Seasonal disparity of the short-term association between air pollution and gastritis outpatient visits: A large scale hospital-based study in eastern China

Abstract

Evidence on associations between outdoor air pollution and the risk of digestive diseases, especially seasonal disparity, is scarce. We aimed to compare the acute effects of air pollution on outpatient visits for gastritis between warm and cold seasons in China. We collected data on six criteria air pollutants [fine particulate matter (PM2.5), inhalable particulate matter (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3)], daily counts of gastritis outpatient visits, and meteorological variables during 2014–2020 (2536 days) in Hefei, China. A time-series analysis with generalized additive model was used, and potential effect modifiers were explored. Totally, 106,429 outpatient visits were recorded. The average concentrations of PM2.5, PM10, CO, NO2, SO2, and O3 were 54.82, 81.95, 886.75, 39.51, 11.81, and 84.75 μg/m3, respectively, exceeding the updated WHO Air Quality Guidelines values. Short-term PM2.5, CO, and NO2 exposures significantly increased the risk of gastritis outpatient visits and the lag response effects varied at different lag days. Each 10 μg/m3 increment of PM2.5, CO, and NO2 at lag 0 day, the excess risks of gastritis outpatient visits increased by 0.50% (95% CI: 0.04%, 0.95%), 0.05% (0%, 0.10%), and 1.50% (0.54%, 2.47%), respectively. We found insignificant differences in age-, sex- or insurance-strata but significant differences in seasonal strata with stronger effects in cold seasons. Null association of exposure to O3, SO2, or PM10 was observed. This study provided first-hand data that short-term exposure to PM2.5, CO, and NO2 but not O3, SO2, or PM10 was positively associated with gastritis outpatient visits, and such association was more evident in cold seasons, further suggesting the need for underscoring the continued efforts for public health intervention and air pollution control, especially in winter.