Breathe Easy: U.S. EPA Seeks To Significantly Tighten Fine Particulate Matter Standards

On January 6, 2023, the U.S. Environmental Protection Agency (EPA) issued a proposed rule to lower the primary National Ambient Air Quality Standard (NAAQS) for fine/inhalable particulate matter (PM2.5). These proposed standards were published in the Federal Register on January 27 triggering a 60-day public comment period that will end on March 28, 2023. EPA is proposing to lower the primary NAAQS PM2.5 emission standard from 12 micrograms per cubic meter (µg/m3) to between nine and ten µg/m. The new standards, if issued as proposed, could result in many areas of the country being designated as nonattainment with the new standards, triggering significant new costs and control requirements for facilities with air permits in those new nonattainment areas.