
Foreman
(Standard Side) Shuttle Car
Operator
Scoop Car Operator/Mucker
Rock Driller
(Off Standard Side) Shuttle Car
Operator
E:\FR\FM\18APR3.SGM
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ER18AP24.101
Job Code
28459
28460
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Attachment 4: MNM Job Codes
The complete list of job codes that are found in IAS, as of March 11, 2022, are included
below with Table C4-1 outlining job codes for MNM miners.
Table C4-1: MNM Job Codes
Job Code
028
029
030
032
034
035
036
037
038
039
041
043
045
046
048
053
057
058
059
079
134
154
179
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216
234
261
279
331
334
342
344
352
367
368
372
375
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Occupation / Activity
Job Code
Brattice Man
376
378
379
385
Diamond Drill Operator
387
Scoop Tram Operator
Mucking Machine Operator
Slusher
Continuous Miner Helper
388
389
Continuous Miner Operator
Cutting Machine Helper
Cutting Machine Operator
392
Hand Loader (Load Only)
393
394
397
Jacksetter
Gathering Arm Loader
Operator
Hangup Man, Chute Blaster
399
StopeMiner
413
416
420
434
Drift Miner
456
Rock Bolter, Roof Bolter
Roof Bolter Mounted
Utility Man
Raise Miner
Crusher Operator, Crusher
Worker, Pan-Feeder Operator
Jet-Piercing Channeler
Operator
Belt Cleaner, Belt Picker
Ball, Rod Or Pebble Mill
Operator
Track Man; Track Gang
479
488
513
514
516
534
Jet-Piercing Drill Operator
579
Battery Station Operator
Hammer Mill Operator
588
Clam-Shell Operator
601
602
603
604
Wagon Drill Operator
Bit Grinder; Bit Sharpener
Car Shake-Out Operator
Iron Worker, Metal Worker
607
Shovel Operator
608
609
612
613
Bulldozer Operator
Barge Attendant, Boat
Operator, Dredge Operator
Road Grader Operator
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Occupation/ Activity
Truck Driver
Mobile Crane Operator
Dryer Operator, Kiln Operator
Lampman
Rotary Bucket Excavator
Operator
Scalper-Screen Operator
Forklift Operator
Toplander, Skip Dumper,
Tipple Operator
Weighman, Scale Man
Carpenter
Yard Engineer Operator
Dimension Stone Cutter And
Polisher; Rock Sawer
Janitor
Salvage Crew
Aerial Tram Operator
Churn Drill Operator
Engineer (Electrical,
Ventilation, Mining, Etc.)
Hydrating Plant Operator
Dry Screening Plant Operator
Building Repair And
Maintenance
Laboratory Technician
Tamping Machine Operator
Jacking Or Stoper Drill
Operator
Slurry, Mixing Or Pumping
Operations Worker
Sizing And Washing
Operations Worker
Conveyor Belt Crew
Electrician
Electrician Helper
Mechanic
Jackhammer Operator,
Chipping Hammer Operator
Mason
Supply Man, Nipper
Belt Vulcanizer
Cleanup Man
E:\FR\FM\18APR3.SGM
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ER18AP24.102
Table C4-1: MNM Job Codes
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table C4-1: MNM Job Codes
Table C4-1: MNM Job Codes
614
616
618
619
622
623
634
649
660
663
668
669
673
674
678
679
682
706
708
710
716
726
728
734
739
747
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750
759
763
765
766
778
779
782
804
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Occupation/ Activity
Job Code
Sampler, Dust Sampler
807
Laborer, Bullgang
Greaser, Oiler
Welder (Welding, Cutting,
Brazing, Hard Surfacing,
Soldering)
Dump Operator
825
833
847
850
878
Surveyor, Transit Man
Rotary (Electrical Or
Hydraulic) Drill Operator
Administrative, Supervisory,
Management Personnel
Machinist
879
894
920
Tractor Operator
921
930
Bin Puller; Truck Loader
934
Shaft Miner, Shaft Sinker
Leaching Operations Worker
Warehouseman; Supply
Handler
Dragline Operator
Flotation Mill Operator;
Concentrator Operator
Scraper-Loader Operator
950
962
969
979
Occupation / Activity
Powder Gang, Powderman,
Powder Monkey, Shooter,
Shotfitter, Blaster
Bobcat Operator
Drill Helper, Chuck Tender
Scaling (Mechanical)
Ramcar Operator
Overhead Crane Operator
Bagging Or Packaging
Operations Worker
Painter
Cager, Cage Attendant, Station
Attendant
Hoist Operator
Skip Tender
Jumbo Percussion Drill
Operator
Shuttle Car Operator
(Electrical)
Trip Rider, Swamper
Motorman
Packaging Operations Worker
Shotcrete Man, Gunite Man
Ventilation Crew
Ground Control (Wood And
Steel), Timberman
Cement Man, Concrete Worker
Grizzley Man, Grizzley Tender
Complete Load/Haul/Dump
Cycle
Rotary (Pneumatic) Drill
Operator
Hand Trimmer (Load And
Dump)
Scaling (Hand)
Shuttle Car Operator
(Electrical)
Raise Borer Operator
Shaft Repairer
Sandfiller (Dry Operations)
Sandfiller (Wet Operations)
Backhoe Operator
Pelletizing Operations Worker
Front-End Loader Operator
Plumber, Pipe Fitter,
Millwri2:ht
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Job Code
28461
28462
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Attachment 5. Examples of Job Code Pocket Cards
Inspectors previously received pocket-sized job code cards for use in filling out forms
with the correct job code. Now, a drop-down menu in IAS is used to select the codes. Table C5-l
contains Underground Coal Mining Occupation Codes from Coal Job Code Cards used by
MESA between 1973 and 1977. Table C5-2 contains Surface Occupation Codes from Coal Job
Codes used by MESA between 1973 and 1977.
Table C5-1 Coal Job Code Cards, Underground Coal Mining Occupation Codes
Table CS-1: Coal Job Code Cards (MESA,
1973-1977)
Underground Coal Mining Occupation Codes
Occupation / Activity
Job Code
Auger Operator
048
054
049
Beater
044
Section Workers (Face)
071
070
031
001
007
032
013
033
034
035
036
037
038
002
003
015
039
040
010
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055
041
016
042
043
008
004
005
010
006
045
046
047
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Auger Helper
Belt Man/Conveyor Man
007
031
007
050
051
008
009
052
010
053
008
011
Blaster
Brattice Man
Cleanup Man
Coal Drill Helper
Coal Drill Operator
Continuous Miner Helper
Continuous Miner Operator
Cutting Machine Helper
Cutting Machine Operator
Electrician
Electrician Helper
Hand Loaders
154
101
112
149
155
113
122
114
102
103
115
118
149
116
108
104
Headgate Operator
Jack Setter (Auger - intake
side)
Jack Setter (Auger - return
side)
Jack Setter (Longwall)
Laborer
Loading Machine Helper
Loading Machine Operator
Mason
Mechanic
Mechanic Helper
Prepman
Rock Duster
Rockman
Roof Bolter
Roof Bolter Helper
PO 00000
Roof Bolter Mounted
Scoop Car Operator
Section Foreman
Sheer Operator/Plow Operator
Longwall
Shooter
Shotfire Helper
Shotfirer
Shuttle Car Operator
Stall Driver
Stonning Builder
Supply Man
Tailgate Operator
Timberman
Utility Man
Ventilation Man
Wireman
General Underground (Non-Face)
Fan Attendant
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Belt Cleaner
Belt Man/Conveyor Man
Belt Vulcanizer
Bullgang Foreman
Chainman
Cleanup Man
Coal Dump Operator
Coal Sampler
Electrician
Electrician Helper
Fan Attendant
Greaser
Labor Foreman
Laborer
Mason
Mechanic
E:\FR\FM\18APR3.SGM
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Job Code
Table CS-1: Coal Job Code Cards (MESA,
1973-1977)
Underground Coal Mining Occupation Codes
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table C5-1: Coal Job Code Cards (MESA,
1973-1977)
Underground Coal Mining Occupation Codes
Job Code
Table C5-1: Coal Job Code Cards (MESA,
1973-1977)
Underground Coal Mining Occupation Codes
Occupation/ Activity
Job Code
Occupation/ Activity
105
Mechanic Helper
118
Oiler
157
Pumper
261
Battery Station Operator
156
Rock Driller
201
Belt Man/Convevor Man
106
Rock Duster
262
Brakeman
158
Rock Machine Operator
277
Bu2:!!V Pusher
117
Rodman
220
Cager
111
Wireman
Underground Transportation (Non-Face)
146
Roof Bolter
265
Dispatcher
160
Shopman
276
Driver
108
Stonning Builder
221
Hoistman
109
SuPPlyMan
240
Leader Head Operator
269
Motorman
Timberman
262
Rope Rider
123
Transmit Man
240
Roscoe Operator
108
Ventilation Man
250
Shuttle Car Operator
159
Water Line Man
216
Trackman
119
Welder
110
28463
Table C5-2 Coal Job Code Cards, Surface Occupation Codes
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Job Code
100
370
Occupation/ Activity
Job Code
Occupation / Activity
*203(b) Miner
322
Coal Strip Operator
Auger Operator
314
Coal Sampler
371
Auger Helper
367
Coal Shovel Operator
372
Barge Attendant
376
Coal Truck Driver
312
Belt Vulcanizer
301
Conveyor Operator
307
Blaster
378
Crane Operator
368
Bulldozer Operator
365
Dispatcher
340
Boom Operator
378
Dragline Operator
362
Brakeman
379
Dryer Operator
320
Cage Attendant/Cager
302
Electrician
373
Car Dropper
303
Electrician Helper
394
Carpenter
315
Fan Attendant
355
Chainman
380
Fine Coal Plant Operator
331
Clam Operator
318
Greaser
374
Cleaning Plant Operator
398
313
Cleanup Man
382
Groundman
Hi2:hlift Operator
333
Coal Drill Helper
383
Hiirhwall Drill Helper
Coal Drill Operator
384
Hi2:hwall Drill Operator
334
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Table C5-2: Coal Job Code Cards (MESA,
1973-1977)
Surface Occupation Codes
04:45 Apr 18, 2024
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Table C5-2: Coal Job Code Cards (MESA,
1973-1977)
Surface Occupation Codes
28464
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table C5-2: Coal Job Code Cards (MESA,
1973-1977)
Surface Occupation Codes
Job Code
321
381
316
385
308
304
305
369
318
310
386
375
356
317
387
388
360
307
307
350
390
391
309
392
323
396
366
395
393
Table C5-2: Coal Job Code Cards (MESA,
1973-1977)
Surface Occupation Codes
Occupation / Activity
Occupation / Activity
Job Code
319
311
397
Hoist Engineer/Operator
Hoist Operator Helper
Laborer Blacksmith
Lampman
Mason
430
Mechanic
Mechanic Helper
497
414
Motorman
Oiler
456
Pan Scraper Operator
462
464
418
402
404
449
489
494
495
481
423
497
496
Refuse Truck Driver
Road Grader Operator
Rock Driller
Rodman
Rotary Bucket Excavator
Operator
Scalper-Screen Operator
Shopman Repair Care
Shooter
Shotfirer
Shuttle Car Operator
Silo Operator
Stripping Shovel Operator
SunnlvMan
Tinnle Operator
590
Transmit Man
591
Watchman
592
593
594
Waterboy
Water Truck Operator
Wei!!hman
Welder (Shop) Blacksmith
Wireman
Yard Engine Operator
Supervisory and Staff
Assistant Mine
Foreman/Assistant Mine
Manager
Clerk
Dust Sampler
Engineers (Electricity,
Ventilation, Mining, etc.)
Fire Boss Pre-Shift Examiner
Inspector
Maintenance Foreman
Master Electrician
Master Mechanic
Mine Foreman/Mine Manager
Outside Foreman
Preparation Plant Foreman
Safety Director
Superintendent
Surveyor
Timekeeper
Union Representative
MESA-State
Education Specialist
Mineral Industry Safety
Officer
Mine Safety Instructor
Safety Representative
Training Specialist
MNM Job Code Cards (1997)
ER18AP24.107
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Table CS-3 includes MNM Job Codes from a MNM Job Code Card printed in 1997 by the GPO
and which referenced a 1981 MSHA form (MSHA Form 4000-50, Sept. 1981).
