Background: Secondhand exposure to tobacco smoke causes heart disease and lung cancer in nonsmoking adults and sudden infant death syndrome, acute respiratory infections, middle ear disease, exacerbated asthma, respiratory symptoms, and decreased lung function in children.
Methods: National Health and Nutrition Examination Survey data from 1999-2008 were analyzed to determine the proportion of the nonsmoking population with serum cotinine (the primary nicotine metabolite) levels ≥0.05 ng/mL, by age, sex, race/ethnicity, household income level, and to determine whether the household included a person who smoked inside the home.
Results: During 2007-2008, approximately 88 million nonsmokers aged ≥3 years in the United States were exposed to secondhand smoke. The prevalence of serum cotinine levels ≥0.05 ng/mL in the nonsmoking population declined significantly from 52.5% (95% CI = 47.1%-57.9%) during 1999-2000 to 40.1% (95% CI = 35.0%-45.3%) during 2007-2008. The decline was significant for each sex, age, race/ethnicity, and income group studied except non-Hispanic whites. The change was greatest from 1999-2000 to 2001-2002. For every period throughout the study, prevalence was highest among males, non-Hispanic blacks, children (aged 3-11 years) and youths (aged 12-19 years), and those in households below the federal poverty level.
Conclusions: Secondhand smoke exposure has declined in the United States, but 88 million nonsmokers aged ≥3 years are still exposed, progress in reducing exposure has slowed, and disparities in exposure persist, with children being among the most exposed. Nearly all nonsmokers who live with someone who smokes inside their home are exposed to secondhand smoke.
Implications for public health practice: The only way to protect nonsmokers fully is to eliminate smoking in indoor spaces. Continued efforts at smoking cessation and comprehensive statewide laws prohibiting smoking in workplaces and public places are needed to ensure that all nonsmokers are protected from this serious health hazard. Health-care providers should educate patients and parents about the dangers of secondhand smoke and follow clinical care guidelines to help smokers quit.