Verification of Underground Coal Mine Operators' Dust Control Plans
and
Compliance Sampling for Respirable Dust [07/07/2000]
Volume 65, Number 131, Page 42122-42185
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DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Parts 70, 75 and 90
RIN 1219-AB14
Verification of Underground Coal Mine Operators' Dust Control
Plans and Compliance Sampling for Respirable Dust
AGENCY: Mine Safety and Health Administration (MSHA), Labor.
ACTION: Proposed rule; notice of hearings.
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SUMMARY: MSHA is proposing to revoke existing operator respirable dust
sampling procedures under parts 70 and 90, and to implement new
regulations that would require each underground coal mine operator to
have a verified mine ventilation plan. Under this proposal, MSHA would
verify the effectiveness of the mine ventilation plan for each
mechanized mining unit (MMU) in controlling respirable dust under
typical mining conditions. MSHA would collect full-shift respirable
dust samples, called ``verification samples,'' to demonstrate the
adequacy of the dust control parameters specified in the mine
ventilation plan in maintaining the concentration of respirable coal
mine and quartz dust at or below 2.0 mg/m\3\ and 100 <greek-m>g/m\3\,
respectively. The adequacy of these parameters would be demonstrated on
shifts during which the amount of the material produced is at or above
the ``verification production level'' (VPL) or the tenth highest
production level recorded in the most recent 30 production shifts.
[[Page 42123]]
The proposal would require mine operators to: First, set and
maintain the dust control parameters during MSHA verification sampling
at levels specified in the plan; second, maintain and make available to
MSHA records of the amount of material produced by each mechanized
mining unit during each production shift; and third, additional
information in mine ventilation plans. For longwall mine operations,
MSHA is also proposing to permit the use of either approved powered,
air-purifying respirators (PAPRs) or verifiable administrative controls
as a supplemental means of compliance if MSHA has determined that
further reduction in respirable dust levels cannot be achieved using
all feasible engineering or environmental controls appropriate for the
operational conditions involved. In addition, through this rule, MSHA
would conduct all compliance and abatement sampling under existing
parts 70 and 90.
DATES: Comments on the proposed rule should be submitted on or before
August 7, 2000.
We are also announcing that we will hold public hearings on the
proposed rule within 30 to 45 days of the publication of this rule. The
hearing dates, times and specific locations will be announced by a
separate document in the Federal Register. The rulemaking record will
remain open 7 days after the last public hearing.
ADDRESSES: You may use mail, facsimile (fax), or electronic mail to
send your comments to MSHA. Clearly identify comments as such and send
them--(1) By mail to: Carol J. Jones, Director, Office of Standards,
Regulations, and Variances, MSHA, 4015 Wilson Boulevard, Room 631,
Arlington, VA 22203;
(2) By fax to: MSHA, Office of Standards, Regulations, and
Variances, 703-235-5551; or
(3) By electronic mail to: comments@msha.gov. Written comments on
the information collection requirements may be submitted directly to
the Office of Information and Regulatory Affairs, OMB, New Executive
Office Building, 725 17th Street, NW, Washington, DC 20503, Attn: Desk
Officer for MSHA; and to Carol J. Jones, Director, Office of Standards,
Regulations, and Variances, MSHA 4015 Wilson Boulevard, Room 631,
Arlington, VA 22203; by facsimile to MSHA, at 703-235-5551; or by
electronic mail to comments@msha.gov.
The hearings will be held in the following locations: Prestonsburg,
Kentucky, (Jenny Wiley State Resort Park); Morgantown, West Virginia;
and Salt Lake City, Utah. The hearing dates, times and specific
locations will be announced by a separate document in the Federal
Register.
FOR FURTHER INFORMATION CONTACT: Carol J. Jones, Director, Office of
Standards, Regulations, and Variances, MSHA; 703-235-1910.
SUPPLEMENTARY INFORMATION:
I. Table of Contents
The preamble discusses: revocation of existing operator respirable
dust sampling requirements, revised procedures for adjusting the
respirable dust standard when quartz is present, the proposed rule,
engineering controls for respirable coal mine dust, dust control
parameters, supplemental controls, health effects of exposure to
respirable coal mine dust, degree and significance of the reduction in
the number of shifts during which there are overexposures, an analysis
of the technological and economical feasibility of this proposed rule,
and regulatory impact and flexibility analyses.
The preamble discussion follows this outline:
I. Table of Contents
II. Background
A. Coal Mine Respirable Dust Task Group
B. Advisory Committee on the Elimination of Pneumoconiosis Among
Coal Mine Workers
III. General Discussion
A. Revocation of the Operator Dust Sampling Program
1. Pre-1980 Sampling Program
2. Post-1980 Sampling Program
3. Issues Affecting the Credibility of Operator Compliance
Sampling
4. Proposed Reforms to the Respirable Dust Monitoring Program
a. Bimonthly Sampling
b. Abatement Sampling
c. Advantages of MSHA Compliance Sampling Over Existing Program
B. Revised Procedures for Setting the Applicable Dust Standard
When Quartz is Present
1. Current Procedures
2. Proposed Revised Procedures
3. Validity of Averaging Percentages
C. Respirable Dust Control Program for Underground Coal Mines
1. Evaluating and Approving Plan Requirements for Respirable
Dust Control
2. Compliance with Plan Requirements for Respirable Dust Control
3. Monitoring Effectiveness of Plan Requirements for Respirable
Dust Control
(a) Monitoring by Mine Operators
(b) Monitoring by MSHA
4. Proposed Procedures for Evaluating, Approving, and Monitoring
Plan Requirements
D. Hierarchy of Dust Controls
1. Selection of Respirators: Loose-Fitting PAPRs
2. Protection Factor for Loose-fitting Powered, Air-Purifying
Respirators
E. Guidelines for Determining What is a Feasible Dust Control
F. Application of Continuous Monitoring Technology to Prevent
Overexposure on Individual Shifts
IV. Discussion of Proposed Rule
A. Summary
B. Section-by-Section Discussion
V. Health Effects
A. Introduction
B. Hazard Identification
1. Agent: Coal
2. Physical State: Coal Mine Dust
3. Biological Action: Respirable Coal Mine Dust
C. Health Effects of Respirable Coal Mine Dust
1. Description of Major Health Effects
a. Simple Coal Workers' Pneumoconiosis (CWP) and Progressive
Massive Fibrosis (PMF)
b. Other Health Effects
2. Toxicological Literature
3. Epidemiological Literature
a. Simple Coal Workers' Pneumoconiosis (CWP) and Progressive
Massive Fibrosis (PMF)
b. Other Health Effects
VI. Quantitative Risk Assessment
VII. Significance of Risk
VIII. Feasibility Issues
A. Technological Feasibility
B. Economic Feasibility
IX. Regulatory Impact Analysis
A. Costs and Benefits: Executive Order 12866
1. Compliance Costs
2. Benefits
B. Regulatory Flexibility Certification and Initial Regulatory
Flexibility Analysis
X. Other Statutory Requirements
A. Plain Language
B. Unfunded Mandates Reform Act of 1995
C. Paperwork Reduction Act of 1995
D. National Environmental Protection Act
E. Executive Order 12630 (Governmental Actions and Interference
with Constitutionally Protected Property Rights)
F. Executive Order 12988 (Civil Justice)
G. Executive Order 13045 (Protection of Children from
Environmental Health Risks and Safety Risks)
H. Executive Order 13084 (Consultation and Coordination with
Indian Tribal Governments)
I. Executive Order 13132 (Federalism)
XI. Public Hearings
Appendix A. Derivation of the Critical Values
Appendix B. References
XII. Regulatory Text
II. Background
Maintaining a work environment free of excessive levels of
respirable coal mine dust and quartz dust (respirable dust) is
essential for long-term health protection. Through the joint
promulgation of the single, full-shift sample and plan verification
proposals, miners would be further protected from the debilitating
effects of occupational
[[Page 42124]]
respiratory disease by limiting their exposures to respirable coal mine
dust to no more than the applicable standard on each shift.\1\
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\1\ For details, see Quantitative Risk Assessment and
Significance of Risk Sections.
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Section 202(b)(2) of the Federal Mine Safety and Health Act of 1977
(Mine Act) requires each operator to continuously maintain the average
concentration of respirable dust in the mine atmosphere, during each
shift to which each miner in the active workings of such mine is
exposed, at or below 2.0 milligrams of respirable dust per cubic meter
of air (mg/m\3\). Under current MSHA regulations, when coal mine dust
contains more than five percent quartz, the respirable coal mine dust
standard is further reduced, by means of a formula. Although MSHA does
not currently enforce a separate standard for respirable quartz dust,
the formula (10 divided by the percentage quartz) used to establish an
applicable dust standard, in effect, limits quartz concentrations to
100 <greek-m>g/m\3\.
Consistent with the Mine Act and MSHA regulations, the primary
focus of the federal respirable dust program is on controlling the
concentrations of respirable dust in the work environment where miners
work or travel through the application of feasible environmental or
engineering control measures. Engineering or environmental control of
respirable dust in the mine environment is the ultimate dust-control
technique and the principal method for protecting miners' health. These
include all methods that control respirable dust levels in the air that
a miner breathes by either reducing dust generation, or by suppressing,
diluting, capturing or diverting the dust that is being generated by
the mining process. Under the Mine Act, the mine operator has primary
responsibility for implementing a program to control respirable dust so
that all miners work in an environment free of excessive levels of
respirable dust. For full compliance, mine operators must develop,
implement, and maintain effective engineering or environmental control
measures, and evaluate them at regular intervals to assure that they
function as intended. These control measures or ``dust control
parameters,'' are specified in the dust control portion of the
operator's mine ventilation plan currently required under Sec. 75.370.
Mine ventilation plans are a long-recognized means of addressing
health issues that are mine specific and for achieving work
environments that are free of excessive concentrations of respirable
dust. Currently, section 75.370 requires each operator of an
underground coal mine to develop and follow a ventilation plan that is
designed to control methane and respirable dust in the mine. The plan
must be suitable to the conditions and mining systems employed at the
mine. Although ventilation plans must be designed to control respirable
dust, there is no requirement that the plan's effectiveness be
verified.
The dust control portion of the mine ventilation plan is a key
element of the operator's strategy to control respirable dust in the
working environment of each mechanized mining unit (MMU) during each
shift. Section 70.2 defines an MMU to mean ``a unit of mining equipment
including hand loading equipment used for the production of material.''
The plans provide a description of specific engineering control
measures in use. The plans also contain procedures for maintenance of
specific dust control equipment, such as scrubbers, dust collectors on
roof bolters, and spray nozzles, or for the replacement of cutting
picks to minimize dust generation. Once approved by the District
Manager, the dust control parameters must be employed on a continuous
basis. By monitoring the parameters, one can be assured that respirable
dust levels are being adequately controlled without needing to rely on
repeated dust sample analyses.
Implementing dust control parameters, which have been determined
effective under typical mining conditions, and maintaining these
controls in proper working order provides reasonable assurance that no
miner will be overexposed. Because technology that continuously
monitors respirable dust and displays dust concentrations in real-time
is not currently used in underground coal mines, adhering to effective
ventilation plans is the only practical means of reasonably assuring,
on a continuous basis, that miners are not overexposed. In 1996, MSHA
implemented revised ventilation standards which, among other
provisions, required an on-shift examination of the dust control
parameters before coal production begins on each MMU. Based on the
recommendations of the MSHA Task Group (MSHA, 1992), this requirement
is intended to focus attention on the need for properly functioning
dust controls before production begins. On-shift examinations of dust
control parameters under existing Sec. 75.362 are important for an
effective respirable dust control strategy.
Recent advances in technology may make it feasible to continuously
monitor certain parameters such as, air quantity and velocity, and
spray water flow rate and pressure (Spencer, et al. 1996). Section
75.362 encourages the use of such monitors as it would eliminate the
need for periodic physical measurements of some dust controls to verify
if they are operating properly. Although current technology allows for
real-time data on the performance, the condition of key dust control
parameters, and for immediate modification of controls, MSHA is not
aware of its use by any operator.
