The U.S. Environmental Protection Agency (EPA) has finalized rulemaking originally proposed in 2016 to remove “emergency” affirmative defense provisions from its Clean Air Act (CAA) permitting regulations for “major sources.” On July 21, the EPA published a final rule amending 40 C.F.R. Sections 70.6 and 71.6 to delete the emergency affirmative defense provisions in light of decisions from the U.S. Court of Appeals for the D.C. Circuit.

The emergency affirmative defense provision under 40 C.F.R. Parts 70 and 71 originated from rulemaking promulgated by the EPA in 1992. This rulemaking was intended to implement the 1990 amendments to the CAA which established Title V, including requirements for operating permitting programs as applicable to among other things, “major sources.” The CAA defines a major source as “any stationary facility or source of air pollutants which directly emits, or has the potential to emit, one hundred tons per year or more of any air pollutant …”. In addition, the CAA also includes as major sources those “that emit[] or ha[ve] the potential to emit considering controls, in the aggregate, 10 tons per year or more of any hazardous air pollutant or 25 tons per year or more of any combination of hazardous air pollutants.”