Residential NO(2) exposure is associated with urgent healthcare use in a thunderstorm asthma cohort

BACKGROUND: There is increasing interest in the role of traffic-related air pollution (TRAP) in allergic airway diseases. Few studies investigate the relationship between TRAP exposure and acute exacerbations of asthma. OBJECTIVE: The 2016 Melbourne thunderstorm asthma epidemic provided an opportunity to investigate the relationship between proxies of TRAP exposure and asthma exacerbation requiring urgent healthcare in the previous 12 months. METHODS: Current asthmatics who presented to the 3 Emergency Departments of Melbourne's second-largest health service with epidemic thunderstorm asthma in November 2016 were identified and completed a standard questionnaire. Their residential addresses were geocoded and the annual average nitrogen dioxide (NO(2)) exposure for each patient was assigned using a validated satellite-based land use regression model. Residential distance to the nearest major road was calculated using ArcGIS. Multivariate logistic regression was used to investigate the relationship between each TRAP proxy and healthcare use, adjusting for potential confounders. RESULTS: From 263 thunderstorm asthma patients, 88 patients identified with current asthma were analysed. Those with higher mean annual residential NO(2) exposure had greater odds of urgent healthcare use in the previous year (odds ratio [OR], 3.45 per one interquartile-range increase; 95% confidence interval [CI], 1.31–9.10; p = 0.01), however distance from major road (OR, 0.95 per 100-m increase; 95% CI, 0.80–1.13; p = 0.57) and living <200 m from a major road (OR, 1.47; 95% CI, 0.29–7.45; p = 0.64) were not significantly associated. CONCLUSION: In current asthmatics who presented during an epidemic thunderstorm asthma event, greater exposure to residential NO(2) was significantly associated with greater odds of asthma exacerbations requiring urgent healthcare in the previous 12 months.