Since establishment of the first comprehensive dust standards in
1969, the implementation of ventilation plans by mine operators and
their enforcement by MSHA has had a significant impact on control of
dust levels in underground coal mines. For example, based on federal
mine inspector sampling results, the average dust concentration in the
environment of a continuous miner operator (occupation code--036) has
been reduced by 86 percent over the past 30 years, from 7.7 mg/m\3\ to
approximately 1.1 mg/m\3\. This accounts for the significant decline in
the percentage of operator continuous miner designated occupation (DO)
samples exceeding 2.0 mg/m\3\, from 49 percent (over 32,000 samples/
shifts) in 1971, to 10 percent (over 2,500 samples/shifts) in 1999.
Analysis of all valid operator DO samples indicates that in 1971, the
2.0 mg/m\3\-dust standard was exceeded on 53,463 (44 percent) of the
122,404 shifts sampled, compared to 3,002 (10 percent) of the 28,727
shifts sampled in 1999 (MSHA, DO Samples by Calendar Year, 1999).
Despite this progress, MSHA has found evidence that a significant
number of overexposures still occur on the shifts sampled during which
the approved dust control parameters are operating at or above approved
levels. This evidence suggests that it is highly probable that some
miners are overexposed to respirable dust on shifts not sampled by
either the operator or by MSHA. In addition, recent medical
surveillance data suggests that miners continue to be at risk of
developing simple coal workers' pneumoconiosis (CWP), progressive
massive fibrosis (PMF) and silicosis (Elam, April 1999).
Certain aspects of the current respirable dust program limit MSHA's
ability to assure the adequacy of the dust control parameters under
typical mining conditions according to two expert panels which reviewed
the federal program designed to prevent pneumoconiosis among coal
miners. Both the Coal Mine Respirable Dust Task Group, an interagency
task group
[[Page 42125]]
established in 1991 by the Assistant Secretary for Mine Safety and
Health, and the Advisory Committee on the Elimination of Pneumoconiosis
Among Coal Mine Workers, established in 1995 by the Secretary of Labor,
considered all aspects of the respirable coal mine dust control program
and made recommendations for improvement.
A. Coal Mine Respirable Dust Task Group
In response to concerns about the Federal coal mine dust program
(MSHA, 1992), MSHA's Coal Mine Respirable Dust Task Group (the Task
Group) undertook an extensive review of the program to control
respirable coal mine dust and made recommendations to improve the
program in 1991. As part of that review, MSHA developed a special
respirable dust ``spot inspection program'' (SIP). This program was
designed to provide the Agency and the Task Group with information on
the dust levels to which underground miners are typically exposed.
Among other recommendations, the Task Group recommended that MSHA
require mine ventilation plans to be effective under typical mining
conditions.
The Task Group found that MSHA's current program did not promote
the development and implementation of quality plans. Based on its
review of a representative number of dust control plans, the Task Group
found that some plans lacked specificity or did not include all the
dust control parameters actually used. For example, the plans for three
major underground coal mines listed the air quantity, the primary means
of controlling concentrations of respirable coal mine dust, to be
18,000 cubic feet per minute (cfm) in the mining section. The actual
quantities measured by MSHA inspectors at these mines during the SIP
varied from 40,000 cfm to over 120,000 cfm.
Based on a review of MSHA Form 2000-86 (Revised), Respirable Dust
Sampling and Monitoring Data, similar differences were found between
air quantity specified in approved ventilation plans and the levels
observed at a number of longwall MMUs inspected in 1999. For example,
20 of the 47 longwall MMUs were using significantly more air than
specified in the ventilation plan (MSHA, September 1999). Under these
circumstances, it would be impossible to assess whether the air volume
specified in the plan was adequate to maintain dust concentrations at
or below the applicable dust standard. It should be noted that air
volume quantities, air velocities, water spray pressures, etc.,
specified in the plan are considered to be a minimum and MSHA
encourages mine operators to exceed their plan parameters, but only
after the levels specified in the plan have been shown to be effective
under the conditions in effect during sampling. In addition, a lack of
specificity in some plans made it difficult for MSHA inspectors to
determine whether the operator was complying with the approved plan.
Although several plans indicated that the mining equipment was to be
provided with water sprays, the plan did not specify the location of
the sprays or the water pressure at the spray nozzle.
The Task Group determined that the use of minimum production levels
for evaluating the effectiveness of dust control parameters can result
in marginal or inadequate plans. A more detailed discussion of the
impact of production on the quality of dust control parameters
specified in mine ventilation plans is provided later in this document
(in sections III.C.1. and IV.B.). Currently, MSHA relies on information
provided by the operator to determine at what production level the plan
should be evaluated. No production records are required for each MMU.
Although operators must submit production data on a quarterly basis,
the data is compiled for the entire mine. In addition, these quarterly
reports provide information on the amount of clean coal produced, which
are much lower than the tonnage of total material produced, and are not
useful for establishing what constitutes a ``normal production shifts''
for sampling purposes.
A follow-up survey conducted by MSHA in 1994 found that 43 percent
or 539 of the 1,245 producing MMUs, worked at least a 9-hour shift. The
Task Group also concluded that current regulations limiting the
duration of sampling to eight hours do not provide for adequate
assessment of respirable dust exposure during nontraditional shifts of
more than eight hours.
Implementation of the Task Group recommendations would have
required regulatory change. The effort to implement these changes was
suspended pending the recommendations of Advisory Committee on the
Elimination of Pneumoconiosis Among Coal Mine Workers, which was
convened in 1995.
B. Advisory Committee on the Elimination of Pneumoconiosis Among Coal
Mine Workers
On January 31, 1995, the Secretary of Labor established the
Advisory Committee on the Elimination of Pneumoconiosis Among Coal Mine
Workers (the Advisory Committee). The Advisory Committee was chartered
to ``make recommendations for improving the program to control
respirable coal mine dust in underground and surface mines in the
United States.'' The Advisory Committee identified and addressed many
of the same issues considered by the Task Group. Findings and consensus
recommendations were developed for each issue (MSHA, 1996). The
Advisory Committee concluded that the dust control portion of the mine
ventilation plan is the key element of an operator's strategy to
control respirable dust in the work environment. They concluded that
the initial evaluation, approval, in-mine verification and monitoring
to demonstrate the effectiveness of the operator's proposed dust
control plan is critical for the protection of miners from lung
disease. Also, believing that the credibility of the current system of
mine operator sampling to monitor compliance with exposure limits has
been severely compromised, the Advisory Committee concluded that
restoration of miner and mine operator confidence in the respirable
coal mine dust sampling program should be one of MSHA's highest
priorities. Accordingly, there was unanimous agreement that in order to
restore confidence in the program MSHA should take full responsibility
for all compliance sampling currently being carried out by mine
operators under 30 CFR parts 70 and 90.
The November 1996 Advisory Committee Report recommended numerous
improvements for the federal program to protect miners from simple CWP,
PMF, and silicosis. Of these, the following have been incorporated in
this proposal:
1. MSHA should take full responsibility for all compliance sampling
at a level which assures representative samples of respirable dust
exposures under usual conditions of work without adversely impacting
the remainder of the Agency's resources and responsibilities.
2. MSHA should, in consultation with the operator, perform
scheduled independent dust monitoring to verify the operator's plan.
3. MSHA should redefine the range of production levels which must
be maintained during sampling to verify the plan. The value should be
sufficiently close to maximum anticipated production level in order to
reasonably assure that the plan would be effective under typical
operations.
4. MSHA should review compliance and production records to
determine when there is a need for plan verification and modification.
[[Page 42126]]
5. MSHA should require that the results and monitoring of dust
control parameters and production be recorded in order to correlate
dust control parameters with dust measurements.
This proposal is intended to eliminate overexposures on individual
shifts and to restore the confidence of miners and mine operators in
the respirable coal mine dust sampling program by addressing the
shortcomings identified by the Task Group and the Advisory Committee in
the current respirable coal mine dust program. The proposal would
revoke the operator dust sampling programs under 30 CFR parts 70 and 90
and require the implementation of mine ventilation plans demonstrated
to be effective in maintaining respirable dust at or below the
applicable standard on each shift. These ventilation plans would be
verified by MSHA using single, full-shift respirable dust samples. The
plans' effectiveness would be monitored on a regular basis by the use
of inspector single, full-shift samples. The proposed rule regarding
the use of single, full-shift measurements of respirable coal mine dust
to determine average concentration is also published in today's Federal
Register.
MSHA recognizes that the Secretary of Labor's Advisory Committee on
the Elimination of Pneumoconiosis Among Coal Workers made several
recommendations that also impact on surface coal mine workers. These
surface coal mine issues will be addressed by the agency in a separate
rulemaking which is currently underway. The scope of that rulemaking
will include many of the issues that are addressed in this underground
rule including requirements for duct control plans, verification of
dust control plans prior to approval, on shift examination of dust
control measures, and the elimination of operator sampling for
compliance purposes.
III. General Discussion
This section describes the current respirable coal mine dust
program and the role of mine ventilation plans in safeguarding the
health of miners. Specifically, this section details:
(1) The reasoning behind MSHA's decision to revoke the operator
dust sampling programs under 30 CFR parts 70 and 90 and to take full
responsibility for all compliance sampling;
(2) The proposed procedures for arriving at an average quartz
percentage that is used to establish an applicable dust standard under
Secs. 70.101 and 90.101;
(3) The existing means for evaluating the effectiveness of dust
control parameters stipulated in mine ventilation plans;
(4) The plan approval process;
(5) Methods of assuring compliance with plan requirements; and
(6) MSHA's efforts to monitor plan effectiveness on a regular
basis.
There is also a detailed discussion of the hierarchy of dust controls
and the continued need for mine ventilation plans to specify dust
control parameters in order to preserve the primacy of engineering
controls. Finally, as a possible alternative to plan verification, we
have included a discussion and a request for comments on the
application of personal continuous monitoring technology which is, or
may become available, to prevent overexposure on individual shifts.
A. Revocation of the Operator Dust Sampling Program
Under the Federal Coal Mine Health and Safety Act of 1969 (Coal
Act) coal mine operators were required to take accurate dust samples at
periodic intervals to measure the amount of respirable dust in the mine
atmosphere where miners work or travel. The Coal Act also required that
citations be issued whenever respirable dust samples collected either
by an operator or by federal mine inspectors showed noncompliance with
the applicable dust standard. The Coal Act was amended in 1977 (Mine
Act), but the respirable dust provisions remained essentially
unchanged.
1. Pre-1980 Sampling Program
In 1970, federal regulations were issued that established the first
comprehensive coal mine operator dust sampling program. Those
regulations required the environment of the occupation on a working
section, or MMU, exposed to the highest respirable dust concentration
to be sampled--the ``high risk'' occupation concept. All other miners
working in the MMU in less risky occupations were assumed to be
protected from excessive concentrations of respirable coal mine dust if
the high risk occupation was in compliance. Under the program, each
operator was required to initially collect and submit ten valid
respirable dust samples to determine the average dust concentration
(across ten production shifts). If analysis showed the average dust
concentration to be within the applicable dust standard, the operator
was required to submit only five valid samples a month. If compliance
continued to be demonstrated, the operator was required to submit only
five valid samples every other month. The initial, monthly, and
bimonthly sampling cycles were referred to as the ``original,''
``standard,'' and ``alternative'' sampling cycles, respectively. When
the average dust concentrations exceeded the standard, the operator
reverted back to the standard sampling cycle.
Additionally, each working miner was sampled individually every 120
or 180 days, depending on the miner's work assignment, or every 90 days
for each miner (now referred to as a part 90 miner) who had a positive
chest x-ray for coal workers' pneumoconiosis (CWP) and who elected to
exercise the option of transferring to a less dusty area. However,
except for the part 90 miner results, these early individual sample
results were not used for enforcement, but were forwarded to the
National Institute for Occupational Safety and Health (NIOSH) to
develop a comprehensive exposure data base for research concerning
black lung disease. Each sample was accompanied by a completed mine
data card that included, among other things, the occupation and social
security number of the sampled miner. This information was also
included in the Agency's computer print-out of sampling results that
was sent to mine operators.
