Fewer teens in the U.S. are smoking but secondhand smoke is still a big problem affecting half of nonsmoking teens.

In a study published in the journal Pediatrics, researchers from the Centers for Disease Control and Prevention showed that millions of children are still feeling the effects of secondhand smoke despite a decline in the problem.

"These findings are concerning because the U.S. Surgeon General has concluded that there is no safe level of secondhand smoke exposure," said Israel Agaku, lead author for the study.

Using data from a national survey, the study involved over 17,000 middle school and high school children. It defined exposure as being around tobacco smoke once within the past week at a minimum.

Based on results, almost 1 out of 4 nonsmoking teens reported daily exposure to tobacco smoke. Earlier studies have tied secondhand smoke inhalation as common in homes and inside cars, and that hasn't changed with the current study, except access areas have expanded to include public spaces and school. However, at least 26 of the country's states have laws to keep indoor public places smoke free.

Secondhand smoke is defined as smoke inhaled involuntarily by a nonsmoking individual from a combination of smoke exhaled by a smoker and smoke that comes from a burning cigarette. Tobacco smoke contains thousands of chemicals, of which hundreds are toxic and about 70 are cancerous.

In children, inhaling secondhand smoke can cause: ear infections; frequent and more severe bouts of asthma; shortness of breath; sneezing; coughing; and respiratory infections (pneumonia and bronchitis). In younger children, secondhand smoke increases risks for sudden infant death syndrome.

In adults, those have never smoked themselves but are exposed to secondhand smoke are likely to develop heart disease, lung cancer and stroke. Exposure is also higher in individuals with low incomes, with service, blue-collar and construction workers being some of the groups exposed to high levels of secondhand smoke.

To protect against secondhand smoke, teens (and everyone else) are advised to spend time in smokefree places. Simply sitting in a restaurant's nonsmoking section, for instance, will not be enough as you will still be in close proximity of secondhand smoke. Make sure also that no one smokes near or in your home or in the car, even with windows down.

Photo: Jim Pennucci | Flickr

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