Respirable Silica (Quartz)
| Citation | 84 FR 45452 |
| Record Number | 2019-18478 |
| Published date | 29 August 2019 |
| Court | Mine Safety And Health Administration |
Federal Register, Volume 84 Issue 168 (Thursday, August 29, 2019)
[Federal Register Volume 84, Number 168 (Thursday, August 29, 2019)]
[Proposed Rules]
[Pages 45452-45456]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-18478]
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DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Parts 56, 57, 70, 71, 72, and 90
[Docket No. MSHA-2016-0013]
RIN 1219-AB36
Respirable Silica (Quartz)
AGENCY: Mine Safety and Health Administration, Labor.
ACTION: Request for information.
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SUMMARY: Metal and nonmetal (MNM) miners and coal miners exposed to
silica (quartz) in respirable dust can develop various forms of
pneumoconiosis that are irreversible, life limiting, and may lead to
death. MSHA's existing standards limit miners' exposures to quartz in
respirable dust. In this Request for Information (RFI), MSHA solicits
information and data on feasible, best practices to protect miners'
health from exposure to quartz in respirable dust, including an
examination of an appropriately reduced permissible exposure limit,
potential new or developing protective technologies, and/or technical
and educational assistance.
DATES: Comments must be received or postmarked by midnight (12 a.m.)
Eastern Daylight Savings Time on October 28, 2019.
ADDRESSES: Submit comments and informational materials, identified by
RIN 1219-AB36 or Docket No. MSHA 2016-0013, by one of the following
methods:
Federal E-Rulemaking Portal: https://www.regulations.gov.
Follow the on-line instructions for submitting comments.
Email: [email protected].
Mail: MSHA, Office of Standards, Regulations, and
Variances, 201 12th Street South, Suite 4E401, Arlington, Virginia
22202-5452.
Hand Delivery or Courier: 201 12th Street South, Suite
4E401, Arlington, Virginia, between 9:00 a.m. and 5:00 p.m. Monday
through Friday, except Federal holidays. Sign in at the receptionist's
desk on the 4th floor East, Suite 4E401.
Fax: 202-693-9441.
Instructions: All submissions must include RIN 1219-AB36 or Docket
No. MSHA 2016-0013. Do not include personal information that you do not
want publicly disclosed; MSHA will post all comments without change to
http://www.regulations.gov and http://arlweb.msha.gov/currentcomments.asp, including any personal information provided.
Docket: For access to the docket to read comments received, go to
http://www.regulations.gov or http://arlweb.msha.gov/currentcomments.asp. To read background documents, go to http://www.regulations.gov. Review the docket in person at MSHA, Office of
Standards, Regulations, and Variances, 201 12th Street South,
Arlington, Virginia, between 9:00 a.m. and 5:00 p.m. Monday through
Friday, except Federal Holidays. Sign in at the receptionist's desk in
Suite 4E401.
Email Notification: To subscribe to receive email notification when
MSHA publishes rulemaking documents in the Federal Register, go to
https://www.msha.gov/subscriptions.
FOR FURTHER INFORMATION CONTACT: Sheila A. McConnell, Director, Office
of Standards, Regulations, and Variances, MSHA, at
[email protected] (email), 202-693-9440 (voice), or 202-693-
9441 (fax). These are not toll-free numbers.
SUPPLEMENTARY INFORMATION:
[[Page 45453]]
I. Background
A. Crystalline Silica Sources, Adverse Health Effects, and Existing
Standards in Metal and Nonmetal (MNM) and Coal Mining
Crystalline silica refers to a chemical compound, silicon dioxide
(SiO2), that 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. Quartz is found in rocks such as granite, sandstone,
limestone, and shale. Mining, milling, and processing crystalline
silica-containing substances can create airborne respirable particles.
Some activities generate more respirable dust than others including,
but not limited to, cutting, sanding, drilling, crushing, grinding,
milling, sawing, scraping, jack hammering, excavating, or disturbing
materials that contain quartz.