2. Post-1980 Sampling Program
In 1980, following hearings held throughout the coal fields (in
1977 and 1978), regulations governing operator sampling were
substantially revised by reducing the operator sampling burden, to
simplify the sampling process, and to enhance the overall quality of
the sampling program. The result was to replace the various sampling
cycles with a bimonthly sampling cycle and to eliminate the requirement
that each working miner be sampled. These are the regulations that
currently govern the mine operator dust sampling program. Like the 1970
rules, the current regulations continue to rely on sampling the
environment of the DO in the MMU that is exposed to the greatest
concentration of respirable coal mine dust, but reduced the number of
shifts required to be sampled from ten to five.
Other changes included replacing the requirement that each working
miner be sampled individually with the bimonthly collection of one
sample from each ``designated area'' (DA) to measure the dust
concentrations associated with dust-generating sources in the active
workings of the mine, such as along haulage ways, at underground
crushers, or at transfer points. These locations are strategically
selected so that the environment where miners normally work or travel
is monitored for compliance with the applicable dust
[[Page 42127]]
standard. The operator's approved ventilation plan identifies the
specific locations where DA samples are required to be collected and
the dust control measures used at these locations. Another change was
to increase the frequency of sampling part 90 miners from every 90 days
to one sample every 60 days.
The revised regulations also eliminated the reporting of personal
identifiers on the dust data card due to miner concerns that the data
may be used by mine operators to characterize the exposure of an
individual miner in future black lung claims. It also provided for
sampling equipment to be properly maintained and calibrated, and
examined during the shift. Additionally, operators' were required to
demonstrate a certain level of competence by passing a test
administered by MSHA. Since proper use of sampling equipment is
essential to the integrity of the sampling process, the certification
requirement was intended to provide reasonable assurance that the
person conducting sampling was competent to perform the task. After
samples have been collected, certified persons are required to properly
fill out the dust data card that accompanies each filter cassette.
These samples must then be transmitted unaltered to MSHA within 24
hours after the end of each sampling shift, to expedite compliance
determinations and minimize periods of miner overexposure.
While not specified in the regulations, operators are permitted by
practice to note on the dust data card any reason why they believe the
sample(s) transmitted are not valid and should not be used by MSHA to
determine compliance. Generally, such samples are voided by MSHA and
the operator is required to submit a substitute sample within that
bimonthly sampling period.
MSHA may also determine that an operator sample is invalid for many
of the same reasons. MSHA may also void operator samples for technical
and administrative reasons, such as samples submitted in excess of the
number required, or DO samples if they were not taken during a ``normal
production shift.'' ``Normal production shift'' is defined in existing
Secs. 70.2(k)(1), 70.207(a) and (d) as a ``production shift during
which the amount of material produced * * * is at least 50 percent of
the average production for the last set of five valid samples * * *''
After MSHA has processed the samples, the operator is provided with
a report of the sample results, which must be posted on the mine
bulletin board for a period of 31 days to provide miners ready access
to current information on respirable dust conditions in the mine.
Operators are also required to report to MSHA in writing any change in
the operating status of the mine, mining unit, or designated area that
affects the sampling requirements, within three working days after the
change occurs.
An operator who is found to be in violation of the reduced dust
standard is issued a citation and must take steps to reduce the dust
levels. After corrections have been made, the operator must collect
five additional samples within a time period specified by MSHA to
demonstrate compliance.
During the development of the 1980 regulations for operator
sampling requirements, we received comments that indicated a lack of
confidence in our reliance on operator samples for enforcement
purposes. In response to these concerns, MSHA published a proposed
regulation in 1980 that would have provided miners' representatives the
right to observe each phase of the operator dust sampling process with
no loss in pay. The proposal intended to promote better cooperation
between mine operators and miners in order to improve the effectiveness
of the program. In 1985, the Agency decided not to finalize regulations
to provide miners' representatives the right to observe operator
sampling, stating that compliance with the 1980 revisions to the
sampling program had resulted in greater confidence in the overall dust
program.
3. Issues Affecting the Credibility of Operator Compliance Sampling
As noted earlier in this proposal, there is general agreement that
significant efforts have been made during the past 30 years to reduce
dust levels in our Nation's mines. While most mine operators have
conscientiously attempted to sample miners' exposure to respirable coal
mine dust as required by regulation, because of the actions of some,
the operator sampling program continues to be plagued by allegations of
fraudulent sampling practices. Despite MSHA's efforts to improve the
quality of the operator dust sampling program and to vigorously
investigate such allegations and prosecute violators, sampling
irregularities continue to be documented involving the physical
alteration of the weight of dust collected on the filter, or the
collection of samples in low-dust areas of the mine or even outside of
the mine.
The Advisory Committee found that during the 10 years prior to the
publication of their report, serious questions had been raised
regarding the representativeness of respirable dust levels measured by
mine operators, the handling of filter cassettes, and the changing of
work assignments and/or working conditions during sample collection.
The credibility of the operator sampling program was questioned by
almost all the representatives of miners who testified before the
Advisory Committee. Since 1990, more than 160 mine operators, agents
and contractors have pled or been found guilty of submitting fraudulent
samples to MSHA. These disclosures correspond with the concerns
expressed by critics of the operator sampling program.
Detailed reviews of the respirable dust program by the Task Group
and the Advisory Committee identified aspects of the current program
that have the potential to negatively affect validity of sampling
results which could impact miner health protection and, consequently,
its credibility in the minds of the very people the program was
designed to protect, the miner. For example, to effectively monitor the
mine environment where miners work or travel, it is essential that
respirable dust samples are ``representative,'' in that they reflect
typical dust conditions to which miners are exposed. The recurrent
pattern of disclosures of tampering with the sampling process has
highlighted the vulnerability of the current monitoring system to the
submission of unrepresentative samples. For example, during the period
1980 to 1990, over 137,000 of the 750,000, or approximately 18 percent
of the operator DO samples showed extremely low concentrations (less
than or equal to 0.1 mg/m\3\), compared to 10 percent for the MSHA
samples. Since 1990, 14 percent of the operator DO samples and 3
percent of the MSHA samples were equal to 0.1 mg/m\3\.
The fact that sampling is controlled by the mine operator also
allows the operator to determine when and under what conditions samples
will be collected during all current bimonthly and abatement sampling.
This permits the operator to conduct sampling during those periods in
the mining cycle when conditions are anticipated to result in lower
dust levels in the mine environment. For example, the operator may
choose to sample during periods when the volume of air on the MMU is
greatest or when ventilation controls are operating at optimum
efficiently. Accordingly, these sample results may not be
representative of typical exposure levels. Other aspects of the
monitoring system that may allow the submission of unrepresentative
samples were reported by the Task Group in its report of
[[Page 42128]]
findings. Because some operators do not sample every bimonthly period
or fail to submit the required number of bimonthly samples, miners may
be potentially exposed to excessive levels of respirable dust.
4. Proposed Reforms to the Respirable Dust Monitoring Program
Believing that one of MSHA's highest priorities must be to restore
the confidence of miners and mine operators in the respirable coal mine
dust sampling program, one of the Advisory Committee's key
recommendations was that MSHA take full responsibility for all
compliance sampling at a level which assures representative samples of
respirable dust exposure under usual conditions of work. It also
recommended that compliance sampling should be carried out at a number
and frequency at least at the level required of operators and MSHA.
Accordingly, MSHA is proposing to revoke the operator dust sampling
programs under 30 CFR parts 70 and 90 and to take full responsibility
for all compliance sampling (i.e., bimonthly and abatement sampling),
in a manner that it believes will be more protective than the current
operator sampling program. MSHA intends to monitor miners' dust
exposure and compliance with the dust control provisions of the
approved mine ventilation plan, or with the respirable dust control
plan for a part 90 miner at underground mines, in accordance with the
procedures and guidelines established in Chapter 1 of the Coal Mine
Health Inspection Procedures Handbook, as modified herein.
(a) Bimonthly Sampling
MSHA would collect a full-shift sample from the working environment
of at least five different occupations, if available, on each producing
MMU, instead of sampling only the DO for five consecutive shifts or on
shifts worked on five consecutive days as under the current bimonthly
sampling program. Proposed revised Sec. 70.2(j) defines full shift, for
purposes of bimonthly compliance sampling, as the entire work shift
including travel time but excluding any time in excess of 480 minutes.
A full-shift sample would also be collected from each DA located inby
the section dumping point (i.e., intake air and roof bolter DAs)
bimonthly, and from all other DAs once each year. All part 90 miners
would be sampled bimonthly as under the current program.
MSHA would issue a citation for noncompliance when a single, full-
shift measurement demonstrates, at a high level of confidence, that the
applicable dust standard is exceeded. Although MSHA would collect
multiple occupational samples from each MMU, we would issue only one
citation on a single shift on any one MMU unless more than one dust-
generating source was involved.
(b) Abatement Sampling
Under this proposal, MSHA would also assume responsibility for all
abatement sampling. As recommended by the Advisory Committee, MSHA
would utilize single, full-shift samples to demonstrate abatement.
Since the criteria under which the effectiveness of ventilation plans
are required to be verified are significantly more stringent than those
for bimonthly sampling, MSHA does not anticipate issuing many citations
to MMUs and sectional DAs. However, should an MMU be cited for
violation of the applicable dust standard, and a determination be made
by the inspector who was onsite that the dust control parameters are no
longer adequate for the present operating conditions, MSHA would
require the operator to revise the dust control portion of the mine
ventilation plan under proposed Sec. 70.219. MSHA would then verify the
effectiveness of the revised plan. Citations for violating the
applicable dust standard would not be based on verification sampling.
If on the other hand, a determination is made that a change in the
plan is not warranted, the operator would take corrective action to
prevent miners from being exposed on subsequent shifts. MSHA would then
sample the MMU, similarly to bimonthly compliance purposes described
previously in paragraph (a) of this section. All five of the
occupational samples taken on a single shift would have to be below the
applicable standard to demonstrate abatement. If any sample result
exceeds the applicable standard, but not at a sufficiently high level
of confidence to warrant a citation, then MSHA may sample additional
shifts or initiate the plan verification process.
We solicit comments on whether MSHA should require a higher level
of confidence that the applicable standards are being complied with
before abating a citation for excessive dust. Specifically, should
abatement determinations be based on the critical values specified in
Sec. 70.209? We also solicit comments on whether abatement sampling
should be conducted at or above the Verification Production Level (VPL)
as defined in Sec. 70.2(aa). Requiring that abatement be demonstrated
under more typical production conditions, as represented by the VPL,
would provide assurance that miners will continue to be protected on a
majority of the production shifts.
MSHA proposes to conduct abatement sampling involving non-MMU DAs
and part 90 miners in the same way as it conducts bimonthly sampling. A
violation would be abated if the result of an abatement sample was less
than the applicable standard. If sample results exceed the applicable
standard but not at a sufficiently high level of confidence to warrant
a citation, MSHA may collect additional single, full-shift samples.
As in the case of MMU abatement samples, we solicit comments on
whether MSHA should require a higher level of confidence that abatement
samples for non-MMU DAs and for part 90 miners demonstrate compliance
with the applicable standards before abating a citation for excessive
dust. Specifically, should abatement determinations be based on the
critical values specified in Sec. 70.209?
(c) Advantages of MSHA Compliance Sampling Over Existing Program
According to section 101(a)(9) of the Mine Act, no health standard
promulgated under this title shall reduce the protection afforded
miners by an existing mandatory health standard.
For the reasons listed below, MSHA believes that, through the joint
promulgation of this proposed rule and the proposed single, full-shift
sample rule, miners would be further protected from the debilitating
effects of occupational respiratory disease by limiting their exposures
to respirable coal mine dust and quartz dust on every shift.
