Coal Mine Respirable Dust Standard Noncompliance Determinations

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