U.S. EPA Finalizes Repeal of 1995 ‘Once In, Always In’ Policy for Major Air Pollution Sources

The U.S. Environmental Protection Agency on Oct. 1 finalized a rule allowing a major source of hazardous air pollutants to reclassify as an “area source,” a less stringent category under the Clean Air Act, any time it implements measures to limit emissions. The action implements the agency’s 2018 guidance that withdrew the 1995 “Once In, Always In” policy, which disallowed reclassification of such a source as a lower-emitting facility, unless the source reduced its potential to emit below a prescribed threshold prior to the first substantive compliance date. The move reduces regulatory burden and provides fairness and flexibility for facilities that cut emissions below major source thresholds, according to the agency.

A facility categorized as a major source emits or has the potential to emit 10 tons per year or more of a single hazardous air pollutant or 25 tons per year or more of a combination of pollutants. The final rule modifies the provisions of the National Emission Standards for Hazardous Air Pollutants to allow sources that lower emissions below the aforementioned levels the flexibility to reclassify as an area source.

EPA identified facilities with emissions below 75 percent of the major source threshold and estimated that about one-third of the estimated 7,183 sources subject to major source standards emit pollutants below the 75-percent level. Reclassifying all of these as area sources could result in savings of $16.1 million in the first year and $90.6 million the subsequent years, according to EPA’s estimates.