Objective: To estimate the extent of exposure of the US population to environmental tobacco smoke and the contribution of the home and workplace environment to environmental tobacco smoke exposure.
Design: Nationally representative cross-sectional survey including questionnaire information from persons aged 2 months and older (n=16818) and measurements of serum cotinine (a metabolite of nicotine) from persons aged 4 years and older (n=10642).
Setting/participants: Participants in the Third National Health and Nutrition Examination Survey, October 25, 1988, to October 21, 1991.
Results: Of US children aged 2 months to 11 years, 43% lived in a home with at least 1 smoker, and 37% of adult non-tobacco users lived in a home with at least 1 smoker or reported environmental tobacco smoke exposure at work. Serum cotinine levels indicated more widespread exposure to nictoine. Of non-tobacco users, 87.9% had detectable levels of serum cotinine. Both the number of smokers in the household and the hours exposed at work were significantly and independently associated (P<.001, multiple regression t test) with increased serum cotinine levels. Serum cotinine levels of children, non-Hispanic blacks, and males indicated that these groups had higher exposure to environmental tobacco smoke. Dietary variables showed no consistent association with serum cotinine levels, and dietary contribution to serum cotinine level, if any, appeared to be extremely small.
Conclusions: The high proportion of the population with detectable serum cotinine levels indicates widespread exposure to environmental tobacco smoke in the US population. Both the home and workplace environments significantly contribute to environmental tobacco smoke exposure in the United States.