[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