Acute effects of ambient air pollution on outpatient children with respiratory diseases in Shijiazhuang, China

Background: Associations between ambient air pollution and child health outcomes have been well documented in developed countries such as the United States; however, only a limited number of studies have been conducted in developing countries. This study aimed to explore the acute effects of five ambient air pollutants (inhalable particles [PM10], fine particles [PM2.5], sulfur dioxide [SO2], nitrogen dioxide [NO2] and 0zone [O-3]) on children hospital outpatients with respiratory diseases in Shijiazhuang, China. Methods: Three years (2013-2015) of daily data, including cause-specific respiratory outpatient records and the concentrations of five air pollutants, were collected to examine the short-term association between air pollution and children's respiratory diseases; using a quasi-Poisson regression generalized additive model. Stratified analyses by season and age were also performed. Results: From 2013 to 2015, a total of 551,678 hospital outpatient records for children with respiratory diseases were collected in Shijiazhuang, China. A 10 mu g/m(3) increase in a two-day average concentration (lag01) of NO2, PM2.5, and SO2 corresponded to an increase of 0.66% (95% confidence interval [CI]: 0.30-1.03%), 0.13% (95% CI: 0.02-0.24%), and 0.33% (95% CI: 0.10-0.56%) in daily hospital outpatient visits for children with respiratory diseases, respectively. The effects were stronger in the transition season (April, May, September and October) than in other seasons (the hot season [June to August] and the cool season [November to March]). Furthermore, results indicated a generally stronger association in older (7-14 years of age) than younger children (< 7 years of age). Conclusions: This research found a significant association between ambient NO2, PM2.5, and SO2 levels and hospital outpatient visits in child with respiratory diseases in Shijiazhuang, China.