[Federal Register Volume 59, Number 34 (Friday, February 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3593]
[[Page Unknown]]
[Federal Register: February 18, 1994]
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Part V
Department of Labor
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Mine Safety and Health Administration
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Department of Health and Human Services
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Centers for Disease Control and Prevention
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Mine Shift Atmospheric Conditions; Coal Mine Respirable Dust Standard
Determinations; Notices
DEPARTMENT OF LABOR
Mine Safety and Health Administration
Coal Mine Respirable Dust Standard Noncompliance Determinations
AGENCY: Mine Safety and Health Administration, Labor.
ACTION: Notice.
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SUMMARY: This notice announces the Mine Safety and Health
Administration's (MSHA) intention to use single, full-shift respirable
dust measurements in addition to the average of multiple, full-shift
respirable dust sample results to determine noncompliance and issue
citations for violations of the respirable dust standard under the MSHA
coal mine respirable dust program. This notice should be read in
conjunction with the joint notice published elsewhere in today's
Federal Register by the Department of Labor and the Department of
Health and Human Services.
DATES: Written comments must be submitted on or before April 19, 1994.
ADDRESSES: Send written comments to the Mine Safety and Health
Administration, Office of Standards, Regulations, and Variances, room
631, Ballston Tower No. 3, 4015 Wilson Boulevard, Arlington, Virginia
22203.
FOR FURTHER INFORMATION CONTACT: Ronald J. Schell, Chief, Division of
Health, Coal Mine Safety and Health, Mine Safety and Health
Administration, 4015 Wilson Boulevard, Arlington, Virginia 22203, (703)
235-1358.
SUPPLEMENTARY INFORMATION: The Secretary of Labor and the Secretary of
Health and Human Services are jointly publishing a notice today
elsewhere in the Federal Register announcing that the Secretaries find
that the average concentration of respirable dust to which each miner
in the active workings of a coal mine is exposed can be accurately
measured over a single shift in accordance with section 202(f)(2) of
the Federal Mine Safety and Health Act of 1977 (Mine Act). Based on
this finding, the Secretaries are proposing to rescind the finding
issued on July 17, 1971, and affirmed on February 23, 1972. In order to
implement this finding for MSHA's respirable dust program, the Agency
proposes to issue citations based on either single, full-shift
measurements or on the average of multiple-sample results that meet or
exceed the minimum values listed in the Values Table published
today.\1\
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\1\MSHA recognizes that any change to the substantive procedures
for operator sampling governed by 30 CFR part 70 would require
rulemaking by the Agency. Therefore, the use of multiple-shift
averaging of operator samples will continue under the regulations
currently in effect to be the sole method of determining
noncompliance. The Agency is studying the appropriateness of
utilizing single, full-shift measurements in the operator's sampling
program.
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MSHA believes that the use of single, full-shift measurements will
enhance mine operators' compliance with the Mine Act requirement
pursuant to section 202(b)(2) to continuously maintain the average
concentration of respirable dust in the mine atmosphere during each
shift where miners work and travel, at or below the applicable
standard.
In May, 1991, the Secretary of Labor directed MSHA to conduct a
thorough review of its program to control respirable coal mine dust and
develop recommendations for program improvements. In response, MSHA
established the Coal Mine Respirable Dust Task Group which conducted a
comprehensive examination of the Agency's respirable dust program. The
Task Group questioned the reliability of the respirable dust samples,
which are submitted to the Agency in accordance with the requirements
of the Mine Act, to accurately measure dust exposures in the Nation's
coal mines. As a result, in July, 1991, the respirable dust Spot
Inspection Program was initiated. This inspection program allowed the
Agency to gather significant information on dust levels to which miners
were exposed. MSHA sampled 615 underground coal mines involving
approximately 50 percent of the mechanized mining units (MMUs) in
operation. During these spot inspections, five different occupations
and the intake air were sampled on each MMU for one full shift.
Because samples were being collected on only one day during the
Spot Inspection Program, citations were issued on individual
measurements that demonstrated, after applying valid statistical
techniques, that the applicable respirable dust standard was exceeded.
Data from these spot inspections show that 203 out of 718 MMUs (28
percent) had single, full-shift measurements that, from a statistical
standpoint, significantly exceeded the applicable standard for those
MMUs. When the average of multiple samples for those MMUs was examined,
however, only 88 out of 717 MMUs (12 percent) exceeded the applicable
standard.
Based on these data, MSHA concluded in the June 1992 report of the
Coal Mine Respirable Dust Task Group that the then-current Agency
sampling strategy used by its inspection staff, which used only the
averaging of multiple samples results as the basis for issuing
citations, did not always respond to known overexposures to respirable
coal mine dust. Specifically, if the average concentration determined
from measurements obtained for five occupations working on the same
shift is below the applicable dust standard, but one or more individual
samples significantly exceed this standard, the then-current MSHA
policy did not provide for enforcement action to be taken. For example,
if the following five samples were obtained, 4.1, 1.0, 1.0, 2.5, and
1.4 mg/m\3\, the average concentration would be 2.0 mg/m\3\. Even
though two of these measurements significantly exceed the applicable
standard, MSHA would not issue a citation or require corrective action
because the average of the concentration measurements is not above the
standard. As seen in this example, the sole use of the average of
multiple, full-shift sample results would not recognize cases where
there is clear evidence that the standard has been exceeded.
