On Tuesday, September 10, the U.S. Environmental Protection Agency (EPA) issued a final rule establishing requirements for major sources of hazardous air pollutants — sources that emit or have the potential to emit 10 tons per year of a single hazardous air pollutant or 25 tons per year of a combination of hazardous air pollutants — that reclassify as area sources below these thresholds. Reversing a rule adopted during the Trump administration, the rule provides that sources emitting any of the seven persistent and bioaccumulative hazardous air pollutants listed under Section 112(c)(6) of the Clean Air Act must continue to comply with major source standards even if otherwise reclassified as area sources. As a result, reclassified sources will still be subject to maximum achievable control technology standards rather than less stringent standards applicable to area sources. In so doing, EPA maintains that at least 90% of the cumulative emissions of these pollutants will be subject to National Emission Standards for Hazardous Air Pollutants (NESHAP) regardless of future source reclassifications.

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