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FACT SHEET <br />FINAL REVISIONS TO THE NATIONAL AMBIENT AIR QUALITY STANDARDS <br />FOR PARTICLE POLLUTION (PARTICULATE MATTER) <br />SUMMARY OF ACTION <br />• To better protect public health and welfare for millions of Americans across the country, <br />EPA on September 21, 2006 issued the Agency's most protective suite of national air quality <br />standards for particle pollution ever. <br />• Particle pollution, also called particulate matter or PM, is a complex mixture of extremely <br />small particles and liquid droplets in the air. When breathed in, these particles can reach the <br />deepest regions of the lungs. Exposure to particle pollution is linked to a variety of <br />significant health problems. Particle pollution also is the main cause of visibility impairment <br />in the nation's cities and national parks. <br />The final standards address two categories of particle pollution: fine particles (PM2.5), which <br />are 2.5 micrometers in diameter and smaller; and inhalable coarse particles (PMIo) which are <br />smaller than 10 micrometers. (A micrometer is 1/1000th of a millimeter; there are 25,400 <br />micrometers in an inch.) <br />• EPA is strengthening the 24-hour fine particle standard from the 1997 level of 65 <br />micrograms per cubic meter (gg/m3) to 35µg/m3, and retains the current annual fine particle <br />standard at 15µg/m3. The Agency also is retaining the existing national 24-hour PMIo <br />standard of 150µg/m3. <br />The Agency is revoking the annual PMIo standard, because available evidence generally does <br />not suggest a link between long-term exposure to current levels of coarse particles and health <br />problems. EPA is protecting all Americans from effects of short-term exposure to inhalable <br />coarse particles by retaining the existing daily PMIo standard of 150 micrograms per cubic <br />meter. <br />Scientific studies have found an association between exposure to particulate matter and <br />significant health problems, including: aggravated asthma; chronic bronchitis; reduced lung <br />function; irregular heartbeat; heart attack; and premature death in people with heart or lung <br />disease. <br />EPA selected levels for the final standards after completing an extensive review of thousands <br />of scientific studies on the impact of fine and coarse particles on public health and welfare. <br />The Agency also carefully reviewed and considered public comment on the proposed <br />standards. EPA held three public hearings and received about 120,000 written comments. <br />• The Agency provisionally assessed new, peer-reviewed studies about particle pollution and <br />health (including some studies received during the comment period) to ensure that the <br />