(CNN) More than a third of American young people who don't smoke have been exposed to secondhand smoke, according to a new study from the US Centers for Disease Control and Prevention.
The researchers looked at nonsmoking youth from 2013 to 2016 and found that 35.4% of those ages 3 to 17 had been exposed to secondhand smoke, which can involve inhaling smoke from burning cigarettes, cigars and pipes.
The study used data from the National Center for Health Statistics' National Health and Nutrition Examination Survey. Young people's blood was tested for levels of serum cotinine, a metabolite of nicotine; 0.05 to 10 nanograms per milliliter identified exposure to secondhand smoke. Any tests above 10 ng/mL were excluded, as that indicates active tobacco use.
Exposure to secondhand smoke can increase the risk of asthma, ear disease, lung infection and other health conditions in children.
There was a drastic difference in exposure among youth from families above and below the federal poverty level, which ranges from an income of $12,490 for individuals to $43,430 for families of eight.
Almost 55% of those from families below the federal poverty level were exposed to secondhand smoke, versus 16% from families making 400% above the poverty level.
Black youth had the highest level of exposure to secondhand smoke at 61.8%, while white youth measured at 34.3%, Asians clocked in at 18.3%, and Hispanic youth hit 24.9%.
If there were two or more smokers in a household, the rate of exposure was more than triple that of youth not living with smokers, the researchers found.