The U.S. Department of Labor (DOL) on June 30 announced a proposal by its Mine Safety and Health Administration (MSHA) to amend current federal standards to better protect the nation’s miners from health hazards related to exposure to respirable crystalline silica, or silica dust. The proposed rule change will ensure miners have at least the same level of protections as workers in other industries.
“Unhealthy levels of silica, a carcinogen, and exposures over time cause severe illnesses, including silicosis; progressive massive fibrosis; non-malignant respiratory disease, such as emphysema; kidney disease; and lung cancer. Exposure to mixed coal mine dust that contains respirable crystalline silica can lead to the development of coal workers’ pneumoconiosis, commonly known as black lung disease; multi-dust pneumoconiosis; and progressive massive fibrosis,” DOL stated.
As early as 1974, the National Institute for Occupational Safety and Health (NIOSH) published the Criteria for a Recommended Standard: Occupational Exposure to Crystalline Silica. NIOSH recommended that occupational exposure to respirable crystalline silica be controlled so that workers are not exposed to concentrations greater than 50 micrograms per cu. meter of air (50 µg/m3 ) as a full-shift sample for up to a 10-hr workday during a 40-hr work week to prevent silicosis. That NIOSH Recommended Exposure Limit (REL) remains 50 µg/m3 today, according to NIOSH.
In 2015, OSHA imposed a Permissible Exposure Limit (PEL) of 50 µg/m3 for General Industry and Construction This was followed in 2022 by MSHA imposing a (PEL) for the airborne concentration of respirable quartz of approximately 100 µg/m3, measured as a time-weighted average for the entire work shift.
“The U.S. Department of Labor recently announced a proposal by MSHA to amend current federal standards to ‘better protect the nation’s miners from health hazards related to exposure to respirable crystalline silica, or silica dust,'” stated Joe McGuire, an industry safety and health consultant, and a frequent contributor to Rock Products. “The proposed rule would require mine operators to maintain miners’ Permissible Exposure Limit, for respirable crystalline silica, at or below 50 µg/m3 for a full shift exposure, calculated as an eight-hour time weighted average.
“The mining industry has long acknowledged the health issues surrounding its workers’ exposure to respirable crystalline silica and during that time it has taken precautions to protect them,” McGuire continued. “In anticipation of a new MSHA Standard, many companies have gone beyond MSHA’s Permissible Exposure Limit of 100 µg/m3 and follow NIOSH’s recommendation and OSHA’s 2015 Silica Rule. Mining companies have been doing sampling, monitoring and testing of workers for silica under the OSHA PEL for years.
“For mining companies already following the OSHA Rule, the proposed MSHA Standard will have very little impact; those following the current MSHA PEL of 100 µg/m3 will need to update their Respiratory Programs but companies hoping for this rule change to ‘go away’ will probably be disappointed,” McGuire concluded.
Following the proposed rule’s publication in the Federal Register, MSHA will welcome public comments and announce dates for upcoming public hearings in Arlington, Va., and Denver. The hearings will be open for in-person or online participation.