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28465
Table C5-3: MNM Job Code Cards (1997)
Job Code
Occupation/ Activity
Development and Production
Jackhammer Operator;
607
Chipping Hammer Operator
Powder Gang; Powderman;
Power Monkey; Shooter;
807
Shotfirer; Blaster
609
Supply Man; Nipper
Ground Control (wood and
710
steel); Timberman
216
516
833
034
134
234
334
434
534
634
734
934
035
036
037
038
045
046
747
847
048
053
057
058
059
759
663
765
766
Track Man; Track Gang
Tamping Machine Operator
Drill Helper; Chuck Tender
Diamond Drill Operator
Jet-Piercing Channeler
Operator
Jet-Piercing Drill Operator
Wagon Drill Operator
Churn Drill Operator
Jackleg or Stoper Drill
Operator
Rotary (electric or hydraulic)
Drill Operator
Rotary (pneumatic) Drill
Operator
Jumbo Percussion Drill
Operator
Continuous Miner Helper
Continuous Miner Onerator
Cutting Machine Helper
Cutting Machine Ooerator
Hangup Man; Chute Blaster
Rock Bolter; Roof Bolter
Scaling (hand)
Scaling (mechanical)
Roof Bolter Mounted
Utility Man
StopeMiner
Drift Miner
Raise Miner
Raise Borer Operator
Shaft Miner; Shaft Sinking
Sandfiller (drv operations)
673
079
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Leaching Operations Worker
Crusher Operator; Crusher
Worker; Pan-Feeder Operator
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Sandfiller (wet operations)
Dimension Stone Cutter and
399
Polisher; Rock Sawer
Ore/Mineral Processing
28466
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table C5-3: MNM Job Code Cards (1997)
179
279
379
479
579
679
779
879
388
488
588
601
420
920
921
622
825
726
028
728
029
030
930
331
039
739
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043
344
750
850
950
154
962
367
368
668
669
969
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Occupation/ Activity
Ball, Rod, or Pebble Mill
Operator
Hammer Mill Operator
Dryer Operator; Kiln Operator
Hydrating Plant Operator
Slurry, Mixing or Pumping
Operations Worker
Flotation Mill Operator;
Concentrator Operator
Pelletizing Operations Worker
Bagging or Packaging
Operations Worker
Scalper-Screen Operator
Drv Screening Plant Operator
Sizing and Washing
Operations Worker
Load/Haul/Oum p
Conveyor Belt Crew
Aerial Tram Operator
Cager; Cage Attendant;
Station Attendant
Hoist Operator
Dump Operator
Bobcat Operator
Grizzly Man; Grizzly Tender
Scoop-Tram Operator
Complete Load/Haul/Dump
Cycle
Mucking Machine Operator
Slusher Operator
Skip Tender
Clam-Shell Operator
Hand Loader (load only)
Hand Trammer (load and
dump)
Gathering Arm Loader
Operator
Car Shake-Out Operator
Shuttle Car Operator (diesel)
Ramcar Operator
Shuttle Car Operator (electric)
Belt Cleaner; Belt Picker
Trip Rider; Swamper
Shovel Onerator
Bulldozer Operator
Tractor Operator
Bin Puller; Truck Loader
Motorman
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Job Code
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
28467
Table CS-3: MNM Job Code Cards (1997)
372
376
378
678
778
878
682
782
387
389
392
393
397
602
603
604
804
706
608
708
612
513
613
416
616
716
618
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619
032
041
342
352
660
261
763
375
385
394
894
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PO 00000
Frm 00251
Occupation / Activity
Barge Attendant; Boat
Operator; DredQe Ooerator
Truck Driver
Mobile Crane Operator
Dragline Operator
Backhoe Operator
Overhead Crane Onerator
Scraper-Loader Operator
Front-End Loader Ooerator
Rotary Bucket Excavator
Operator
Forklift Ooerator
Toplander; Skip Dumper;
Tipple Ooerator
Weighman· Scale Man
Yard Engine Onerator
Maintenance
Electrician
Electrician Heloer
Mechanic
Plumber; Pipe Fitter;
Millwright
Shotcrete Man; Gunite Man
Mason
Ventilation Crew
Belt Vulcanizer
Building Repair and
Maintenance
Cleanup Man
Salvage Crew
Laborer; Bullgang
Cement Man; Concrete
Worker
Greaser; Oiler
Welder (welding, cutting,
brazing, hard surfacing,
soldering)
Brattice Man
Jacksetter
Bit Grinder; Bit Sharoener
Iron Worker; Metal Worker
Machinist
Battery Station Ooerator
Shaft Reoairer
Road Grader Ooerator
Lampman
Carpenter
Painter
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Job Code
28468
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Table C5-3: MNM Job Code Cards (1997)
Occupation / Activity
Job Code
Miscellaneous
649
456
674
Laboratory Technician
Sampler; Dust Sampler
Surveyor; Transmit Man
Administrative, Supervisory,
Management Personnel
Engineer (electrical,
ventilation, mining, etc.);
Technical Services
Warehouseman; Supply
Handler
BILLING CODE 4520–43–C
30 CFR Part 75
List of Subjects
Coal, Mine safety and health,
Reporting and recordkeeping
requirements, Underground coal mines,
Ventilation.
30 CFR Part 56
Chemicals, Electric power,
Explosives, Fire prevention, Hazardous
substances, Incorporation by reference,
Metal and nonmetal mining, Mine safety
and health, Noise control, Reporting and
recordkeeping requirements, Surface
mining.
30 CFR Part 57
Chemicals, Electric power,
Explosives, Fire prevention, Gases,
Hazardous substances, Incorporation by
reference, Metal and nonmetal mining,
Mine safety and health, Noise control,
Radiation protection, Reporting and
recordkeeping requirements,
Underground mining.
30 CFR Part 60
Coal, Incorporation by reference,
Metal and nonmetal mining, Medical
surveillance, Mine safety and health,
Respirable crystalline silica, Reporting
and recordkeeping requirements,
Surface mining, Underground mining.
30 CFR Part 70
ddrumheller on DSK120RN23PROD with RULES3
Janitor
30 CFR Part 90
Coal, Mine safety and health,
Reporting and recordkeeping
requirements, Respirable dust.
Christopher J. Williamson,
Assistant Secretary of Labor for Mine Safety
and Health.
For the reasons discussed in the
preamble, the Mine Safety and Health
Administration is amending 30 CFR
subchapters K, M, and O as follows:
Subchapter K—Metal and Nonmetal Mine
Safety and Health
PART 56—SAFETY AND HEALTH
STANDARDS—SURFACE METAL AND
NONMETAL MINES
1. The authority citation for part 56
continues to read as follows:
■
Authority: 30 U.S.C. 811.
Subpart D—Air Quality and Physical
Agents
2. Amend § 56.5001 by revising the
introductory text to read as follows:
Coal, Mine safety and health,
Reporting and recordkeeping
requirements, Respirable dust,
Underground coal mines.
■
30 CFR Part 71
The following is required until April
7, 2026. Except as permitted by
§ 56.5005—
*
*
*
*
*
■ 3. Add § 56.5001T to read as follows:
§ 56.5001 Exposure limits for airborne
contaminants.
Coal, Mine safety and health,
Reporting and recordkeeping
requirements, Surface coal mines,
Underground coal mines.
30 CFR Part 72
§ 56.5001T Exposure limits for airborne
contaminants.
Coal, Health standards, Incorporation
by reference, Mine safety and health,
Training, Underground mining.
As of April 8, 2026 the following is
required, except as permitted by
§ 56.5005—
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(a) TLVs standard. Except as provided
in paragraph (b) of this section and in
part 60 of this chapter, the exposure to
airborne contaminants shall not exceed,
on the basis of a time weighted average,
the threshold limit values adopted by
the American Conference of
Governmental Industrial Hygienists, as
set forth and explained in the 1973
edition of the Conference’s publication,
entitled TLV’s Threshold Limit Values
for Chemical Substances in Workroom
Air Adopted by ACGIH for 1973, pages
1 through 54. This publication is
incorporated by reference into this
section with the approval of the Director
of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5450; (202) 693–9440; or at any Mine
Safety and Health Enforcement District
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov. The material may be obtained
from American Conference of
Governmental Industrial Hygienists,
1330 Kemper Meadow Drive, Attn:
Customer Service, Cincinnati, OH
45240; www.acgih.org.
(b) Asbestos standard—(1)
Definitions. Asbestos is a generic term
for a number of asbestiform hydrated
silicates that, when crushed or
processed, separate into flexible fibers
made up of fibrils.
Asbestos means chrysotile,
cummingtonite-grunerite asbestos
(amosite), crocidolite, anthophylite
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ER18AP24.111
413
514
614
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
asbestos, tremolite asbestos, and
actinolite asbestos.
Asbestos fiber means a fiber of
asbestos that meets the criteria of a fiber.
Fiber means a particle longer than 5
micrometers (mm) with a length-todiameter ratio of at least 3-to-1.
(2) Permissible Exposure Limits
(PELs)—(i) Full-shift limit. A miner’s
personal exposure to asbestos shall not
exceed an 8-hour time-weighted average
full-shift airborne concentration of 0.1
fiber per cubic centimeter of air (f/cc).
(ii) Excursion limit. No miner shall be
exposed at any time to airborne
concentrations of asbestos in excess of
1 fiber per cubic centimeter of air (f/cc)
as averaged over a sampling period of 30
minutes.
(3) Measurement of airborne asbestos
fiber concentration. Potential asbestos
fiber concentration shall be determined
by phase contrast microscopy (PCM)
using the OSHA Reference Method in
OSHA’s asbestos standard found in 29
CFR 1910.1001, Appendix A, or a
method at least equivalent to that
method in identifying a potential
asbestos exposure exceeding the 0.1 f/cc
full-shift limit or the 1 f/cc excursion
limit. When PCM results indicate a
potential exposure exceeding the 0.1 f/
cc full-shift limit or the 1 f/cc excursion
limit, samples shall be further analyzed
using transmission electron microscopy
according to NIOSH Method 7402 or a
method at least equivalent to that
method.
(c) Required action. Employees shall
be withdrawn from areas where there is
present an airborne contaminant given a
‘‘C’’ designation by the Conference and
the concentration exceeds the threshold
limit value listed for that contaminant.
§ 56.5001
[Removed]
4. Effective April 8, 2026, remove
§ 56.5001.
■
§ 56.5001T
[Redesignated as § 56.5001]
5. Effective April 8, 2026, redesignate
§ 56.5001T as § 56.5001.
■ 6. Amend § 56.5005 by revising the
introductory text to read as follows:
■
ddrumheller on DSK120RN23PROD with RULES3
§ 56.5005 Control of exposure to airborne
contaminants.
The following is required until April
7, 2026. Control of employee exposure
to harmful airborne contaminants shall
be, insofar as feasible, by prevention of
contamination, removal by exhaust
ventilation, or by dilution with
uncontaminated air. However, where
accepted, engineering control measures
have not been developed or when
necessary by the nature of work
involved (for example, while
establishing controls or occasional entry
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into hazardous atmospheres to perform
maintenance or investigation),
employees may work for reasonable
periods of time in concentrations of
airborne contaminants exceeding
permissible levels if they are protected
by appropriate respiratory protective
equipment. Whenever respiratory
protective equipment is used a program
for selection, maintenance, training,
fitting, supervision, cleaning, and use
shall meet the following minimum
requirements:
*
*
*
*
*
■ 7. Add § 56.5005T to read as follows:
§ 56.5005T Control of exposure to airborne
contaminants.
As of April 8, 2026, the following is
required. Control of employee exposure
to harmful airborne contaminants shall
be, insofar as feasible, by prevention of
contamination, removal by exhaust
ventilation, or by dilution with
uncontaminated air. However, where
accepted engineering control measures
have not been developed or when
necessary by the nature of work
involved (for example, while
establishing controls or occasional entry
into hazardous atmospheres to perform
maintenance or investigation),
employees may work for reasonable
periods of time in concentrations of
airborne contaminants exceeding
permissible levels if they are protected
by appropriate respiratory protective
equipment. Whenever respiratory
protective equipment is used, its
selection, fitting, maintenance, cleaning,
training, supervision, and use shall meet
the following minimum requirements:
(a) Respirators approved by NIOSH
under 42 CFR part 84 which are
applicable and suitable for the purpose
intended shall be furnished and miners
shall use the protective equipment in
accordance with training and
instruction.
(b) A written respiratory protection
program consistent with the
requirements of ASTM F3387–19,
Standard Practice for Respiratory
Protection, approved August 1, 2019,
which is incorporated by reference into
this section with the approval of the
Director of the Federal Register under 5
U.S.C. 552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5450; (202) 693–9440; or any Mine
Safety and Health Enforcement District
PO 00000
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28469
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov. The material may be obtained
from ASTM International, 100 Barr
Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428–2959;
www.astm.org.
(c) When respiratory protection is
used in atmospheres immediately
dangerous to life or health (IDLH), the
presence of at least one other person
with backup equipment and rescue
capability shall be required in the event
of failure of the respiratory equipment.
§ 56.5005
[Removed]
8. Effective April 8, 2026, remove
§ 56.5005.
■
§ 56.5005T
[Redesignated as § 56.5005]
9. Effective April 8, 2026, redesignate
§ 56.5005T as § 56.5005.
■
PART 57—SAFETY AND HEALTH
STANDARDS—UNDERGROUND
METAL AND NONMETAL MINES
10. The authority citation for part 57
continues to read as follows:
■
Authority: 30 U.S.C. 811.
Subpart D—Air Quality, Radiation,
Physical Agents, and Diesel Particulate
Matter
11. Amend § 57.5001 by revising the
introductory text to read as follows:
■
§ 57.5001 Exposure limits for airborne
contaminants.
The following is required until April
7, 2026. Except as permitted by
§ 57.5005—
*
*
*
*
*
■ 12. Add § 57.5001T to read as follows:
§ 57.5001T Exposure limits for airborne
contaminants.
As of April 8, 2026, except as
permitted by § 57.5005—
(a) TLVs standard. Except as provided
in paragraph (b) of this section and in
part 60 of this chapter, the exposure to
airborne contaminants shall not exceed,
on the basis of a time weighted average,
the threshold limit values adopted by
the American Conference of
Governmental Industrial Hygienists, as
set forth and explained in the 1973
edition of the Conference’s publication,
entitled TLV’s Threshold Limit Values
for Chemical Substances in Workroom
Air Adopted by ACGIH for 1973, pages
1 through 54. This publication is
incorporated by reference into this
section with the approval of the Director
of the Federal Register under 5 U.S.C.
E:\FR\FM\18APR3.SGM
18APR3
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552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5450; (202) 693–9440; or at any Mine
Safety and Health Enforcement District
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov. The material may be obtained
from American Conference of
Governmental Industrial Hygienists,
1330 Kemper Meadow Drive, Attn:
Customer Service, Cincinnati, OH
45240; www.acgih.org.
(b) Asbestos standard—(1)
Definitions. Asbestos is a generic term
for a number of asbestiform hydrated
silicates that, when crushed or
processed, separate into flexible fibers
made up of fibrils.
Asbestos means chrysotile,
cummingtonite-grunerite asbestos
(amosite), crocidolite, anthophylite
asbestos, tremolite asbestos, and
actinolite asbestos.
Asbestos fiber means a fiber of
asbestos that meets the criteria of a fiber.
Fiber means a particle longer than 5
micrometers (mm) with a length-todiameter ratio of at least 3-to-1.
(2) Permissible Exposure Limits
(PELs)—(i) Full-shift limit. A miner’s
personal exposure to asbestos shall not
exceed an 8-hour time-weighted average
full-shift airborne concentration of 0.1
fiber per cubic centimeter of air (f/cc).
(ii) Excursion limit. No miner shall be
exposed at any time to airborne
concentrations of asbestos in excess of
1 fiber per cubic centimeter of air (f/cc)
as averaged over a sampling period of 30
minutes.