Mechanized operations can generate large amounts of dust,
potentially exposing miners to elevated levels of airborne dust,
including quartz.\1\ Particles with an aerodynamic diameter smaller
than 10 micrometer ([micro]m) are more likely to be respirable, and as
particle diameter decreases, the proportion of particles that can reach
the lungs' alveolar region increases. Quartz particles that are small
enough to reach the alveolar spaces (respirable particles) may be
deposited and retained there, leading to disease development. The
amount of time for a miner to develop lung disease such as chronic
obstructive pulmonary disease (COPD) or various forms of pneumoconiosis
such as silicosis, coal workers' pneumoconiosis (CWP), progressive
massive fibrosis (PMF), and rapidly progressive pneumoconiosis (RPP)
depends on various factors such as cumulative dust exposure and genetic
predisposition to lung damage.2 3 The MNM mining industry
includes many commodities that contain various percentages of quartz.
MNM miners' exposure to quartz dust depends, in part, on the type of
rock or mineral being mined or processed. Each commodity, however, has
common dust sources related to the mining process, which includes
drilling, blasting, loading, hauling, and crushing. MSHA regulates MNM
miners' exposure to respirable dust containing quartz under 30 CFR
56.5001 for surface mining operations and under 30 CFR 57.5001 for
underground mining operations. MSHA's existing standard is based on the
American Conference of Governmental Industrial Hygienists (ACGIH)
Threshold Limit Value (TLV)[supreg] published in 1973 \4\ that was
incorporated by reference by MSHA's predecessor agency, the Mine
Enforcement Safety Administration (MESA) in 1974 \5\ and then
recodified by MSHA in 1985.\6\ MSHA's existing standard for MNM mines
is 10 mg/m\3\/(percent respirable quartz + 2) expressed as the
concentration of respirable dust for a full shift or an 8-hour
equivalent time-weighted average (TWA).\7\
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\1\ National Institute for Occupational Safety and Health
(NIOSH). 2019. Dust control handbook for industrial minerals mining
and processing. Second edition. By Cecala AB, O'Brien AD, Schall J,
Colinet JF, Franta RJ, Schultz MJ, Haas EJ, Robinson J, Patts J,
Holen BM, Stein R, Weber J, Strebel M, Wilson L, and Ellis M.
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. 2019-
124, RI 9701. https://doi.org/10.26616/NIOSHPUB2019124.
\2\ Blanc P. and A. Seaton. 2016. Editorial Pneumoconiosis
Redux--Coal Workers' Pneumoconiosis and Silicosis Are Still a
Problem. Am J Respir Crit Care Med. 193(6): 603-604.
\3\ Cohen, R. 2015. Clarifying Distribution, Trends, and
Determinants of Adverse Health in United States Miners: Exploration
and Integration of Existing Data Systems. ALPHA Foundation for the
Improvement of Mine Safety and Health--Final Technical Report. Grant
Number: AFC113-4. University of Illinois at Chicago, School of
Public Health.
\4\ American Conference of Governmental Industrial Hygienists
(ACGIH). 1973. TLVs Threshold Limit Values for Chemical Substances
in Workroom Air Adopted by ACGIH for 1973. Cincinnati, Ohio.
\5\ Mine Enforcement Safety Administration (MESA). 1974. Parts
55/56/57--Health and Safety Standards--Miscellaneous Amendments. 39
FR 24316.
\6\ Mine Safety and Health Administration (MSHA). 1985.
Recodification of Safety and Health Standards for Metal and Nonmetal
Mines--Final Rule. 50 FR 4048.
\7\ Example: If the quartz content of the sample is 18.0%, the
TLV[supreg] for quartz is: 10 mg/m\3\/18.0% quartz + 2 = 10 mg/m\3\/
20.0 = 0.50 mg/m\3\.
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Coal miners are exposed to quartz during the extraction and
processing of coal. Exposure to quartz during extraction occurs when
miners disturb the rock above, below, or within the coal seam. Exposure
also occurs in processing plants as the coal is being sized, crushed,
dried, and conveyed. MSHA's standards (30 CFR 70.101, 71.101, and
90.101) limit coal miners' exposure to respirable quartz in relation to
the respirable dust standard. When respirable dust samples are analyzed
for quartz and the concentration of quartz exceeds 0.1 mg/m\3\ (100
micrograms per cubic meter of air or [micro]g/m\3\) MRE (British Mining
Research Establishment) equivalent concentration, MSHA reduces the
applicable respirable dust standard for sections of the mine
represented by the sample data. MSHA computes the reduced dust standard
by dividing 10 by the percent of quartz (10/percent quartz \8\).
