Passive smoking and chronic respiratory disease symptoms in non-smoking adults.

A prospective study was conducted to investigate the possible effects of environmental tobacco smoke (ETS) on the development of definite symptoms of airway obstructive disease (AOD) in a non-smoking adult population. In all 3914 subjects completed a standardized respiratory symptoms questionnaire in 1977 and 1987 and a computerized algorithm was used to identify new cases of definite symptoms of AOD during the follow-up period. In multivariate logistic regression models which adjusted for age, gender, income, educational level, years smoked in the past, and concentrations of ambient air pollutants, ETS exposure during childhood only was associated with a relative risk (RR) of 1.09 (95% confidence interval [CI]: 0.69-1.79), during adulthood only with an RR of 1.28 (95% CI: 0.90-1.79), and during both childhood and adult life with an RR of 1.72 (95% CI: 1.31-2.23). Results were not significantly changed when only lifetime never-smokers were used in analyses, and no interaction between ETS exposure and concentrations of ambient air pollutants was observed.