Short Term Particle Pollution

Nearly one in five (19.8%) people in the United States live in an area with unhealthful short-term levels of particle pollution.

  • Nearly 61 million Americans live in 76 counties that experienced too many days with unhealthy spikes in particle pollution, fewer people and fewer counties than in the 2010 report.
  • Short-term spikes in particle pollution can last from hours to several days and can increase the risk of heart attacks, strokes and emergency-room visits for asthma and cardiovascular disease, and most importantly, can increase the risk of early death.

Unlike with year-round particle pollution levels, fewer cities with the worst short-term levels improved in 2007-2009. Only 12 cities had fewer unhealthy days or lower daily levels, while 16 of the cities on the list did worse than in 2006-2008. One city stayed the same.1

  • Twelve cities on the “most polluted list” improved, having cut the average number of days with high particle levels2: Pittsburgh, PA; Los Angeles, CA; Visalia, CA; Birmingham, AL; Sacramento, CA; Modesto, CA; Stockton, CA; Philadelphia, PA; Louisville, KY; Phoenix, AZ; San Jose- San Francisco-Oakland, CA; and Wheeling, WV.
  • One city stayed the same. The Chicago metropolitan area had the same average number of unhealthy days in 2007-2009 as in 2006-2008.
  • The remaining sixteen cities had more days or higher daily levels: Bakersfield, CA (ranked most polluted); Fresno, CA; Salt Lake City, UT; Provo, UT; Hanford, CA; Logan, UT; Merced, CA; Eugene-Springfield, OR; San Diego, CA; Seattle-Tacoma, WA; Fairbanks, AK; Macon, GA; Green Bay, WI; Davenport, IA; Portland, OR; and Madison, WI.

What are “short-term levels” of particle pollution?

Particle pollution can be harmful even if it is inhaled over just a few hours or days, even if the year-round averages are low. “Short-term levels” refers to just such spikes. These represent levels averaged over a 24-hour period. Those days or weeks of high levels can be dangerous, even deadly.

25 Cities Most Polluted by Short-term Particle Pollution

  1. The usual list of the 25 cities with the most short-term particle pollution actually includes 29 cities because of ties in the rankings.
  2. Full names for all these metropolitan areas can be found in the tables showing the most polluted and cleanest cities. The full metropolitan areas often include multiple counties, incorporated cities and counties in adjacent states.

FACT: The most widespread kinds of air pollution are ozone (smog) and particle pollution (soot). Breathing either can harm your body and risk your life.

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SOTA 2011 Survey