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\8\ Example: A valid representative dust sample with an
equivalent concentration of 1.12 mg/m\3\ contains 12.3% of quartz
dust corresponds to a quartz concentration of 138 mg/m\3\. The
respirable dust standard when quartz is present is maintained on
each shift at or below 0.8 mg/m\3\ (10/12.3% = 0.8 mg/m\3\).
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Since 1974, the National Institute for Occupational Safety and
Health (NIOSH) has recommended an exposure limit for respirable
crystalline silica (quartz) of 0.05 mg/m\3\ (50 [mu]g/m\3\) ISO.\9\ In
2000, the ACGIH revised its Threshold Limit Value (TLV[supreg]) for
respirable crystalline silica (quartz) to 50 [mu]g/m\3\ (ISO) and has
since further lowered its TLV[supreg] to 25 [mu]g/m\3\ (ISO).\10\ In
2016, the Occupational Safety and Health Administration (OSHA) amended
MSHA's existing respirable crystalline silica standards to establish a
permissible exposure limit (PEL) of 50 [mu]g/m\3\ (ISO).\11\
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\9\ National Institute for Occupational Safety and Health
(NIOSH). 1974. Criteria for a recommended standard . . .
Occupational Exposure to Crystalline Silica. HEW Publication No.
(NIOSH) 75-120.
\10\ American Conference of Governmental Industrial Hygienists
(ACGIH). 2006. Silica, Crystalline: [alpha]-Quartz and cristobalite.
Cincinnati, Ohio.
\11\ Occupational Safety and Health Administration (OSHA). 2016.
Occupational Exposure to Respirable Crystalline Silica--Final Rule.
81 FR 16286.
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B. Existing Controls, Including Respiratory Protection
MSHA requires engineering or environmental controls as the primary
means of controlling respirable dust. This is consistent with section
202(h) of the Federal Mine Safety and Health Act of 1977 (Mine Act),
which provides that the use of respirators shall not be substituted for
environmental control measures in the active workings. Engineering or
environmental controls reduce dust generation by suppressing, diluting,
capturing, or diverting the dust being generated by the mining process.
MSHA addressed the use of supplementary means of controlling
miners' exposures to respirable dust in previous rulemakings. In the
preambles to the 2000 \12\ and 2003 \13\ proposed rules \14\ on
Verification of Underground
[[Page 45454]]
Coal Mine Operators' Dust Control Plans and Compliance Sampling for
Respirable Dust (Plan Verifications proposed rules), MSHA discussed a
petition for rulemaking to allow the use of powered air purifying
respirators (PAPRs) as a supplemental means of compliance. In the
preamble to the 2000 proposed rule, MSHA proposed to ``permit, under
certain circumstances, the limited use of either approved loose-fitting
PAPRs or verifiable administrative controls for compliance purposes''
(65 FR 42135). In the preamble to the 2003 proposed rule, MSHA proposed
to ``permit the limited use of either approved PAPRs, administrative
controls, or a combination of both for compliance purposes in those
circumstances where further reduction of dust levels cannot be
reasonably achieved using all feasible engineering controls.'' (68 FR
10800).
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\12\ Mine Safety and Health Administration (MSHA). 2000.
Verification of Underground Coal Mine Operators' Dust Control Plans
and Compliance Sampling for Respirable Dust--Proposed rule; notice
of hearings. 65 FR 42122.
\13\ Mine Safety and Health Administration (MSHA). 2003.
Verification of Underground Coal Mine Operators' Dust Control Plans
and Compliance Sampling for Respirable Dust--Proposed rule; notice
of hearings; close of record. 68 FR 10784.
\14\ The 2010 proposed rule (75 FR 64413) combined the following
rulemaking actions: (1) ``Occupational Exposure to Coal Mine Dust
(Lowering Exposure);'' (2) ``Verification of Underground Coal Mine
Operators' Dust Control Plans and Compliance Sampling for Respirable
Dust'' (Plan Verification) (65 FR 42122, July 7, 2000, and 68 FR
10784, March 6, 2003); (3) ``Determination of Concentration of
Respirable Coal Mine Dust'' (Single Sample) (65 FR 42068, July 7,
2000, and 68 FR 10940 March 6, 2003); and (4) ``Respirable Coal Mine
Dust: Continuous Personal Dust Monitor (CPDM)'' (74 FR 52708,
October 14, 2009). The 2010 proposed rule was finalized on May 1,
2014 (84 FR 24814).