<bullet> Providing and maintaining a work environment free of
excessive levels of respirable dust is essential for long-term health
protection. While monitoring of the work environment provides an
indication of how effective the existing dust control measures are,
monitoring alone does not control dust levels. Requiring mine operators
to implement and maintain dust control parameters which, for the first
time, have been determined effective under typical mining conditions,
will provide reasonable assurance that no miner will be overexposed on
individual shifts.
<bullet> Implementing single, full-shift sample determinations will
more likely detect excessive dust concentrations and thus protect
miners. Averaging samples taken on multiple shifts can mask
overexposures on individual shifts. Although MSHA would be sampling
fewer shifts, MSHA believes the proposed sampling methodology
[[Page 42129]]
would provide a more accurate representation of dust conditions to
which miners are exposed.
<bullet> Under the existing operator sampling program, only the DO
is sampled. Under the proposed program, MSHA would sample multiple
occupations on the same shift. This would provide a more comprehensive
assessment of dust conditions to which miners are exposed.
<bullet> Since MSHA will be doing all the sampling, we will be able
to monitor the dust control parameters and work practices in effect
during sampling. This will enable MSHA to determine the effectiveness
of the operator dust control program.
<bullet> Unlike the current sampling program, which allows
operators control over when to sample and under what operating
conditions, MSHA's visits will be unannounced. As a result, all phases
of the mining cycle are likely to be sampled eventually (i.e.,
construction activity, longwall start-up, turning crosscuts, etc.), and
samples should be more representative of typical mining conditions.
<bullet> The miners' representative will have walkaround rights
during sampling, thereby increasing miners' confidence in the dust
sampling program.
B. Procedures for Setting the Applicable Dust Standard When Quartz is
Present
Section 202(b)(2) of the Mine Act and the implementing MSHA
regulations require each operator to continuously maintain the average
concentration of respirable dust in the mine atmosphere during each
shift to which each miner in the active workings of such mine is
exposed at or below 2.0 mg/m\3\. Under current MSHA regulations in
Secs. 70.101, and 90.101, the applicable coal mine dust standard is
lowered further, by means of a formula (10 divided by the percentage of
quartz) prescribed by Secretary of Health, Education, and Welfare in
1971, whenever the respirable coal mine dust in the mine atmosphere of
the active workings contains more than five percent quartz. \2\ This is
based on the recognition that the toxicity of coal mine dust increases
when higher levels of quartz are present. Consequently, as the quartz
content of respirable coal mine dust present in the mine atmosphere
increases over five percent, the applicable respirable coal mine dust
standard is correspondingly lowered. For example, if 10 percent quartz
was present, the mine operator would have to continuously maintain
respirable dust at or below 1.0 mg/m\3\.
---------------------------------------------------------------------------
\2\ The applicable dust standard for intake air in
Sec. 70.100(b) and for miners who have exercised rights under part
90 regulations in Sec. 90.100 is 1.0 mg/m\3\. Those standards are
also lowered if quartz exceeds 5 percent. However, no effect occurs
until the quartz content exceeds 10 percent.
---------------------------------------------------------------------------
The following provides an overview of MSHA's current and proposed
revised procedures for arriving at an average quartz percentage that is
used to establish an applicable dust standard.
1. Current Procedures
Until 1985, the applicable dust standard was adjusted based on the
percentage of quartz determined from a single, full-shift (8 hours or
less in duration) respirable dust sample taken by an MSHA inspector.
Since MSHA sampled less frequently than we currently do, a reduced
standard could remain in place anywhere from 12 to 24 months. During
that period the level of quartz could have either increased or
decreased significantly. As a result in December 1985, MSHA implemented
the procedures in effect. This program, for the first time, enabled
mine operators to participate voluntarily in the process of setting
reduced dust standards. These procedures are contained in Chapter 1 of
MSHA's Coal Mine Health Inspection Procedures Handbook.
The most significant program change involved the use of individual
quartz percentages determined from one MSHA and, under certain
conditions, up to two coal mine operator full-shift respirable dust
samples, referred to as ``optional samples,'' to arrive at an average
quartz percentage. It also provides for the automatic reevaluation of
work areas and occupations on a reduced dust standard every six months.
Under the existing system, if an MSHA sample contains more than
five percent quartz, an operator is afforded the opportunity to submit
an optional sample. Provided it has sufficient weight gain (0.45 mg),
the quartz content will be averaged with the MSHA sample when sample
results do not differ by more than <plus-minus> 2.0 percent, and the
standard set accordingly. If an operator fails to submit an optional
sample or it contains insufficient weight for analysis, the standard is
adjusted based on the MSHA sample alone. Operators are afforded the
ability to submit a second optional sample whenever sample results
differ by more than <plus-minus> 2.0 percent. All three results are
then used to compute the average quartz percentage.
Also, in November 1994, MSHA refined its analytical procedure
enabling us to analyze inspector low-mass respirable dust samples
(0.100 to 0.449 mg) for quartz. Only those samples containing 25
micrograms or more of quartz were used in the standard-setting process.
However, this change applied only to filters that were preweighed to
0.001 mg for use by MSHA enforcement personnel. It did not apply to
operator-submitted optional samples, which were collected with filters
preweighed to 0.01 mg, for which we required a minimum of 0.45 mg of
dust to be analyzed for quartz. The ability to accurately analyze
samples containing small amounts of dust reinforced MSHA's views about
the severity of quartz exposures in some coal mining operations.
A review of MSHA data for FY 1999 shows that of the 778 entities
(i.e., MMUs, DAs, designated work positions (DWPs), roof bolters, and
part 90 miners) (MSHA, Results of Quartz Sampling Operator Involvement,
1999) placed on an initial reduced standard as a result of an MSHA
sample containing more than five percent quartz, 753 (96 percent) of
the entities submitted an optional sample. One would expect the level
of participation to be high since failure to respond would result in
the setting of a lowered dust standard based on the result of the MSHA
sample, which first triggered the standard-setting process. Of the 753
entities submitting an optional sample, 231 were afforded the ability
to submit a second optional sample (Ibid.). Again, as expected, over 73
percent (170) of those 231 entities submitted a second optional sample,
probably because doing so could reduce the quartz average quartz
percentage used to establish the applicable dust standard. For
comparison, in FY 1992, 93 percent of the operators afforded the
opportunity submitted an optional first sample, and 82 percent of the
operators given the opportunity submitted a second optional sample.
However, as the following data show, operator participation tended
to decline significantly when operators were given the opportunity to
submit samples involving established entities on reduced standards. Of
the 1122 entities given the option to submit a sample, only 450 or 29
percent responded, compared to 96 percent for entities placed on an
initial reduced standard. In 1992, 32 percent of the operators elected
to participate.
2. Proposed Revised Procedures
Consistent with MSHA's decision to assume full responsibility for
compliance sampling, the Agency is also proposing to rely only on MSHA
samples as the basis for setting the applicable dust standard when
quartz is present. As discussed below, while the proposed scheme
reduces the burden and cost on mine operators to take and
[[Page 42130]]
submit optional samples, it does not diminish the protections afforded
operators under the current program. It continues to consider temporal
variability associated with quartz determinations by averaging three
MSHA samples collected on different shifts. MSHA recently published a
proposed ``Program Policy Letter (PPL) on Samples Used to Determine the
Respirable Dust Level When Quartz is Present'' for public comment [64
FR 65671, November 23, 1999] whereby the applicable dust standard would
be set based on the results of multiple MSHA samples. It proposes that
mine operator samples would no longer be used in combination with MSHA
samples to determine the average quartz percentage that is used to set
an applicable dust standard. In the proposed rule, MSHA is adopting the
sampling approach set out in the PPL. The proposed rule supercedes the
proposed PPL, and consequently, the proposed PPL is withdrawn.
We believe that results under the proposed process will be more
representative of the quartz level to which miners are exposed. Unlike
the current process, which may cause a standard to be set based on the
quartz content of a single MSHA sample, three valid MSHA samples would
be used to set a reduced standard under the proposed revised procedures
[64 FR 65671].\3\ Since MSHA is sampling underground mines bimonthly
and surface mines semi-annually, we will have no difficulty in
collecting the required number of samples to arrive at the average
quartz percentage. If initial sampling shows that miners may be exposed
to excessive levels of quartz, MSHA intends to sample at a greater
frequency to ensure that miners are being protected. This level of
sampling should also allay any operator concerns regarding the
collection of ``misleadingly high'' samples during atypical periods.
MSHA would also begin reporting quartz levels to the nearest tenth of a
percent. This is intended to be more protective for the miner than the
current truncation of results to a full percentage point.
---------------------------------------------------------------------------
\3\ Unlike MSHA's objective in compliance sampling, the
objective in measuring quartz content is to establish a reduced
standard that will apply to all shifts. This enables an operator to
design a ventilation plan that will be protective on every shift.
Therefore, it is appropriate to estimate the quartz content by
averaging quartz measurements obtained over an extended time period.
---------------------------------------------------------------------------
Under the proposed revised procedures, when an MSHA sample contains
more than five percent quartz, we would average the percent of quartz
present in three most recent MSHA respirable coal mine dust samples to
set the applicable dust standard. If an MMU, DA, DWP, or part 90 miner
is already on a reduced standard, a new applicable dust standard will
be established by averaging the results of the first two MSHA samples
taken under the proposed procedures with the quartz percentage
associated with the reduced standard in effect. If fewer than two MSHA
samples are taken, the existing reduced standard will continue to
remain in effect.
Assume an MMU is on a 1.0 mg/m\3\-standard (10 percent quartz). If
the first MSHA sample contains 7.2 percent of quartz, the existing
standard of 1.0 mg/m\3\ would continue to remain in effect. If,
however, the next sample contains 16.1 percent, the average quartz
percentage would be 11.1 percent [(10.0% + 7.2% + 16.1%) <divide> 3 =
11.1%], resulting in a 0.9 mg/m\3\<ls-thn-eq>-standard (10 <divide>
11.1% = 0.9 mg/m\3\). For MMUs, DAs, DWPs, or part 90 miners not on a
reduced standard, MSHA would collect and analyze three samples for
quartz to determine if a reduced standard was warranted.
Under the proposed procedures, if the newly-established standard is
lower than the one in effect, the new standard would become effective
seven days after the date of the notice informing the mine operator of
the change in the applicable dust standard. However, if it is higher
than the current standard, the newly-established dust standard would
become effective on the date of the notice.
As published elsewhere in today's Federal Register, MSHA is also
proposing to take enforcement actions on the basis of inspector single,
full-shift, respirable dust measurements. For entities on a reduced
standard, MSHA would delay any enforcement action until the sample is
analyzed for quartz. If an exposure measurement significantly exceeds
the existing standard and the quartz content of that sample would cause
the standard to be lowered below the existing reduced standard, the
operator would be cited for violation of the applicable standard
currently in effect. On the other hand, if the quartz content of the
sample would cause the dust standard and the corresponding citation
threshold value (CTV) to increase so that the single, full-shift
measurement would no longer indicate noncompliance, no citation would
be issued. This is illustrated by way of the following example.
For example, suppose that the MMU is on a 1.3-mg/m\3\ standard and
a single, full-shift measurement of 1.6 mg/m\3\ is obtained. Since this
measurement exceeds the applicable standard, the operator is in
violation of the standard. However, analysis of the DO sample shows
that the sample contained 6 percent quartz which, if used, would result
in a 1.7-mg/m\3\ standard. This indicates that the quartz level in the
environment of the DO has changed, suggesting that the current standard
may no longer be valid. Therefore, since the original measurement of
1.6 mg/m\3\ is less than the 1.7-mg/m\3\ standard that should have been
in effect on the shift sampled, a citation should not be issued.
