The Mine Safety and Health Administration’s (MSHA) landmark rule to reduce miners’ exposure to respirable crystalline silica is now tied up in litigation—and its enforcement timeline has shifted yet again. While the rule remains on the books, coal operators will not see enforcement until the courts weigh in. However, metal/nonmetal (MNM) mining companies still face an April 8, 2026 compliance deadline.

For health and safety leaders (especially in the coal mining industry) the uncertainty is challenging. But one thing remains clear: silica exposure poses a well-documented risk, and preparation is still the best defense.

Exposure to mixed coal mine dust containing respirable crystalline silica can lead to the development of black lung disease and progressive massive fibrosis.

Major aspects of the final rule are that it:

• Reduces the permissible exposure limit (PEL) for silica dust to 50 micrograms per cubic meter (µg/m3) of air;
• creates an action level of 25 µg/m3;
• establishes uniform exposure monitoring and control requirements for coal and MNM mines;
• creates medical surveillance at MNM mines;
• and updates respiratory protection standards to better protect coal and MNM miners from exposure to all airborne hazards, including silica dust, diesel particulate matter, asbestos and other contaminants.

The final rule was published into the federal register on April 18, 2024. Originally, the coal mining industry had until April 14, 2025 and the MNM industry had until April 8, 2026 for compliance deadlines.

Judicial Stay for Coal Mines
On April 4, 2025, the Eighth Circuit Court of Appeals issued a stay of the silica rule’s compliance deadlines for coal operations while litigation proceeds. In response, MSHA formally paused enforcement for coal mines “until the litigation is concluded.” A tentative date of August 18, 2025 was established as the new deadline for the coal mining industry. However, that date has come and gone and the case is still tied up in litigation.

MNM Timeline Unchanged—for Now
The compliance deadline for metal and nonmetal mining remains April 8, 2026. No stay has been announced for those sectors, though ongoing litigation could alter that timeline.

Litigation in Motion
Several industry groups have challenged the rule, and the case is now consolidated before the Eighth Circuit. Status reports filed this summer suggest MSHA and industry are exploring potential settlement, while unions have sought to intervene in the case. The final outcome may reshape enforcement dates—or even the rule itself.

Even with enforcement paused, the rule’s text is still in effect. Its key provisions include:

• A uniform permissible exposure limit (PEL) of 50 µg/m³ (8-hour TWA) across all mines.
• An action level of 25 µg/m³, triggering additional monitoring.
• Mandatory sampling and reporting using ISO-compliant devices and accredited labs.
• Expanded medical surveillance (respiratory testing, chest imaging, clinical exams) for MNM miners, aligning requirements with those long in place for coal.
• A hierarchy of controls emphasizing engineering solutions before reliance on respirators.
• Written respiratory protection programs with proper selection, fit testing, and training.

1. Don’t Treat the Pause as a Reprieve
   The enforcement stay offers breathing room, but once litigation concludes, compliance could be required on short notice.
2. Stay on Track for MNM Compliance
   With April 2026 still in force, MNM operators should continue preparing—sampling, upgrading controls, and setting up medical surveillance programs.
3. Advance Coal Mine Readiness
   Even though coal operators aren’t currently under enforcement, aligning programs now will reduce last-minute pressure if the stay is lifted.
4. Strengthen Controls and Programs
   Review ventilation, dust suppression, enclosed cabs, and maintenance. Update respiratory protection and medical surveillance programs to meet rule requirements.
5. Monitor Legal Developments
   Assign a compliance lead to track updates from MSHA and the Eighth Circuit. A settlement or court ruling could change timelines quickly.

The silica rule is in limbo, but miners’ health risks are not. Whether compliance dates hold, shift, or reset after litigation, proactive preparation remains the wisest path for health and safety managers. By acting now—despite the enforcement pause—operators can protect workers, reduce liability, and be ready for whatever the courts decide.