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MSHA explained that there may be only limited situations where
exposures could not be consistently controlled by available
technologies (65 FR 42134; 68 FR 10798-10799, 10818). MSHA reiterated
that engineering or environmental controls are the primary means to
control respirable dust in the mine atmosphere, which is consistent
with sections 201(b) and 202(h) of the Mine Act. MSHA also noted that
the Dust Advisory Committee unanimously recommended that respiratory
protection should not replace engineering or environmental controls,
but should continue to be provided to miners until controls are
implemented that are capable of maintaining respirable dust levels in
compliance with the standards.\15\ In those limited situations, mine
operators are required to provide respiratory protection to miners
while they adjust engineering and environmental controls to reduce dust
levels to at or below the standard.
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\15\ U.S. Department of Labor, Mine Safety and Health
Administration. 1996. Report of the Secretary of Labor's Advisory
Committee on the Elimination of Pneumoconiosis Among Coal Mine
Workers. Washington, DC. October 1996.
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In addition, in MSHA's 2014 rulemaking on Lowering Miners' Exposure
to Respirable Coal Mine Dust, including Continuous Personal Dust
Monitors (Dust Rule),\16\ commenters advocated the use of PAPRs, not
only as a temporary supplementary control, but also as an engineering
control. Other commenters stated that using respirators as a means of
complying with the dust standard is contrary to the Mine Act and would
provide miners with a false sense of protection. Some commenters cited
the difficulty of wearing respirators in hot and sweaty jobs, and in
dusty, dirty conditions, including in low coal. While the final rule
allows operators to use engineering and administrative controls, the
rule did not contain provisions to allow operators to use respirators,
including PAPRs, as supplementary controls to achieve compliance with
the respirable dust standards. As specified in Sections 201(b) and
202(h) of the Mine Act and since passage of the Federal Coal Mine
Health and Safety Act of 1969, MSHA has enforced an environmental
standard at coal mines; that is, the concentration of respirable dust
in the mine atmosphere is measured rather than the breathing zone of
any individual miner.
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\16\ Mine Safety and Health Administration (MSHA). 2014.
Lowering Miners' Exposure to Respirable Coal Mine Dust, Including
Continuous Personal Dust Monitors--Final rule. 79 FR 24814.
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Engineering controls, also known as environmental controls, are the
most protective means of controlling dust generation at the source.
MSHA is aware that there may be conditions where existing engineering
or environmental controls may not be adequate to continuously protect
miners' health in areas where there are high levels of quartz dust.
NIOSH researchers have documented large clusters of coal miners in
eastern Kentucky, West Virginia, and southwest Virginia with PMF, the
most severe form of black lung disease.17 18 NIOSH reported
that a high proportion of these cases had r-type opacities, category B
and C large opacities, and coal mining tenure of less than 20 years,
which are indications of exceptionally severe and rapidly progressive
disease. Historically, the typical progression (latency) from a normal
chest X-ray to advanced pneumoconiosis in coal miners exposed to coal
dust was 15 to 25 years of working tenure.\19\ However, as mining has
become highly mechanized, some miners may be exposed to higher
concentrations of dusts, including quartz.\20\ NIOSH defined rapid
progression of the disease as an increase of greater than one small ILO
(International Labor Organization) category within a period of 5 years,
or the development of PMF.21 22 23 Researchers also noted
that one potential cause of a rapidly progressive disease is
overexposure to respirable quartz.24 25 26
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\17\ Blackley, D., C. Halldin, and A. Laney. 2016. Resurgence of
Progressive Massive Fibrosis in Coal Miners--Eastern Kentucky, 2016.
Morbidity and Mortality Weekly Report, 65 (49):1385-9.
\18\ Blackley, D., L. Reynolds, C. Short, et al. 2018b. Research
Letter: Progressive Massive Fibrosis in Coal Miners from 3 Clinics
in Virginia. JAMA, 319(5):500-1.
