EPA Proposed Rule Would Implement Withdrawal of Once-In-Always-In Policy

On June 25, 2019, EPA announced a proposed rule to implement withdrawal of the agency's Once-In-Always-In (OIAI) policy thereby allowing major sources of hazardous air pollutants (HAP) to reclassify as area sources after acting to limit emissions to below major source thresholds.

The proposed rule follows an EPA memorandum issued last year on January 25, 2018 establishing guidance to withdraw the agency's previous OIAI policy. That memorandum supersedes an original May 16, 1995 EPA interpretation of Section 112 of the Clean Air Act (CAA) that required facilities identified as major sources for HAPs on the "first compliance date" to comply permanently with the maximum achievable control technology (MACT) standard.

EPA will seek comments  on all aspects of the proposal including the agency's interpretation of the statutory definitions in the CAA and whether safeguards may be appropriate to protect against emissions increases. The public comment period will be open for  60 days once the proposed rule is published in the Federal Register.