Sitting in a car with a smoker is about as close to lighting up as a nonsmoker can get.
And quite a few schoolchildren get exposed to secondhand smoke this way, according to an estimate by researchers at the Centers for Disease Control and Prevention.
About 1 in 5 nonsmoking kids in middle and high school reported sharing a car with a smoker who had lit up within a week of answering a survey in 2009. The researcher say the survey, which included responses from thousands of students, give an accurate snapshot of what's happening across the country.