Smoke-free air laws and asthma prevalence, symptoms, and severity among nonsmoking youth.

OBJECTIVE We investigated the association between smoke-free laws and asthma prevalence, symptoms, and severity among nonsmoking youth (aged 3-15 years). METHODS We examined data from the 1999-2006 National Health and Nutrition Examination Survey, a cross-sectional survey designed to monitor the health and nutritional status of the US population. Survey locations were dichotomized as having or not having at least 1 smoke-free workplace, restaurant, or bar law at the county or state level that covered the entire county population. Asthma prevalence was assessed as self-reported current asthma and as ever having asthma with current symptoms. Asthmatic symptoms included persistent wheeze, chronic night cough, and wheeze-medication use. We also examined asthma severity (asthma attack or emergency-department visit for asthma) and persistent ear infection. RESULTS Smoke-free laws were not associated with current asthma but were significantly associated with lower odds of asthmatic symptoms (odds ratio [OR]: 0.67 [95% confidence interval (CI): 0.48-0.93]) among nonsmoking youth. The association between smoke-free laws and ever having asthma with current symptoms approached significance (OR: 0.74 [95% CI: 0.53-1.03]). Smoke-free laws were associated with lower odds of asthma attacks (OR: 0.66 [95% CI: 0.28-1.56]) and emergency-department visits for asthma (OR: 0.55 [95% CI: 0.27-1.13]), although these results were not statistically significant. CONCLUSIONS Our results suggest that smoke-free laws reduce asthmatic symptoms, including persistent wheeze, chronic night cough, and wheeze-medication use in nonsmoking youth.