Best and Worst Cities
  • Metropolitan Areas Most Polluted by Short-term Particle Pollution (24-Hour PM2.5)
  • Metropolitan Areas Most Polluted by Year-Round Particle Pollution (Annual PM2.5)
  • 25 Most Ozone-Polluted Cities
  • 25 Counties Most Polluted by Short-Term Particle Pollution (24-Hour PM2.5)
  • 25 Counties Most Polluted by Long-Term Particle Pollution (Annual PM2.5)
  • 25 Most Ozone-Polluted Counties
  • Cleanest U.S. Cities for Short-term Particle Pollution (24-Hour PM2.5)
  • Cleanest U.S. Cities for Long-term Particle Pollution (Annual PM2.5)
  • Cleanest U.S. Cities for Ozone Air Pollution
  • Cleanest Counties for Short-term Particle Pollution (24-Hour PM2.5)
  • Cleanest Counties for Long-term Particle Pollution (Annual PM2.5)
  • Cleanest Counties for Ozone Air Pollution
Metropolitan Areas Most Polluted by Short-term Particle Pollution (24-Hour PM2.5)
2006 Rank1 / Metropolitan Areas
1 / Los Angeles-Long Beach-Riverside, CA
2 / Bakersfield, CA
3 / Fresno-Madera, CA
4 / Pittsburgh-New Castle, PA
5 / Salt Lake City-Ogden-Clearfield, UT
6 / Logan, UT-ID
7 / Eugene-Springfield, OR
8 / Sacramento-Arden-Arcade-Truckee, CA-NV
9 / Provo-Orem, UT
10 / Cleveland-Akron-Elyria, OH
11 / Visalia-Porterville, CA
12 / Washington-Baltimore-Northern Virginia, DC-MD-VA-WV
13 / Hanford-Corcoran, CA
14 / San Diego-Carlsbad-San Marcos, CA
15 / New York-Newark-Bridgeport, NY-NJ-CT-PA
15 / Detroit-Warren-Flint, MI
17 / Birmingham-Hoover-Cullman, AL
18 / Modesto, CA
18 / Louisville-Elizabethtown-Scottsburg, KY-IN
20 / Weirton-Steubenville, WV-OH
20 / San Jose-San Francisco-Oakland, CA
20 / Cincinnati-Middletown-Wilmington, OH-KY-IN
23 / Merced, CA
24 / Harrisburg-Carlisle-Lebanon, PA
25 / Chicago-Naperville-Michigan City, IL-IN-WI
(1) Cities are ranked using the highest weighted average for any county within that metropolitan area.
Metropolitan Areas Most Polluted by Year-Round Particle Pollution (Annual PM2.5)
2006 Rank1 / Metropolitan Areas
1 / Los Angeles-Long Beach-Rivereside, CA
2 / Bakersfield, CA
3 / Pittsburgh-New Castle, PA
4 / Visalia-Porterville, CA
5 / Fresno-Madera, CA
6 / Detroit-Warren-Flint, MI
7 / Hanford-Corcoran, CA
8 / Cleveland-Akron-Elyria, OH
9 / Birmingham-Hoover-Cullman, AL
9 / Atlanta-Sandy Springs-Gainesville, GA-AL
11 / Chicago-Naperville-Michigan City, IL-IN-WI
12 / Weirton-Steubenville, WV-OH
13 / York-Hanover-Gettysburg, PA
13 / St. Louis-St. Charles-Farmington, MO-IL
13 / Cincinnati-Middletown-Wilmington, OH-KY-IN
16 / New York-Newark-Bridgeport, NY-NJ-CT-PA
16 / Lancaster, PA
18 / Merced, CA
18 / Canton-Massillon, OH
20 / Charleston, WV
21 / Washington-Baltimore-Northern Virginia, DC-MD-VA-WV
22 / Reading, PA
22 / Hagerstown-Martinsburg, MD-WV
24 / Indianapolis-Anderson-Columbus, IN
25 / Louisville-Elizabethtown-Scottsburg, KY-IN
(1) Cities are ranked using the highest design value for any county within that metropolitan area.
25 Most Ozone-Polluted Cities
2006 Rank1 / Metropolitan Areas
1 / Bakersfield,CA
2 / Los Angeles-Long Beach-Riverside,CA
3 / Visalia-Porterville,CA
4 / Fresno-Madera,CA
5 / Merced,CA
6 / Houston-Baytown-Huntsville,TX
7 / Sacramento-Arden-Arcade-Truckee,CA-NV
8 / Dallas-Fort Worth, TX
9 / New York-Newark-Bridgeport, NY-NJ-CT-PA
10 / Philadelphia-Camden-Vineland, PA-NJ-DE-MD
11 / Hanford-Corcoran,CA
12 / Washington-Baltimore-Northern Virginia, DC-MD-VA-WV
13 / Modesto,CA
14 / Knoxville-Sevierville-La Follette, TN
15 / Charlotte-Gastonia-Salisbury, NC-SC
16 / Cleveland-Akron-Elyria,OH
17 / Pittsburgh-New Castle, PA
18 / Columbus-Marion-Chillicothe,OH
19 / Raleigh-Durham-Cary,NC
20 / Youngstown-Warren-East Liverpool, OH-PA
20 / Cincinnati-Middletown-Wilmington, OH-KY-IN
20 / Baton Rouge-Pierre Part, LA
23 / San Antonio, TX
24 / St. Louis-St. Charles-Farmington,MO-IL
25 / South Bend-Mishawaka, IN-MI
25 / Huntington-Ashland, WV-KY-OH
25 / Buffalo-Niagara-Cattaraugus,NY
(1) Cities are ranked using the highest weighted average for any county within that metropolitan area.
