MSHA’s 2024 final rule on respirable crystalline silica (“RCS”), officially titled Lowering Miners’ Exposure to Respirable Crystalline Silica and Improving Respiratory Protection, was published as a final rule in the Federal Register on April 18, 2024. At that time, MSHA set compliance deadlines of April 14, 2025, for Coal mine operators, and April 8, 2026, for all remaining Metal/Nonmetal (M/NM) operators.
This week, on April 6, 2026, MSHA published a final rule in the Federal Register announcing that “Since a judicial stay is in effect, this notification delays the conforming amendments indefinitely, pending judicial review.”
The final rule comes after a March 9, 2026, update posted to MSHA’s website that, in essence, states the same intent to respect the 8th Circuit Court of Appeals’ judicial stay.
On April 11, 2025, the United States Court of Appeals for the Eighth Circuit issued an order staying the Silica Rule’s compliance deadlines until the Court completes a substantive review of the petition. Accordingly, MSHA will continue to temporarily pause enforcement of the Silica Rule requirements for mine operators until the litigation is concluded.
For background, immediately after the rule was published, it was challenged by trade groups representing mining companies across various industries and across the nation. (see our previous blogs on MSHA’s silica rulemaking). The challenge is pending before the United States Court of Appeal for the Eighth Circuit, based in St. Louis, Missouri.
The challengers filed initial briefs supporting their respective petitions and seeking various relief from the 8th Circuit. Likewise, MSHA filed a brief in support of the final rule. Amid those filings, President Trump was inaugurated for his second term. With that, DOL and MSHA ’s political leadership shifted from the Biden administration, which championed the 2024 rule.
As the Coal compliance deadline approached, MSHA announced a voluntary stay delaying enforcement for Coal from April 2025 until August 2025, while the M/NM deadline remained unchanged.
Following MSHA’s voluntary stay of the Coal rule, industry challengers moved the 8th Circuit to issue a nationwide judicial stay of its implementation. This judicial stay was granted on April 11, 2025, effectively preventing MSHA from enforcing the rule and requiring compliance with its new provisions until the case before the 8th Circuit is resolved or settled, or the parties move to lift the stay. That judicial stay remains in effect to date.
With the judicial stay in place, the 8th Circuit is not expected to rule soon. The court granted the parties’ request to hold the litigation “in abeyance”—that is, pause it—while they attempt to resolve the legal challenge through negotiation. Instead, the parties have been filing regular status updates with the 8th Circuit to keep the court informed of developments and to ensure the case does not languish on the court’s docket.
In its November 2025 update to the court, MSHA announced that the agency intended to engage in “limited rulemaking” to “reconsider and seek comments on portions of the Silica Rule impacted by this appeal.” MSHA reiterated that intention in its January 2026 update to the court.
Once MSHA publicizes the Notice of Proposed Rulemaking (NPRM), it will provide another opportunity for stakeholders and the public to comment. After the notice-and-comment period—which will be scheduled once the NPRM is published—MSHA will work to develop a supported final rule and preamble. Afterward, interested parties may again challenge the rule.
Any meaningful changes to the 2024 RCS rule risk the agency running afoul of the “no less protection” rule in Section 101(a)(9) of the Mine Act. This section provides that “no mandatory health or safety standard promulgated under this subchapter shall reduce the protection afforded miners by an existing mandatory health or safety standard.” 30 U.S.C.A. § 811. Simply put, by statute, MSHA cannot promulgate a standard that lessens existing protections for miners. This powerful mandate likely means labor or union representatives will scrutinize MSHA’s changes and challenge the new rule as less protective. Conversely, if the revised rule does not adequately address industry representatives’ concerns, they might also challenge the agency legally.
The key takeaway: The judicial stay remains in effect, meaning MSHA cannot enforce the 2024 RCS rule until the 8th Circuit permits it. Therefore, Coal and M/NM mine operators should continue to operate under the prior standards regulating respirable silica / quartz. But beware: MSHA is still enforcing the existing Threshold Limit Value (TLV) and requiring the installation of engineering controls for abatement, using language similar to that of the 2024 final rule. Meanwhile, legal challenges to MSHA’s 2024 RCS rule persist, prolonging uncertainty for Coal and M/NM mine operators about future enforcement timelines.
