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Oregon Department of Environmental Quality

Air Quality

Particulate Matter (PM) 

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Particulate Matter


PM2.5 compares to human hair and sandParticulate Matter (PM) is a mixture of extremely small particles and liquid droplets found in the air. Sources of particulate pollution include woodstoves, fires, wind-blown dust, automobiles, and industry. PM10 refers to particulate matter 10 microns in diameter and smaller, whereas PM2.5 refers to particulate matter 2.5 microns in diameter and smaller. (The average strand of human hair is 70 microns in diameter.)

Health studies over the past decade show that there are harmful effects from breathing PM particles. PM can be inhaled deep into the lungs and can lodge there for weeks and months, aggravating asthma, heart disease, and other respiratory and heart conditions.

PM2.5 NAAQS Standard

On December 18, 2006, EPA reduced the 24-hour fine particulate matter (PM2.5) National Ambient Air Quality Standard (NAAQS). By issuing this rule, EPA intends to further protect vulnerable individuals from air pollution in communities across the U.S. DEQ plans to work with Oregon communities interested in developing strategies to reduce particulate pollution.

Additional Information

Air Quality Coordinator's Annual Meeting

2015 Presentations

2011 Presentations

Information on PM Forecasting

[print version]

For questions about air quality regulations or permits, see our Contacts page.

For more information about Air Quality call 503-229-5696

For reporting pollution problems contact Complaints

For technical assistance contact DEQINFO

Oregon Department of Environmental Quality
Headquarters: 700 NE Multnomah Street, Suite 600, Portland, OR 97232
Phone: 503-229-5696 or toll free in Oregon 1-800-452-4011
Oregon Telecommunications Relay Service: 1-800-735-2900  FAX: 503-229-6124

The Oregon Department of Environmental Quality is a regulatory agency authorized to protect Oregon's environment by
the State of Oregon and the Environmental Protection Agency.

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