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August 23rd, 2023
Respirable crystalline silica, or silica dust, is created by coal mining and other industrial operations, and according to the Mine Safety and Health Administration (MSHA) is a recognized cause of silicosis, emphysema, chronic bronchitis, lung cancer, and kidney disease. In fact, the incidence rate of one of the most severe forms of silicosis, progressive massive fibrosis (or PMF), has risen noticeably after decades of decreasing occurrence.
The mineral quartz is a common form of silica. Currently MSHA limits exposure to quartz in some mines (called metal/nonmetal mines) to 100 micrograms per cubic meter (µg/m3) as an eight-hour time-weighted average, or TWA. This means that a worker may not be exposed to more than an average of 100-µg/m3 over an eight-hour period. MSHA does not currently have a separate exposure limit for respirable crystalline silica for coal mines, only a standard of 2 milligrams per cubic meter (or 20 times higher than the exposure limit for quartz) for all respirable dust.
Recently MSHA proposed to implement a permissible exposure limit for respirable crystalline silica of 50 µg/m3 as an eight-hour TWA, or half of the current limit for exposure to quartz. Notably, MSHA’s proposed exposure limit for coal mining is the same as the limit already implemented by the Occupational Safety and Health Administration for other industries, as well as the recommendation of the National Institute for Occupational Safety and Health. MSHA estimates that implementation of and compliance with its proposed rule will reduce the risk of death from silica exposures by 9.5% and reduce the risk of illness from silica exposures by 41.9%.
MSHA’s proposed rule also includes new requirements for respiratory protective equipment, testing of workplaces to ensure compliance, and medical surveillance to identify illnesses in miners. In the introduction to its proposed rule, MSHA notes that engineering controls designed to reduce the hazard at its source, such as ventilation and water sprays to keep down dust, are the most effective methods of compliance. This is consistent with general principles of industrial hygiene, which consider respiratory protection and similar tools as last resorts where engineering controls are less effective.
MSHA’s proposed rule on respirable crystalline silica exposure is still receiving public comments and is not final. However, the proposed rule is an important step in improving the safety of coal miners. It is worth noting that in issuing its proposed rule MSHA considered an exposure limit as low as 25 µg/m3, but settled on the higher standard because some mines might not be able to comply with that lower limit, attempting to balance worker safety with the potential burden on the industry.
This fact illustrates that creating a safe workplace can be complicated. Ideally regulatory standards provide a floor for safety, not a ceiling, and an employer can work with employees and their representatives to make sure that the conditions of a unique workplace are safe for everyone. When this does not happen, a lawyer experienced in claims involving unsafe working conditions can help protect workers’ rights.
