Law & Order

EPA Issues Regulation Strengthening Air Quality Standards for PM 2.5

By the SEMA Washington, D.C., office

The U.S. Environmental Protection Agency (EPA) issued a final rule to strengthen the national ambient air quality standards (NAAQS) for fine particulate matter (PM2.5). The current standard, which has been in place for more than a decade, limits the average annual amount of fine particle pollution to 12 micrograms per cubic meter of air. The EPA will now require a 25% reduction in the allowable PM 2.5 to 9.0 micrograms per cubic meter but will retain the previous standards for all other PM standards. 

The tougher standard on particulate matter, often referred to as the "soot rule," will be fully implemented by 2032. The EPA maintains that the reduced PM 2.5 standard will result in $46 billion in public health benefits. 

The EPA's new rule will trigger the following actions to implement the revised PM2.5 NAAQS: 

  • Stationary source permitting: 

               • Prevention of Significant Deterioration (attainment area permitting) applies with respect to a new standard in all areas of the United States designated as "attainment" areas, which comply with the new pollutant standard upon the effective date. 

              • Nonattainment New Source Review applies in areas designated "nonattainment" for the pollutant, which includes any areas newly designated nonattainment at or after the effective date of nonattainment designations. 

  • Within two years after a final NAAQS is issued: For areas with available information, EPA must "designate" attainment and nonattainment areas using the final NAAQS that considers the most recent air quality monitoring data and input from states and tribes. All PM 2.5 nonattainment areas are initially designated as "moderate." 
  • Within three years after a final NAAQS is issued: Clean Air Act section 110 requires all states to submit state implementation plan revisions to show they have the basic air quality management program components in place to implement the final NAAQS. 
  • Within 18 months after the effective date of designations: Nonattainment area PM 2.5 state implementation plans are due. 
  • End of the 6th calendar year after the effective date of designations: "Moderate" area attainment date. 

SEMA will continue to monitor the implementation of this new rule for the impact that may cause more states to not be able to attain the new standard. This may change other emissions, such as heavy truck and passenger vehicle requirements, as states implement plans to achieve the new standard. 

For more information on particle pollution and to read the final rule, visit