PURPOSE OF THE STUDY.
To investigate the relationship between smoke-free laws and asthma prevalence, symptoms, and severity among nonsmoking children aged 3 to 15 years.
The data were obtained from the National Health and Nutrition Examination Survey 1999–2006 (NHANES).
Survey sites were designated as having or not having at least 1 smoke-free work location, restaurant, or bar law at the county or state level that encompassed 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. The authors also examined asthma severity defined by asthma episode or emergency department visit for asthma.
Smoke-free laws were significantly related with lower odds of asthma symptoms (odds ratio [OR]: 0.67 [95% confidence interval (CI): 0.48–0.93]) among nonsmoking youth. The relationship between smoke-free laws and ever having asthma with current symptoms trended to significance (OR: 0.74 [95% CI: 0.53–1.03]). Smoke-free laws were associated with lower odds of asthma episodes (OR: 0.66 [95% CI: 0.28–1.56]) and emergency department visits for asthma (OR: 0.55 [95% CI: 0.27–1.13]), but these outcomes were not statistically significant.
Smoke-free laws decrease asthma symptoms, including persistent wheeze, chronic nocturnal cough, and wheeze-medication use in youthful nonsmoking populations.
This study was limited by the county-limited definition of smoke-free laws, which is only an estimate of individual exposure to secondhand tobacco smoke outside the home. Misclassification of county smoke-free laws might not reflect individual exposure, and misclassification of current asthma is possible because self-reports were not validated by objective measures or clinical assessment. However, the findings of this study are consistent with those of other studies of secondhand smoke. In summary, the take-home message and conclusion of this important study is that smoke-free laws are associated with decreased exposure to secondhand smoke but equally with decreased respiratory symptoms as well.
- Copyright © 2011 by the American Academy of Pediatrics