(3) Measurement of airborne asbestos
fiber concentration. Potential asbestos
fiber concentration shall be determined
by phase contrast microscopy (PCM)
using the OSHA Reference Method in
OSHA’s asbestos standard found in 29
CFR 1910.1001, Appendix A, or a
method at least equivalent to that
method in identifying a potential
asbestos exposure exceeding the 0.1 f/cc
full-shift limit or the 1 f/cc excursion
limit. When PCM results indicate a
potential exposure exceeding the 0.1 f/
cc full-shift limit or the 1 f/cc excursion
limit, samples shall be further analyzed
using transmission electron microscopy
according to NIOSH Method 7402 or a
method at least equivalent to that
method.
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(c) Required action. Employees shall
be withdrawn from areas where there is
present an airborne contaminant given a
‘‘C’’ designation by the Conference and
the concentration exceeds the threshold
limit value listed for that contaminant.
§ 57.5001
■
[Removed]
13. April 8, 2026, remove § 57.5001.
§ 57.5001T
[Redesignated as § 57.5001]
14. Effective April 8, 2026,
redesignate § 57.5001T as § 57.5001.
■ 15. Amend § 57.5005 by revising the
introductory text to read as follows:
■
§ 57.5005 Control of exposure to for
airborne contaminants.
The following is required until April
7, 2026. Control of employee exposure
to harmful airborne contaminants shall
be, insofar as feasible, by prevention of
contamination, removal by exhaust
ventilation, or by dilution with
uncontaminated air. However, where
accepted engineering control measures
have not been developed or when
necessary by the nature of work
involved (for example, while
establishing controls or occasional entry
into hazardous atmospheres to perform
maintenance or investigation),
employees may work for reasonable
periods of time in concentrations of
airborne contaminants exceeding
permissible levels if they are protected
by appropriate respiratory protective
equipment. Whenever respiratory
protective equipment is used a program
for selection, maintenance, training,
fitting, supervision, cleaning, and use
shall meet the following minimum
requirements:
*
*
*
*
*
■ 16. Add § 57.5005T to read as follows:
§ 57.5005T Control of exposure to airborne
contaminants.
As of April 8, 2026, the following is
required. Control of employee exposure
to harmful airborne contaminants shall
be, insofar as feasible, by prevention of
contamination, removal by exhaust
ventilation, or by dilution with
uncontaminated air. However, where
accepted engineering control measures
have not been developed or when
necessary by the nature of work
involved (for example, while
establishing controls or occasional entry
into hazardous atmospheres to perform
maintenance or investigation),
employees may work for reasonable
periods of time in concentrations of
airborne contaminants exceeding
permissible levels if they are protected
by appropriate respiratory protective
equipment. Whenever respiratory
protective equipment is used, its
PO 00000
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selection, fitting, maintenance, cleaning,
training, supervision, and use shall meet
the following minimum requirements:
(a) Respirators approved by NIOSH
under 42 CFR part 84 which are
applicable and suitable for the purpose
intended shall be furnished and miners
shall use the protective equipment in
accordance with training and
instruction.
(b) A written respiratory protection
program consistent with the
requirements of ASTM F3387–19,
Standard Practice for Respiratory
Protection, approved August 1, 2019,
which is incorporated by reference into
this section with the approval of the
Director of the Federal Register under 5
U.S.C. 552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5450; (202) 693–9440; or any Mine
Safety and Health Enforcement District
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov. The material may be obtained
from ASTM International, 100 Barr
Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428–2959;
www.astm.org.
(c) When respiratory protection is
used in atmospheres immediately
dangerous to life or health (IDLH), the
presence of at least one other person
with backup equipment and rescue
capability shall be required in the event
of failure of the respiratory equipment.
§ 57.5005
[Removed]
17. Effective April 8, 2026, remove
§ 57.5005.
■
§ 57.5005T
[Redesignated as § 57.5005]
18. Effective April 8, 2026,
redesignate § 57.5005T as § 57.5005.
■
Subchapter M—Uniform Mine Health
Regulations
19. Add part 60 to subchapter M to
read as follows:
■
PART 60—RESPIRABLE
CRYSTALLINE SILICA
Sec.
60.1 Scope; compliance dates.
60.2 Definitions.
60.10 Permissible exposure limit (PEL).
60.11 Methods of compliance.
60.12 Exposure monitoring.
60.13 Corrective actions.
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
60.14 Respiratory protection.
60.15 Medical surveillance for metal and
nonmetal mines.
60.16 Recordkeeping requirements.
60.17 Severability.
§ 60.12
Authority: 30 U.S.C. 811, 813(h) and 957.
§ 60.1
Scope; compliance dates.
(a) This part sets forth mandatory
health standards for each surface and
underground metal, nonmetal, and coal
mine subject to the Federal Mine Safety
and Health Act of 1977, as amended.
Requirements regarding medical
surveillance for metal and nonmetal
mines are also included.
(b) The compliance dates for the
provisions of this part are as follows:
(1) For coal mine operators, April 14,
2025.
(2) For metal and nonmetal mine
operators, April 8, 2026.
§ 60.2
Definitions.
The following definitions apply in
this part:
Action level means an airborne
concentration of respirable crystalline
silica of 25 micrograms per cubic meter
of air (mg/m3) for a full-shift exposure,
calculated as an 8-hour time-weighted
average (TWA).
Respirable crystalline silica means
quartz, cristobalite, and/or tridymite
contained in airborne particles that are
determined to be respirable by a
sampling device designed to meet the
characteristics for respirable-particlesize-selective samplers that conform to
the International Organization for
Standardization (ISO) 7708:1995: Air
Quality—Particle Size Fraction
Definitions for Health-Related
Sampling.
Specialist means an American BoardCertified Specialist in Pulmonary
Disease or an American Board-Certified
Specialist in Occupational Medicine.
§ 60.10
Permissible exposure limit (PEL).
The mine operator shall ensure that
no miner is exposed to an airborne
concentration of respirable crystalline
silica in excess of 50 mg/m3 for a fullshift exposure, calculated as an 8-hour
TWA.
ddrumheller on DSK120RN23PROD with RULES3
§ 60.11
Methods of compliance.
(a) The mine operator shall install,
use, and maintain feasible engineering
controls, supplemented by
administrative controls when necessary,
to keep each miner’s exposure at or
below the PEL, except as specified in
§ 60.14.
(b) Rotation of miners shall not be
considered an acceptable administrative
control used for compliance with this
part.
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Exposure monitoring.
(a) Sampling. (1) Mine operators shall
commence sampling by the compliance
date in § 60.1 to assess the full shift, 8hour TWA exposure of respirable
crystalline silica for each miner who is
or may reasonably be expected to be
exposed to respirable crystalline silica.
(2) If the sampling under paragraph
(a)(1) of this section is:
(i) Below the action level, the mine
operator shall take at least one
additional sampling within 3 months.
(ii) At or above the action level but at
or below the PEL, the mine operator
shall take another sampling within 3
months.
(iii) Above the PEL, the mine operator
shall take corrective actions and sample
pursuant to § 60.12(b).
(3) Where the most recent sampling
indicates that miner exposures are at or
above the action level but at or below
the PEL, the mine operator shall
continue to sample within 3 months of
the previous sampling.
(4) The mine operator may
discontinue sampling when two
consecutive samplings indicate that
miner exposures are below the action
level. The second of these samplings
must be taken after the operator receives
the results of the prior sampling but no
sooner than 7 days after the prior
sampling was conducted.
(b) Corrective actions sampling.
Where the most recent sampling
indicates that miner exposures are
above the PEL, the mine operator shall
sample after corrective actions are taken
pursuant to § 60.13 until the sampling
indicates that miner exposures are at or
below the PEL. The mine operator shall
immediately report all operator samples
above the PEL to the MSHA District
Manager or to any other MSHA office
designated by the District Manager.
(c) Periodic evaluation. At least every
6 months after commencing sampling
under 60.12(a)(1) or whenever there is a
change in: production; processes;
installation or maintenance of
engineering controls; installation or
maintenance of equipment;
administrative controls; or geological
conditions; mine operators shall
evaluate whether the change may
reasonably be expected to result in new
or increased respirable crystalline silica
exposures. Once the evaluation is
completed, the mine operator shall:
(1) Make a record of the evaluation,
including the evaluated change, the
impact on respirable crystalline silica
exposure, and the date of the evaluation;
and
(2) Post the record on the mine
bulletin board and, if applicable, by
electronic means, for the next 31 days.
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28471
(d) Post-evaluation sampling. If the
mine operator determines as a result of
the periodic evaluation under paragraph
(c) of this section that miners may be
exposed to respirable crystalline silica
at or above the action level, the mine
operator shall perform sampling to
assess the full shift, 8-hour TWA
exposure of respirable crystalline silica
for each miner who is or may reasonably
be expected to be at or above the action
level.
(e) Sampling requirements. (1)
Sampling shall be performed for the
duration of a miner’s regular full shift
and during typical mining activities,
including shaft and slope sinking,
construction, and removal of
overburden.
(2) The full-shift, 8-hour TWA
exposure for such miners shall be
measured based on:
(i) Personal breathing-zone air
samples for metal and nonmetal
operations; or
(ii) Occupational environmental
samples collected in accordance with
§ 70.201(c), § 71.201(b), or § 90.201(b) of
this chapter for coal operations.
(3) Where several miners perform the
same tasks on the same shift and in the
same work area, the mine operator may
sample a representative fraction (at least
two) of these miners to meet the
requirements in paragraphs (a) through
(e) of this section. In sampling a
representative fraction of miners, the
mine operator shall select the miners
who are expected to have the highest
exposure to respirable crystalline silica.
(4) The mine operator shall use
respirable-particle-size-selective
samplers that conform to ISO
7708:1995(E) to determine compliance
with the PEL. ISO 7708:1995(E), Air
quality—Particle size fraction
definitions for health-related sampling,
First Edition, 1995–04–01, is
incorporated by reference into this
section with the approval of the Director
of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5450; (202) 693–9440; or any Mine
Safety and Health Enforcement District
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov. The material may be obtained
from the International Organization for
E:\FR\FM\18APR3.SGM
18APR3
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
Standardization (ISO), CP 56, CH–1211
Geneva 20, Switzerland; phone: + 41 22
749 01 11; fax: + 41 22 733 34 30;
website: www.iso.org.
(f) Methods of sample analysis. (1)
The mine operator shall use a laboratory
that is accredited to ISO/IEC 17025
‘‘General requirements for the
competence of testing and calibration
laboratories’’ with respect to respirable
crystalline silica analyses, where the
accreditation has been issued by a body
that is compliant with ISO/IEC 17011
‘‘Conformity assessment—Requirements
for accreditation bodies accrediting
conformity assessment bodies.’’
(2) The mine operator shall ensure
that the laboratory evaluates all samples
using respirable crystalline silica
analytical methods specified by MSHA,
the National Institute for Occupational
Safety and Health (NIOSH), or the
Occupational Safety and Health
Administration (OSHA).
(g) Sampling records. For each sample
taken pursuant to paragraphs (a)
through (e) of this section, the mine
operator shall make a record of the
sample date, the occupations sampled,
and the concentrations of respirable
crystalline silica and respirable dust and
post the record and the laboratory report
on the mine bulletin board and, if
applicable, by electronic means, for the
next 31 days, upon receipt.
ddrumheller on DSK120RN23PROD with RULES3
§ 60.13
Corrective actions.
(a) If any sampling indicates that a
miner’s exposure exceeds the PEL, the
mine operator shall:
(1) Make approved respirators
available to affected miners before the
start of the next work shift in
accordance with § 60.14(b) and (c);
(2) Ensure that affected miners wear
respirators properly for the full shift or
during the period of overexposure until
miner exposures are at or below the
PEL; and
(3) Immediately take corrective
actions to lower the concentration of
respirable crystalline silica to at or
below the PEL.
(b) Once corrective actions have been
taken, the mine operator shall:
(1) Conduct sampling pursuant to
§ 60.12(b); and
(2) Take additional or new corrective
actions until sampling indicates miner
exposures are at or below the PEL.
(c) The mine operator shall make a
record of corrective actions and the
dates of the corrective actions under
paragraph (a) of this section.
§ 60.14
Respiratory protection.
(a) Temporary use of respirators at
metal and nonmetal mines. The metal
and nonmetal mine operator shall use
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respiratory protection as a temporary
measure in accordance with paragraph
(c) of this section when miners must
work in concentrations of respirable
crystalline silica above the PEL while:
(1) Engineering control measures are
being developed and implemented; or
(2) It is necessary by the nature of
work involved (for example, occasional
entry into hazardous atmospheres to
perform maintenance or investigation).
(b) Miners unable to wear respirators
at all mines. Upon written
determination by a physician or other
licensed health care professional
(PLHCP) that an affected miner is
unable to wear a respirator, the miner
shall be temporarily transferred either to
work in a separate area of the same mine
or to an occupation at the same mine
where respiratory protection is not
required.
(1) The affected miner shall continue
to receive compensation at no less than
the regular rate of pay in the occupation
held by that miner immediately prior to
the transfer.
(2) The affected miner may be
transferred back to the miner’s initial
work area or occupation when
temporary use of respirators under
paragraph (a) of this section or section
60.13 is no longer required.
(c) Respiratory protection
requirements at all mines. (1) Affected
miners shall be provided with a NIOSHapproved atmosphere-supplying
respirator or NIOSH-approved airpurifying respirator equipped with the
following:
(i) Particulate protection classified as
100 series under 42 CFR part 84; or
(ii) Particulate protection classified as
High Efficiency ‘‘HE’’ under 42 CFR part
84.
(2) When approved respirators are
used, the mine operator must have a
written respiratory protection program
that meets the following requirements in
accordance with ASTM F3387–19:
program administration; written
standard operating procedures; medical
evaluation; respirator selection; training;
fit testing; maintenance, inspection, and
storage. ASTM F3387–19, Standard
Practice for Respiratory Protection,
approved August 1, 2019, is
incorporated by reference into this
section with the approval of the Director
of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
PO 00000
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Street South, Arlington, VA 22202–
5450; (202) 693–9440; or any Mine
Safety and Health Enforcement District
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov. The material may be obtained
from ASTM International, 100 Barr
Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428–2959;
www.astm.org.
§ 60.15 Medical surveillance for metal and
nonmetal mines.
