Short-term associations of ambient air pollution and cause-specific emergency department visits in Guangzhou, China

Evidence of association of ambient air pollution with cause-specific emergency department visits in China is still limited. This study aimed to investigate short-term associations between exposures to air pollutants and daily cause-specific emergency department visits using a large-scale multicenter database involving a total of 65 sentinel hospitals in Guangzhou, the most densely-populated city in south China, during 2013–2015. We obtained data on 162,771 emergency department visits from 65 hospitals from the Emergency Medical Command Center in Guangzhou between January 1, 2013 and December 31, 2015. Daily air pollution data on particulate matter (PM) of aerodynamic diameter < 10 and 2.5 μm (PM10, and PM2.5, respectively), sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) were collected from the Daily Quality Report of the Guangzhou Environmental Protection Bureau during the study period. Visits for neurologic, respiratory and circulatory diseases were assessed in relation to air pollutants using Poisson generalized additive models. Mean daily number of emergency department visits for neurologic, respiratory and circulatory diseases was 89, 24 and 35, respectively. After adjustment for other pollutants (PM2.5, PM10, NO2 and O3), meteorological factors and time-varying confounders, a 7.98-μg/m3 (interquartile range) increment in 2-day moving average of same-day and previous-day SO2 concentrations was associated with the statistically significant increase of 4.89% (95% confidence interval: 2.86, 6.95) in neurologic emergency department visits; elevation in SO2 level (per 7.98 μg/m3) was linked to a 5.19% (95% confidence interval: 2.03, 8.44) increase in circulatory emergency department visits. Most positive links were seen during the cold season. The results of this study contribute to the evidence of the significant associations between SO2 and specific neurologic and circulatory conditions, and also provide insight into the planning of clinical services and emergency contingency response for air pollution exposures in Guangzhou.