Environmental tobacco smoke exposure during childhood is associated with increased prevalence of asthma in adults.

OBJECTIVE To examine if exposure to environmental tobacco smoke (ETS) during childhood has an impact on asthma prevalence in adults, and to identify the amount of nuisance from ETS and other lower airway irritants (LAWIs) in a city population. DESIGN A postal survey. SETTING The municipality of Orebro, Sweden. PARTICIPANTS A total of 8,008 randomly selected inhabitants aged 15 to 69 years. MEASUREMENTS Exposures, airway symptoms, and respiratory history were assessed using a questionnaire. RESULTS The response rate was 84%. In never-smokers with childhood ETS exposure, the prevalence of physician-diagnosed asthma was 7.6% vs 5.9% in nonexposed subjects (p = 0.036). In never-smokers without a family history of asthma, the prevalence of physician-diagnosed asthma in subjects reporting childhood ETS exposure was 6.8% vs 3.8% in nonexposed subjects (p < 0.001). Subjects with childhood ETS exposure were more likely to start smoking in adulthood. The prevalence of ever-smokers was 54.5% vs 33.8% (p < 0.0001) in nonexposed subjects. ETS was the most commonly reported LAWI in the total sample (21%), followed by exercise in cold air (20%), dust (19%), exercise (16%), perfume (15%), cold air (12%), pollen (10%), and pets (8%). All LAWIs were more frequently reported by women. CONCLUSIONS Childhood exposure to ETS is associated with an increased prevalence of asthma among adult never-smokers, especially in nonatopic subjects. Children exposed to ETS are also more likely to become smokers. ETS is as a major LAWI.