Since MSHA samples are viewed to be more representative of the
respirable dust concentration to which miners are exposed, MSHA is
proposing to revise section 70.101 to clarify that the Secretary will
determine the quartz level by sampling. Operator samples may no longer
be submitted for determining the applicable standard. It is our belief
that the procedures being proposed for setting reduced standards should
be more protective for the miners than those in effect. The proposed
approach provides for stringent monitoring exposure to quartz which is
consistent with Advisory Committee's recommendation that MSHA increase
surveillance and reduce exposure to this serious health hazard.
As under the current program, if operating conditions should change
following establishment of a lowered dust standard that affect the
level of quartz in the working environment, mine operators or miners'
representatives will be able to request MSHA to conduct a quartz
reevaluation. In the absence of continuous monitoring, mine operators
should be cautious in preventing overexposures when abnormal conditions
(such as cutting rock to install an overcast or other frequent but
short-lived events involving cutting of rock) are encountered between
MSHA sampling visits.
3. Validity of Averaging Percentages
The average quartz percentage used to set the applicable dust
standard for a particular sampling location or area of a mine is
determined in accordance with accepted mathematical procedures for
arriving at an average value from a set of values (i.e., adding
together the individual quartz percentages and dividing by the number
of analyses that are in the set). MSHA believes that this is the most
appropriate method to use.
One commenter who responded to the PPL (op cit.) contended that
MSHA's approach of arriving at the average quartz percentage was
mathematically incorrect. This commenter recommended that, to more
accurately
[[Page 42131]]
reflect the true quartz concentration, the average quartz percentage be
calculated by dividing total mass of quartz in micrograms by the total
mass of dust collected (based on three samples in the example
submitted). In the commenter's example, the average percentage obtained
using MSHA's proposed averaging method was larger than that obtained
using the commenter's approach.
The following two scenarios in Table III-1 clearly demonstrate that
MSHA's averaging method does not always result in a larger average
quartz percentage value.
Table III-1.--For Two Scenarios, Using Alternate Methods, Percent of Quartz in Respirable Dust
----------------------------------------------------------------------------------------------------------------
Scenario I Scenario II
----------------------------------------------------------------------------------------------------------------
Dust mass SiO<INF>2</INF> mass % SiO<INF>2</INF> Dust mass SiO<INF>2</INF> mass % SiO<INF>2</INF>
----------------------------------------------------------------------------------------------------------------
1.7 0.136 8 1.7 0.17 10
1.0 0.04 4 1.0 0.08 8
2.5 0.3 12 2.5 0.15 6
----------------------------------------------------------------------------------------------------------------
MSHA's Method Average of % SiO<INF>2</INF> = 8 MSHA's Method Average of % SiO<INF>2</INF> = 8
----------------------------------------------------------------------------------------------------------------
Commenter's Commenter's
Method Sum (SiO<INF>2</INF> Mass) <divide> Sum (Dust Method Sum (SiO<INF>2</INF> Mass) <divide> Sum (Dust
Mass) = 9.2% Mass) = 7.7%
----------------------------------------------------------------------------------------------------------------
These examples show that for situations where MSHA would have
determined a quartz percentage of 8 percent, the commenter's method
would yield 9 percent in one case and 7 percent in the other.
C. Respirable Dust Control Program for Underground Coal Mines
The primary focus of the underground coal mine respirable dust
program is to limit the concentration of respirable dust to which
miners are exposed in the work environment. To ensure that miners are
not being exposed to excessive concentrations of respirable dust,
current regulations require mine operators to:
<bullet> Design a mine ventilation plan that effectively controls
respirable dust under typical mining conditions;
<bullet> Implement the plan's dust control parameters when approved
by MSHA before commencing production;
<bullet> Maintain the dust control parameters specified in the
approved plan and to monitor their function and operation through
required on-shift examinations; and
<bullet> Evaluate their effectiveness with bimonthly samples in
order to provide reasonable assurance that the dust control parameters
continue to function as intended.
To control dust in the work environment, existing Sec. 75.370
requires mine operators to develop and submit ventilation plans that
are designed to control methane and respirable dust in the mine to MSHA
for approval. Each plan must be suitable to the conditions and mining
system in use at the mine. These plans provide detailed requirements
for the protection of miners by specifying engineering controls. These
engineering controls may include:
<bullet> The quantity and the velocity of the air current used to
ventilate the MMU;
<bullet> The number, type, and location of water sprays;
<bullet> The pressure and quantity of water delivered by the
sprays; and
<bullet> Additional environmental controls, such as dust scrubbers
or devices which collect mine air and filter out dust particles.
Plans also contain procedures for maintenance of dust control
equipment used on the mining machine and roof bolter. Mine operators
frequently do not fully describe all dust controls in use at the mine.
If such information is not fully disclosed, it is impossible for MSHA
to fully enforce the plan provisions and to determine when the MMU is
out of compliance with the ventilation plan.
When an operator submits a proposed mine ventilation plan or
revision in accordance with Sec. 75.370, the MSHA district office
reviews it for completeness and adequacy. The District Manager will
approve the plan if it meets MSHA requirements, and he is confident
that the dust control parameters specified will have a reasonable
likelihood of maintaining dust concentrations within the allowable
limits. Most proposed plans or revisions are approved immediately, or
tentatively approved, based on engineering judgement, or experience, or
both, until they are assessed by MSHA inspector sampling or, to a
lesser extent and only under certain circumstances, by mine operator
bimonthly sampling. Generally, MSHA samples within 60 days of plan
approval. Current regulations prohibit a mine operator from initiating
any mining activity without an approved ventilation plan. MSHA allows
operators to commence mining by granting tentative approval. However,
plans may be implemented which are later determined to be inadequate
under typical mining conditions under the existing process.
1. Evaluating and Approving Plan Requirements for Respirable Dust
Control
Under the current program, the effectiveness of the plan's dust
control parameters is assessed through sampling of the DO and other
occupations associated with the MMU. Since there is no requirement for
verifying plan effectiveness, we have had to rely on samples that may
not be representative of dust concentrations to which miners are
exposed.
MSHA sampled annually at each underground mine until recently. The
Agency now samples bimonthly in each underground coal mine. This
increased sampling effort is part of MSHA's initiative to increase
confidence in the federal respirable dust program and to eliminate
simple CWP, PMF, and silicosis among coal miners. During sampling
inspections, we monitor compliance with the applicable dust standard,
measure the concentration of respirable quartz dust; and identify
occupations other than the DO that the mine operator should routinely
monitor because they are at risk of exposure to excessive
concentrations of respirable dust.
Under current inspection procedures, MSHA inspectors sample at
least five different occupations, if available, on each MMU on each
shift. Samples are normally taken under the mining conditions in effect
during sampling. In conjunction with this sampling, the MSHA inspector
checks and measures the dust control parameters early in the shift to
determine whether the ventilation plan is being followed. The inspector
records the findings, and all
[[Page 42132]]
the dust controls and work practices in use during sampling on MSHA
Form 2000-86 (Revised), Respirable Dust Sampling and Monitoring Data.
MSHA will issue a citation if the mine operator fails to follow any of
the dust control parameters specified in the plan. Normally, the
citation requires immediate corrective action to abate the violation.
This may involve, for example, unplugging some water sprays or
increasing the amount of ventilating air delivered to the MMU. At the
conclusion of the sampling shift for an MMU, the inspector determines
the total amount of material that was mined (in tons) during the shift.
If the average concentration of the samples taken in one shift is
less than, or equal to, the applicable standard, and the actual
production is at least 60 percent of the average production over the
last 30 production shifts, the MSHA inspector will normally terminate
sampling after the first day and will recommend that the plan
parameters be approved by the District Manager. This would occur even
if the samples were found to contain more than 5 percent of quartz.
Such a finding could result in MSHA lowering the dust standard below
that in effect at the MMU. Since 1985, MSHA has provided mine operators
the opportunity to participate in the process to establish a lower dust
standard based on the level of quartz. Mine operators can submit up to
two optional samples which are averaged with the MSHA sample to
determine the average percentage of quartz which is used to establish a
new dust standard for the MMU. MSHA published a proposed Program Policy
Letter for comment (64 FR 65671, November 23, 1999) whereby the
standard would be determined based solely on the results of multiple
MSHA samples. Under that proposal, mine operator samples would no
longer be used to calculate a reduced dust standard. Instead,
applicable dust standards will be set based solely on the results of
MSHA samples.
If the average concentration falls below the standard in effect,
but one or more samples exceed it, no decision is made regarding the
plan's effectiveness or regarding compliance with the applicable
standard. Instead, the inspector must collect additional samples on
subsequent production days or shifts to establish that the dust control
provisions of the ventilation plan are adequate.
To a lesser extent, if MSHA is unable to schedule a mine visit
within the period established by the individual district, the District
Manager may rely on the results of operator bimonthly sampling to
approve a plan. Generally, this occurs in the case where a plan is
upgraded with a change which has been established as effective. MSHA
does not routinely approve plans based on operator bimonthly sampling
because these samples may be collected during periods when production
is not reflective of typical production levels. The current program
permits the operator to submit samples which may not be representative
of normal dust conditions in the working environment. Under current
regulations, operator bimonthly samples will be considered valid,
unless voided by MSHA, when the MMU produces at least 50 percent of the
average level reported for the last set of five valid bimonthly
samples. Since a mine's ``normal production'' level for sampling
purposes and the typical production level may diverge greatly over the
course of several sampling periods, granting approval under these
conditions may not reflect the plan's effectiveness under more typical
mining conditions.
2. Compliance with Plan Requirements for Respirable Dust Control
Once MSHA determines that the dust control measures are adequate
and approves the mine ventilation plan, the specified dust control
parameters are to be employed on a continuous basis to safeguard the
health of miners. Since maintaining the approved dust control
parameters provides reasonable assurance that respirable dust can be
controlled, failure to comply with these requirements would defeat the
purpose of the mine ventilation plan and needlessly expose miners to
excessive concentrations of respirable dust. Section 75.362 requires
mine operators to perform an on-shift examination of the dust control
parameters before the MMU begins production in order to assure full
compliance. Any deficiencies must be corrected before production
begins.
Compliance with approved plan parameters is checked during MSHA's
routine sampling inspections: as part of six-month plan reviews, during
other non-sampling inspections or investigations, or in conjunction
with an ongoing sampling inspection.
3. Monitoring Effectiveness of Plan Requirements for Respirable Dust
Control
Because of the dynamic nature of mining, conditions can change
significantly in a short period of time. For example, an increase in
the concentration of respirable quartz dust will require the applicable
standard to be reduced below the level that was effective when the dust
control parameters were first evaluated. Such changes can directly
impact the effectiveness of the dust-control measures. It is important
to regularly monitor the adequacy of the approved dust control
requirements to ensure that they remain suitable for the current
conditions at the mine and to determine whether the plan should be
upgraded. Currently, both MSHA and the mine operator regularly monitor
the operator's dust control program. However, for MMUs the mine
operator is responsible for making sure that all provisions of the
ventilation plan are in effect on every shift.
(a) Monitoring by Mine Operators. Since 1980, the current
regulations have required mine operators to take five valid samples
from the DO in each MMU on a bimonthly basis and submit them to MSHA
for processing, to determine compliance with the applicable dust
standard. Section 70.207(e) identifies the DO for each method of
mining. These are collected either on consecutive normal production
shifts, or on production shifts worked on consecutive days, during
which the amount of material produced by the MMU is at least 50 percent
of the average production reported for the last bimonthly sampling
period. These samples must be collected portal-to-portal during the
entire shift or for 8 hours, whichever time is less.
Bimonthly samples have provided a periodic evaluation of the
quality of the air miners breathe. They also have provided some insight
into the effectiveness of the operator's dust control system on the
days in which the samples are taken. Mine operators may exceed their
minimum plan requirements once they have been approved as effective
under current evaluation criteria. Currently, there is no requirement
for mine operators to record the dust control measures in use as part
of the on-shift examination. Because there is no requirement for such
records, MSHA cannot assess the continued adequacy of the approved dust
control requirements unless the inspector observes the sampling
process.
