Skip to content
Air Quality

Air Pollutants - Particulate Matter (PM) - Standards & Requirements

National Ambient Air Quality Standards for Particulate Matter

Since the first PM National Ambient Air Quality Standard (NAAQS, or standard) was established in 1971, the U.S. Environmental Protection Agency (EPA) has revised them several times. Using the tabs and links below you can find information on the current PM standard and regulatory actions, as well as a detailed history of the current and previous PM standards.

1997 National Ambient Air Quality Standard for PM (July 18, 1997)
(Primary and Secondary Standards are the same)

  Averaging Time Level (Micrograms per cubic meter)
PM2.5 24-hour 1 65
Annual 2 15
PM10 24-hour 3 150
Annual 4 50 (Revoked in 2006)

1 To meet this standard, the annual mean of PM2.5 levels, averaged over 3 years measured at each monitor within an area cannot exceed 65 micrograms per cubic meter.

2 To meet this standard, the annual mean of PM2.5 levels, averaged over 3 years measured at each monitor within an area cannot exceed 15 micrograms per cubic meter.

3 To meet this standard, no monitor in an area can exceed 150 micrograms per cubic meter more than once per year on average over a 3-year period.

4 To meet this standard, the annual mean of PM10 levels, averaged over 3 years measured at each monitor within an area cannot exceed 50 micrograms per cubic meter.

History and Implementation of the 1997 PM Standard

May 16, 2008 EPA published the implementation rule for PM2.5 for the New Source Review program.
April 25, 2007 EPA published the Clean Air Fine Particulate Implementation Rule.
July 30, 2004 EPA revised the 1997 PM standard in response to the decision by the U.S. Court of Appeals for the D.C. Circuit on the 1997 PM standard.
July 18, 1997 The White House published a memo on implementing the 1997 ozone and PM standard.
July 18, 1997 EPA published the final 1997 PM standard. This revision added the standards for PM2.5 and lowered the annual PM10 standard.
December 13, 1996 EPA published proposed revisions to the 1987 PM standard.

Additional Resources

For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.