The Auto Asthma Index is a pollution report card for today's automobiles. Based on real world pollution measurements for more than 2.5 million vehicles in California's Smog Check program—as well as automaker's estimates for 3,737 newer vehicles—the Auto Asthma Index provides pollution ratings and brand-by-brand comparisons that can help you choose the cleanest vehicles. Our Index even takes into account the local air quality patterns of the region where you and your family live.


You must fill out all fields in this section to rate a vehicle. To compare it to another vehicle, complete the second section as well.

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Why can't I find my vehicle here?

If you do not find a particular vehicle model listed here, you can choose a similar vehicle to get an idea of the level of smog chemical pollution it might produce. For example, if the four-wheel drive version of a vehicle is not listed, choose the two-wheel drive version. If the station wagon version of a vehicle is not listed, choose the car version. (Why isn't my vehicle listed?)

Why can't I compare the Auto Asthma Index for older and newer vehicles?

The Auto Asthma Index was compiled using two datasets: For vehicles manufactured in the years 1985-2000, millions of real world emissions measurements from the California Smog Check program were used to rank different models. For newer vehicles exempt from typical Smog Check requirements, EPA certified maximum levels of pollution within at least 100,000 miles of driving were used. The two types of data are so different that Index values produced one dataset cannot be compared to the other. (FAQ)

Read the report and learn about how cars contribute to America's asthma epidemic. Smog causes lifelong damage to our children's lungs.

The Cleanest Cars

2003 Ford Explorer
Check the Auto Asthma Index for a different vehicle.