Background: Few studies have investigated the associations between outdoor air pollution and outpatient visits for respiratory diseases (RDs) in general population.
Methods: We collected daily outpatient data of primary RDs from five hospitals in Jinan during January 2012 and December 2016, as well as daily measurements of air pollutants from the Jinan Environmental Monitoring Center and daily meteorological variables from the China Meteorological Data Sharing Service System. A generalized additive model (GAM) with quasi-Poisson regression was constructed to estimate the associations between daily average concentrations of outdoor air pollutants (PM2.5,PM10, SO2, NO2, CO and O3) and daily outpatient visits of RDs after adjusting for long-time trends, seasonality, the "day of the week" effect, and weather conditions. Subgroup analysis stratified by gender, age group and the type of RDs was conducted.
Results: A total of 1,373,658 outpatient visits for RDs were identified. Increases of 10 μg/m3 in PM2.5, PM10, NO2, CO and O3 were associated with0.168% (95% CI, 0.072-0.265%), 0.149% (95% CI, 0.082-0.215%), 0.527% (95% CI, 0.211-0.843%), 0.013% (95% CI, 0.003-0.023%), and 0.189% (95% CI, 0.032-0.347%) increases in daily outpatient visits for RDs, respectively. PM2.5 and PM10 showed instant and continuous effects, while NO2, CO and O3 showed delayed effects on outpatient visits for RDs. In stratification analysis, PM2.5 and PM10 were associated with acute RDs only.
Conclusions: Exposure to outdoor air pollutants including PM2.5, PM10, NO2, CO and O3 associated with increased risk of outpatient visits for RDs.
Keywords: Air pollution; Generalized additive model; Outpatient visits; Respiratory diseases.