Association Between Exposure To Air Pollutants and The Risk of Inflammatory Bowel Diseases Visits

Abstract Background The topic of inflammatory bowel disease (IBD) has attracted more and more attentions. Accumulating evidence suggests that exposure to air pollutants is associated with IBD, yet the results are inconsistent and study about daily exposure is few. This study evaluated the association between daily air pollution and IBD in Hefei, China. Methods Daily IBD admission data were obtained from two hospitals in Hefei from January 1, 2019 to December 31, 2019. Daily concentrations of major air pollutants were provided by the Hefei Environmental Protection Bureau. Meteorological data were collected from China Meteorological Data Network. Distributed lag nonlinear model (DLNM) considering both the lag effects of exposure factors and nonlinear relationship of exposure-reaction was used to assess the effect of daily air pollutants exposure on IBD admission. Results During the study period, totally 886 cases of IBD were recruited, including 313 cases of ulcerative colitis (UC) and 573 cases of Crohn's disease (CD). The findings showed PM2.5, O3 and CO exposure significantly increased the risk of IBD. Mean concentrations of PM2.5, O3 and CO in Hefei were 43.85ug/m³, 100.78ug/m³, and 0.76mg/m³, respectively. Each increase of 10mg/m³ in PM2.5/ O3 and 0.1mg/m³ in CO increased the risk of IBD. The strongest effects of these three pollutants on IBD were observed in lag2-lag3 (RR = 1.037, 95% CI: 1.005–1.070%), lag3 (RR = 1.020, 95% CI: 1.002–1.038%) and lag2 (RR = 1.036, 95% CI: 1.003–1.071%), respectively. In warm seasons, PM2.5, O3 and CO had a stronger effect increased the risk of IBD, which were observed in lag2 (RR = 1.104, 95% CI: 1.032–1.181%), lag2 and lag5 (RR = 1.023, 95% CI: 1.002–1.044%; RR = 1.036, 95% CI: 1.004–1.069%) and lag2 (RR = 1.071, 95% CI: 1.012–1.133%), respectively. Conclusions Air pollutants (PM2.5, O3 and CO) exposure could increase the risk of IBD, while the most susceptibility seasons for the exposure were mainly in warm seasons. This study contributes to the knowledge of the association between air pollution and IBD, but the associations need to be verified by further studies.