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On May 1, 2025, the Senate exercised its authority under the Congressional Review Act (CRA) approving a resolution repealing a Biden Administration EPA rule that tightened restrictions on major sources of hazardous air pollutant (HAP) emissions that convert to area source status [<em>i.e.</em>, “Review of Final Rule Reclassification of Major Sources as Area Sources Under Section 112 of the Clean Air Act’’ 89 Fed. Reg. 73,293 (September 10, 2024)]. The House is expected to pass a similar resolution, and the joint resolution will then be presented to the President for final approval. The CRA allows Congress to repeal most federal agency rules with a simple majority vote. Thereafter, agencies are generally prohibited from adopting new rules that are substantially similar to an invalidated regulation.

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During the first Trump Administration, EPA promulgated its Reclassification of Major Sources as Area Sources (MM2A) Rule (85 Fed. Reg. 73,854) allowing major sources to lower their “potential to emit” HAP emissions and reclassify to area source status. Under the MM2A rule, reclassified area sources would no longer be subject to major source federal national emission standards for hazardous air pollutant limitations. The MM2A rule repealed EPA’s 1995 “Once In, Always In” policy that prohibited major sources of HAPs from reclassifying to area source status. Rather, the “Once In, Always In” policy required that they permanently be classified as major sources regardless of their emission rates. The MM2A rule was not affected by the recent Senate CRA resolution.

The Biden Administration promulgated its own rule placing restrictions on sources converting from major source to area source status under the Trump era MM2A rule. One restriction prevented sources emitting seven persistent, bioaccumulative HAPs from reclassifying to area source status. The Biden era rule also imposed notification requirements on area sources that reclassified. It is this Biden era rule, and its restrictions, that the Senate voted to invalidate.

If the CRA resolution is passed by the House and approved by the President, the Trump era MM2A rule will remain in effect without restrictions on its use. The EPA’s 1995 "Once In, Always In" will remain invalid. The CRA will preclude EPA from promulgating future rules substantially affecting the MM2A rule or reinstating the “Once In, Always In” policy without congressional approval.

We are closely monitoring these developments. Please contact your Michael Best attorney to discuss how these changes may impact your business.

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Senate Approves Congressional Review Act Resolution Repealing Amendments to the “Major MACT to Area” Source Rule

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