Although the current operator sampling program may limit the
utility of bimonthly samples for plan approval purposes, they allow
MSHA to identify approved plans that may no longer be suitable to the
conditions at a mine. If multiple individual samples, or their average,
exceed the applicable dust standard after the required on-shift
examination has been conducted, the approved plan parameters may no
longer be effective and may need to be upgraded. If cited, the operator
must
[[Page 42133]]
take corrective action to lower the concentration of respirable dust to
within the permissible concentration as described in current
Sec. 70.201(d). The operator must demonstrate, through sampling, that
the underlying condition(s) which caused the violation has been
corrected. Since MSHA inspectors are not present to observe the
action(s) taken by the operator to abate the violation, the ventilation
plan is usually not amended to include the changes the operators make
to the parameters in order to abate the violation. However, if the
operator has a record of noncompliance and MSHA determines that the
approved plan parameters may no longer be adequate, MSHA will notify
the operator to submit an improved plan. Under current plan approval
procedures, if the operator fails to address MSHA's concerns after
receiving the second notification, MSHA will move to revoke the
operator's mine ventilation plan. If the plan is revoked, the mine must
not operate.
As discussed earlier, MSHA is proposing to revoke operators'
sampling program in underground mines and assume full responsibility
for all compliance sampling.
(b) Monitoring by MSHA. One of the objectives of MSHA's dust
sampling program is to verify that the controls specified in the
approved mine ventilation plan continue to control concentrations of
respirable dust under existing mining conditions. As part of this
program, the dust control parameters must be checked and measured early
in the shift to assure compliance with the approved plan. These checks
also verify that the operator is performing the required on-shift
examinations. Operators have the opportunity to adjust their dust
controls to reflect that which has been approved so the plan can be
evaluated. However, most operators choose not to make adjustments for a
number of reasons. While inspection procedures require the ventilation
plan to include the dust control measures in use during the evaluation,
most approved plans do not incorporate all the measures that were
actually in place during MSHA sampling. This makes it difficult for
MSHA to assess the continued adequacy of the approved dust control
parameters. Frequently, decisions must be based only on prior
experience or engineering judgment.
When an operator is cited based on MSHA samples, the inspector may
require the operator to describe what type of corrective action will be
taken. However, if a plan change is required, MSHA must follow similar
plan approval procedures. The operator must be notified in writing that
the plan is inadequate. In this case, MSHA has sample results and a
record of the actual parameters in place which can be used to document
the need for a plan change. Most plans which are revised simply
incorporate only those dust controls that were in use when MSHA
sampled.
MSHA reviews each mine ventilation plan every six months under
Sec. 75.370. The review includes: all plan revisions, respirable dust
inspection reports, citations for exceeding the applicable dust
standard, and comments from representatives of miners. When a
deficiency in the respirable dust control portion of the plan is found,
the MSHA inspector records comments on MSHA Form 2000-86. MSHA sends
these results to the mine operator along with an explanation of whether
the operator must make any changes, the reasons for the changes, and
the date for submitting a plan revision. MSHA will send a second
notification if the operator fails to respond. MSHA may revoke the
operator's mine ventilation plan if the operator does not comply.
4. Proposed Procedures for Evaluating, Approving, and Monitoring
Ventilation Plan Requirements
The dust control portion of the mine ventilation plan is the key
element of an operator's strategy to control respirable dust in the
work environment, thereby protecting miners. In recognition of this,
MSHA's proposal makes a number of changes to the process for
evaluating, approving, and monitoring mine ventilation plans, many of
which are based on the Advisory Committee's recommendations.
Consistent with the Advisory Committee recommendations, MSHA
proposes to add provisions to verify the effectiveness of the
ventilation plan in controlling dust, at a production level high enough
to demonstrate the plan's effectiveness under typical operating
conditions. This would require that MSHA implement procedures for
reviewing compliance and production records. It would also require that
dust control parameters and production associated with samples on a
given shift be recorded in order to demonstrate that parameters
specified continue to be effective in controlling dust.
This proposal would require a ventilation plan to include all
engineering or environmental controls necessary for maintaining dust
concentrations at acceptable levels. A plan must also include any
specific work practices or other means used to supplement these
controls in order to minimize the dust exposure of individual miners.
Unlike plans under the current program, you would have to identify all
measures necessary for achieving continuous compliance with the
applicable dust standard in the plan.
MSHA proposes to require you to include information on the length
of each normal production shift in Sec. 75.371(f) and to specify the
VPL as defined in Sec. 70.2 in every ventilation plan. The VPL is the
tenth highest production level recorded in the most recent 30
production shifts. This value will represent the minimum production
level at which effectiveness of the plan must be demonstrated.
We believe that the production criteria used to evaluate plan
effectiveness may not adequately represent typical conditions under
which miners work. Requiring that plans be verified at or above the VPL
would provide assurance that excessive dust concentrations will be
avoided, even on shifts with higher-than-average production. This is
more protective of miners than the current practice of evaluating plan
adequacy based on MSHA inspector samples taken when production can be
as low as 60 percent of the average production.
MSHA would require you to maintain records of the amount of
material produced by each MMU during each shift. This would enable you
to establish the VPL. Because verification of a plan's effectiveness is
conditioned on the VPL, these records are necessary to ensure that the
VPL continues to represent higher-than-average production. Although a
VPL would be included in the ventilation plan, MSHA would not cite you
for producing at levels exceeding the VPL.
Under the proposed plan verification procedures, MSHA will notify
you of when we intend to initiate verification sampling. To enable MSHA
to evaluate the effectiveness of the plan parameters at or above the
VPL, you must make sure that all the dust control parameters specified
in your ventilation plan are fully implemented. On the date scheduled
for verification sampling, you should arrange to be producing at or
above the VPL specified in the plan, using only the dust control
parameters and other measures listed in the plan.
Under the proposal, MSHA would perform the sampling necessary to
verify your plan. We will collect full-shift samples from the work
environment of multiple occupations on each MMU, including the DO. We
will collect all samples in accordance with procedures described in
Chapter 1 of MSHA's Coal Mine Health Inspection Procedures Handbook (op
cit.). In addition, on every shift on which we
[[Page 42134]]
collect verification samples, we would measure and record all of the
quantitative engineering or environmental parameters. We would also
record any other means used to reduce miners' dust exposure on the
sampled shift. We will provide you with this information, along with
verification sample results, for posting on your mine bulletin board.
In accordance with section 103(f) of the Mine Act, you must provide
miners and their representatives the same walkaround rights during plan
verification sampling as they are provided during any other physical
inspection made pursuant to the provisions of section 103(a) by an
authorized representative of MSHA.\4\
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\4\ MSHA believes that under the guidance of the Interpretive
Bulletin 43 FR 17546 (April 25, 1978) these rights arise when: (1)
an ``inspection'' is made for the purposes set forth in section
103(a), and (2) the inspector is physically present at the mine to
observe or monitor safety and health conditions as part of direct
safety and health enforcement activity.
Verification sampling is necessary to obtain information related
to approval of the mine's ventilation plan and whether coal mine
dust will be adequately controlled to protect miners health.
Consequently, miners and their representative would have the right
to accompany the inspector with no loss of pay for the time during
which the representative exercises this right. However, this right
is limited by Section 103(f) to only one such representative of
miners.
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Unlike the existing program, the proposal would allow you, for the
first time, to use either approved PAPRs or verifiable administrative
controls to supplement your engineering or environmental controls for
compliance purposes at longwall mining operations. This would be
permitted only on an interim basis and only after MSHA determined that
you had exhausted all feasible engineering or environmental controls.
Finally, under this proposal, MSHA has established rigorous
criteria for determining when to approve a plan. We would approve a
plan only when a sufficient number of verification samples demonstrate,
at a high level of confidence, that the plan is effective at production
levels at or above the VPL.
D. Hierarchy of Dust Controls
Consistent with the Mine Act, engineering or environmental controls
have been the principal method used for preventing or minimizing
miners' exposure to these primary and secondary dust sources in the
workplace over the past 30 years. Control of dust throughout the work
environment gives reasonable assurance that all miners in the area will
be adequately protected. Well-designed engineering or environmental
controls provide consistent and reliable protection to all workers
because they are not dependent upon constant human supervision or
intervention, except for the periodic checks, to insure that they are
functioning as intended. MSHA requires mine operators to utilize all
feasible engineering or environmental controls, which are specified in
the mine ventilation plan, to maintain concentrations of respirable
dust in the work environment of MMUs at or below the applicable dust
standard. Engineering or environmental controls include all methods
that control the level of respirable dust by reducing dust generation
(e.g., machine parameters) or by suppressing (e.g., water sprays,
wetting agents, foams, water infusion, etc.), diluting (e.g.,
ventilation), capturing (e.g., dust collectors) or diverting (e.g.,
shearer clearer, passive barriers, etc.) the dust being generated by
the mining process. The importance of using engineering or
environmental controls was not only recognized by the Advisory
Committee, but also by NIOSH in its criteria document: Occupational
Exposure to Respirable Coal Mine Dust (NIOSH, 1995), when it
recommended that such controls must continue to be relied upon as the
primary means of protecting coal miners. The primacy of engineering or
environmental controls is preserved under this proposal. The proposal
requires mine operators to utilize all feasible engineering or
environmental controls to reduce concentrations of respirable dust to a
level at or below the applicable standard.
Administrative controls are another method of avoiding
overexposure. Administrative controls refer to work practices that
reduce miner's daily exposure to respirable dust hazards by altering
the way in which work is performed. They consist of such actions as
rotation of miners to areas having lower dust concentrations,
rescheduling of tasks, and modifying work activities. The Task Group
found that administrative controls were used increasingly, even when it
was feasible to implement additional engineering or environmental
controls. The use of administrative controls was found to be increasing
at mines employing longwall mining systems. The most frequent
administrative control in use consisted of restricting the activities
of miners required to work downwind of the longwall operator, or the
occupation designated as 044 by MSHA. This particular form of
administrative control is in use at some of the 51 longwall MMUs that
were operating on October 28, 1999. MSHA has observed the use of this
particular administrative control, even after changing the location of
the DO from the 044 to the 060 occupation--the miner who works nearest
the return air side of the longwall working face. Unlike engineering or
environmental controls, to be effective, administrative controls rely
on the ability of miners to follow specified procedures. However,
difficulty in ensuring that miners adhere to the administrative
controls, labor/management agreements, and limitations on the number of
qualified miners capable of handling specific tasks may limit the use
and effectiveness of such controls. The Advisory Committee Report
states that the use of administrative controls does not reduce the
operator's responsibility to maintain ambient dust levels in active
workings at or below the standard. However, the Advisory Committee
noted that ``while not a substitute for engineering controls,
administrative controls, which restrict the amount of time that miners
spend in an area with uniform exposure level, can result in lower
personal exposures (MSHA, 1996).''
Under the Mine Act and current regulations, mine operators are
required to make approved respiratory equipment available to all
affected underground miners whenever exposure to concentrations of
respirable dust exceeds the applicable dust standard. However, miners
are not compelled to use them. While required for interim protection,
mine operators cannot use respirators as a substitute for engineering
or environmental control measures. Engineering or environmental
controls have been found to provide more consistent and reliable
protection to all workers. In comparison to respirator programs, the
effectiveness of engineering or environmental controls does not rely
heavily upon constant supervision or miners' consistent and correct use
of the equipment. Furthermore, we can measure dust concentrations to
which miners are exposed when engineering or environmental controls are
in use. It is more difficult to monitor the effectiveness of a
respirator program because the assessment methods are indirect. For
these reasons, MSHA's longstanding policy has been that respirators
should be used in underground coal mines only as an interim method of
protection until feasible engineering or environmental controls are
available.
Approved respirators are not acceptable substitutes for feasible
engineering or environmental controls.
[[Page 42135]]
It is MSHA's position that technology is available to control
respirable dust to at or below the applicable standard at MMUs
employing continuous and conventional methods of mining. However, MSHA
recognizes that, unlike other mining systems, longwall MMUs may have
acute dust problems caused by the face-ventilation airstream carrying
the shearer-generated face dust over the miners working along the face
downwind of the shearer operator (occupation code 044). This makes it
more difficult to control the work environment on a consistent basis.
