Time-series analysis of association between air pollution and hospital outpatient visits in a district of Shanghai from 2015 to 2019

Objective To explore the association between air pollutants and hospital outpatient visits in a district of Shanghai.

Methods Daily meteorological data， environmental data， data of outpatient visits to two secondary hospitals and two tertiary hospitals in this district from January 1， 2015 to December 31， 2019 were collected. A Poisson regression generalized linear model was used to analyze the exposure-response relationship between the air pollutants and hospital outpatient visits in this area.

Results During the study period， the total number of outpatient visits in the included hospitals was 17 802 634， with an average daily total of （9 750±4 191） outpatient visits，and an average daily of （761±341） respiratory outpatient visits. In the lag effect of single pollutant model， when the concentration of air pollutant increased by 10 μg·m^-3， PM_2.5， SO₂， NO₂ had the maximum lag effect on the number of outpatient visits in the department of internal medicine for respiratory diseases on lag day 4， day 5 and day 7， respectively. And the RR values and 95%CI were 1.002 0（1.001 3‒1.002 6）， 1.0154（1.012 3‒1.018 5）， and 1.006 1（1.005 3‒1.006 9）， respectively.

Conclusion There is a exposure-response relationship between air pollutants and the number of outpatient visits in each department of the hospitals， and different pollutants have different degrees of lag effects.