County Smoke-Free Laws and Asthma Discharges: Evidence from 17 US States

Impact of Air Pollution on Asthma Outcomes

Asthma is a chronic respiratory disease characterized by variable airflow obstruction, bronchial hyperresponsiveness, and airway inflammation. Evidence suggests that air pollution has a negative impact on asthma outcomes in both adult and pediatric populations. The aim of this review is to summarize the current knowledge on the effect of various outdoor and indoor pollutants on asthma outcomes, their burden on its management, as well as to highlight the measures that could result in improved asthma outcomes. Traffic-related air pollution, nitrogen dioxide and second-hand smoking (SHS) exposures represent significant risk factors for asthma development in children. Nevertheless, a causal relation between air pollution and development of adult asthma is not clearly established. Exposure to outdoor pollutants can induce asthma symptoms, exacerbations and decreases in lung function. Active tobacco smoking is associated with poorer asthma control, while exposure to SHS increases the risk of asthma exacerbations, respiratory symptoms and healthcare utilization. Other indoor pollutants such as heating sources and molds can also negatively impact the course of asthma. Global measures, that aim to reduce exposure to air pollutants, are highly needed in order to improve the outcomes and management of adult and pediatric asthma in addition to the existing guidelines.

County Smoke-Free Laws and Cigarette Smoking Among U.S. Adults, 1995-2015

INTRODUCTION

Tobacco use remains the leading cause of preventable death worldwide. Though research on smoke-free policies in the U.S. exists at the state or national level, there is limited evidence on such policies at the county level. This study examined the association between changes in county-level comprehensive smoke-free laws and smoking behavior among U.S. adults.

METHODS

Data were used from the 1995/1996 to the 2014/2015 Tobacco Use Supplement to the Current Population Survey, analyzed in 2019. Changes in county smoke-free law population coverage over time were used as a natural experiment. Quasi-experimental analyses were performed to examine the association between changes in county-level comprehensive smoke-free laws and smoking behavior (smoking status and number of cigarettes smoked).

RESULTS

During the study period, current smoking prevalence decreased from 21.6% to 11.9%. Specifically, the prevalence of every day smoking decreased from 17.1% to 9.1% and some days smoking decreased from 4.4% to 2.9%. The number of cigarettes smoked per day for every day smokers decreased from 18.5 to 13.6, and from 5.9 to 4.1 for those who smoked some days. Comprehensive smoke-free legislation was associated with lower odds of cigarette smoking (AOR=0.76, 95% CI=0.74, 0.79). Adults living in counties with comprehensive smoke-free policies smoked fewer cigarettes per day both for every day smokers (β= -1.55, p<0.0001) and some days smokers (β= -0.79, p<0.0001).

CONCLUSIONS

County smoke-free policies in the U.S. may have contributed significantly to the reduction in smoking prevalence as well as the reduction in the number of cigarettes smoked among continuing cigarette smokers.