Table 7-7: Air Pollution in the 50 Largest Metropolitan Areas: 2003–2010

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(Number of days with AQI values greater than 100)

Metropolitan area AQI days > 100
2003 2004 2005 2006 2007 2008 2009 2010
Atlanta-Sandy Springs-Marietta, GA 61 36 32 52 65 56 31 16
Austin-Round Rock, TX 8 10 10 11 14 4 2 4
Baltimore-Towson, MD 59 30 31 36 33 45 23 11
Birmingham-Hoover, AL 39 38 18 42 43 44 15 5
Boston-Cambridge-Quincy, MA-NH 42 16 9 21 10 21 9 5
Buffalo-Niagara Falls, NY 29 13 8 23 7 27 4 1
Charlotte-Gastonia-Concord, NC-SC 51 16 20 32 24 36 24 3
Chicago-Naperville-Joliet, IL-IN-WI 56 44 47 61 35 53 48 26
Cincinnati-Middletown, OH-KY-IN 80 52 56 67 38 50 14 7
Cleveland-Elyria-Mentor, OH 92 74 63 98 71 69 58 6
Columbus, OH 46 23 13 32 11 30 10 1
Dallas-Fort Worth-Arlington, TX 54 49 50 80 54 34 30 32
Denver-Aurora, CO 31 35 6 13 27 23 10 7
Detroit-Warren-Livonia, MI 54 37 37 62 38 35 24 9
Hartford-West Hartford-East Hartford, CT 34 13 11 19 15 24 10 3
Houston-Sugar Land-Baytown, TX 62 74 66 93 64 47 24 26
Indianapolis-Carmel, IN 53 38 22 49 30 42 8 10
Jacksonville, FL 57 10 15 20 35 16 10 3
Kansas City, MO-KS 38 56 35 52 74 44 39 43
Las Vegas-Paradise, NV 36 42 22 34 35 24 12 5
Los Angeles-Long Beach-Santa Ana, CA 154 147 134 113 98 102 94 99
Louisville/Jefferson County, KY-IN 82 67 69 88 68 99 58 35
Memphis, TN-MS-AR 41 40 14 49 33 33 10 4
Miami-Fort Lauderdale-Pompano Beach, FL 5 4 11 4 12 10 5 2
Milwaukee-Waukesha-West Allis, WI 23 18 7 22 6 14 3 5
Minneapolis-St. Paul-Bloomington, MN-WI 5 18 11 11 1 5 1 3
Nashville-Davidson-Murfreesboro-Franklin, TN 38 23 7 29 17 37 11 1
New Orleans-Metairie-Kenner, LA 4 15 12 13 13 17 2 6
New York-Northern New Jersey-Long Island, NY-NJ-PA 68 41 40 50 40 40 31 15
Oklahoma City, OK 16 16 6 15 33 5 5 5
Orlando-Kissimmee, FL 7 8 6 10 8 11 2 1
Philadelphia-Camden-Wilmington, PA-NJ-DE-MD 100 76 39 62 55 46 30 7
Phoenix-Mesa-Scottsdale, AZ 49 51 23 49 50 21 27 10
Pittsburgh, PA 162 129 118 123 94 97 81 58
Portland-Vancouver-Beaverton, OR-WA 7 2 4 4 2 5 3 5
Providence-New Bedford-Fall River, RI-MA 39 19 10 22 16 21 6 2
Raleigh-Cary, NC 45 11 10 26 9 24 11 0
Richmond, VA 55 28 18 41 21 37 19 1
Riverside-San Bernardino-Ontario, CA 180 163 157 142 133 144 131 114
Sacramento--Arden-Arcade--Roseville, CA 103 79 66 62 79 53 61 43
Salt Lake City, UT 41 23 38 33 26 35 19 22
San Antonio, TX 27 21 15 15 21 3 9 3
San Diego-Carlsbad-San Marcos, CA 40 50 31 30 39 34 43 25
San Francisco-Oakland-Fremont, CA 29 15 11 7 21 6 13 7
San Jose-Sunnyvale-Santa Clara, CA 24 14 8 4 14 3 13 8
Seattle-Tacoma-Bellevue, WA 16 16 7 7 14 10 7 12
St. Louis, MO-IL 90 71 38 82 31 40 24 11
Tampa-St. Petersburg-Clearwater, FL 106 87 50 47 38 47 24 18
Virginia Beach-Norfolk-Newport News, VA-NC 33 10 6 12 13 11 16 0
Washington-Arlington-Alexandria, DC-VA-MD-WV 62 32 32 49 37 43 22 5

KEY: AQI = Air Quality Index

NOTES: The Air Quality Index (AQI) integrates information on six major pollutants (particulate matter less than 10 microns in diameter, particulate matter less than 2.5 microns in diameter, sulfur dioxide, carbon monoxide, ozone, and nitrogen dioxide) across an entire monitoring network into a single number that represents the worst daily air quality experienced in an urban area. An AQI greater than 100 indicates that at least 1 criteria pollutant exceeded air quality standards on a given day; therefore, air quality would be in the unhealthful range on that day. Metropolitan area rank is based on U.S. Census Bureau's population estimates for July 1, 2000 and geographic definitions for 2000 available at http://www.census.gov/popest/data/index.html as of May 3, 2012. The U.S. Environmental Protection Agency reports data for metropolitan areas as they were defined in 2000.

SOURCE: U.S. Environmental Protection Agency, Office of Air and Radiation, Air Trends, Air Quality Index Information available at www.epa.gov/airtrends/aqi_info.html as of June 2013.