Smoke-Free Air Laws Can Reduce Asthma Hospitalizations

A study in Preventing Chronic Disease suggests that the implementation of a Smoke-Free Air (SFA) law in Michigan was associated with a reduction in adult asthma hospitalization rates. The study also looked at racial disparities in hospitalization for asthma.

Previous studies have demonstrated that smoking bans can reduce the rates of myocardial infarction and stroke, but this is among the first (alongside a similar finding in Kentucky) to show a positive affect for adult asthma. Tobacco smoke is a known asthma trigger. The Michigan SFA law, implemented May 1, 2010, banned smoking in Michigan bars, restaurants, hotels and motels, bowling alleys, bingo halls, nonfood work places and other indoor public areas.

According to the study, in 2013 in Michigan, 11.5% of the adult population self-reported currently having asthma, the third highest asthma prevalence in the country. Although the prevalence of asthma in Michigan black and white adult populations is similar (10.7% vs. 9.5%, respectively), black adults are more than 4 times as likely to be hospitalized for asthma. Michigan women are hospitalized slightly more often than men (19.3 per 10,000 vs. 7.7 per 10,000), but women also have a higher asthma prevalence (12.6% vs. 7.0%).

Data for the study was 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 time of year. Race-based and sex-based analyses were also performed.

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.

“This study is the first to use statewide data on asthma hospitalizations and to show a racial disparity in health benefits resulting from the SFA law,” the study authors noted. “SFA laws have been shown to encourage smokers to reduce smoking or quit smoking altogether. If race is a marker for economic status, whites may have more resources to help them quit smoking. Likewise, more middle-class and upper-class people will patronize bars and restaurants and benefit from the reduction in secondhand smoke exposure... We were surprised to find such a significant health disparity by race following the SFA law. More work is necessary to understand the causes for these disparate hospitalization rates to promote the health benefits to all Michigan populations.”