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AnnouncementsMarch 29, 2007 - EPA finalizes Clean Air Fine Particle Implementation Rule defining requirements for state plans to meet the 1997 national air quality standards for fine particle pollution.
September 21, 2006 - EPA strengthens National Ambient Air Quality Standards for Particle Pollution.
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"Particulate matter," also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles.
The size of particles is directly linked to their potential for causing health problems. EPA is concerned about particles that are 10 micrometers in diameter or smaller because those are the particles that generally pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects. EPA groups particle pollution into two categories:
- "Inhalable coarse particles," such as those found near roadways and dusty industries, are larger than 2.5 micrometers and smaller than 10 micrometers in diameter.
- "Fine particles," such as those found in smoke and haze, are 2.5 micrometers in diameter and smaller. These particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.
Basic Information - Basics about particle pollution.
Health and Welfare - Effects of particle pollution.
PM Standards - Links to technical information related to setting the national air quality standards for particle pollution.
PM Designations - Regional, state and local information related to PM nonattainment.
PM Implementation - Programs and requirements for reducing particle pollution.
Regulatory Actions - Links to proposed and final rules, fact sheets, and other rulemaking documents.
PM Research - Links to PM research and development, monitoring, and daily reporting and forecasting.
Air Quality Trends - Progress made in reducing particle pollution.
Air Emission Sources - Summarizes particulate matter emissions by source at national, state and local levels.
Publications - Publications related to particle pollution.
Related Links - Other information related to particle pollution.