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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.

2012 National Ambient Air Quality Standards for PM

Primary Standards

  Averaging Time Level (Micrograms per cubic meter)
PM2.5 24-hour 1 35
Annual 2 12
PM10 24-hour 3 150

1 To meet this standard, the 3-year average of the 98th percentile of the annual average PM2.5 levels measured at each monitor within an area could not exceed 35 micrograms per cubic meter.

2 To meet this standard, the 3-year average of the annual arithmetic mean of the PM2.5 levels measured at each monitor within an area could not exceed 12 micrograms per cubic meter.

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

Secondary Standards

  Averaging Time Level (Micrograms per cubic meter)
PM2.5 24-hour4 35
Annual5 15
PM10 24-hour 6 150

4 To meet this standard, the 3-year average of the 98th percentile of the annual average PM2.5 levels measured at each monitor within an area could not exceed 35 micrograms per cubic meter.

5 To meet this standard, the 3-year average of the annual arithmetic mean of the PM2.5 levels measured at each monitor within an area could not exceed 15 micrograms per cubic meter.

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

History and Implementation of the 2012 Standard

December 14, 2012 EPA issued final revisions to the PM NAAQS. EPA lowered the annual standard for PM2.5 from 15 micrograms per cubic meter to 12 micrograms per cubic meter. EPA did not revise the current daily PM2.5 standard or the daily standard for PM10. EPA also did not issue a secondary standard for visibility, as it had proposed to do. For more information see EPA's PM website.
June 14, 2012 EPA proposed revisions to the PM NAAQS. These proposed revisions included lowering the annual standard for PM2.5 from 15 micrograms per cubic meter to within a range of 12 to 13 micrograms per cubic meter. EPA is also proposing a secondary standard for visibility protection. EPA proposes to retain the current daily PM2.5 standard, and the daily standard for PM10. For more information, see EPA's PM website.

Additional Resources

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