\19\ Petsonk, E., C. Rose, and R. Cohen. 2013. Coal Mine Dust
Lung Disease--New Lessons from an Old Exposure. Am J Respir Crit
Care Med., 187(11):1178-1185.
\20\ ``Drilling into the typical quartz-containing rock
surrounding coal seams (e.g., driving tunnels to the seam and
drilling the roof to bolt supports to rock above to prevent
collapse) long has been recognized to cause silicosis. In addition,
however, extrusions of quartz into coal seams may occur . . .
accelerated silicosis may result from exploitation of thin seams
using coal cutters that take slices of the roof and floor'' (Blanc
and Seaton, 2016, page 604).
\21\ Antao, V.C. dos S., E.L. Petsonk, L.Z. Sokolow, et. al.
2005. Rapidly Progressive Coal Workers' Pneumoconiosis in the United
States: Geographic Clustering and Other Factors. Occup Environ Med.,
62(10):670-674.
\22\ Cohen, R.A., A. Patel, and F.H. Green. 2008. Lung Disease
Caused By Exposure to Coal Mine and Silica Dust. Seminars in
Respiratory and Critical Care Medicine, 29(6):651-661. Epub. Feb 16,
2009.
\23\ National Academies of Sciences, Engineering, and Medicine.
2018. Monitoring and Sampling Approaches to Assess Underground Coal
Mine Dust Exposures. Washington, DC: The National Academies Press.
doi: https://www.nap.edu/catalog/25111/monitoring-and-sampling-approaches-to-assess-underground-coal-mine-dust-exposures. Page 16.
\24\ Halldin, C., A. Wolfe, and A. Laney. 2015(b). Debilitating
Lung Disease Among Surface Coal Miners With No Underground Mining
Tenure. JOEM, 57():62-67.
\25\ Petsonk, E., C. Rose, and R. Cohen. 2013. Coal Mine Dust
Lung Disease--New Lessons from an Old Exposure. Am J Respir Crit
Care Med., 187(11):1178-1185.
\26\ Cohen, RA., E. Petsonk, C. Rose, et al. 2016. Lung
Pathology in U.S. Coal Workers with Rapidly Progressive
Pneumoconiosis Implicates Silica and Silicates. Am J Respir Crit
Care Med Vol 193(6): 673-680.
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Recent studies indicate that over-exposure to quartz presents same
health risks to MNM miners.27 28 29 30 Although
[[Page 45455]]
most MNM miners with early-stage silicosis (ILO categories 0/1 or 1/0)
typically do not experience respiratory symptoms, the primary risk to
the affected miner is progression of disease with progressive decline
of lung function. Several studies of MNM miners exposed to respirable
crystalline silica (quartz) have shown that, once silicosis is detected
by x-ray, a substantial proportion of affected miners can progress
beyond ILO category 1 silicosis, even after exposure has
ceased.31 32 33 34
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\27\ Institute of Occupational Medicine (IOM 2011). Health,
socio-economic and environmental aspects of possible amendments to
the EU Directive on the protection of workers from the risks related
to exposure to carcinogens and mutagens at work--Respirable
crystalline silica. IOM Research Project: P937/8. May 2011.
Edinburgh, UK.
\28\ National Institute for Occupational Safety and Health
(NIOSH). 2019. Dust control handbook for industrial minerals mining
and processing. Second edition. By Cecala AB, O'Brien AD, Schall J,
Colinet JF, Franta RJ, Schultz MJ, Haas EJ, Robinson J, Patts J,
Holen BM, Stein R, Weber J, Strebel M, Wilson L, and Ellis M.
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. 2019-
124, RI 9701. https://doi.org/10.26616/NIOSHPUB2019124.
\29\ Occupational Safety and Health Administration (OSHA). 2016.
Occupational Exposure to Respirable Crystalline Silica--Final Rule.
81 FR 16286.
\30\ U.S. Department of Labor (USDOL). 2008. A Practical Guide
to an Occupational Health Program for Respirable Crystalline Silica.
A Joint Project of: The Industrial Minerals Association--North
America and the Mine Safety and Health Administration. Instruction
Guide Series IG 103. January 25, 2008.