Improvements in dust control technology have not kept pace with
increases in production technology associated with high-production
longwall MMUs. Average longwall shift production reported during
bimonthly sampling has increased more than five-fold since 1980, from
approximately 890 tons per shift (tps) to more than 4,900 tps in 1998.
In fact, 49 percent of the shifts sampled averaged 4,000 to 8,000 tps,
while approximately 8 percent of the shifts exceeded 8,000 tps. A major
milestone in mining history was achieved in 1997, when a single
longwall mine produced more than 1 million tons of coal in a single
month (Fiscor, 1998).
Unfortunately, as more coal is mined, greater quantities of
respirable dust are generated. The increase in longwall production
levels has resulted in the generation of far more dust which must be
controlled (Webster, et al., 1990; Haney, et al., 1993; O'Green, 1994).
According to published literature, several thousand milligrams of
respirable dust per ton of coal cut can be formed and liberated during
the cutting process (National Research Council, 1980). Of course, the
quantity of respirable dust produced by the cutting process can vary
greatly, depending on the type of coal, its moisture content, the
amount of rock bands in the coal, sharpness of the cutting bits, the
particular mining machine, and many other factors. Although a
considerable amount of respirable dust is formed by the cutting
operation, most of these particles do not become airborne.
Nevertheless, given the amount of dust that is produced per ton of coal
mined, a larger quantity of respirable dust would be generated from
cutting 8,000 tons of coal than from cutting 4,000 tons. An operator is
not required to produce, on a sampled shift, more than 50 percent of
the average production reported during the last bimonthly period.
Therefore, dust concentrations on sampled shifts may be substantially
lower than what is typical and therefore not reflect the dust exposure
on that shift.
While significant efforts have been made to implement available
control technology, no significant new advancements in longwall control
technology have been reported since 1989 (U.S. Bureau of Mines,
undated). From 1989 to 1999, the percentage of operators' longwall DO
samples exceeding 2.0 mg/m\3\ dropped from 34 percent to 20 percent,
reflecting the impact of the implementation of those advances in
longwall control technology. Although this represents a significant
improvement, especially in view of the five-fold increase in average
shift production, the 1999 data clearly show that miners continue to be
overexposed on a significant number of shifts.
Over the past ten years, MSHA and the former U.S. Bureau of Mines,
now part of NIOSH, have made unsuccessful efforts to conduct a joint
research program that would evaluate the effectiveness of available
longwall dust control technology. The objective of such research would
have been to quantify the effects of employing all state-of-the-art
dust-control technology available for a longwall operation.
Unfortunately, such a study has never been undertaken because no
industry partner has agreed to participate. Based on our experience,
MSHA's position remains that feasible engineering and environmental
controls exist for maintaining dust exposures at or below the
applicable standard, even at longwall operations. MSHA has concluded
that the proposed plan verification process will lead to further
improvements in the design and quality of mine ventilation plans. At
some high-producing longwall MMUs, however, the engineering or
environmental controls available may not succeed in sustaining
continuous compliance with the applicable dust standard at certain
locations downwind of the longwall operator (occupation code--044).
Mining industry representatives have repeatedly urged MSHA to
accept the use of powered, air-purifying respirators (PAPRs) (e.g.,
Racal<Register> Airstream helmets),\5\ as an alternative means of
complying with the applicable dust standard when engineering or
environmental controls failed or were not feasible. The Airstream
helmet originated in the early 1970s at the Safety in Mines Research
Establishment in England which developed it primarily for mining use to
provide protection for head, eyes, and lungs in a single convenient
unit. Because these devices provide a continuous stream of filtered air
over the miner's face, it has been suggested that they be viewed as
miniature environmental controls, rather than respirators. In September
1997, Energy West Mining Company (Energy West) petitioned the Secretary
of Labor to amend the mandatory health standards for underground coal
mines at 30 CFR part 70 to allow Airstream helmets or other types of
PAPRs to be used as a supplemental means of complying with the
applicable dust standard. The petition for rulemaking proposed that the
Secretary issue a standard which would supersede the current interim
statutory standard, specified in Section 202(h) of the Mine Act. Energy
West contended that PAPRs are necessary as a supplemental means of
controlling respirable dust because even the most diligent application
of feasible engineering/environmental controls could not always prevent
overexposure. MSHA has consistently acknowledged that PAPRs can be
effective as an interim method of protecting miners when properly
selected, used, and maintained. However, MSHA has never considered the
Racal<Register> Airstream helmet (or the 3M\TM\ Airstream\TM\ Helmet-
Mounted PAPR), or any other respiratory protective device approved and
labeled as such by the National Institute for Occupational Safety and
Health (NIOSH), to be an engineering, environmental, or administrative
control. Hence, it cannot be used as an environmental control to comply
with the respirable dust standard.
---------------------------------------------------------------------------
\5\ References to specific equipment, trade names or
manufacturers does not imply endorsement by MSHA.
---------------------------------------------------------------------------
In order to provide the greatest possible protection for all miners
under typical mining conditions, MSHA is proposing to permit, under
certain circumstances, the limited use of either approved loose-fitting
PAPRs or verifiable administrative controls for compliance purposes.
This would provide you with the flexibility to select the most
appropriate option for supplementing your engineering or environmental
controls. We believe that permitting longwall mine operators to use
loose-fitting PAPRs or verifiable administrative controls for
compliance purposes will not reduce the level of protection afforded
longwall miners by the existing standard.
This aspect of the proposal is limited to longwall mine operations
because technology is available to control respirable dust at or below
the applicable standard at MMUs employing continuous and conventional
methods of mining. Their use at longwall operations would be permitted
[[Page 42136]]
only after MSHA determines that for a specific MMU, excessive dust
concentrations cannot be prevented in the environment of miners
required to work downwind of the longwall shearer operator (occupation
code--044) by implementing all feasible engineering or environmental
controls. We solicit comments concerning the availability of feasible
engineering or environmental controls to lower dust levels.
1. Selection of Respirators: Loose-Fitting PAPRs
Loose-fitting PAPRs completely surround the head and cover the face
with a full visor or shield. The functional and physical
characteristics of loose-fitting PAPRs as described below make them
especially well-suited to underground coal mining conditions, and it is
for these reasons that MSHA determined that loose-fitting PAPRs are the
most suitable type of respirator protection for these conditions.
A loose-fitting PAPR protects the wearer from excessive levels of
respirable dust by providing a continuous flow of filtered air and
imposing minimal breathing resistance upon the wearer. Loose-fitting
PAPRs do not require fit-testing,\6 7\ unlike tight-fitting
respirators. Furthermore, it is not necessary to be clean shaven for
this type of PAPR to be protective.
---------------------------------------------------------------------------
\6 7\ Quantitative fit testing and qualitative fit testing are
methods used to determine the facepiece seal and fit of a tight-
fitting respirator.
---------------------------------------------------------------------------
Loose-fitting PAPRs provide safety advantages over other forms of
PAPRs or tight-fitting respirators. In addition to protecting the
lungs, the helmet and visor of a PAPR can simultaneously protect the
eyes and head from high-velocity nuisance dust, spray, and small pieces
of coal from the cutting drums and face and from loose coal falling
from the roof. Loose-fitting PAPRs provide easier communication between
miners, rather than the muffled communication between workers which is
experienced between miners wearing tight-fitting facepieces.
The Racal<Register> Airstream helmet has been in use in underground
coal mines since the late 1970s. Over 50 percent of the longwall mines
operating have miners who wear Airstream helmets for added protection.
This respirator was developed primarily for mining use by the Safety in
Mines Research Establishment (SMRE) in England. It combines face, head,
and respiratory protection in a single convenient unit. The support
hardware which provides the filtered air is packaged in the helmet.
Power for the system is provided by a belt-mounted battery. Dusty air
enters the helmet through a rear entrance port, passes through a pre-
filter assembly that removes the coarse material, and then passes
through the fan and into a final-filter assembly that is located
between the head of the wearer and the outer helmet shield. The
filtered air then sweeps down across the wearer's face, behind the
face-shield visor, and exits at the chin. Soft plastic seals join the
face-shield visor to the sides of the head and jaw limiting entry of
unfiltered mine air (Greenough, 1979). The original Airstream helmet
has undergone numerous design improvements since it was first
introduced in British coal mines in the mid 1970s. The Airstream helmet
is produced by 3M (3M\TM\ Helmet-Mounted Airstream\TM\ series).
2. Protection Factor for Loose-fitting Powered, Air-Purifying
Respirators
The type and degree of protection of any respirator depends on the
ability of a respirator to prevent hazards from entering the worker's
breathing zone. In an underground coal mine, the level of protection
afforded by a loose-fitting PAPR to protect a miner depends on the type
and condition of the filter material of the air-purifying element, the
nature and concentration of the respirable coal mine dust, proper
maintenance of the PAPR and battery pack, and especially, how
consistently the miner properly wears the PAPR, including having the
visor properly lowered. The protection factor, the ratio of the
respirable dust concentration outside the respirator to the
concentration inside, measure how much protection a respirator might
provide to the wearer.
In the NIOSH Respirator Decision Logic (May 1987), based on
simulated laboratory tests and some workplace protection tests (none of
which replicated conditions in underground coal mines) NIOSH assigned
loose-fitting, helmeted PAPRs, properly worn, a protection factor (APF)
of 25. NIOSH made the following cautionary statement:
Despite the fact that some of the PF's [APFs] have a statistical
basis, they are still only estimates of the approximate level of
protection. It must not be assumed that the numerical values of the
APF's presented in this decision logic represent the absolute
minimum level of protection that would be achieved for all workers
in all jobs against all respiratory hazards. The industrial
hygienist or other professional responsible for providing
respiratory protection or evaluating respiratory protection programs
is therefore encouraged to evaluate as accurately as possible the
actual protection being provided by the respirator (NIOSH, May
1987).
Furthermore, in its Guide to Industrial Respiratory Protection
(September 1987), published after the NIOSH Respirator Decision Logic,
NIOSH offered an additional caveat with regard to the effectiveness of
PAPRs:
Until recently, powered air-purifying respirators were
considered positive pressure devices. Field studies by NIOSH as well
as others, have indicated that these devices are not positive
pressure, and that their assigned protection factors are
inappropriately high (NIOSH, September 1987).
There is virtually no positive pressure in the PAPR. Respirable
dust may invade the miners' breathing zone through openings along the
side and bottom of the visor, even when it is maintained in the full
lowered position. The extent to which respirable dust invades a miner's
breathing zone, depends, in part, on the MMU's ventilation air velocity
and on the miner's work rate and his angle of orientation to the
airflow.
Questions have arisen concerning the applicability of NIOSH's APF
of 25 for loose-fitting PAPRs to some work environments. It has been
contended that NIOSH overestimates the minimum level of protection
provided in the workplace even when used within the context of a good
respirator program (Myers, et al., 1984). The environmental conditions
assumed in NIOSH's estimation of the APF for loose-fitting PAPRs are
not consistent with those in underground longwall mining operations.
For example, various unique conditions of coal mining (obstructed views
and difficulty communicating) may compel miners to lift their visors.
Once the visor is raised, the respirator is no longer being worn in
accordance with conditions required for an APF of 25. Also, the high
velocities of air customarily found on longwall mining faces, are not
comparable to the air velocities experienced in most industry sectors
nor in those represented in the studies used to determine the APF of
25. The actual fit or seal of the respirator helmet to the wearer,
repeated work-task motions in confined work spaces, raising the visor,
and high air velocities along the longwall face all may significantly
reduce the actual degree of protection provided in the workplace.
Unlike an APF, an effective protection factor (EPF) reflects the
protection provided by a respirator over an actual work shift given
specific occupational environmental conditions such as ventilation
velocity, when the wearer performs typical work activities and uses the
respirator in a typical manner.
