MSHA Proposes Updated Silica Exposure Rule
The Mine Safety and Health Administration proposes revised respirable crystalline silica standards while keeping a lowered exposure limit.
Updated on Nov. 11, 2026 in Asthma
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The Mine Safety and Health Administration announced a proposed update to its rule on respirable crystalline silica exposure in mines. The proposal retains a permissible exposure limit of 50 micrograms per cubic meter of air, averaged over an 8-hour period.
Why it matters
The proposal would change how mines sample silica levels, enforce citations and conduct medical examinations for miners. Silica exposure is linked to serious lung disease, and multiple studies show cases of coal workers' pneumoconiosis are rising.
The proposed exposure limit is 50 micrograms of respirable crystalline silica per cubic meter of air, averaged over an 8-hour period. The public comment period closes Jan. 11, and the final outcome of the rule remains unresolved pending comments and litigation.
The players
Mine Safety and Health Administration
The federal agency within the Department of Labor that regulates safety and health conditions at U.S. mines, and which issued the proposed silica rule update.
Keith Sonderling
A public official who is involved in the Department of Labor's oversight of workplace safety rules, including this proposal.
Bobby Scott
A Virginia Democratic congressman who has been a prominent critic of the proposed changes to silica rules.
National Stone, Sand & Gravel Association
An industry trade group that filed a lawsuit in the 8th U.S. Circuit Court of Appeals challenging the 2024 silica rule.
The details
The proposal amends sampling so it can occur as frequently as necessary, removes periodic evaluation and post-evaluation sampling requirements, and limits citations to samples exceeding the limit based on laboratory analysis. It also makes medical exams for miners new to metal and nonmetal industry voluntary, removes the requirement to report chest X-ray classifications to NIOSH, and prohibits rotating miners as a corrective action for overexposure.
Timeline
2024: A final rule reduced the silica permissible exposure limit to 50 micrograms per cubic meter.
April: MSHA indefinitely delayed the compliance deadline for metal and nonmetal miners.
Nov. 10: MSHA announced the proposed rule update.
Nov. 12: The proposal was scheduled for publication.
Dec. 15: A virtual public hearing will be held at 9 a.m. Eastern.
Regulatory Context
The proposal keeps the 50-microgram limit set by MSHA's 2024 final rule, which is now under challenge in the 8th U.S. Circuit Court of Appeals by the National Stone, Sand & Gravel Association. Its changes to sampling and medical monitoring follow the agency's April decision to indefinitely delay the compliance deadline for metal and nonmetal miners.
Miners and mine employers face changes in how silica exposure is sampled, enforced and monitored, including voluntary rather than mandatory medical exams for newly hired metal and nonmetal miners. Workers concerned about silica-related lung disease can submit comments on the proposal before the Jan. 11 deadline.
The takeaway
Stricter sampling and medical monitoring rules matter most for miners whose lung health depends on consistent exposure tracking. Readers following the issue should watch the Dec. 15 hearing and the Jan. 11 comment deadline.
What happens next
Public comments on the proposed rule are due Jan. 11, and a virtual public hearing will be held Dec. 15 at 9 a.m. Eastern.
Further reading
For related background, explore Asthma coverage that connects respiratory disease to workplace exposures.
Source note: This article includes information reported by Safety+Health Magazine.
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