Particulate Matter Resources

Proposed Decision for the Reconsideration of the National Ambient Air Quality Standards for Particulate Matter (PM)

In January 2023, the EPA announced its proposed decision to revise the primary (health-based) annual PM2.5 standard from its current level of 12.0 µg/m3 to within the range of 9.0 to 10.0 µg/m3. EPA also proposed not to change the current:

  • secondary (welfare-based) annual PM2.5 standard,
  • primary and secondary 24-hour PM2.5 standards, and
  • primary and secondary PM10 standards.

Fact sheets and more information are available from EPA at:

General Information on Particulate Matter, finalized in 2012

Particulate Matter, PM 10 and PM 2.5, is one of the components of smoke of greatest concern from a regulatory standpoint. The current The National Ambient Air Quality Standard for PM was finalized in 2012 and available in the Federal Register: