These changes will likely produce massive disruptions in the industry, since for each shift that a sample shows a measurement over the limit, operators will be required to “take immediate action.” This will take place despite the proven unreliability and errors found in prototypes of the CPDM devices, and the fact that MSHA has yet to figure out how to account for the errors and the unreliability in the device. Estimates have been made by mining experts that the rule will result in more than 250,000 samples per year and about 10,000 overexposure results.

If these impacts were not overwhelming enough, MSHA also adopted a table of Excessive Concentration Values (ECVs) ranging from 0.23 mg/m3 to 2.26 mg/m3 for single-shift samples collected by a CPDM. An ECV is the statistical calculation of a coal dust sample reading used by MSHA to determine if a mine operator is out of compliance with the exposure limit. According to MSHA, ECVs account for the error inherent in the measurement at the applicable exposure level, which depends on the percentage of silica.

Further, MSHA’s final rule includes a separate quartz dust exposure limit of 100 micrograms per cubic meter (µg/m3), as well as a formula that lowers the new 1.5 mg/m3 dust limit when the quartz content exceeds 5% (using the formula 10/% of quartz). In fact, the applicable standard can be as low as 0.2 mg/m3, depending on the concentration of quartz dust. The following example provided in the proposed rule illustrates how MSHA will calculate the applicable dust standard: Assume the sampled active working area is on a 1.5-mg/m3 dust standard. Suppose a valid representative dust sample with an equivalent concentration of 1.12 mg/m3 contains 12.3% of quartz dust, which corresponds to a quartz concentration of 138 µg/m3. Therefore, the average concentration of respirable dust in the mine atmosphere associated with that active working area shall be maintained on each shift at or below 0.8 mg/m3 (10/12.3% = 0.8 mg/m3).

Despite this, the agency recognizes that the CPDM does not measure silica, so it requires its inspectors to measure silica about once per quarter, and the results will be applied to all future samples, until MSHA measures silica again, perhaps in the next quarter. MSHA did not forget that silica content changes constantly, from place to place, and time to time, and that today’s sample does not relate to tomorrow’s sample. Instead, in an amazing twist of logic, the agency said that because its new device does not measure silica, it doesn’t need to be concerned with the silica content of a sample, although that very sample will be measured and judged against a silica-reduced dust standard. MSHA has not answered the question of how miners are protected from silica-caused hazards without knowing how much silica is in a sample used to measure silica compliance. Nor did it answer the question of why an operator should be penalized for a silica limit, without knowing if there is any silica in the sample used for the compliance determination, much less the amount of silica in the sample.

We ask: unintended consequences or bad government policy? You decide.

The MSHA dust sampling changes do not end there, and a full explanation of them would far exceed the limits of this article. However, operators should know that the rule requires operators to collect respirable dust samples for the full shift that a miner works rather than a maximum of eight hours under the prior standards. Further, what represents a “normal production shift” to permit sampling is redefined. Underground mine operators are required to take samples in production areas when production is at least 80% of the average production over the last 30 production shifts or at least 80% of the average production for all production shifts if fewer than 30 shifts of production data are available.

In light of all these changes, we are proud to represent the industry in a court challenge to the new rule in front of the U.S. Court of Appeals for the 11th Circuit. However, we note that the results of the challenge may not be known for months. In the interim, coal mine operators should understand this new rule; determine the best way to document MSHA sampling and analysis, procedures and errors; develop evidence to debunk and defend against improper citations; and make contingency plans to deal with the disruptive nature of the rule, well in advance of MSHA’s implementation schedule.


Linda Otaigbe is an associate in the Washington, D.C., region office of Jackson Lewis P.C. She focuses her practice on all aspects of workplace safety and health law. She can be reached at linda.otaigbe@jacksonlewis.com.