By Dr. Brian McDonough

PHILADELPHIA (CBS) – A new report out today sheds light on the amount of exposure to secondhand smoke children and teenagers receive. The danger, according to the Centers for Disease Control, lurks in the car.

We know that exposure to secondhand smoke can lead to serious health problems, and there have been many laws put in place to try to reduce exposure. But there is one area where kids still are at great risk, that’s in the car.

According to a new report in the journal Pediatrics, from the Centers of Disease Control and Prevention, more than one in five high school students and middle schoolers ride in cars while others are smoking.

On many cases parents are smoking, but in a growing number of cases, it might be another teenager.

The CDC says there is no risk-free level of secondhand smoke.