Acute Effects of Ambient Air Pollution on Asthma Emergency Department Visits in Ten US States

BACKGROUND: Previous studies of short-term ambient air pollution exposure and asthma morbidity in the United States have been limited to a small number of cities and/or pollutants and with limited consideration of effects across ages.OBJECTIVES: To estimate acute age group-specific effects of fine and coarse particulate matter (PM), major PM components, and gaseous pollutants on emergency department (ED) visits for asthma during 2005-2014 across the United States.METHODS: We acquired ED visit and air quality data in regions surrounding 53 speciation sites in 10 states. We used quasi-Poisson log-linear time -series models with unconstrained distributed exposure lags to estimate site-specific acute effects of air pollution on asthma ED visits overall and by age group (1-4, 5-17, 18-49, 50-64, and 65+ y), controlling for meteorology, time trends, and influenza activity. We then used a Bayesian hierarchi-cal model to estimate pooled associations from site-specific associations. RESULTS: Our analysis included 3.19 million asthma ED visits. We observed positive associations for multiday cumulative exposure to all air pollu-tants examined [e.g., 8-d exposure to PM2.5: rate ratio of 1.016 with 95% credible interval (CI) of (1.008, 1.025) per 6.3-mu g/m3 increase, PM10-2.5: 1.014 (95% CI: 1.007, 1.020) per 9.6-mu g/m3 increase, organic carbon: 1.016 (95% CI: 1.009, 1.024) per 2.8-mu g/m3 increase, and ozone: 1.008 (95% CI: 0.995, 1.022) per 0.02-ppm increase]. PM2.5 and ozone showed stronger effects at shorter lags, whereas associations of traffic-related pollutants (e.g., elemental carbon and oxides of nitrogen) were generally stronger at longer lags. Most pollutants had more pronounced effects on children (<18 y old) than adults; PM2.5 had strong effects on both children and the elderly (>64 y old); and ozone had stronger effects on adults than children.CONCLUSIONS: We reported positive associations between short-term air pollution exposure and increased rates of asthma ED visits. We found that air pollution exposure posed a higher risk for children and older populations. https://doi.org/10.1289/EHP11661

Automated summary

This study examined the association between short-term ambient air pollution exposure and emergency department visits for asthma in the United States. The results showed that air pollution exposure was positively associated with increased rates of asthma ED visits. The effects of air pollution were more pronounced in children and older populations.