Ambient Air Quality Standards (AAQS)
This page last reviewed July 2, 2013
- Ambient Air Quality Standards chart
On December 14, 2012 the U.S. EPA revised the national annual primary PM2.5 standard. This chart has been updated to reflect the revised standard.
Ozone, a major component of smog, is a reactive gas capable of damaging the tissues of the lungs and respiratory tract. ARB staff reviewed the scientific literature and recommended revisions to the ozone standard based on that review. The revised standard became effective on May 17, 2006.
Nitrogen Dioxide is a reactive gas capable of damaging the cells lining the respiratory tract. ARB staff reviewed the scientific literature and recommended revisions to the NO2 standards based on that review. On February 19, 2007, the Board adopted staff's recommendations; the revised standards became effective on March 20, 2008.
Particulate Matter (PM) consists of tiny particles that are easily inhaled deep into the lungs and may cause a variety of harmful health effects. In an evaluation of current California air quality standards mandated by the Children's Environmental Health Protection Act, PM standards were identified as a top priority for review. ARB staff reviewed the scientific literature and recommended revisions to the PM standards based on that review. On June 20, 2002, the Board adopted staff's recommendations and the revised standards became effective on July 5, 2003.
- Methodology for Quantifying PM-Associated Mortality
On August 31, 2010 the ARB released a report describing updated methodology, based on the U.S. Environmental Protection Agency's recent assessment, for estimating the number of premature deaths associated with PM2.5 exposure. Further details can be found at this link.
For more information on Ambient Air Quality Standards please contact Dr. Linda Smith or at (916) 327-8225.