The Mine Safety and Health Administration (“MSHA”) released its long-anticipated silica rule on Tuesday, April 16, 2024. (See the rule here) The rule is aimed at reducing miners’ exposure to respirable crystalline silica, otherwise known as silica or quartz dust. The final version of the rule is mostly consistent with the version MSHA proposed last year. It modifies the limits of exposure to crystalline silica and increases existing protections against other airborne particulates at mine sites. The rule will be published in the Federal Register on April 18, 2024, and will take effect in two months.

The rule requires both underground and surface mines to reduce the “permissible exposure limit” for breathable silica from 100 micrograms of silica per cubic meter of air (100 μg/m3) to 50 micrograms (50 μg/m3) during an 8-hour shift. Operators must also begin taking some protective measures where silica levels reach an “action level” of 25 micrograms (25 μg/m3). These changes make MSHA’s standard consistent with the standards set by the Occupational Safety and Health Administration (“OSHA”) in 2016 for factories, oil drilling sites, and construction projects.

The rule also requires metal and non-metal mine operators to establish medical surveillance programs similar to those already required for coal miners under existing standards. These programs provide periodic health examinations at no cost to miners.

Coal mine operators will have one year after the regulation’s effective date to comply with the rule. Metal and non-metal mine operators will have two years following the rule’s effective date to comply with the new requirements.

In a press release announcing the rule, MSHA emphasized the hazard, noting the inhalation of respirable crystalline silica “can cause serious lung and other diseases, such as silicosis, lung cancer, progressive massive fibrosis, chronic bronchitis and kidney disease.” MSHA also explained that exposure to “mixed coal mine dust containing respirable crystalline silica can lead to the development of black lung disease and progressive massive fibrosis.” Based on the evaluation of these hazards and the new controls, MSHA believes that the rule change will result in over 1,000 avoided deaths and almost 4,000 avoided cases of silica-related illnesses.