(a) Medical surveillance. Each
operator of a metal and nonmetal mine
shall provide to each miner periodic
medical examinations performed by a
physician or other licensed health care
professional (PLHCP) or specialist, as
defined in § 60.2, at no cost to the
miner.
(1) Medical examinations shall be
provided at frequencies specified in this
section.
(2) Medical examinations shall
include:
(i) A medical and work history, with
emphasis on: past and present exposure
to respirable crystalline silica, dust, and
other agents affecting the respiratory
system; any history of respiratory
system dysfunction, including
diagnoses and symptoms of respiratory
disease (e.g., shortness of breath, cough,
wheezing); history of tuberculosis; and
smoking status and history;
(ii) A physical examination with
special emphasis on the respiratory
system;
(iii) A chest X-ray (a single
posteroanterior radiographic projection
or radiograph of the chest at full
inspiration recorded on either film (no
less than 14 x 17 inches and no more
than 16 x 17 inches) or digital
radiography systems), classified
according to the International Labour
Office (ILO) International Classification
of Radiographs of Pneumoconioses by a
NIOSH-certified B Reader; and
(iv) A pulmonary function test to
include forced vital capacity (FVC) and
forced expiratory volume in one second
(FEV1) and FEV1/FVC ratio,
administered by a spirometry technician
with a current certificate from a NIOSHapproved Spirometry Program Sponsor
or by a pulmonary function technologist
with a current credential from the
National Board for Respiratory Care.
(b) Voluntary medical examinations.
Each mine operator shall provide the
opportunity to all miners employed at
the mine to have the medical
examinations specified in paragraph (a)
of this section as follows:
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(1) During an initial 12-month period;
and
(2) At least every 5 years after the end
of the period in paragraph (b)(1). The
medical examinations shall be available
during a 6-month period that begins no
less than 3.5 years and not more than
4.5 years from the end of the last 6month period.
(c) Mandatory medical examinations.
For each miner who begins work in the
mining industry for the first time, the
mine operator shall provide medical
examinations specified in paragraph (a)
of this section as follows:
(1) An initial medical examination no
later than 60 days after beginning
employment;
(2) A follow-up medical examination
no later than 3 years after the initial
examination in paragraph (c)(1) of this
section; and
(3) A follow-up medical examination
conducted by a specialist no later than
2 years after the examinations in
paragraph (c)(2) of this section if the
chest X-ray shows evidence of
pneumoconiosis or the spirometry
examination indicates evidence of
decreased lung function.
(d) Medical examinations results. (1)
The mine operator shall ensure that the
results of medical examinations or tests
made pursuant to this section shall be
provided from the PLHCP or specialist
within 30 days of the medical
examination to the miner, and at the
request of the miner, to the miner’s
designated physician or another
designee identified by the miner.
(2) The mine operator shall ensure
that, within 30 days of the medical
examination, the PLHCP or specialist
provides the results of chest X-ray
classifications to the National Institute
for Occupational Safety and Health
(NIOSH), once NIOSH establishes a
reporting system.
(e) Written medical opinion. The mine
operator shall obtain a written medical
opinion from the PLHCP or specialist
within 30 days of the medical
examination. The written opinion shall
contain only the following:
(1) The date of the medical
examination;
(2) A statement that the examination
has met the requirements of this section;
and
(3) Any recommended limitations on
the miner’s use of respirators.
28473
(f) Written medical opinion records.
The mine operator shall maintain a
record of the written medical opinions
received from the PLHCP or specialist
under paragraph (e) of this section.
§ 60.16
Recordkeeping requirements.
(a) Table 1 to this paragraph (a) lists
the records the mine operator shall
retain and their retention period.
(1) Evaluation records made under
§ 60.12(c) shall be retained for at least 5
years from the date of each evaluation.
(2) Sampling records made under
§ 60.12(g) shall be retained for at least 5
years from the sample date.
(3) Corrective actions records made
under § 60.13(c) shall be retained for at
least 5 years from the date of each
corrective action. These records must be
stored with the records of related
sampling under § 60.12(g).
(4) Written determination records
received from a PLHCP under § 60.14(b)
shall be retained for the duration of the
miner’s employment plus 6 months.
(5) Written medical opinion records
received from a PLHCP or specialist
under § 60.15(f) shall be retained for the
duration of the miner’s employment
plus 6 months.
TABLE 1 TO PARAGRAPH (a)—RECORDKEEPING REQUIREMENTS
Section
references
Record
1.
2.
3.
4.
5.
Evaluation records ..................................................................
Sampling records ....................................................................
Corrective actions records ......................................................
Written determination records received from a PLHCP .........
Written medical opinion records received from a PLHCP or
specialist.
(b) Upon request from an authorized
representative of the Secretary, from an
authorized representative of miners, or
from miners, mine operators shall
promptly provide access to any record
listed in this section.
ddrumheller on DSK120RN23PROD with RULES3
§ 60.17
Severability.
Each section of this part, as well as
sections in 30 CFR parts 56, 57, 70, 71,
72, 75, and 90 that address respirable
crystalline silica or respiratory
protection, is separate and severable
from the other sections and provisions.
If any provision of this subpart is held
to be invalid or unenforceable by its
terms, or as applied to any person,
entity, or circumstance, or is stayed or
enjoined, that provision shall be
construed so as to continue to give the
maximum effect to the provision
permitted by law, unless such holding
shall be one of utter invalidity or
unenforceability, in which event the
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§ 60.12(c)
§ 60.12(g)
§ 60.13(c)
§ 60.14(b)
§ 60.15(f)
Retention period
At least 5 years from date of each evaluation.
At least 5 years from sample date.
At least 5 years from date of each corrective action.
Duration of miner’s employment plus 6 months.
Duration of miner’s employment plus 6 months.
provision shall be severable from these
sections and shall not affect the
remainder thereof.
Subchapter O—Coal Mine Safety and Health
PART 70—MANDATORY HEALTH
STANDARDS—UNDERGROUND COAL
MINES
20. The authority citation for part 70
continues to read as follows:
■
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart A—General
§ 70.2
[Amended]
21. Effective April 14, 2025, amend
§ 70.2 by removing the definition of
‘‘Quartz’’.
■
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Subpart B—Dust Standards
§ 70.101
[Removed and Reserved]
22. Effective April 14, 2025, remove
and reserve § 70.101.
■
Subpart C—Sampling Procedures
23. Amend § 70.205 by adding
introductory text to read as follows:
■
§ 70.205 Approved sampling devices;
operation; air flowrate.
The following is required until April
14, 2025:
*
*
*
*
*
■ 24. Add § 70.205T to read as follows:
§ 70.205T Approved sampling devices;
operation; air flowrate.
As of April 14, 2025:
(a) Approved sampling devices shall
be operated at the flowrate of 2.0 L/min
if using a CMDPSU; at 2.2 L/min if
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using a CPDM; or at a different flowrate
recommended by the manufacturer.
(b) If using a CMDPSU, each approved
sampling device shall be examined each
shift by a person certified in sampling
during:
(1) The second hour after being put
into operation to assure it is in the
proper location, operating properly, and
at the proper flowrate. If the proper
flowrate is not maintained, necessary
adjustments shall be made by the
certified person. This examination is not
required if the sampling device is being
operated in an anthracite coal mine
using the full box, open breast, or slant
breast mining method.
(2) The last hour of operation to
assure that the sampling device is
operating properly and at the proper
flowrate. If the proper flowrate is not
maintained, the respirable dust sample
shall be transmitted to MSHA with a
notation by the certified person on the
back of the dust data card stating that
the proper flowrate was not maintained.
Other events occurring during the
collection of respirable dust samples
that may affect the validity of the
sample, such as dropping of the
sampling head assembly onto the mine
floor, shall be noted on the back of the
dust data card.
(c) If using a CPDM, the person
certified in sampling shall monitor the
dust concentrations and the sampling
status conditions being reported by the
sampling device at mid-shift or more
frequently as specified in the approved
mine ventilation plan to assure: The
sampling device is in the proper
location and operating properly; and the
work environment of the occupation or
DA being sampled remains in
compliance with the standard at the end
of the shift. This monitoring is not
required if the sampling device is being
operated in an anthracite coal mine
using the full box, open breast, or slant
breast mining method.
§ 70.205
[Removed]
25. Effective April 14, 2025, remove
§ 70.205.
■
§ 70.205T
[Redesignated as § 70.205]
26. Effective April 14, 2025,
redesignate § 70.205T as § 70.205.
ddrumheller on DSK120RN23PROD with RULES3
■
§§ 70.206 and 70.207
Reserved]
[Removed and
27. Effective April 14, 2025, remove
and reserve §§ 70.206 and 70.207.
■
28. Amend § 70.208 by revising the
introductory text to read as follows:
■
VerDate Sep<11>2014
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§ 70.208 Quarterly sampling; mechanized
mining units.
The following is required from
February 1, 2016, until April 14, 2025:
*
*
*
*
*
■ 29. Add § 70.208T to read as follows:
§ 70.208T Quarterly sampling; mechanized
mining units.
As of April 14, 2025:
(a) The operator shall sample each
calendar quarter:
(1) The designated occupation (DO) in
each MMU on consecutive normal
production shifts until 15 valid
representative samples are taken. The
District Manager may require additional
groups of 15 valid representative
samples when information indicates the
operator has not followed the approved
ventilation plan for any MMU.
(2) Each other designated occupation
(ODO) specified in paragraphs (b)(1)
through (10) of this section in each
MMU or specified by the District
Manager and identified in the approved
mine ventilation plan on consecutive
normal production shifts until 15 valid
representative samples are taken.
Sampling of each ODO type shall begin
after fulfilling the sampling
requirements of paragraph (a)(1) of this
section. When required to sample more
than one ODO type, each ODO type
must be sampled over separate time
periods during the calendar quarter.
(3) The quarterly periods are:
(i) January 1–March 31
(ii) April 1–June 30
(iii) July 1–September 30
(iv) October 1–December 31.
(b) Unless otherwise directed by the
District Manager, the approved
sampling device shall be worn by the
miner assigned to perform the duties of
the DO or ODO specified in paragraphs
(b)(1) through (10) of this section or by
the District Manager for each type of
MMU.
(1) Conventional section using cutting
machine. DO—The cutting machine
operator;
(2) Conventional section blasting off
the solid. DO—The loading machine
operator;
(3) Continuous mining section other
than auger-type. DO—The continuous
mining (CM) machine operator or
mobile bridge operator when using
continuous haulage; ODO—The roof
bolting machine operator who works
nearest the working face on the return
air side of the continuous mining
machine; the face haulage operators on
MMUs using blowing face ventilation;
the face haulage operators on MMUs
ventilated by split intake air (‘‘fishtail
ventilation’’) as part of a super-section;
and face haulage operators where two
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continuous mining machines are
operated on an MMU.
(4) Continuous mining section using
auger-type machine. DO—The jacksetter
who works nearest the working face on
the return air side of the continuous
mining machine;
(5) Scoop section using cutting
machine. DO—The cutting machine
operator;
(6) Scoop section, blasting off the
solid. DO—The coal drill operator;
(7) Longwall section. DO—The
longwall operator working on the
tailgate side of the longwall mining
machine; ODO—The jacksetter who
works nearest the return air side of the
longwall working face, and the
mechanic;
(8) Hand loading section with a
cutting machine. DO—The cutting
machine operator;
(9) Hand loading section blasting off
the solid. DO—The hand loader exposed
to the greatest dust concentration; and
(10) Anthracite mine sections. DO—
The hand loader exposed to the greatest
dust concentration.
I [Reserved]
(d) If a normal production shift is not
achieved, the DO or ODO sample for
that shift may be voided by MSHA.
However, any sample, regardless of
production, that exceeds the standard
by at least 0.1 mg/m3 shall be used in
the determination of the equivalent
concentration for that occupatioI(e)
When a valid representative sample
taken in accordance with this section
meets or exceeds the ECV in table 1 to
this section that corresponds to the
particular sampling device used, the
operator shall:
(1) Make approved respiratory
equipment available to affected miners
in accordance with § 72.700 of this
chapter;
(2) Immediately take corrective action
to lower the concentration of respirable
dust to at or below the respirable dust
standard; and
(3) Make a record of the corrective
actions taken. The record shall be
certified by the mine foreman or
equivalent mine official, no later than
the end of the mine f’reman’s or
equivalent of’icial’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
representative of miners.
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(f) Noncompliance with the standard
is demonstrated during the sampling
period when:
(1) Three or more valid representative
samples meet or exceed the ECV in table
1 to this section that corresponds to the
particular sampling device used; or
(2) The average for all valid
representative samples meets or exceeds
the ECV in table 1 to this section that
corresponds to the particular sampling
device used.
(g)(1) Unless otherwise directed by
the District Manager, upon issuance of
a citation for a violation of the standard
involving a DO in an MMU, paragraph
(a)(1) of this section shall not apply to
the DO in that MMU until the violation
is abated and the citation is terminated
in accordance with paragraphs (h) and
(i) of this section.
(2) Unless otherwise directed by the
District Manager, upon issuance of a
citation for a violation of the standard
involving a type of ODO in an MMU,
paragraph (a)(2) of this section shall not
apply to that ODO type in that MMU
until the violation is abated and the
citation is terminated in accordance
with paragraphs (g) and (h) of this
section.
(h) Upon issuance of a citation for
violation of the standard, the operator
shall take the following actions
sequentially:
(1) Make approved respiratory
equipment available to affected miners
in accordance with § 72.700 of this
chapter;
(2) Immediately take corrective action
to lower the concentration of respirable
coal mine dust to at or below the
standard; and
(3) Make a record of the corrective
actions taken. The record shall be
certified by the mine foreman or
equivalent mine official, no later than
the end of the mine f’reman’s or
equivalent of’icial’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
representative of miners.
(4) Begin sampling, within 8 calendar
days after the date the citation is issued,
the environment of the affected
occupation in the MMU on consecutive
normal production shifts until five valid
representative samples are taken.
(i) A citation for a violation of the
standard shall be terminated by MSHA
when:
(1) Each of the five valid
representative samples is at or below the
standard; and
(2) The operator has submitted to the
District Manager revised dust control
parameters as part of the mine
ventilation plan applicable to the MMU
in the citation and the changes have
been approved by the District Manager.
