The air people breathe in their cars can be up to 10 times more polluted than the air outside, according to a study released yesterday by California air quality officials. As much as half of the pollution inside the vehicles tested was spewed by the vehicle ahead. Car ventilation systems were shown to be marginally successful at filtering out tiny soot particles, but toxic gases such as benzene got into cars no matter what. Turning on air conditioning or opening and closing windows and vents didn’t help matters. To avoid breathing pollutants, motorists and passengers are advised to stay away from rush-hour driving, or at least avoid getting stuck behind diesel buses and old cars.

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