Introduction: Exposure to secondhand smoke has immediate adverse respiratory and cardiovascular effects. A growing body of literature examining health trends following the implementation of public smoking bans has demonstrated reductions in the rates of myocardial infarction and stroke, but there has been no extensive work examining asthma hospitalizations. The aim of this study was to determine the impact of the Michigan Smoke-Free Air Law (SFA law) on the rate of asthma hospitalizations among adults in Michigan and to determine any differential effects by race or sex.
Methods: Data on adult asthma hospitalizations were obtained from the Michigan Inpatient Database (MIDB). Poisson regression was used to model relative risks for asthma hospitalization following the SFA law with adjustments for sex, race, age, insurance type, and month of year. Race-based and sex-based analyses were performed.
Results: In the first year following implementation of the SFA law, adjusted adult asthma hospitalization rates decreased 8% (95% confidence interval [CI], 7%-10%; P < .001). While asthma hospitalization rates for both blacks and whites declined in the 12 months following implementation of the SFA law, blacks were 3% more likely to be hospitalized for asthma than whites (95% CI, 0%-7%; P = .04). The rate of decline in adult asthma hospitalizations did not differ by sex.
Conclusion: The implementation of the SFA law was associated with a reduction in adult asthma hospitalization rates, with a greater decrease in hospitalization rates for whites compared with blacks. These results demonstrate that the SFA law is protecting the public's health and saving health care costs.