The revised parameters shall reflect the
control measures used by the operator to
abate the violation.
TABLE 1 TO § 70.208T—EXCESSIVE CONCENTRATION VALUES (ECV) BASED ON A SINGLE SAMPLE, THREE SAMPLES, OR
THE AVERAGE OF FIVE OR FIFTEEN FULL-SHIFT CMDPSU/CPDM CONCENTRATION MEASUREMENTS
ECV (mg/m3)
Section
Samples
CMDPSU
70.208 (e) .....................................................................
70.208(f)(1) ...................................................................
70.208(f)(2) ...................................................................
70.208(f)(2) ...................................................................
70.208(i)(1) ...................................................................
§ 70.208
[Removed]
30. Effective April 14, 2025, remove
§ 70.208.
■
§ 70.208T
[Redesignated as § 70.208]
31. Effective April 14, 2025,
redesignate § 70.208T as § 70.208 and
redesignate table 1 to § 70.208T as table
1 to § 70.208.
■ 32. Amend § 70.209 by revising the
introductory text to read as follows:
■
ddrumheller on DSK120RN23PROD with RULES3
§ 70.209
areas.
Quarterly sampling; designated
The following is required until April
14, 2025:
*
*
*
*
*
■ 33. Add § 70.209T to read as follows:
§ 70.209T
areas.
Quarterly sampling; designated
As of April 14, 2025:
VerDate Sep<11>2014
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70.1–0(a)—Single sample ............................................
70.1–0(b)—Single sample ............................................
70.1–0(a)—3 or more samples ....................................
70.1–0(b)—3 or more samples ....................................
70.1–0(a)—5 sample average ......................................
70.1–0(b)—5 sample average ......................................
70.1–0(a)—15 sample average ....................................
70.1–0(b)—15 sample average ....................................
70.1–0(a)—Each of 5 samples .....................................
70.1–0(b)—Each of 5 samples .....................................
(a) The operator shall sample
quarterly each designated area (DA) on
consecutive production shifts until five
valid representative samples are taken.
The quarterly periods are:
(1) January 1–March 31
(2) April 1–June 30
(3) July 1–September 30
(4) October 1–December 31.
(b) [Reserved].
(c) When a valid representative
sample taken in accordance with this
section meets or exceeds the ECV in
table 1 to this section that corresponds
to the particular sampling device used,
the operator shall:
(1) Make approved respiratory
equipment available to affected miners
in accordance with § 72.700 of this
chapter;
(2) Immediately take corrective action
to lower the concentration of respirable
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1.79
0.74
1.79
0.74
1.63
0.61
1.58
0.57
1.79
0.74
CPDM
1.70
0.57
1.70
0.57
1.59
0.53
1.56
0.52
1.70
0.57
dust to at or below the respirable dust
standard; and
(3) Make a record of the corrective
actions taken. The record shall be
certified by the mine foreman or
equivalent mine official, no later than
the end of the mine foreman’s or
equivalent official’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
representative of miners.
(d) Noncompliance with the standard
is demonstrated during the sampling
period when:
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(1) Two or more valid representative
samples meet or exceed the ECV in table
1 to this section that corresponds to the
particular sampling device used; or
(2) The average for all valid
representative samples meets or exceeds
the ECV in table 1 to this section that
corresponds to the particular sampling
device used.
(e) Unless otherwise directed by the
District Manager, upon issuance of a
citation for a violation of the standard,
paragraph (a) of this section shall not
apply to that DA until the violation is
abated and the citation is terminated in
accordance with paragraphs (e) and (f)
of this section.
(f) Upon issuance of a citation for a
violation of the standard, the operator
shall take the following actions
sequentially:
(1) Make approved respiratory
equipment available to affected miners
in accordance with § 72.700 of this
chapter;
(2) Immediately take corrective action
to lower the concentration of respirable
coal mine dust to at or below the
standard; and
(3) Make a record of the corrective
actions taken. The record shall be
certified by the mine foreman or
equivalent mine official, no later than
the end of the mine foreman’s or
equivalent official’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
representative of miners.
(4) Begin sampling, within 8 calendar
days after the date the citation is issued,
the environment of the affected DA on
consecutive normal production shifts
until five valid representative samples
are taken.
(g) A citation for a violation of the
standard shall be terminated by MSHA
when:
(1) Each of the five valid
representative samples is at or below the
standard; and
(2) The operator has submitted to the
District Manager revised dust control
parameters as part of the mine
ventilation plan applicable to the DA in
the citation, and the changes have been
approved by the District Manager. The
revised parameters shall reflect the
control measures used by the operator to
abate the violation.
TABLE 1 TO § 70.209T—EXCESSIVE CONCENTRATION VALUES (ECV) BASED ON A SINGLE SAMPLE, TWO SAMPLES, OR
THE AVERAGE OF FIVE OR FIFTEEN FULL-SHIFT CMDPSU/CPDM CONCENTRATION MEASUREMENTS
ECV (mg/m3)
Section
Samples
CMDPSU
70.209 (c) .....................................................................
70.209(d)(1) ..................................................................
70.209(d)(2) ..................................................................
70.209(d)(2) ..................................................................
70.209(g)(1) ..................................................................
§ 70.209
[Removed]
Subpart A—General
34. Effective April 14, 2025, remove
§ 70.209.
■
§ 70.209T
70.100(a)—Single sample ............................................
70.100(b)—Single sample ............................................
70.100(a)—2 or more samples ....................................
70.100(b)—2 or more samples ....................................
70.100(a)—5 sample average ......................................
70.100(b)—5 sample average ......................................
70.100(a)—15 sample average ....................................
70.100(b)—15 sample average ....................................
70.100(a)—Each of 5 samples .....................................
70.100(b)—Each of 5 samples .....................................
§ 71.2
[Amended]
38. Effective April 14, 2025, amend
§ 71.2 by removing the definition of
‘‘Quartz’’.
■
[Redesignated as § 70.209]
35. Effective April 14, 2025,
redesignate § 70.209T as § 70.209 and
redesignate table 1 to § 70.209T as table
1 to § 70.209.
■
Tables 70–1 and 70–2 to Subpart C of
Part 70 [Removed]
36. Effective April 14, 2025, remove
tables 70–1 and 70–2 to subpart C of
part 70.
ddrumheller on DSK120RN23PROD with RULES3
■
37. The authority citation for part 71
continues to read as follows:
§ 71.101
39. Effective April 14, 2025, remove
and reserve § 71.101.
■
Subpart C—Sampling Procedures
40. Amend § 71.205 by adding
introductory text to read as follows:
§ 71.205 Approved sampling devices;
operation; air flowrate.
The following is required until April
14, 2025:
*
*
*
*
*
■ 41. Add § 71.205T to read as follows:
§ 71.205T Approved sampling devices;
operation; air flowrate.
Authority: 30 U.S.C. 811, 813(h), 957.
VerDate Sep<11>2014
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[Removed and Reserved]
■
PART 71—MANDATORY HEALTH
STANDARDS—SURFACE COAL MINES
AND SURFACE WORK AREAS OF
UNDERGROUND COAL MINES
■
Subpart B—Dust Standards
As of April 14, 2025:
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0.74
1.79
0.74
1.63
0.61
1.58
0.57
1.79
0.74
CPDM
1.70
0.57
1.70
0.57
1.59
0.53
1.56
0.52
1.70
0.57
(a) Approved sampling devices shall
be operated at the flowrate of 2.0 L/min,
if using a CMDPSU; at 2.2 L/min, if
using a CPDM; or at a different flowrate
recommended by the manufacturer.
(b) If using a CMDPSU, each sampling
device shall be examined each shift by
a person certified in sampling during:
(1) The second hour after being put
into operation to assure it is in the
proper location, operating properly, and
at the proper flowrate. If the proper
flowrate is not maintained, necessary
adjustments shall be made by the
certified person.
(2) The last hour of operation to
assure that it is operating properly and
at the proper flowrate. If the proper
flowrate is not maintained, the
respirable dust sample shall be
transmitted to MSHA with a notation by
the certified person on the back of the
dust data card stating that the proper
flowrate was not maintained. Other
events occurring during the collection of
respirable dust samples that may affect
the validity of the sample, such as
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dropping of the sampling head assembly
onto the mine floor, shall be noted on
the back of the dust data card.
(c) If using a CPDM, the person
certified in sampling shall monitor the
dust concentrations and the sampling
status conditions being reported by the
sampling device at mid-shift or more
frequently as specified in the approved
respirable dust control plan, if
applicable, to assure: The sampling
device is in the proper location and
operating properly; and the work
environment of the occupation being
sampled remains in compliance with
the standard at the end of the shift.
District Manager with a list identifying
the specific work positions where DWP
samples will be collected for:
(1) Active mines—by October 1, 2014.
(2) New mines—Within 30 calendar
days of mine opening.
(3) DWPs with a change in operational
status that increases or reduces the
number of active DWPs—within 7
calendar days of the change in status.
(e) Each DWP sample shall be taken
on a normal work shift. If a normal work
shift is not achieved, the respirable dust
sample shall be transmitted to MSHA
with a notation by the person certified
in sampling on the back of the dust data
card stating that the sample was not
§ 71.205 [Removed]
taken on a normal work shift. When a
normal work shift is not achieved, the
■ 42. Effective April 14, 2025, remove
sample for that shift may be voided by
§ 71.205.
MSHA. However, any sample,
§ 71.205T [Redesignated as § 71.205]
regardless of whether a normal work
shift was achieved, that exceeds the
■ 43. Effective April 14, 2025,
standard by at least 0.1 mg/m3 shall be
redesignate § 71.205T as § 71.205.
used in the determination of the
■ 44. Amend § 71.206 by adding
equivalent concentration for that
introductory text to read as follows:
occupation.
§ 71.206 Quarterly sampling; designated
(f) Unless otherwise directed by the
work positions.
District Manager, DWP samples shall be
taken by placing the sampling device as
The following is required until April
follows:
14, 2025:
(1) Equipment operator: On the
*
*
*
*
*
equipment operator or on the equipment
■ 45. Add § 71.206T to read as follows:
within 36 inches of the operator’s
normal working position.
§ 71.206T Quarterly sampling; designated
work positions.
(2) Non-equipment operators: On the
miner assigned to the DWP or at a
As of April 14, 2025:
location that represents the maximum
(a) Each operator shall take one valid
concentration of dust to which the
representative sample from the DWP
miner is exposed.
during each quarterly period. The
(g) Upon notification from MSHA that
quarterly periods are:
any valid representative sample taken
(1) January 1–March 31
from a DWP to meet the requirements of
(2) April 1–June 30
paragraph (a) of this section exceeds the
(3) July 1–September 30
standard, the operator shall, within 15
(4) October 1–December 31.
(b) [Reserved].
calendar days of notification, sample
(c) Designated work position samples
that DWP each normal work shift until
shall be collected at locations to
five valid representative samples are
measure respirable dust generation
taken. The operator shall begin
sources in the active workings. The
sampling on the first normal work shift
specific work positions at each mine
following receipt of notification.
where DWP samples shall be collected
(h) When a valid representative
include:
sample taken in accordance with this
(1) Each highwall drill operator
section meets or exceeds the excessive
(MSHA occupation code 384);
concentration value (ECV) in table 1 to
(2) Bulldozer operators (MSHA
this section that corresponds to the
occupation code 368); and
particular sampling device used, the
(3) Other work positions designated
mine operator shall:
by the District Manager for sampling in
(1) Make approved respiratory
accordance with § 71.206(m).
equipment available to affected miners
(d) Operators with multiple work
in accordance with § 72.700 of this
positions specified in paragraphs (b)(2)
chapter;
and (3) of this section shall sample the
(2) Immediately take corrective action
DWP exposed to the greatest respirable
to lower the concentration of respirable
dust concentration in each work
coal mine dust to at or below the
position performing the same activity or standard; and
(3) Make a record of the corrective
task at the same location at the mine and
actions taken. The record shall be
exposed to the same dust generation
certified by the mine foreman or
source. Each operator shall provide the
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28477
equivalent mine official, no later than
the end of the mine foreman’s or
equivalent official’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
representative of miners.
(i) Noncompliance with the standard
is demonstrated during the sampling
period when:
(1) Two or more valid representative
samples meet or exceed the ECV in table
1 to this section that corresponds to the
particular sampling device used; or
(2) The average for all valid
representative samples meets or exceeds
the ECV in table 1 to this section that
corresponds to the particular sampling
device used.
(j) Unless otherwise directed by the
District Manager, upon issuance of a
citation for a violation of the standard,
paragraph (a) of this section shall not
apply to that DWP until the violation is
abated and the citation is terminated in
accordance with paragraphs (j) and (k)
of this section.
(k) Upon issuance of a citation for
violation of the standard, the operator
shall take the following actions
sequentially:
(1) Make approved respiratory
equipment available to affected miners
in accordance with § 72.700 of this
chapter;
(2) Immediately take corrective action
to lower the concentration of respirable
coal mine dust to at or below the
standard; and
(3) Make a record of the corrective
actions taken. The record shall be
certified by the mine foreman or
equivalent mine official, no later than
the end of the mine foreman’s or
equivalent official’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
representative of miners.
(4) Begin sampling, within 8 calendar
days after the date the citation is issued,
the environment of the affected DWP on
consecutive normal work shifts until
five valid representative samples are
taken.
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(l) A citation for violation of the
standard shall be terminated by MSHA
when the equivalent concentration of
each of the five valid representative
samples is at or below the standard.
(m) The District Manager may
designate for sampling under this
section additional work positions at a
surface coal mine and at a surface work
area of an underground coal mine where
a concentration of respirable dust
exceeding 50 percent of the standard
has been measured by one or more
MSHA valid representative samples.
(n) The District Manager may
withdraw from sampling any DWP
designated for sampling under
paragraph (m) of this section upon
finding that the operator is able to
maintain continuing compliance with
the standard. This finding shall be based
on the results of MSHA and operator
valid representative samples taken
during at least a 12-month period.
TABLE 1 TO § 71.206T—EXCESSIVE CONCENTRATION VALUES (ECV) BASED ON A SINGLE SAMPLE, TWO SAMPLES, OR
THE AVERAGE OF FIVE FULL-SHIFT CMDPSU/CPDM CONCENTRATION MEASUREMENTS
ECV (mg/m3)
Section
Samples
CMDPSU
71.206(h) ......................................................................
