title: Smoke-free air laws and asthma prevalence, symptoms, and severity among nonsmoking youth.
abstract: 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.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA. melaniesdove@gmail.com
authors.forename: Melanie S
authors.initials: MS
authors.lastname: Dove
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Dockery
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Connolly
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012720:Severity of Illness Index; D012907:Smoking / Q000331:legislation & jurisprudence*; D000074606:Smoking Prevention; D014481:United States