Abstract: Objective To examine the effect of ambient PM_2.5 on daily outpatient visits of children with respiratory diseases in Panyu District, Guangzhou. Methods Data on daily outpatient visits of pediatric respiratory diseases from 2015 to 2017 were collected from a hospital in Panyu District though the hospital information system. Meanwhile, environmental quality data were collected from the Guangzhou Municipal Ecological Environment Bureau and meteorological data were collected from the China Meteorological Data Service Center. The Spearman correlation analysis and the time-series analysis with generalized additive model （GAM） were applied to analyze the association between the ambient PM_2.5 concentration and outpatient visits of children with respiratory diseases during the same period. Results The Spearman correlation analysis revealed a significant association between PM_2.5 concentration and the outpatient visits of children with respiratory diseases （r=0.16, P<0.05）.The GAM model indicated that the effect of PM_2.5 on daily outpatient visits of children with respiratory diseases was observed in lag 3 to 5 days（P<0.05）, and the effect was greatest in lag4. An increment of 10 μg/m³ in concentration of PM_2.5 was associated with an increment in the hospital outpatient visits of children with respiratory diseases by 0.72%（ 95% CI： 0.22%-1.23%） . Conclusion Ambient PM_2.5 pollution affected the daily outpatient visits of children with respiratory diseases significantly, with a lag effect in Panyu District from 2015 to 2017. The increase of PM_2.5 concentration would lead to the increase of outpatient visits of children with respiratory diseases.

Key words: PM_2.5, Time series study, Children, Respiratory disease