71.206(i)(1) ...................................................................
71.206(i)(2) ...................................................................
71.206(l) ........................................................................
§ 71.206
[Removed]
46. Effective April 14, 2025, remove
§ 71.206.
■
§ 71.206T
[Redesignated as § 71.206]
47. Effective April 14, 2025,
redesignate § 71.206T as § 71.206 and
redesignate table 1 to § 71.206T as table
1 to § 71.206.
■
Subpart D—Respirable Dust Control
Plans
48. Amend § 71.300 by adding
introductory text to read as follows:
■
§ 71.300 Respirable dust control plan;
filing requirements.
The following is required until April
14, 2025:
*
*
*
*
*
■ 49. Add § 71.300T to read as follows:
ddrumheller on DSK120RN23PROD with RULES3
§ 71.300T Respirable dust control plan;
filing requirements.
As of April 14, 2025:
(a) Within 15 calendar days after the
termination date of a citation for
violation of the standard, the operator
shall submit to the District Manager for
approval a written respirable dust
control plan applicable to the DWP
identified in the citation. The respirable
dust control plan and revisions thereof
shall be suitable to the conditions and
the mining system of the coal mine and
shall be adequate to continuously
maintain respirable dust to at or below
the standard at the DWP identified in
the citation.
(1) The mine operator shall notify the
representative of miners at least 5 days
prior to submission of a respirable dust
control plan and any revision to a dust
control plan. If requested, the mine
operator shall provide a copy to the
representative of miners at the time of
notification;
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Single sample ...............................................................
2 or more samples .......................................................
5 sample average .........................................................
Each of 5 samples ........................................................
(2) A copy of the proposed respirable
dust control plan, and a copy of any
proposed revision, submitted for
approval shall be made available for
inspection by the representative of
miners; and
(3) A copy of the proposed respirable
dust control plan, and a copy of any
proposed revision, submitted for
approval shall be posted on the mine
bulletin board at the time of submittal.
The proposed plan or proposed revision
shall remain posted until it is approved,
withdrawn, or denied.
(4) Following receipt of the proposed
plan or proposed revision, the
representative of miners may submit
timely comments to the District
Manager, in writing, for consideration
during the review process. Upon
request, a copy of these comments shall
be provided to the operator by the
District Manager.
(b) Each respirable dust control plan
shall include at least the following:
(1) The mine identification number
and DWP number assigned by MSHA,
the operator’s name, mine name, mine
address, and mine telephone number
and the name, address, and telephone
number of the principal officer in charge
of health and safety at the mine;
(2) The specific DWP at the mine to
which the plan applies;
(3) A detailed description of the
specific respirable dust control
measures used to abate the violation of
the respirable dust standard; and
(4) A detailed description of how each
of the respirable dust control measures
described in response to paragraph
(b)(3) of this section will continue to be
used by the operator, including at least
the specific time, place and manner the
control measures will be used.
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§ 71.300
CPDM
1.79
1.79
1.63
1.79
1.70
1.70
1.59
1.70
[Removed]
50. Effective April 14, 2025, remove
§ 71.300.
■
§ 71.300T
[Redesignated as § 71.300]
51. Effective April 14, 2025,
redesignate § 71.300T as § 71.300.
■ 52. Amend § 71.301 by adding
introductory text to read as follows:
■
§ 71.301 Respirable dust control plan;
approval by District Manager and posting.
The following is required until April
14, 2025:
*
*
*
*
*
■ 53. Add § 71.301T to read as follows:
§ 71.301T Respirable dust control plan;
approval by District Manager and posting.
As of April 8, 2026:
(a) The District Manager will approve
respirable dust control plans on a mineby-mine basis. When approving
respirable dust control plans, the
District Manager shall consider whether:
(1) The respirable dust control
measures would be likely to maintain
concentrations of respirable coal mine
dust at or below the standard; and
(2) The operator’s compliance with all
provisions of the respirable dust control
plan could be objectively ascertained by
MSHA.
(b) MSHA may take respirable dust
samples to determine whether the
respirable dust control measures in the
operator’s plan effectively maintain
concentrations of respirable coal mine
dust at or below the applicable
standard.
(c) The operator shall comply with all
provisions of each respirable dust
control plan upon notice from MSHA
that the respirable dust control plan is
approved.
(d) The approved respirable dust
control plan and any revisions shall be:
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(1) Provided upon request to the
representative of miners by the operator
following notification of approval;
(2) Made available for inspection by
the representative of miners; and
(3) Posted on the mine bulletin board
within 1 working day following
notification of approval, and shall
remain posted for the period that the
plan is in effect.
(e) The operator may review
respirable dust control plans and submit
proposed revisions to such plans to the
District Manager for approval.
§ 71.301
[Removed]
54. Effective April 14, 2025, remove
§ 71.301.
■
§ 71.301T
[Redesignated as § 71.301]
55. Effective April 14, 2025,
redesignate § 71.301T as § 71.301.
■
PART 72—HEALTH STANDARDS FOR
COAL MINES
56. The authority citation for part 72
continues to read as follows:
■
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart E—Miscellaneous
■
57. Revise § 72.710 to read as follows:
ddrumheller on DSK120RN23PROD with RULES3
58. Add § 72.710T to read as follows:
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■
As of April 14, 2025: Approved
respirators shall be selected, fitted,
used, and maintained in accordance
with the provisions of a written
respiratory protection program
consistent with the requirements of
ASTM F3387–19. ASTM F3387–19,
Standard Practice for Respiratory
Protection, approved August 1, 2019, is
incorporated by reference into this
section with the approval of the Director
of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5450; (202) 693–9440; or any Mine
Safety and Health Enforcement District
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov. The material may be obtained
from ASTM International, 100 Barr
Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428–2959;
www.astm.org.
§ 72.800T Single, full-shift measurement of
respirable coal mine dust.
[Removed]
59. Effective April 14, 2025, remove
§ 72.710.
■
The following is required until April
14, 2025. In order to ensure the
maximum amount of respiratory
protection, approved respirators shall be
selected, fitted, used, and maintained in
accordance with the provisions of the
American National Standards Institute’s
(ANSI) Practices for Respiratory
Protection ANSI Z88.2–1969, which is
incorporated by reference into this
section with the approval of the Director
of the Federal Register under 5 U.S.C.
552(a) and 1 CFR part 51. This
incorporation by reference (IBR)
material is available for inspection at
the Mine Safety and Health
Administration (MSHA) and at the
National Archives and Records
Administration (NARA). Contact MSHA
at: MSHA’s Office of Standards,
Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202–
5450; (202) 693–9440; or any Mine
Safety and Health Enforcement District
Office. For information on the
availability of this material at NARA,
visit www.archives.gov/federal-register/
cfr/ibr-locations or email fr.inspection@
nara.gov.
■
§ 72.710T Selection, fit, use, and
maintenance of approved respirators.
§ 72.710
§ 72.710 Selection, fit, use, and
maintenance of approved respirators.
28479
§ 72.710T
[Redesignated as § 72.710]
60. Effective April 14, 2025,
redesignate § 72.710T as § 72.710.
■ 61. Revise § 72.800 to read as follows:
The Secretary will use a single, fullshift measurement of respirable coal
mine dust to determine the average
concentration on a shift since that
measurement accurately represents
atmospheric conditions to which a
miner is exposed during such shift. As
of April 14, 2025, noncompliance with
the respirable dust standard, in
accordance with this subchapter, is
demonstrated when a single, full-shift
measurement taken by MSHA meets or
exceeds the applicable ECV in table 1 to
§ 70.208, table 1 to § 70.209, table 1 to
§ 71.206, or table 1 to § 90.207 of this
chapter that corresponds to the
particular sampling device used. Upon
issuance of a citation for a violation of
the standard, and for MSHA to
terminate the citation, the mine operator
shall take the specified actions in this
subchapter.
§ 72.800
The Secretary will use a single, fullshift measurement of respirable coal
mine dust to determine the average
concentration on a shift since that
measurement accurately represents
atmospheric conditions to which a
miner is exposed during such shift.
Until April 14, 2025, noncompliance
with the respirable dust standard, in
accordance with this subchapter, is
demonstrated when a single, full-shift
measurement taken by MSHA meets or
exceeds the applicable ECV in table 1 to
§ 70.208, table 1 to § 70.209, table 1 to
§ 71.206, or table 1 to § 90.207 of this
chapter that corresponds to the
particular sampling device used. Upon
issuance of a citation for a violation of
the standard, and for MSHA to
terminate the citation, the mine operator
shall take the specified actions in this
subchapter.
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[Removed]
63. Effective April 14, 2025, remove
§ 72.800.
■
§ 72.800T
[Redesignated as § 72.800]
64. Effective April 14, 2025,
redesignate § 72.800T as § 72.800.
■
PART 75—MANDATORY SAFETY
STANDARDS—UNDERGROUND COAL
MINES
65. The authority citation for part 75
continues to read as follows:
■
Authority: 30 U.S.C. 811, 813(h), 957.
■
§ 72.800 Single, full-shift measurement of
respirable coal mine dust.
62. Add § 72.800T to read as follows:
Subpart D—Ventilation
66. Amend § 75.350 by adding
introductory text to read as follows:
■
§ 75.350
Belt air course ventilation.
The following is required until April
14, 2025:
*
*
*
*
*
■ 67. Add § 75.350T to read as follows:
§ 75.350T
Belt air course ventilation.
As of April 14, 2025:
(a) The belt air course must not be
used as a return air course; and except
as provided in paragraph (b) of this
section, the belt air course must not be
used to provide air to working sections
or to areas where mechanized mining
equipment is being installed or
removed.
(1) The belt air course must be
separated with permanent ventilation
controls from return air courses and
from other intake air courses except as
provided in paragraph (c) of this
section.
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(2) Effective December 31, 2009, the
air velocity in the belt entry must be at
least 50 feet per minute. When
requested by the mine operator, the
district manager may approve lower
velocities in the ventilation plan based
on specific mine conditions. Air
velocities must be compatible with all
fire detection systems and fire
suppression systems used in the belt
entry.
(b) The use of air from a belt air
course to ventilate a working section, or
an area where mechanized mining
equipment is being installed or
removed, shall be permitted only when
evaluated and approved by the district
manager in the mine ventilation plan.
The mine operator must provide
justification in the plan that the use of
air from a belt entry would afford at
least the same measure of protection as
where belt haulage entries are not used
to ventilate working places. In addition,
the following requirements must be met:
(1) The belt entry must be equipped
with an AMS that is installed, operated,
examined, and maintained as specified
in § 75.351.
(2) All miners must be trained
annually in the basic operating
principles of the AMS, including the
actions required in the event of
activation of any AMS alert or alarm
signal. This training must be conducted
prior to working underground in a mine
that uses belt air to ventilate working
sections or areas where mechanized
mining equipment is installed or
removed. It must be conducted as part
of a miner’s 30 CFR part 48 new miner
training (§ 48.5), experienced miner
training (§ 48.6), or annual refresher
training (§ 48.8).
(3)(i) The average concentration of
respirable dust in the belt air course,
when used as a section intake air
course, shall be maintained at or below
0.5 milligrams per cubic meter of air
(mg/m3).
(ii) A permanent designated area (DA)
for dust measurements must be
established at a point no greater than 50
feet upwind from the section loading
point in the belt entry when the belt air
flows over the loading point or no
greater than 50 feet upwind from the
point where belt air is mixed with air
from another intake air course near the
loading point. The DA must be specified
and approved in the ventilation plan.
(4) The primary escapeway must be
monitored for carbon monoxide or
smoke as specified in § 75.351(f).
(5) The area of the mine with a belt
air course must be developed with three
or more entries.
(6) In areas of the mine developed
after the effective date of this rule,
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unless approved by the district manager,
no more than 50% of the total intake air,
delivered to the working section or to
areas where mechanized mining
equipment is being installed or
removed, can be supplied from the belt
air course. The locations for measuring
these air quantities must be approved in
the mine ventilation plan.
(7) The air velocity in the belt entry
must be at least 100 feet per minute.
When requested by the mine operator,
the district manager may approve lower
velocities in the ventilation plan based
on specific mine conditions.
(8) The air velocity in the belt entry
must not exceed 1,000 feet per minute.
When requested by the mine operator,
the district manager may approve higher
velocities in the ventilation plan based
on specific mine conditions.
(c) Notwithstanding the provisions of
§ 75.380(g), additional intake air may be
added to the belt air course through a
point-feed regulator. The location and
use of point feeds must be approved in
the mine ventilation plan.
(d) If the air through the point-feed
regulator enters a belt air course which
is used to ventilate a working section or
an area where mechanized mining
equipment is being installed or
removed, the following conditions must
be met:
(1) The air current that will pass
through the point-feed regulator must be
monitored for carbon monoxide or
smoke at a point within 50 feet upwind
of the point-feed regulator. A second
point must be monitored 1,000 feet
upwind of the point-feed regulator
unless the mine operator requests that a
lesser distance be approved by the
district manager in the mine ventilation
plan based on mine specific conditions;
(2) The air in the belt air course must
be monitored for carbon monoxide or
smoke upwind of the point-feed
regulator. This sensor must be in the
belt air course within 50 feet of the
mixing point where air flowing through
the point-feed regulator mixes with the
belt air;
(3) The point-feed regulator must be
provided with a means to close the
regulator from the intake air course
without requiring a person to enter the
crosscut where the point-feed regulator
is located. The point-feed regulator must
also be provided with a means to close
the regulator from a location in the belt
air course immediately upwind of the
crosscut containing the point-feed
regulator;
(4) A minimum air velocity of 300 feet
per minute must be maintained through
the point-feed regulator;
(5) The location(s) and use of a pointfeed regulator(s) must be approved in
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the mine ventilation plan and shown on
the mine ventilation map; and
(6) An AMS must be installed,
operated, examined, and maintained as
specified in § 75.351.
§ 75.350
[Removed]
68. Effective April 14, 2025, remove
§ 75.350.
■
§ 75.350T
[Redesignated as § 75.350]
69. Effective April 14, 2025,
redesignate § 75.350T as § 75.350.
