Last January, the U.S. Environmental Protection Agency (EPA) issued a memorandum withdrawing the “once in always in” (OIAI) policy that had provided interpretation of the Clean Air Act since 1995. Under the Clean Air Act, the regulations air pollution sources must comply with, depend on whether the source counts as “major” or “nonmajor”; the OIAI policy dictated that once a source qualified as major, subsequent changes in its emission levels would not enable the source to downgrade to nonmajor.
In making its decision to withdraw the policy, the EPA found that imposing a permanent categorization on emitting sources was contrary to the plain language of the Clean Air Act. Permanently categorizing facilities as major sources disincentivized sources implementing voluntary improvements or achieving greater efficiencies. Rescinding the OIAI policy, the EPA determined, could remove this barrier and lead to increased voluntary technological or operational improvements at facilities.
Roughly a year later, with California’s challenge to the OIAI withdrawal still pending in court, the EPA sent a proposed rulemaking to the Office of Management and Budget at the end of February 2019, intending to enshrine in regulation this change of policy. Meanwhile, Pennsylvania has proposed a change to its own air quality permitting program at the state level.