MM2A rule allows facilities that reduce their air emissions to become less regulated
On October 1, 2020, EPA finalized a rule to remove a long-standing clean air policy known as “once in, always in.” As applied, that policy meant that once a facility was classified as a major source of air pollution it would always be classified as a major source, even if it took steps to reduce its air emissions.
The new final rule, also called the final Major Maximum Achievable Control Technology (MACT) to Area or “MM2A” rule, allows a major source of air pollution to reclassify as an “area source” at any time after successfully limiting its emissions. Under the National Emission Standards for Hazardous Air Pollutants (NESHAPS), a major source is defined as a facility that emits or has the potential to emit 10 tons or more per year of any of the 188 listed hazardous air pollutants, or 25 tons or more per year of a combination of these pollutants. An area source is any facility that is not a major source.
The MM2A rule does not require any source to reclassify its status under the NESHAPS; however, reclassifying as a smaller source could potentially save facilities substantial costs in air permitting fees and reduced regulatory compliance requirements such as monitoring, recordkeeping, and reporting associated with being a major source.
The final rule codifies guidance released in a 2018 EPA memo from former EPA head Scott Pruitt that discussed the statutory provisions that describe when a major sour subject to the NESHAPS can be reclassified. It also pointed to the language of Clean Air Act section 112(a), which defines major sources and minor sources.
EPA argues that the former “once in, always in” policy discouraged facilities from modernizing and upgrading equipment or implementing voluntary pollution abatement efforts.
The rule will become effective 60 days after publication in the Federal Register.
