Effects Of Exposure To Air Pollutants On Acute Episodes Of Inflammatory Bowel Disease

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 The First Affiliated Hospital of Anhui Medical University and The Second Affiliated Hospital of Anhui Medical University 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.In addition,IBD is divided into Ulcerative colitis（UC）and Crohn’s disease（CD）,and the seasons are divided into warm season and cold season.Stratified analyses were performed using IBD classification UC and CD)and season（warm and cold seasons）to assess the impact of exposure to air pollutantsResults:During the study period,totally 886 cases of IBD were recruited,including 313cases of ulcerative colitis（UC）and 573 cases of Crohn’s disease（CD）.The findings showed PM_2.5,O₃and CO exposure significantly increased the risk of IBD.Mean concentrations of PM_2.5,O₃and CO in Hefei were 43.85ug/m~3,100.78ug/m~3,and0.76mg/m~3,respectively.Each increase of 10mg/m~3in PM_2.5/O₃and 0.1mg/m~3in 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,PM_2.5,O₃and 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(PM_2.5,O₃and CO)exposure could increase the risk of IBD,while the most susceptibility seasons for the exposure were mainly in warm seasons.The results of this study suggest that air pollutants increase the risk of IBD patients in Hefei,China,providing a basis for developing countries to improve effective prevention of IBD,and a potential opportunity to avoid part of the risk of the onset or recurrence of IBD.This study contributes to the knowledge of the association between air pollution and IBD,but the associations need to be verified by further studies.