PM Standards Revision - 2006 

 Background

 What do the new standards mean for your area?

 Maps

 Timeline

 More information

Background

Particle pollution, also called particulate matter or PM, is a complex mixture of extremely small 

particles and liquid droplets in the air. When breathed in, these particles can reach the deepest 

regions of the lungs. Exposure to particle pollution is linked to a variety of significant health problems, 

ranging from aggravated asthma to premature death in people with heart and lung disease. Particle 

pollution also is the main cause of visibility impairment in the nation’s cities and national parks.

To protect public health and welfare, EPA issues National Ambient Air Quality Standards (NAAQS) for 

six criteria pollutants, particulate matter is one of these. EPA first issued standards for particulate 

matter in 1971; and revised the standards in 1987 and 1997. In September 2006, the Agency revised 

the 1997 standards.

The revised 2006 standards address two categories of particle pollution: fine particles (PM2.5), which 

are 2.5 micrometers in diameter and smaller; and inhalable coarse particles (PM10) which are smaller 

than 10 micrometers and larger than 2.5 micrometers. 

The 2006 standards tighten the 24-hour fine particle standard from 65 micrograms per cubic meter 

(μg/m3) to 35 μg/m3, and retain the current annual fine particle standard at 15 μg/m3.

EPA has decided to retain the existing 24-hour PM10 standard of 150 μg/m3. Due to a lack of evidence 

linking health problems to long-term exposure to coarse particle pollution, the Agency has revoked the 

annual PM10 standard. 

The Agency selected the levels for the final standards after reviewing thousands of peer-reviewed 

scientific studies about the effects of particle pollution on public health and welfare. External scientific 

advisors and the public examined EPA's science and policy review documents. The Agency also 

carefully considered public comments on the proposed standards. EPA held three public hearings and 

received over 120,000 written comments.

While EPA provisionally assessed new, peer-reviewed studies about particulate matter and health 

(including some studies received during the comment period), these studies were not the basis for the 
final decision. EPA will consider those studies during the next review of the PM standards. Learn more 

about the process of reviewing air quality standards.

What do the New Standards Mean for Your Area?

In 2004, several areas in the United States were designated as not meeting the 1997 air quality 

standards for fine particulate matter (PM2.5). See if your area was designated as not meeting the 

1997 standards.

In 2006, EPA strengthened the air quality standards for particle pollution. The Agency expects 

designations based on 2007-2009 air quality data to take effect in 2010.

Maps

 Graph and Maps (10/25/06) (PDF, 10 pp, 1.2 MB) 

Timeline 

Milestone 1997 PM2.5 Primary NAAQS 2006 PM2.5 Primary NAAQS

Promulgation of Standard July 1997 Sep. 2006

Effective Date of Standard Sep. 1997 Dec. 18, 2006

State Recommendations to 

EPA

Feb. 2004

(based on 2001-2003 

monitoring data)

Dec. 18, 2007 

(based on 2004-2006 

monitoring data)

Final Designations Signature Dec. 2004 October 8, 2009

Effective Date of 

Designations

April 2005 30 days after publication in the 

Federal Register

SIPs Due April 2008 3 years after effective date of 

designations 

Attainment Date April 2010 

(based on 2007-2009 

monitoring data)

No later than 5 years after

effective date of designations 

Attainment Date with 

Extension

Up to April 2015 No later than 10 years from 

effective date of designations 
More Information

 Final Rule

 Learn more about what state, tribal and local governments do to reduce particle pollution 

emissions