Smoking is bad for health is a known fact but its impact on adolescents are way higher than once though. And according to a University of Cincinnati study published in the journal Pediatrics as little as one hour of exposure to tobacco smoke per week can significantly impact the health of teens. According to the researchers teenagers who are exposed to just one hour of second-hand smoke per week are 1.5 times more likely to find it harder to exercise; 2 times more likely to experience breathlessness during or after exercise; 2 times more likely to have a dry cough