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Environmental Assessment

Particulate Matter

The Issue
Particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets in the air. Particulate matter causes concern because it is associated with serious health effects such as aggravated asthma, difficulty breathing, chronic bronchitis, decreased lung function, and premature death. PM contributes to haze and can harm the environment by changing the natural nutrient and chemical balance of the soil.

EPA Action
EPA scientists are conducting research to better understand which attributes of particulate matter cause ill health effects, who may be most susceptible to these effects, how particles form in the atmosphere, and what the contributions are from various sources in different regions of the country.

EPA's National Center for Environmental Assessment periodically evaluates the latest research concerning the public health and welfare effects of ozone and publishes the Integrated Science Assessment for Particulate Matter. This final document provides the scientific basis for the establishment of national air quality standards for PM.

The latest version of the Integrated Science Assessment for Particulate Matter was published in December 2009. EPA's Integrated Science Assessment documents are vetted through a rigorous peer review process, including review by the Clean Air Scientific Advisory Council and by anyone during the public comment period.

Related Links

Best Resources

U.S. EPA. 2009 Final Report: Integrated Science Assessment for Particulate Matter. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/139F, 2009.

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