Although secondhand smoke exposure has been cut in half since 1999, tens of millions of Americans are still at risk, according to a report from the the Centers for Disease Control and Prevention.

"More than a quarter of those exposed to the dangerous fumes are children," Dr. Marc Siegel said on "Happening Now" today.

Dr. Brian A. King, with the CDC, said that there are 58 million Americans - including 15 million children - who continue to be exposed to secondhand smoke.

Siegel noted that the CDC has said that there is no safe amount of secondhand smoke, which can result in a variety of dangerous conditions in children, such as bronchitis, asthma, ear infections and even sudden infant death syndrome. As adults they can develop heart disease, strokes and lung cancer.

Additionally, they are also likely to imitate their parents' behavior and become smokers themselves.

Siegel reported that a recent CDC report endorses more statewide laws to prohibit smoking at workplaces, public places and multi-unit housing, adding that smoke-free homes and vehicles are critical to protecting non-smokers.

Watch the clip above.