Laboratory and in-mine studies (EPF studies) show that mine
ventilation air flow or velocity, the primary means
[[Page 42137]]
longwall operators use to control respirable dust levels, may be the
single biggest factor affecting the level of protection provided by the
PAPR on a longwall mining face. Cecala, et al., (1981) found protection
of loose fitting PAPRs (Racal<Register> Airstream helmets) to be
inversely related to ambient air velocity in both laboratory and in-
mine settings (Ibid). In other words, increased air velocity leads to
decreased effectiveness of the PAPR.
The level of protection from a loose-fitting PAPR is also affected
by the orientation of the helmet to the airflow. Cecala's wind tunnel
tests clearly showed that, at the higher flow rates, helmet efficiency
was greatest when facing directly against the airflow and was reduced
when the helmet was oriented in other directions. This is extremely
important since miners are more likely to orient their heads at an
angle to the airflow, or to face downwind, than to face directly into
the airflow.
Cecala's in-mine testing of the loose-fitting, helmeted PAPRs
produced an EPF confirming the inverse relationship between wind speed
and the level of protection provided by PAPRs shown during wind tunnel
testing. Air velocity in underground mines is measured in units of feet
per minute (fpm). Under normal face-velocity conditions (less than 400
fpm), the Airstream helmet averaged a respirable dust reduction of 84
percent, which is equivalent to an EPF of 6.4. However, under high
face-velocity conditions (1,200 fpm), the helmet's dust reduction
efficiency decreased significantly, averaging only 49 percent, which is
equivalent to an EPF of 2.
Other researchers have reported that helmeted PAPR systems are
vulnerable to inward leakage into the wearer's breathing zone (Howie,
et al., 1987; Sherwood, 1991). For example, Howie, et al., found that
increasing airflow velocities from approximately 400 to 800 fpm doubled
the inward leakage of the helmet when the airflow impinged on the
wearer's head only, and increased the leakage further when the airflow
impinged on the wearer's body and head (Howie, 1987). Subsequent
testing of a redesigned unit at a wind velocity of approximately 700
fpm showed decreased inward leakage, yielding a protection factor of
6.3. This met the target protection factor of 5, which was subsequently
proposed by the European Community to be the standard for powered
helmet respirators.
More recent studies conducted by Bhaskar, et al. (1994) at four
medium-velocity western longwalls indicated loose-fitting PAPRs had an
average dust reduction efficiency of 83.8 percent (Ibid.). Although a
different sampling procedure was used, this result is consistent with
the average value of 84 percent obtained by Cecala, et al., under
normal mine face-velocity conditions. During the test period, the
headgate velocity ranged from 345 to 500 fpm, with approximately 88
percent of the recorded velocities falling below 500 fpm. The tailgate
velocities ranged from 280 to 550 fpm and only one exceeded 500 fpm. No
tests were conducted under high mine face-velocity conditions.
The headgate and tailgate velocities observed by MSHA inspectors at
55 longwall MMUs were reviewed in 1999. The headgate and tailgate
velocities ranged from 365 to 1,645 fpm and from 200 to 1,400 fpm,
respectively. More importantly, headgate velocities at 60 percent of
the MMUs exceeded 500 FPM and some 18 percent exceeded 800 fpm.
Approximately 55 percent of tailgate velocities exceeded 500 fpm and 11
percent exceeded 800 fpm.
PAPRs have been demonstrated to be effective on longwall MMUs when
air velocities do not exceed 500 fpm, but, as described above, there is
evidence that their effectiveness is reduced when air velocities are
increased. Therefore, given the range of observed longwall face air
velocities to which miners are exposed and the proposed requirement
that the verified ventilation plan demonstrate that the longwall
shearer operator (occupation code--044) be at or below the applicable
standard, MSHA is proposing to grant a protection factor of two for
loose-fitting PAPRs used under this proposal. Multiplying either the
respirable dust standard or the verification limit (whichever is
applicable) by the protection factor yields the maximum concentration
of respirable dust against which a particular type of respirator can be
used. In other words, if MSHA permits a longwall operator to use PAPRs,
then the maximum concentration of respirable coal mine dust and quartz
dust against which these particular respirators can be used are 4.0 mg/
m\3\ and 200 <greek-m>g/m\3\, respectively. A complete respiratory
protection program is required to assure that a respirator's protective
value is not compromised by improper fitting or usage.
MSHA's determination is based on the best scientific and technical
information available as well as sound engineering judgment. However we
encourage you to submit comments on the protection factor. We are
particularly interested in obtaining more recent data that may be
available concerning protection factors as well as the conditions for
the use of PAPRs. If you believe MSHA should establish a different
protection factor, please submit these data supporting your position.
E. Guidelines for Determining What Is a Feasible Dust Control
The proposal would require a mine operator to implement all
feasible engineering or environmental controls that are technologically
and economically feasible. The Federal Mine Safety and Health Review
Commission (Commission) has addressed the issue of what MSHA must
consider, when determining what is a feasible control for enforcement
purposes. In cases involving the noise standard for metal and nonmetal
mines, the Commission has held that a control is feasible when it: (1)
reduces exposure, (2) is economically achievable, and (3) is
technologically achievable. See Secretary of Labor v. Callanan
Industries, Inc., 5 FMSHRC 19 00 (1983), and Secretary of Labor v. A.
H. Smith, 6 FMSHRC 199 (1984).
In determining technological feasibility of an engineering control,
the Commission has ruled that a control is deemed achievable if through
reasonable application of existing products, devices, or work methods
with human skills and abilities, a workable engineering control can be
applied to the exposure source. The control does not have to be ``off-
the-shelf'' or already available but, it must have a realistic basis in
present technical capabilities. Further, the Commission has held that
MSHA must assess whether the cost of the control is disproportionate to
the ``expected benefits,'' and whether the cost is so great that it is
irrational to require its use to achieve those results. The Commission
has expressly stated that cost-benefit analysis is unnecessary in order
to determine whether an engineering control is feasible. According to
the Commission, an engineering control may be feasible even though it
fails to reduce the exposure to permissible levels in the standard, as
long as there is a significant reduction in exposure.
Consistent with the Commission case law, MSHA would consider three
factors in determining whether engineering or environmental controls
are feasible at a particular mine: (1) the nature and extent of the
overexposure; (2) the demonstrated effectiveness of available
technology; and (3) whether the committed resources are
disproportionate to the expected results. As explained in the
discussion of proposed Sec. 70.211 in Section IV of the
[[Page 42138]]
proposal, the formal determination of whether all feasible engineering
or environmental controls have, in fact, been implemented at a specific
mine to prevent excessive dust concentrations would be made by the
Administrator for Coal Mine Safety and Health based on the best
available information, experience, and engineering judgment.
F. Application of Continuous Monitoring Technology to Prevent
Overexposures on Individual Shifts
Because approved technology that continuously monitors respirable
dust and displays dust concentrations in real-time is not available,
effective ventilation plans remain the only practical means to provide
reasonable assurance, on a continuous basis, that miners are not
overexposed on individual shifts. However, MSHA recognizes that person-
wearable continuous respirable dust monitors under development may lead
to significant improvements in monitoring the work environment in order
to improve miner health protection. In an effort to reduce occupational
respiratory disease among underground coal miners, MSHA encourages mine
operators to adopt new and better dust monitoring technology as part of
the approved ventilation plan.
Unlike the current monitoring system, which relies on periodic
sampling and requires that corrective action be taken after the
necessary delay in obtaining dust level information, continuous
monitoring would allow mine operators and miners to be aware of the
actual dust conditions at all times, thereby enabling immediate action
to avert possible overexposure. The ability to monitor dust exposure
continuously during the shift, predict end-of-shift cumulative
exposures, and to display the actual end-of-shift exposure would be far
more effective in preventing simple CWP and PMF than the current
system.
The health benefits of continuous monitoring were clearly
recognized by both the Task Group and the Advisory Committee. Both
recommended development, field testing, and immediate deployment of
such monitors for a variety of purposes. The Task Group concluded that
continuous monitoring of the mine environment and dust control
parameters offered the best long-term solution for improving the
existing federal program designed to prevent simple CWP and PMF among
coal miners. Similarly, the Advisory Committee stated in its report
that:
Worker exposure to excessive levels of dust can be prevented by
implementing a hazard surveillance program that provides mine
personnel with current information on actual dust levels in the work
environment at all times, and on the status of key dust control
parameters. The availability of this information on a real-time
basis would enable mine personnel to focus attention immediately on
the need to adjust control parameters to avert possible
overexposure. The recent development of continuous dust and
continuous dust control parameter monitors, which have both direct
reading and data recording/processing capabilities, offers the
potential to improve monitoring of the work environment
significantly and contribute to the effective control of exposure.
(MSHA, 1996).
MSHA has sought a means to measure the concentration of respirable
coal mine dust in coal mines on a continuous basis for nearly two
decades. Beginning in the 1970's, at the request of MSHA, the former
U.S. Bureau of Mines funded several developments of fast-response,
direct-readout respirable dust monitors for measuring the concentration
of respirable dust.
One type of fast-response respirable dust monitor determined the
mass of respirable dust particles collected on a grease-coated disk by
the attenuation of beta radiation caused by the dust spot on the
impaction disk. The unit was capable of operating for long periods,
taking up to 450 1-minute samples, and printing the individual and
time-integrated concentrations on a tape.
Other devices have used light-scattering technology to measure and
provide an immediate direct readout of dust concentrations. Since light
scattering is often dependent on particle characteristics such as size,
surface properties, and refractive index, this type of dust monitor
does not measure a mass concentration directly and can provide only a
relative measurement. However, it can be calibrated in the laboratory
to give an approximate mass concentration.
The light-scattering technology was later incorporated in a
machine-mounted, continuous respirable dust monitor for use in
underground mines. In the early 1980's, however, it was determined that
this technology was not effective for monitoring compliance with the
applicable dust standard. Nevertheless, instruments which used the
light scattering principle were found to be useful tools to locate dust
sources and to determine its magnitude. Such instruments continue to be
especially useful for evaluating dust-control techniques such as dust
collectors and water sprays that can be turned on and off quickly and
repeatedly.
The 1992 Task Group report recommended the accelerated development
of a fixed-site underground dust monitor, capable of providing
continuous information on dust levels and personal sampling devices
capable of providing both short-term and full-shift exposure
measurements. In response to this recommendation, the former Bureau of
Mines, with MSHA's assistance, again evaluated existing technology that
could be used in the development of a fixed-site underground mine dust
monitor. This was made possible because of advances in sensing and
electronic signal processing technology that had occurred since
development of the first generation machine-mounted dust monitor in the
late 1970's. Eventually a fixed site/machine-mounted continuous
respirable dust monitor based on the proprietary mass-measurement
technology known as the tapered element oscillating microbalance
(TEOM<Register>) was developed and field tested.
The TEOM technique is capable of continuously weighing a filter
upon which dust is collected. It provides a real-time record and a
permanent record of the total mass collected on the filter. The device
can display the time-weighted average (TWA) concentration of respirable
coal mine dust (total mass of dust collected divided by the length of
time the unit was operated), the instantaneous (real-time)
concentration, and the projected full-shift concentration. This would
allow a mine operator to adjust control measures or optimize mining
procedures to prevent miner overexposure. The full-shift concentration
of respirable coal mine dust would be available at the end of the
shift. The developer of the fixed-site monitor is also working on a
person-wearable, end of shift/continuous respirable dust monitor using
the same TEOM technology.
In addition to the TEOM technology, NIOSH is developing another
person-wearable device that has the potential for continuously
monitoring the mine environment. This device measures the mass of
respirable dust indirectly based on the amount of pressure drop
detected across the collection filter.
MSHA is seeking ways to encourage voluntary deployment of this
technology, once it has been verified as reliable. MSHA has considered
allowing mine operators to adopt a continuous personal monitoring
strategy as part of the approved ventilation plan, in lieu of plan
verification. Under this approach, the operator would have the
flexibility of choosing fro |
