Effects of air pollution on moderate and severe asthma exacerbations

AbstractBackground: Few studies have evaluated the impact of air pollutionlevels on the severity of exacerbations. Thus, we compared the relative risks posed by air pollutantlevels on moderate and severe exacerbations.Methods: Exacerbationepisodes of 618 from 143 adult asthmatics were retrospectively collected between 2005 and 2015 in a tertiary hospital of Korea. Air pollutionGPS data for the location closest to each patient’s home were obtained from the national ambient monitoring station. The relative impacts of air pollutantson asthma exacerbationswere evaluated via a time-trend controlled symmetrical, bidirectional, case-crossover design using conditional logistic regressionmodels on the day of the exacerbation(T-0) and up to 3 days before the exacerbation(T-1–T-3).Results: Overall asthma exacerbationwere associated with O3 levels in summer and winter (OR: 1.012[1.003–1.02] and 1.009[1.003–1.016]), SO2 levels in spring and summer (OR: 1.009[1–1.018] and 1.02[1.006–1.035]) and NO2 levels in ...