■
PART 90—MANDATORY HEALTH
STANDARDS—COAL MINERS WHO
HAVE EVIDENCE OF THE
DEVELOPMENT OF
PNEUMOCONIOSIS
70. The authority citation for part 90
continues to read as follows:
■
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart A—General
■
71. Revise § 90.2 to read as follows:
§ 90.2
Definitions.
Until April 14, 2025, the following
definitions apply in this part:
Act. The Federal Mine Safety and
Health Act of 1977, Public Law 91–173,
as amended by Public Law 95–164 and
Public Law 109–236.
Active workings. Any place in a coal
mine where miners are normally
required to work or travel.
Approved sampling device. A
sampling device approved by the
Secretary and Secretary for Health and
Human Services (HHS) under part 74 of
this subchapter.
Certified person. An individual
certified by the Secretary in accordance
with § 90.202 to take respirable dust
samples required by this part or
certified in accordance with § 90.203 to
perform the maintenance and
calibration of respirable dust sampling
equipment as required by this part.
Coal mine dust personal sampler unit
(CMDPSU). A personal sampling device
approved under part 74, subpart B, of
this subchapter.
Concentration. A measure of the
amount of a substance contained per
unit volume of air.
Continuous personal dust monitor
(CPDM). A personal sampling device
approved under part 74, subpart C, of
this subchapter.
District Manager. The manager of the
Coal Mine Safety and Health District in
which the mine is located.
Equivalent concentration. The
concentration of respirable coal mine
dust, including quartz, expressed in
milligrams per cubic meter of air (mg/
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m3) as measured with an approved
sampling device, determined by
dividing the weight of dust in
milligrams collected on the filter of an
approved sampling device by the
volume of air in cubic meters passing
through the filter (sampling time in
minutes (t) times the sampling airflow
rate in cubic meters per minute), and
then converting that concentration to an
equivalent concentration as measured
by the Mining Research Establishment
(MRE) instrument. When the approved
sampling device is:
(1) The CMDPSU, the equivalent
concentration is determined by
multiplying the concentration of
respirable coal mine dust by the
constant factor prescribed by the
Secretary.
(2) The CPDM, the device shall be
programmed to automatically report
end-of-shift concentration
measurements as equivalent
concentrations.
Mechanized mining unit (MMU). A
unit of mining equipment including
hand loading equipment used for the
production of material; or a specialized
unit which uses mining equipment
other than specified in § 70.206(b) or in
§ 70.208(b) of this subchapter. Each
MMU will be assigned a four-digit
identification number by MSHA, which
is retained by the MMU regardless of
where the unit relocates within the
mine. However, when:
(1) Two sets of mining equipment are
used in a series of working places
within the same working section and
only one production crew is employed
at any given time on either set of mining
equipment, the two sets of equipment
shall be identified as a single MMU.
(2) Two or more sets of mining
equipment are simultaneously engaged
in cutting, mining, or loading coal or
rock from working places within the
same working section, each set of
mining equipment shall be identified as
a separate MMU.
MRE instrument. The gravimetric dust
sampler with a four channel horizontal
elutriator developed by the Mining
Research Establishment of the National
Coal Board, London, England.
MSHA. The Mine Safety and Health
Administration of the U.S. Department
of Labor.
Normal work duties. Duties which the
part 90 miner performs on a routine
day-to-day basis in his or her job
classification at a mine.
Part 90 miner. A miner employed at
a coal mine who has exercised the
option under the old section 203(b)
program (30 CFR part 90, effective as of
July 1, 1972), or under § 90.3 of this part
to work in an area of a mine where the
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average concentration of respirable dust
in the mine atmosphere during each
shift to which that miner is exposed is
continuously maintained at or below the
applicable standard, and who has not
waived these rights.
Quartz. Crystalline silicon dioxide
(SiO2) not chemically combined with
other substances and having a
distinctive physical structure.
Representative sample. A respirable
dust sample, expressed as an equivalent
concentration, that reflects typical dust
concentration levels in the working
environment of the part 90 miner when
performing normal work duties.
Respirable dust. Dust collected with a
sampling device approved by the
Secretary and the Secretary of HHS in
accordance with part 74 (Coal Mine
Dust Sampling Devices) of this
subchapter.
Secretary. The Secretary of Labor or a
delegate.
Secretary of Health and Human
Services. The Secretary of Health and
Human Services (HHS) or the Secretary
of Health, Education, and Welfare.
Transfer. Any change in the work
assignment of a part 90 miner by the
operator and includes:
(1) Any change in occupation code of
a part 90 miner;
(2) any movement of a part 90 miner
to or from an MMU; or
(3) any assignment of a part 90 miner
to the same occupation in a different
location at a mine.
Valid respirable dust sample. A
respirable dust sample collected and
submitted as required by this part,
including any sample for which the data
were electronically transmitted to
MSHA, and not voided by MSHA.
■ 72. Add § 90.2T to read as follows:
§ 90.2T
Definitions.
As April 14, 2025, the following
definitions apply in this part:
Act. The Federal Mine Safety and
Health Act of 1977, Public Law 91–173,
as amended by Public Law 95–164 and
Public Law 109–236.
Active workings. Any place in a coal
mine where miners are normally
required to work or travel.
Approved sampling device. A
sampling device approved by the
Secretary and Secretary for Health and
Human Services (HHS) under part 74 of
this subchapter.
Certified person. An individual
certified by the Secretary in accordance
with § 90.202 to take respirable dust
samples required by this part or
certified in accordance with § 90.203 to
perform the maintenance and
calibration of respirable dust sampling
equipment as required by this part.
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Coal mine dust personal sampler unit
(CMDPSU). A personal sampling device
approved under part 74, subpart B, of
this subchapter.
Concentration. A measure of the
amount of a substance contained per
unit volume of air.
Continuous personal dust monitor
(CPDM). A personal sampling device
approved under part 74, subpart C, of
this subchapter.
District Manager. The manager of the
Coal Mine Safety and Health District in
which the mine is located.
Equivalent concentration. The
concentration of respirable coal mine
dust, including quartz, expressed in
milligrams per cubic meter of air (mg/
m3) as measured with an approved
sampling device, determined by
dividing the weight of dust in
milligrams collected on the filter of an
approved sampling device by the
volume of air in cubic meters passing
through the filter (sampling time in
minutes (t) times the sampling airflow
rate in cubic meters per minute), and
then converting that concentration to an
equivalent concentration as measured
by the Mining Research Establishment
(MRE) instrument. When the approved
sampling device is:
(1) The CMDPSU, the equivalent
concentration is determined by
multiplying the concentration of
respirable coal mine dust by the
constant factor prescribed by the
Secretary.
(2) The CPDM, the device shall be
programmed to automatically report
end-of-shift concentration
measurements as equivalent
concentrations.
Mechanized mining unit (MMU). A
unit of mining equipment including
hand loading equipment used for the
production of material; or a specialized
unit which uses mining equipment
other than specified in § 70.206(b) or in
§ 70.208(b) of this subchapter. Each
MMU will be assigned a four-digit
identification number by MSHA, which
is retained by the MMU regardless of
where the unit relocates within the
mine. However, when:
(1) Two sets of mining equipment are
used in a series of working places
within the same working section and
only one production crew is employed
at any given time on either set of mining
equipment, the two sets of equipment
shall be identified as a single MMU.
(2) Two or more sets of mining
equipment are simultaneously engaged
in cutting, mining, or loading coal or
rock from working places within the
same working section, each set of
mining equipment shall be identified as
a separate MMU.
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MRE instrument. The gravimetric dust
sampler with a four channel horizontal
elutriator developed by the Mining
Research Establishment of the National
Coal Board, London, England.
MSHA. The Mine Safety and Health
Administration of the U.S. Department
of Labor.
Normal work duties. Duties which the
part 90 miner performs on a routine
day-to-day basis in his or her job
classification at a mine.
Part 90 miner. A miner employed at
a coal mine who has exercised the
option under the old section 203(b)
program (30 CFR part 90, effective as of
July 1, 1972), or under § 90.3 to work in
an area of a mine where the average
concentration of respirable dust in the
mine atmosphere during each shift to
which that miner is exposed is
continuously maintained at or below the
standard, and who has not waived these
rights.
Representative sample. A respirable
dust sample, expressed as an equivalent
concentration, that reflects typical dust
concentration levels in the working
environment of the part 90 miner when
performing normal work duties.
Respirable dust. Dust collected with a
sampling device approved by the
Secretary and the Secretary of HHS in
accordance with part 74 (Coal Mine
Dust Sampling Devices) of this
subchapter.
Secretary. The Secretary of Labor or a
delegate.
Secretary of Health and Human
Services. The Secretary of Health and
Human Services (HHS) or the Secretary
of Health, Education, and Welfare.
Transfer. Any change in the work
assignment of a part 90 miner by the
operator and includes:
(1) Any change in occupation code of
a part 90 miner;
(2) any movement of a part 90 miner
to or from an MMU; or
(3) any assignment of a part 90 miner
to the same occupation in a different
location at a mine.
Valid respirable dust sample. A
respirable dust sample collected and
submitted as required by this part,
including any sample for which the data
were electronically transmitted to
MSHA, and not voided by MSHA.
ddrumheller on DSK120RN23PROD with RULES3
§ 90.2
[Removed]
73. Effective April 14, 2025, remove
§ 90.2.
■
§ 90.2T
[Redesignated as § 90.2]
74. Effective April 14, 2025,
redesignate § 90.2T as § 90.2.
■ 75. Amend § 90.3 by adding the
introductory text to read as follows:
■
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§ 90.3 Part 90 option; notice of eligibility;
exercise of option.
The following is required until April
14, 2025:
*
*
*
*
*
■ 76. Add § 90.3T to read as follows:
§ 90.3T Part 90 option; notice of eligibility;
exercise of option.
Effective April 14, 2025:
(a) Any miner employed at a coal
mine who, in the judgment of the
Secretary of HHS, has evidence of the
development of pneumoconiosis based
on a chest X-ray, read and classified in
the manner prescribed by the Secretary
of HHS, or based on other medical
examinations shall be afforded the
option to work in an area of a mine
where the average concentration of
respirable dust in the mine atmosphere
during each shift to which that miner is
exposed is continuously maintained at
or below the standard. Each of these
miners shall be notified in writing of
eligibility to exercise the option.
(b) Any miner who is a section 203(b)
miner on January 31, 1981, shall be a
part 90 miner on February 1, 1981,
entitled to full rights under this part to
retention of pay rate, future actual wage
increases, and future work assignment,
shift and respirable dust protection.
(c) Any part 90 miner who is
transferred to a position at the same or
another coal mine shall remain a part 90
miner entitled to full rights under this
part at the new work assignment.
(d) The option to work in a low dust
area of the mine may be exercised for
the first time by any miner employed at
a coal mine who was eligible for the
option under the old section 203(b)
program (www.msha.gov/
REGSTECHAMEND.htm), or is eligible
for the option under this part by sending
a written request to the Chief, Division
of Health, Mine Safety and Health
Enforcement, MSHA, 201 12th Street
South, Arlington, VA 22202–5452.
(e) The option to work in a low dust
area of the mine may be re-exercised by
any miner employed at a coal mine who
exercised the option under the old
section 203(b) program (www.msha.gov/
REGSTECHAMEND.htm) or exercised
the option under this part by sending a
written request to the Chief, Division of
Health, Mine Safety and Health
Enforcement, MSHA, 201 12th Street
South, Arlington, VA 22202–5452. The
request should include the name and
address of the mine and operator where
the miner is employed.
(f) No operator shall require from a
miner a copy of the medical information
received from the Secretary or Secretary
of HHS.
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§ 90.3
[Removed]
77. Effective April 14, 2025, remove
§ 90.3.
■
§ 90.3T
[Redesignated as § 90.3]
78. Effective April 14, 2025,
redesignate § 90.3T as § 90.3.
■
Subpart B—Dust Standards, Rights of
Part 90 Miners
79. Amend § 90.100 by adding
introductory text to read as follows:
■
§ 90.100
Respirable dust standard.
The following is required until April
14, 2025. After the 20th calendar day
following receipt of notification from
MSHA that a part 90 miner is employed
at the mine, the operator shall
continuously maintain the average
concentration of respirable dust in the
mine atmosphere during each shift to
which the part 90 miner in the active
workings of the mine is exposed, as
measured with an approved sampling
device and expressed in terms of an
equivalent concentration, at or below:
*
*
*
*
*
■ 80. Add § 90.100T to read as follows:
§ 90.100T
Respirable dust standard.
The following is required as of April
14, 2025. After the 20th calendar day
following receipt of notification from
MSHA that a part 90 miner is employed
at the mine, the operator shall
continuously maintain the average
concentration of respirable dust in the
mine atmosphere during each shift to
which the part 90 miner in the active
workings of the mine is exposed, as
measured with an approved sampling
device and expressed in terms of an
equivalent concentration, at or below
0.5 mg/m3.
§ 90.100
[Removed]
81. Effective April 14, 2025, remove
§ 90.100.
■
§ 90.100T
[Redesignated as § 90.100]
82. Effective April 14, 2025,
redesignate § 90.100T as § 90.100.
■
§ 90.101
[Removed and Reserved]
83. Effective April 14, 2025, remove
and reserve § 90.101.
■ 84. Amend § 90.102 by adding
introductory text to read as follows:
■
§ 90.102
Transfer; notice.
The following is required until April
14, 2025:
*
*
*
*
*
■ 85. Add § 90.102T to read as follows:
§ 90.102T
Transfer; notice.
As of April 14, 2025:
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(a) Whenever a part 90 miner is
transferred in order to meet the
standard, the operator shall transfer the
miner to an existing position at the same
coal mine on the same shift or shift
rotation on which the miner was
employed immediately before the
transfer. The operator may transfer a
part 90 miner to a different coal mine,
a newly created position or a position
on a different shift or shift rotation if the
miner agrees in writing to the transfer.
The requirements of this paragraph do
not apply when the respirable dust
concentration in a part 90 miner’s work
position complies with the standard but
circumstances, such as reductions in
workforce or changes in operational
status, require a change in the miner’s
job or shift assignment.