\31\ Hessel, P.A., G.K. Sluis-Cremer, E. Hnizdo; et al. 1988.
Progression OF Silicosis in Relation to Silica Dust Exposure. Ann.
O. Hyg., 32(Suppl 1):689-696.
\32\ Kreiss K. and B. Zhen. 1996. Risk of silicosis in a
Colorado mining community. Am J Ind Med., 30(5):529-39.
\33\ Ng T.P., S.L. Chan, and K.P. Lam. 1987a. Radiological
progression and lung function in silicosis: A ten year follow up
study. Br Med J., 295:164-168.
\34\ Yang, H., L. Yang, J. Zhang, et al. 2006. Natural Course of
Silicosis in Dust-exposed Workers. J. Huazhong University of Science
and Technology, [Med Sci]. 26(2):257-260.
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Respiratory protection may play an important role in reducing
miners' exposure to respirable quartz. MSHA's existing coal (30 CFR
72.700, 72.701, and 72.710) and MNM standards (30 CFR 56/57.5005)
require respiratory protection to be approved by NIOSH under 42 CFR
part 84 (Approval of Respiratory Protective Devices), and incorporate
by reference the American National Standards Institute's (ANSI's)
``Practices for Respiratory Protection ANSI Z88.2-1969'' standard.\35\
MSHA is aware that in 2015, ANSI updated the Z88.2 standard.\36\ A copy
of the 2015 ANSI standard is in the docket and MSHA seeks comment on
this updated standard.
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\35\ American National Standards Institute (ANSI). 1969.
Practices for Respiratory Protection ANSI Z88.2-1969. New York, New
York.
\36\ American National Standards Institute (ANSI). American
National Standard--Practices for Respiratory Protection--ANSI/ASSE
Z88.2-2015. American National Standards Institute, Inc. American
Society of Safety Engineers, Park Ridge, Illinois. Approved March 4,
2015.
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Under MSHA's MNM standards (30 CFR 56/57.5005), control of miners'
exposure to respirable quartz must, where feasible, be achieved 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, miners may work for
reasonable periods of time in a location where concentrations of
respirable quartz exceed permissible levels only if they are protected
by appropriate respiratory protective equipment.
MSHA's standards for coal dust (30 CFR 70.208, 70.209, 71.206, and
90.207) require that either during operator exposure monitoring when a
valid representative sample meets or exceeds the excessive
concentration value, or when the mine operator receives a citation for
a violation of the applicable standard, the mine operator must take
actions to protect miners, including making respiratory protection
available while evaluating and implementing dust control measures, as
necessary, to reduce miners' exposures to respirable dust. Under MSHA's
existing coal standards, however, miners are not compelled to wear
respirators and mine operators cannot use respirators as a substitute
for engineering or environmental controls. Also MSHA cannot credit mine
operators' use of respiratory protection in achieving compliance.
C. Hierarchy of Controls
Controlling exposures to occupational hazards is the primary way to
protect workers. Traditionally, mine operators use a hierarchy of
controls to determine how to implement feasible and effective control
solutions and are considered generally accepted industry hygiene
principles. The hierarchy of controls begins with the most effective
controls: Elimination and substitution of hazards. Elimination and
substitution of hazards, while most effective at reducing risks, are
not feasible to reduce exposures to respirable crystalline quartz for
MNM or coal mining. The controls that are relevant in mining are:
Engineering controls, administrative controls, and personal protective
equipment (PPE).
Engineering controls are favored over administrative controls and
PPE for controlling miner exposures in the workplace because they are
designed to remove the hazard at the source, before miners are exposed.
Well-designed, installed, and maintained engineering controls can be
highly effective in protecting miners and are typically independent of
worker interactions (human factors) to provide a high level of
protection.\37\
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\37\ National Institute for Occupational Safety and Health
(NIOSH). 2015. Hierarchy of Controls. NIOSH website at: https://www.cdc.gov/niosh/topics/hierarchy/. Accessed June 4, 2019, last
reviewed January 13, 2015.
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Administrative controls and PPE are frequently used with existing
workplace practices where hazards are not well controlled. These
methods for protecting miners have proven to be less effective than
engineering controls, requiring significant effort by the mine operator
and affected miners.
