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Fine Particle (PM2.5) Designations


March 31, 2015 - EPA is establishing or revising initial area designations and a technical amendment to correct an inadvertent error in the initial designation for one area for the 2012 annual national ambient air quality standards for fine particle pollution. Learn more

December 18, 2014 – EPA issued final designations for most areas of the country for the 2012 annual fine particle standard. Learn more

This Web site provides information about EPA's actions designating areas whose air quality does not meet the health-based standards established in 1997, 2006, and 2012 for fine particle pollution.

The Clean Air Act requires EPA to issue designations after the agency sets a new National Ambient Air Quality Standard (NAAQS) or revises an existing standard. EPA formally designates areas as “nonattainment” (not meeting the standard), “unclassifiable/attainment” (meeting the standard or expected to be meeting the standard despite a lack of monitoring data), or “unclassifiable” (insufficient data to classify).

Once nonattainment designations take effect, the state and local governments must develop implementation plans outlining how areas will attain and maintain the standards by reducing air pollutant emissions contributing to fine particle concentrations.

EPA strengthened the air quality standards for particle pollution in 2006 and 2012. Learn more about the 2012 standards.

Learn more about area Designations for the 2012 Annual PM2.5 Standard.

Learn more about the area designations for the 2006 daily fine particle standards.

Learn more about the area designations for the 1997 fine particle standards.

This Web site contains the following information:

Area Designations for the 2012 Annual PM2.5 Standard: EPA has worked closely with states and tribes to issue initial area designations. Information on this process is summarized here.

Area Designations for the 2006 24-Hour Fine Particle (PM2.5) Standards: EPA completed these area designations on October 23, 2012. They are summarized here.

Area Designations for the 1997 Fine Particle (PM2.5) Standards: EPA issued these designations on December 18, 2004 and made modifications in April 2005. They are summarized here.

Air Quality Forecast: Links to the Air NOW Web site with PM2.5 air quality forecasts for dozens of cities around the country. 

Basic Information: Background on PM2.5 attainment issues and EPA actions to address PM2.5 emission concerns.

PM and Human Health: Information about the health effects of particle pollution. 

Frequent Questions: Answers to common questions regarding fine particles and the designations process.

Related Links: Related sites offering further information and assistance.

Glossary: Explanations of the technical terms and acronyms used throughout the site.

EPA has similar sets of web pages for ozone designations, nitrogen dioxide (NO2) designations, sulfur dioxide (SO2) designations, and lead (Pb) designations.


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