Even if smokers don't light up at home -- their children are often exposed to secondhand smoke in the car.
Researchers at Massachusetts General Hospital interviewed 795 parents about their car-smoking policies...
Nearly three-quarters said someone had smoked in their car in the past 3 months.
Most had a strict "no smoking" rule for the house, but just a quarter had one for their vehicles.
About 12% of parents who smoked were told by a pediatrician to have a smoke-free car.