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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.

2006 National Ambient Air Quality Standard for PM (October 17, 2006)
(Primary and Secondary Standards are the same)

  Averaging Time Level (Micrograms per cubic meter)
PM2.5 24-hour 1 35
Annual 2 15
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 cannot 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 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.

History and Implementation of the 2006 24-hour PM2.5 Standard

February 24, 2009 The U.S. Court of Appeals for the DC circuit remanded the standard back to EPA for review. The standard remains in place, and EPA has consolidated the remand review with the 5-year review.
October 17, 2006 EPA published the final 2006 PM2.5 standard. This standard revoked the 1997 annual PM10 standard, and lowered the 24-hour PM10 standard.
January 17, 2006 EPA proposed the 2006 24-hour PM2.5 standard.

Additional Resources

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