An estimated 9.6 million U.S. adolescents are exposed to tobacco smoke, according to the Center for Disease Control and Prevention.

Since the 1960s, researchers have been looking at the health effects of secondhand smoking and have linked this exposure with an increased likelihood of getting ear infections, lung infections and even contributing to poor lung development in small children.

Additional research has demonstrated secondhand smoke exposure in children both increases the likelihood of suffering from asthma and worsens the severity of it in children afflicted by this condition.

Researchers from the University of Cincinnati wanted to understand the effects of secondhand smoke in otherwise healthy teenagers whose lungs are fully developed and who should be past the stage of frequent colds and ear infections.