Which vehicles are the best and worst in your hometown?

No two cities are alike. We examined key factors leading to smog formation over the most polluted regions of the U.S. (What is smog?) By targeting the places where smog is doing the most damage, and providing vehicle information specific to the local air conditions of each region, we can help you make driving choices that protect the health of your kids and your community.

Local conditions including man-made and natural emissions of the two pollutants—volatile organic compounds (VOCs) and nitrogen oxides (NOx)—as well as temperature, wind patterns, and geography, all play a role in the formation of smog. The relative importance of the two pollutants to smog formation depends on this balance, as do the most effective ways to reduce smog. As a result, local smog dynamics determine which vehicles are best and worst in your town.


Find out about the best and worst vehicles for smog in your area.

Customize this list for your hometown by selecting your location from the pulldowns below. If you don't see your city listed, choose your state, then pick your typical driving environment—urban, rural, or suburban/mixed.


rank* smoggiest regions
of the US
total population kids with asthma adults with asthma pollutant of concern
1 Bakersfield, CA 734,846 19,004 39,061 VOCs
2 Los Angeles-Long Beach-Riverside, CA 17,516,110 412,677 969,762 VOCs
3 Visalia-Porterville, CA 401,502 11,055 20,726 VOCs + NOx
4 Fresno-Madera, CA 1,005,723 25,799 53,635 VOCs + NOx
5 Merced, CA 237,005 6,536 12,205 NOx
6 Houston-Baytown-Huntsville, TX 5,280,752 126,682 272,580 VOCs + NOx
7 Sacramento-Arden-Arcade-
Truckee, CA-NV
2,159,756 46,908 123,379 VOCs + NOx
8 Dallas-Fort Worth, TX 5,931,956 139,989 307,273 VOCs + NOx
9 New York-Newark-Bridgeport, NY-NJ-CT-PA 21,858,830 451,660 1,467,303 VOCs
10 Philadelphia-Camden-
Vineland, PA-NJ-DE-MD
5,951,797 124,093 400,635 VOCs
11 Hanford-Corcoran, CA 142,561 3,372 7,801 VOCs + NOx
12 Washington-Baltimore-
Northern Virginia, DC-MD-VA-WV
8,026,807 170,436 467,406 VOCs + NOx
13 Modesto, CA 498,355 12,580 26,808 VOCs
14 Knoxville-Sevierville-La Follette, TN 817,867 14,984 57,435 NOx
15 Charlotte-Gastonia-
Salisbury, NC-SC
2,067,810 45,126 116,343 NOx
16 Cleveland-Akron-Elyria, OH 2,942,303 60,118 189,311 VOCs
17 Pittsburgh-New Castle, PA 2,494,949 45,266 171,493 VOCs + NOx
18 Columbus-Marion-
Chillicothe, OH
1,920,601 40,464 123,622 VOCs
19 Raleigh-Durham-Cary,NC 1,467,434 31,258 82,865 NOx
20 Youngstown-Warren-East Liverpool, OH-PA 701,557 13,331 46,138 VOCs + NOx
20 Cincinnati-Middletown-
Wilmington, OH-KY-IN
2,100,501 44,968 132,969 VOCs
20 Baton Rouge-Pierre Part, LA 751,965 16,174 34,181 NOx
23 San Antonio, TX 1,854,050 43,485 96,115 VOCs
24 St. Louis-St. Charles-Farmington, MO-IL 2,824,778 58,681 191,293 VOCs + NOx
25 South Bend-Mishawaka, IN-MI 318,192 6,912 19,849 VOCs + NOx
25 Huntington-Ashland, WV-KY-OH 287,038 5,197 20,664 VOCs + NOx
25 Buffalo-Niagara-
Cattaraugus, NY
1,237,557 24,150 84,449 VOCs + NOx
 
SMOGGY REGIONS FROM PREVIOUS YEARS
rank smoggiest regions
of the US
total population kids with asthma adults with asthma pollutant of concern
from 2005 Detroit-Warren-Flint, MI 5,415,338 118,508 368,210 VOCs
from 2005 Sheboygan, WI 113,376 2,324 6,415 VOCs
from 2005 Chicago-Naperville-Michigan City, IL-IN-WI 9,549,014 214,789 532,303 VOCs
from 2005 El Centro, CA 149,232 3,813 8,802 VOCs + NOx
from 2005 Lancaster, PA 482,775 10,610 29,877 VOCs + NOx
from 2004 Greensboro-Winston-Salem-
High Point, NC
1,315,361 26,717 64,630 NOx
from 2004 San Diego-Carlsbad-San Marcos, CA 2,906,660 62,386 138,713 VOCs
from 2004 Phoenix-Mesa-Scottsdale, AZ 3,500,151 79,857 229,436 VOCs
from 2004 Atlanta-Sandy Springs-
Gainesville, GA
4,844,726 107,579 262,356 VOCs + NOx
from 2004 Morristown-Newport, TN 159,648 3,013 10,145 NOx

Source: American Lung Association. 2004, 2005, 2006. State of the Air reports. Available at http://www.lungusa.org.
RANK: Rankings are based on EPA measurements of smog-forming pollutants.