Occupational exposure to high levels of respirable quartz can result in respiratory and other diseases in humans….MSHA regulates exposure to respirable quartz in coal mines indirectly through reductions in the respirable coal mine dust exposure limit based on the content of quartz in the airborne respirable dust. 

The effectiveness of this indirect approach to control quartz exposure was evaluated by analyzing respirable dust samples collected by MSHA inspectors from 1995 through 2008. The performance of the current regulatory approach was found to be lacking due to the use of a variable property — quartz content in airborne dust — to establish a standard for subsequent exposures. In one situation, 11.7% (4370/37,346) of samples that were below the applicable respirable coal mine dust exposure limit exceeded 100 µg/m3 quartz. In a second situation, 4.4% (895/20,560) of samples with 5% or less quartz content in the airborne respirable dust exceeded 100 µg/m3 quartz. In these two situations, the samples exceeding 100 µg/m3 quartz were not subject to any potential compliance action. Therefore, the current respirable quartz exposure control approach does not reliably maintain miner exposure below 100 µg/m3 quartz. A separate and specific respirable quartz exposure standard may improve control of coal miners’ occupational exposure to respirable quartz.

A new proposed MSHA silica regulation can be expected to replicate OSHA’s August, 2013, proposed rule, including:
• An exposure limit of 50ug/m3.
• An Action Level of 25ug/m3 triggering air monitoring and analysis.
• Above the PEL mandates for engineering controls, medical monitoring, respirator programs, restricted work areas, dirty clothing protections, training, recordkeeping, and others.

Undoubtedly, MSHA’s expected proposal will create challenges similar to — and even greater than — its coal dust proposal. Sampling and analytical inaccuracy, a refusal to recognize filtered air helmets as a primary control method, and a lack of feasibility of engineering controls at the very low limits under consideration are among the concerns raised by an anticipated silica rule.

In addition, while there is general agreement that isolated regional occurrences of silica-related disease must be prevented, and can be under current regulatory limits, the Centers for Disease Control and prevention data demonstrates that silica-related mortality is disappearing in the United States. (See graph.) The data rebuts the claimed need for new regulatory mandates. Yet MSHA, like OSHA, seems intent on advancing them as a priority item.

Given MSHA’s focus on silica, we suggest that operators review historical sampling results, the validity of current citations, and their control and protection programs in advance of further agency attempts to justify the expected rulemaking proposals.

Henry Chajet is a partner in the Washington, D.C., office of Jackson Lewis (henry.chajet@jacksonlewis.com). He counsels and represents clients in environmental, health and safety (EH&S) matters and antitrust matters. He defends investigations and enforcement actions by the Mine Safety and Health Administration (MSHA), Environmental Protection Agency (EPA) and other agencies, as well as in related tort claims and criminal cases, and in EH&S whistleblower or discrimination claims.