25 Counties Most Polluted by Short-Term Particle Pollution (24-Hour PM2.5)
2006 Rank1 / County / ST
1 / RIVERSIDE / CA
2 / KERN / CA
3 / FRESNO / CA
4 / LOS ANGELES / CA
5 / ALLEGHENY / PA
6 / SALTLAKE / UT
7 / SAN BERNARDINO / CA
8 / CACHE / UT
9 / ORANGE / CA
10 / LANE / OR
11 / KLAMATH / OR
12 / SACRAMENTO / CA
13 / UTAH / UT
14 / CUYAHOGA / OH
15 / TULARE / CA
16 / BALTIMORECITY / MD
17 / KINGS / CA
18 / SAN DIEGO / CA
19 / NEW HAVEN / CT
19 / WAYNE / MI
19 / UNION / NJ
22 / JEFFERSON / AL
23 / STANISLAUS / CA
23 / JEFFERSON / KY
25 / CONTRA COSTA / CA
25 / HAMILTON / OH
25 / JEFFERSON / OH
(1) Counties are ranked by weighted average.
25 Counties Most Polluted by Long-Term Particle Pollution (Annual PM2.5)
2006 Rank1 / County / ST
1 / RIVERSIDE / CA
2 / SAN BERNARDINO / CA
3 / LOS ANGELES / CA
4 / KERN / CA
5 / ALLEGHENY / PA
6 / TULARE / CA
7 / FRESNO / CA
8 / WAYNE / MI
9 / KINGS / CA
10 / ORANGE / CA
10 / CUYAHOGA / OH
12 / JEFFERSON / AL
12 / FULTON / GA
14 / LAKE / IN
15 / HANCOCK / WV
16 / MADISON / IL
16 / HAMILTON / OH
16 / JEFFERSON / OH
16 / YORK / PA
20 / NEW YORK / NY
20 / LANCASTER / PA
22 / MERCED / CA
22 / STARK / OH
22 / BROOKE / WV
25 / KANAWHA / WV
(1) Counties are ranked by design value.
25 Most Ozone-Polluted Counties
2006 Rank1 / County / ST
1 / KERN / CA
2 / SAN BERNARDINO / CA
3 / RIVERSIDE / CA
4 / TULARE / CA
5 / LOS ANGELES / CA
6 / FRESNO / CA
7 / MERCED / CA
8 / HARRIS / TX
9 / EL DORADO / CA
10 / SACRAMENTO / CA
11 / TARRANT / TX
12 / NEVADA / CA
13 / VENTURA / CA
14 / MARIPOSA / CA
15 / FAIRFIELD / CT
16 / CAMDEN / NJ
16 / OCEAN / NJ
18 / KINGS / CA
19 / PLACER / CA
20 / ANNE ARUNDEL / MD
21 / HARFORD / MD
22 / STANISLAUS / CA
23 / FAIRFAX / VA
24 / NEW HAVEN / CT
24 / BLOUNT / TN
24 / SEVIER / TN
(1) Counties are ranked by weighted average.
Top 25 Cleanest U.S. Cities for Long-term Particle Pollution (Annual PM2.5)1
2006 Rank2 / Metropolitan Area
1 / Cheyenne, WY
2 / Santa Fe-Espanola, NM
3 / Honolulu, HI
4 / Great Falls, MT
5 / Tucson, AZ
6 / Anchorage, AK
7 / Farmington, NM
7 / Bismarck, ND
9 / Albuquerque, NM
10 / Rapid City, SD
11 / Pueblo, CO
12 / Fort Collins-Loveland,CO
12 / Fargo-Wahpeton, ND-MN
12 / Duluth, MN-WI
15 / Salinas, CA
15 / Midland-Odessa, TX
17 / Palm Bay-Melbourne-Titusville, FL
18 / Colorado Springs, CO
18 / CapeCoral-Fort Myers, FL
18 / Albany-Corvallis-Lebanon, OR
21 / Reno-Sparks, NV
22 / Redding, CA
22 / Port St. Lucie-Fort Pierce, FL
24 / Santa Barbara-Santa Maria-Goleta, CA
25 / San Luis Obispo-Paso Robles, CA
(1) This list represents cities with the lowest levels of annual PM2.5 air pollution.
(2) Cities are ranked by using the lowest design value for any county within that metropolitan area.
Top 25 Cleanest Counties for Long-term Particle Pollution (Annual PM2.5)1
Rank2 / County / State
1 / CONVERSE / WY
2 / ELBERT / CO
3 / BILLINGS / ND
4 / LARAMIE / WY
5 / SANTA FE / NM
5 / SANDOVAL / NM
5 / MAUI / HI
5 / BREWSTER / TX
9 / LAKE / CA
9 / SAN MIGUEL / CO
11 / HONOLULU / HI
12 / MC KENZIE / ND
13 / JACKSON / SD
14 / CASCADE / MT
15 / BURKE / ND
16 / ARCHULETA / CO
17 / INYO / CA
18 / PIMA / AZ
18 / GRANT / NM
18 / CAMPBELL / WY
18 / HANCOCK / ME
22 / ANCHORAGE / AK
22 / MEADE / SD
22 / COLUMBIA / OR
22 / MERCER / ND
(1) This list represents counties with the lowest levels of monitored long term PM2.5 air pollution.
(2) Counties are ranked by design value.