Since the implementation of the one-day respirable dust spot
inspection program, MSHA has continued to use full-shift, single-
measurements in making noncompliance decisions under the Agency's
respirable coal dust program. Single-sample enforcement strategies are
also being used currently by the Agency to determine noncompliance with
permissible exposure standards in metal/nonmetal mining and mineral
processing operations and by the Occupational Safety and Health
Administration (OSHA) in non-mining industries. Therefore, consistent
with the joint finding of the Secretary of Labor and the Secretary of
Health and Human Services, as well as with recognized industrial
hygiene and public health practice, MSHA believes that a single, full-
shift measurement can be used reliably to detect violations of the dust
standard on the shift during which the sample was taken. Accordingly,
single, full-shift measurements should be used for this purpose.
Statistical Basis for and Application of the Single-Sample
Enforcement Strategy
The statistical test for noncompliance determinations is based on
the calculation of a one-sided, 95-percent confidence interval for
different applicable respirable dust standards. The calculation
includes variability associated with the sampling and analytical
methods. The sampling and analytical variability is expressed as the
coefficient of variation, computed by combining random variability
associated with the pre- and post-weighing of the filter capsule (.14
mg/m\3\), flowrate variability (5 percent), and variability associated
with flowrate adjustment (5 percent). Using an overall coefficient of
variation of 10 percent at 2.0 mg/m\3\, MSHA has determined using
standard statistical methods that a single-shift measurement of 2.4 mg/
m\3\, for example, would indicate noncompliance with a 2.0 mg/m\3\ dust
standard with (at least) 97.5 confidence. Other minimum values at which
MSHA would issue citations for violations of the applicable dust
standard are listed in the Values Table below. Therefore, when a
single, full-shift measurement is at or above the minimum value listed
in column 1 of the Values Table, it can be concluded, with at least 95
percent confidence, that the applicable dust standard has been
exceeded.
Additionally, to provide the level of health protection to miners
required by the Mine Act, MSHA proposes to continue to cite violations
of the dust standard based on the average of multiple, full-shift
sample results. For example, if five sample results of 2.2, 2.3, 2.3,
2.3, and 2.2 mg/m\3\ were obtained from a mechanized mining unit on a
2.0 mg/m\3\ dust standard, the average measurement would be 2.26 mg/
m\3\. If MSHA were to issue citations based solely on single, full-
shift measurements by using the Values Table, no citations would be
issued and no corrective action would be required because no individual
sample result was at or above 2.4 mg/m\3\. However, the average
measurement of 2.26 mg/m\3\ would indicate (at a confidence level
greater than 99 percent) that the applicable dust standard was
exceeded. In such cases, when noncompliance is indicated with a high
degree of confidence, MSHA would take enforcement action, and require
the mine operator to take corrective action to reduce the dust levels
in the working environment.
For cases when four or fewer valid measurements are available, the
Values Table contains the minimum values at which an average of the
measurements would indicate noncompliance with the applicable standard
at a confidence level of at least 95 percent. When, for example, the
average of three measurements equals or exceeds the minimum value
listed in column 3 of the Values Table, MSHA would issue a citation for
a violation of the applicable dust standard.
In considering enforcement action, MSHA would first examine the
average of multiple, full-shift sample results to determine if the
applicable dust standard has been exceeded. If the average measurement
is less than the minimum value listed in the Values Table, the Agency
would then examine the samples on an individual basis and issue a
citation when any measurement is greater than or equal to the column 1
minimum value. Thus, in assessing noncompliance, MSHA intends to use
both the average of multiple, full-shift sample results and single,
full-shift measurements, and will issue citations based on either
criterion, not both, for any given set of samples.
MSHA specifically requests that interested persons submit comments
concerning this notice to the address listed above. Written comments
submitted on or before April 19, 1994 will be considered before MSHA
finalizes this notice on the use of single, full-shift measurements and
the average of multiple, full-shift sample results.
Dated: February 11, 1994.
J. Davitt McAteer,
Assistant Secretary for Mine Safety and Health.
Values Table--Minimum Values For Citing Violations Based on Four or
Fewer Full-Shift Measurements
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No. of measurements
Applicable standard -------------------------------
1 2 3 4
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2.0..................................... 2.33 2.23 2.19 2.17
1.9..................................... 2.22 2.13 2.08 2.06
1.8..................................... 2.11 2.02 1.98 1.96
1.7..................................... 2.00 1.91 1.87 1.85
1.6..................................... 1.90 1.81 1.77 1.75
1.5..................................... 1.79 1.71 1.67 1.65
1.4..................................... 1.68 1.60 1.56 1.54
1.3..................................... 1.58 1.50 1.46 1.44
1.2..................................... 1.47 1.39 1.36 1.34
1.1..................................... 1.36 1.28 1.25 1.23
1.0..................................... 1.26 1.18 1.15 1.13
0.9..................................... 1.15 1.08 1.04 1.03
0.8..................................... 1.05 0.98 0.94 0.93
0.7..................................... 0.94 0.87 0.84 0.82
0.6..................................... 0.84 0.77 0.74 0.72
0.5..................................... 0.74 0.67 0.64 0.62
0.4..................................... 0.64 0.57 0.54 0.52
0.3..................................... 0.53 0.46 0.43 0.42
0.2..................................... 0.43 0.36 0.33 0.32
0.1..................................... 0.33 0.26 0.23 0.22
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[FR Doc. 94-3593 Filed 2-17-94; 8:45 am]
BILLING CODE 4510-43-P
