Ultrafine particulate air pollution and pediatric emergency-department visits for main respiratory diseases in Shanghai, China

Background: Few studies have explored the short-termeffects of ultrafine particles (UFPs, particles < 0.1 mu m) air pollution on the exacerbations of pediatric respiratory diseases. Objectives: We aimed to evaluate short-termassociation between UFP and emergency-department visits (EDVs) for main pediatric respiratory diseases. Methods: We collected daily data on UFP and pediatric EDVs for main respiratory diseases [asthma, pneumonia, bronchitis and upper respiratory tract infections (URTI)] from66 hospitals in Shanghai, China from2016 to 2018. Generalized additive models combined with polynomial distributed lag models were applied to explore the associations between UFP level and pediatric EDVs for respiratory diseases. We fitted two-pollutant models with criteria air pollutants and performed stratified analyses by gender and age. Results: UFP was associated with increased EDVs for all respiratory diseases in cumulative lags up to 2 d and 3 d. The greatest risk was found at cumulative lags (0-2 d) for all respiratory diseases. At cumulative lags (0-2 d), an interquartile range increase in concentrations of UFP (1800 particles/cm3) was associated with relative risks of EDVs due to asthma [1.35, 95% confidence interval (CI): 1.14-1.59], pneumonia (1.20, 95% CI: 1.04-1.38), bronchitis (1.17, 95% CI: 1.03-1.33) and URTI (1.14, 95% CI: 1.02-1.28). These associations were almost unchanged when controlling for criteria air pollutants, and there was no threshold below which the associations were not present. There were stronger associations in children aged 0-13 years. Conclusions: Short-term exposure to UFP may independently increase the risks of EDVs for asthma, pneumonia, bronchitis and URTI exacerbations among children. (c) 2021 Elsevier B.V. All rights reserved.