Updated: Sep 9
In Wednesday’s Federal Register, the U.S. Environmental Protection Agency (EPA) published its finalized determination that Allegheny County has attained the 2012 National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM2.5).
The determination is “based on three years of certified, complete, and valid ambient air monitoring data between 2018 and 2020.”
“The annual 2012 NAAQS for PM2.5 is 15 micrograms per cubic meter. To attain the standard, the three-year average of annual mean concentrations cannot exceed that level,” GASP senior staff attorney John Baillie explained. “The inhalation of PM2.5 causes a variety of health problems, so the attainment of the NAAQS is welcome news, even though EPA’s own Integrated Science Assessment conducted in 2019 found that the 2012 annual PM2.5 standard may not adequately protect human health.”
As a practical matter, EPA’s determination effectively suspends any obligation for Allegheny County to submit contingency measures (meaning, additional pollution control requirements) to EPA for as long as the county continues to attain the NAAQS, and also means that EPA will not impose a “federal implementation plan” on the county as long as it continues to attain the standard (a federal implementation plan is an additional set of regulations meant to assure attainment and compliance with the NAAQS).
EPA’s determination also leaves the county free to request that EPA formally redesignate it as being in attainment of the 2012 annual PM2.5 standard, which requires the submission of a “maintenance plan” to EPA.
Editor’s Note: You can read more about the determination process here.