(b) On or before the 20th calendar day
following receipt of notification from
MSHA that a part 90 miner is employed
at the mine, the operator shall give the
District Manager written notice of the
occupation and, if applicable, the MMU
unit to which the part 90 miner shall be
assigned on the 21st calendar day
following receipt of the notification
from MSHA.
(c) After the 20th calendar day
following receipt of notification from
MSHA that a part 90 miner is employed
at the mine, the operator shall give the
District Manager written notice before
any transfer of a part 90 miner. This
notice shall include the scheduled date
of the transfer.
§ 90.102
[Removed]
86. Effective April 14, 2025, remove
§ 90.102.
■
§ 90.102T
[Redesignated as § 90.102]
87. Effective April 14, 2025,
redesignate § 90.102T as § 90.102.
■ 88. Revise § 90.104 to read as follows:
■
ddrumheller on DSK120RN23PROD with RULES3
§ 90.104
option.
Waiver of rights; re-exercise of
The following is required until April
14, 2025:
(a) A part 90 miner may waive his or
her rights and be removed from MSHA’s
active list of miners who have rights
under part 90 by:
(1) Giving written notification to the
Chief, Division of Health, Mine Safety
and Health Enforcement, MSHA, that
the miner waives all rights under this
part;
(2) Applying for and accepting a
position in an area of a mine which the
miner knows has an average respirable
dust concentration exceeding the
applicable standard; or
(3) Refusing to accept another
position offered by the operator at the
same coal mine that meets the
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requirements of §§ 90.100, 90.101 and
90.102(a) after dust sampling shows that
the present position exceeds the
applicable standard.
(b) If rights under part 90 are waived,
the miner gives up all rights under part
90 until the miner re-exercises the
option in accordance with § 90.3(e) (Part
90 option; notice of eligibility; exercise
of option).
(c) If rights under part 90 are waived,
the miner may re-exercise the option
under this part in accordance with
§ 90.3(e) (Part 90 option; notice of
eligibility; exercise of option) at any
time.
■ 89. Add § 90.104T to read as follows:
§ 90.104T
option.
Waiver of rights; re-exercise of
As of April 14, 2025:
(a) A part 90 miner may waive his or
her rights and be removed from MSHA’s
active list of miners who have rights
under part 90 by:
(1) Giving written notification to the
Chief, Division of Health, Mine Safety
and Health Enforcement, MSHA, that
the miner waives all rights under this
part;
(2) Applying for and accepting a
position in an area of a mine which the
miner knows has an average respirable
dust concentration exceeding the
standard; or
(3) Refusing to accept another
position offered by the operator at the
same coal mine that meets the
requirements of §§ 90.100, 90.101 and
90.102(a) after dust sampling shows that
the present position exceeds the
applicable standard.
(b) If rights under part 90 are waived,
the miner gives up all rights under part
90 until the miner re-exercises the
option in accordance with § 90.3(e) (Part
90 option; notice of eligibility; exercise
of option).
(c) If rights under part 90 are waived,
the miner may re-exercise the option
under this part in accordance with
§ 90.3(e) (Part 90 option; notice of
eligibility; exercise of option) at any
time.
§ 90.104
[Removed]
90. Effective April 14, 2025, remove
§ 90.104.
■
§ 90.104T
[Redesignated as § 90.104]
91. Effective April 14, 2025,
redesignate § 90.104T as § 90.104.
■
Subpart C—Sampling Procedures
92. Amend § 90.205 by adding
introductory text to read as follows:
■
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§ 90.205 Approved sampling devices;
operation; air flowrate.
The following is required until April
14, 2025:
*
*
*
*
*
■ 93. Add § 90.205T to read as follows:
§ 90.205T Approved sampling devices;
operation; air flowrate.
As of April 14, 2025:
(a) Approved sampling devices shall
be operated at the flowrate of 2.0 L/min
if using a CMDPSU; at 2.2 L/min if
using a CPDM; or at a different flowrate
recommended by the manufacturer.
(b) If using a CMDPSU, each approved
sampling device shall be examined each
shift, by a person certified in sampling
during:
(1) The second hour after being put
into operation to assure it is in the
proper location, operating properly, and
at the proper flowrate. If the proper
flowrate is not maintained, necessary
adjustments shall be made by the
certified person. This examination is not
required if the sampling device is being
operated in an anthracite coal mine
using the full box, open breast, or slant
breast mining method.
(2) The last hour of operation to
assure that the sampling device is
operating properly and at the proper
flowrate. If the proper flowrate is not
maintained, the respirable dust sample
shall be transmitted to MSHA with a
notation by the certified person on the
back of the dust data card stating that
the proper flowrate was not maintained.
Other events occurring during the
collection of respirable dust samples
that may affect the validity of the
sample, such as dropping of the
sampling head assembly onto the mine
floor, shall be noted on the back of the
dust data card.
(c) If using a CPDM, the person
certified in sampling shall monitor the
dust concentrations and the sampling
status conditions being reported by the
sampling device at mid-shift or more
frequently as specified in the approved
respirable dust control plan, if
applicable, to assure: The sampling
device is in the proper location and
operating properly; and the work
environment of the Part 90 miner being
sampled remains in compliance with
the standard at the end of the shift. This
monitoring is not required if the
sampling device is being operated in an
anthracite coal mine using the full box,
open breast, or slant breast mining
method.
§ 90.205
[Removed]
94. Effective April 14, 2025, remove
§ 90.205.
■
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Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
[Redesignated as § 90.205]
95. Effective April 14, 2025,
redesignate § 90.205T as § 90.205.
■ 96. Amend § 90.206 by adding
introductory text to read as follows:
■
§ 90.206 Exercise of option or transfer
sampling.
The following is required until April
14, 2025:
*
*
*
*
*
■ 97. Add § 90.206T to read as follows:
§ 90.206T Exercise of option or transfer
sampling.
(a) The operator shall take five valid
representative dust samples for each
part 90 miner within 15 calendar days
after:
(1) The 20-day period specified for
each part 90 miner in § 90.100; and
(2) Implementing any transfer after
the 20th calendar day following receipt
of notification from MSHA that a part 90
miner is employed at the mine.
(b) Noncompliance with the standard
shall be determined in accordance with
§ 90.207(d).
(c) Upon issuance of a citation for a
violation of the standard, the operator
shall comply with § 90.207(f).
§ 90.206
[Removed]
98. Effective April 14, 2025, remove
§ 90.206.
■
§ 90.206T
[Redesignated as § 90.206]
99. Effective April 14, 2025,
redesignate § 90.206T as § 90.206.
■ 100. Amend § 90.207 by adding
introductory text to read as follows:
■
§ 90.207
Quarterly sampling.
The following is required until April
14, 2025:
*
*
*
*
*
■ 101. Add § 90.207T to read as follows:
§ 90.207T
Quarterly sampling.
As of April 14, 2025:
(a) Each operator shall take five valid
representative samples every calendar
quarter from the environment of each
part 90 miner while performing normal
work duties. Part 90 miner samples
shall be collected on consecutive work
days. The quarterly periods are:
(1) January 1–March 31
(2) April 1–June 30
(3) July 1–September 30
(4) October 1–December 31.
(b) [Reserved]
(c) When a valid representative
sample taken in accordance with this
section meets or exceeds the ECV in
table 1 to this section corresponding to
the particular sampling device used, the
mine operator shall:
(1) Make approved respiratory
equipment available to affected miners
in accordance with § 72.700 of this
chapter;
(2) Immediately take corrective action
to lower the concentration of respirable
coal mine dust to below the standard;
and
(3) Make a record of the corrective
actions taken. The record shall be
certified by the mine foreman or
equivalent mine official, no later than
the end of the mine foreman’s or
equivalent official’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
part 90 miner.
(d) Noncompliance with the standard
is demonstrated during the sampling
period when:
(1) Two or more valid representative
samples meet or exceed the ECV in table
1 to this section that corresponds to the
particular sampling device used; or
(2) The average for all valid
representative samples meets or exceeds
the ECV in table 1 to this section that
corresponds to the particular sampling
device used.
(e) Unless otherwise directed by the
District Manager, upon issuance of a
citation for a violation of the standard,
paragraph (a) of this section shall not
apply to that Part 90 miner until the
violation is abated and the citation is
terminated in accordance with
paragraphs (e) and (f) of this section.
(f) Upon issuance of a citation for a
violation of the standard, the operator
shall take the following actions
sequentially:
(1) Make approved respiratory
equipment available to the affected part
90 miner in accordance with § 72.700 of
this subchapter.
(2) Immediately take corrective action
to lower the concentration of respirable
dust to below the standard. If the
corrective action involves:
(i) Reducing the respirable dust levels
in the work position of the part 90
miner identified in the citation, the
operator shall implement the proposed
corrective actions and begin sampling
the affected miner within 8 calendar
days after the date the citation is issued,
until five valid representative samples
are taken.
(ii) Transferring the Part 90 miner to
another work position at the mine to
meet the standard, the operator shall
comply with § 90.102 and then sample
the affected miner in accordance with
§ 90.206(a).
(3) Make a record of the corrective
actions taken. The record shall be
certified by the mine foreman or
equivalent mine official, no later than
the end of the mine foreman’s or
equivalent official’s next regularly
scheduled working shift. The record
shall be made in a secure book that is
not susceptible to alteration or
electronically in a computer system so
as to be secure and not susceptible to
alteration. Such records shall be
retained at a surface location at the mine
for at least 1 year and shall be made
available for inspection by authorized
representatives of the Secretary and the
part 90 miner.
(g) A citation for a violation of the
standard shall be terminated by MSHA
when the equivalent concentration of
each of the five valid representative
samples is below the standard.
TABLE 1 TO § 90.207T—EXCESSIVE CONCENTRATION VALUES (ECV) BASED ON A SINGLE SAMPLE, TWO SAMPLES, OR
THE AVERAGE OF FIVE FULL-SHIFT CMDPSU/CPDM CONCENTRATION MEASUREMENTS
ECV (mg/m3)
ddrumheller on DSK120RN23PROD with RULES3
Section
Samples
CMDPSU
90.207(c) .......................................................................
90.207(d)(1) ..................................................................
90.207(d)(2) ..................................................................
90.207(g) ......................................................................
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Single sample ...............................................................
2 or more samples .......................................................
5 sample average .........................................................
Each of 5 samples ........................................................
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18APR3
0.74
0.74
0.61
0.74
CPDM
0.57
0.57
0.53
0.57
Federal Register / Vol. 89, No. 76 / Thursday, April 18, 2024 / Rules and Regulations
§ 90.207
[Removed]
102. Effective April 14, 2025, remove
§ 90.207.
■
§ 90.207T
[Redesignated as § 90.207]
103. Effective April 14, 2025],
redesignate § 90.207T as § 90.207.
■
Subpart D—Respirable Dust Control
Plans
104. Amend § 90.300 by adding
introductory text to read as follows:
■
§ 90.300 Respirable dust control plan;
filing requirements.
The following is required until April
14, 2025:
*
*
*
*
*
■ 105. Add § 90.300T to read as follows:
§ 90.300T Respirable dust control plan;
filing requirements.
§ 90.300
ddrumheller on DSK120RN23PROD with RULES3
As of April 14, 2025:
(a) If an operator abates a violation of
the standard by reducing the respirable
dust level in the position of the Part 90
miner, the operator shall submit to the
District Manager for approval a written
respirable dust control plan for the Part
90 miner in the position identified in
the citation within 15 calendar days
after the citation is terminated. The
respirable dust control plan and
revisions thereof shall be suitable to the
conditions and the mining system of the
coal mine and shall be adequate to
continuously maintain respirable dust
below the standard for that Part 90
miner.
(b) Each respirable dust control plan
shall include at least the following:
(1) The mine identification number
assigned by MSHA, the operator’s name,
mine name, mine address, and mine
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telephone number and the name,
address and telephone number of the
principal officer in charge of health and
safety at the mine;
(2) The name and MSHA Individual
Identification Number of the part 90
miner and the position at the mine to
which the plan applies;
(3) A detailed description of how each
of the respirable dust control measures
used to continuously maintain
concentrations of respirable coal mine
dust below the standard; and
(4) A detailed description of how each
of the respirable dust control measures
described in response to paragraph
(b)(3) of this section will continue to be
used by the operator, including at least
the specific time, place, and manner the
control measures will be used.
[Removed]
106. Effective April 14, 2025, remove
§ 90.300.
■
§ 90.300T
[Redesignated as § 90.300]
107. Effective April 14, 2025,
redesignate § 90.300T as § 90.300.
■ 108. Amend § 90.301 by adding
introductory text to read as follows:
■
§ 90.301 Respirable dust control plan;
approval by District Manager; copy to part
90 miner.
The following is required until April
14, 2025:
*
*
*
*
*
■ 109. Add § 90.301T to read as follows:
§ 90.301T Respirable dust control plan;
approval by District Manager; copy to part
90 miner.
As of April 14, 2025:
(a) The District Manager will approve
respirable dust control plans on a mine-
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28485
by-mine basis. When approving
respirable dust control plans, the
District Manager shall consider whether:
(1) The respirable dust control
measures would be likely to maintain
concentrations of respirable coal mine
dust below the standard; and
(2) The operator’s compliance with all
provisions of the respirable dust control
plan could be objectively ascertained by
MSHA.
(b) MSHA may take respirable dust
samples to determine whether the
respirable dust control measures in the
operator’s plan effectively maintain
concentrations of respirable coal mine
dust below the standard.
(c) The operator shall comply with all
provisions of each respirable dust
control plan upon notice from MSHA
that the respirable dust control plan is
approved.
(d) The operator shall provide a copy
of the current respirable dust control
plan required under this part to the part
90 miner. The operator shall not post
the original or a copy of the plan on the
mine bulletin board.
(e) The operator may review
respirable dust control plans and submit
proposed revisions to such plans to the
District Manager for approval.
§ 90.301
[Removed]
110. Effective April 14, 2025, remove
§ 90.301.
■
§ 90.301T
[Redesignated as § 90.301]
111. Effective April 14, 2025,
redesignate § 90.301T as § 90.301.
■
[FR Doc. 2024–06920 Filed 4–16–24; 8:45 am]
BILLING CODE 4520–43–P
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| File Type | application/pdf |
| File Modified | 2024-04-18 |
| File Created | 2024-04-18 |