Air pollution and asthma attacks in children: A case-crossover analysis in the city of Chongqing, China

Data on particulate matter of diameter <2.5 μm (PM2.5) in the city of Chongqing were first announced in 2013. We wished to assess the effects of pollutants on asthmatic children in Chongqing, China. Daily numbers of hospital visits because of asthma attacks in children aged 0-18 years in 2013 were collected from the Children's Hospital of Chongqing Medical University. Data on pollutants were accessed from the nine air quality-monitoring stations in Chongqing. A time-stratified case-crossover design was applied and conditional logistic regression was undertaken to analyze the data. We found that short-term exposure to PM10, PM2.5, sodium dioxide, nitrogen and carbon monoxide could trigger hospital visits for asthma in children. Nitrogen dioxide had an important role, whereas ozone had no effect.