In mining, engineering or environmental controls include all
methods that control the level of respirable dust by reducing dust
generation (machine parameters) or by suppressing (water sprays,
wetting agents, foams, water infusion, etc.), diluting (ventilation),
capturing dust (dust collectors) or diverting dust (shearer clearer,
passive barriers, etc.).
Administrative controls refer to work practices that reduce miners'
daily exposure to respirable dust hazards by altering the way in which
work is performed. Administrative controls consists of such actions as
rotation of miners to areas having lower dust concentrations,
rescheduling of tasks, and modifying work activities. The effectiveness
of administrative controls requires oversight to ensure that miners
adhere to the controls, such as restrictions of time in an area or
switching duties. Using administrative controls also requires a
sufficient number of qualified miners available to perform the specific
duties.
A form of PPE, an air purifying respirator is designed to protect
miners from the inhalation of hazardous contaminants. Respirators can
protect miners by removing contaminants from the air they breathe.
Particulate air-purifying respirators remove or filter airborne
contaminants from the air before they can be inhaled. Examples of this
type of respirator include dust masks (filtering face pieces), half or
full-mask (elastomeric) respirators, and PAPRs.
Engineering controls are more effective than respirators in
continuously protecting miners from respirable crystalline quartz. Many
factors affect the effectiveness of respirators to protect miners. The
protection of a respirator is reduced dramatically or voided when the
respirator is improperly worn such as with facial hair that interferes
with the seal or when the respirator is removed in contaminated
atmospheres during periods of exposure, even for short durations. For
example, if a miner properly wears a half-mask respirator continually
during an 8-hour exposure duration, the protection factor afforded is
10; however, removing the respirator for 24 minutes during the 8-hour
exposure duration reduces the protection factor to 6.9. If the miner
wears the respirator for only half of the exposure duration, the
protection factor is reduced to 1.8 (2015 ANSI Z88.2--Table A.7-1).
Many respirators may not be comfortable, and a miner's tolerance to
wearing a respirator can decrease
[[Page 45456]]
over an extended period of time. Miners are also likely to remove
respirators when performing arduous tasks, communicating, chewing
tobacco, are sick, hot or sweaty, or when the respirator is
uncomfortable, thereby subjecting miners to respirable crystalline
silica concentrations above the standard.
MSHA addressed the ``hierarchy of controls'' in the 2000 (65 FR
42122) and 2003 (68 FR 10784) Plan Verification proposed rules, and in
the 2014 Dust rule (79 FR 24814). Commenters to the Dust rule noted
that MSHA permits the use of ``hierarchy of controls'' in MNM mines to
control miners' exposure to diesel particulate matter (79 FR 24930). In
the Plan Verification proposed rules, and in the Dust rule, MSHA
reiterated that engineering or environmental controls are the primary
means to control respirable dust in the mine atmosphere, which is
consistent with sections 201(b) and 202(h) of Mine Act. However, MSHA
also recognizes the importance of controlling miners' exposure to
quartz and seeks information and data to determine if existing
engineering and environmental controls can continuously protect miners
and ensure that they do not suffer material impairment of health or
functional capacity over their working lives from working in areas with
high levels of quartz.
II. Information Request
MSHA is interested in data and information on economically and
technologically feasible best practices to protect coal and MNM miners'
health from exposure to quartz, including a reduced standard, new or
developing protective technologies, and/or technical and educational
assistance.
MSHA specifically requests input from industry, labor, and other
interested parties on best practices that will improve health
protections for coal and MNM miners from exposure to quartz dust.
1. Please provide any information on new or developing technologies
and best practices that can be used to protect miners from exposure to
quartz dust.
2. Please provide any information on 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. Please provide any information on additional feasible dust-
control methods that could be used by mining operations to reduce
miners' exposure to respirable quartz during high-silica cutting
situations, such as on development sections, shaft and slope work, and
cutting overcasts.
4. Please provide any other experience, data, or information that
may be useful to MSHA in evaluating miners' exposures to quartz.
Authority: 30 U.S.C. 811, 813(h), 957.
David G. Zatezalo,
Assistant Secretary of Labor for Mine Safety and Health Administration.
[FR Doc. 2019-18478 Filed 8-28-19; 8:45 am]
BILLING CODE 4520-43-P
