Short-term effects of air pollutants and meteorological factors on daily outpatient visits for urticaria in Shijiazhuang, Hebei Province, China

Abstract Objective: The associations of air pollutants and meteorological factors with the outpatient visits of urticaria remain poorly studied. This study aimed to assess the short-term effects of air pollutants and meteorological factors on daily outpatient visits for urticaria in Shijiazhuang, China, during 2014-2019.Methods: Daily recordings of air pollutants concentrations, meteorological data, and the outpatient visits data for urticaria were collected during the 6 years. Descriptive research methods were used to describe the distribution characteristics and demographic features of urticaria. A combination of the generalized linear regression model (GLM) and distribution lag nonlinear model (DLNM) was used to evaluate the lag effect of environmental factors on daily outpatient visits for urticaria. Results: The dose-response relationship between daily urticaria visits and CO, NO2, O3, temperature, and relative humidity was nonlinear. High concentrations of CO, NO2, O3, and high temperatures increased the risk of urticaria outpatient visits. The maximum cumulative effect of high concentrations of CO, NO2, and O3 was lag 0-14 days (CO: RR = 1.10, 95%CI: 1.06, 1.31; NO2: RR = 1.09, 95%CI: 1.01, 1.08; O3: RR = 1.16, 95%CI: 1.08, 1.25), and high temperatures was lag 0-7 days (RR = 1.27, 95%CI: 1.14, 1.41). Low concentrations of NO2, O3, and high humidity, on the other hand, act as protective factors for the urticaria outpatient. The maximum cumulative effect of low concentrations of NO2 was the 0-day lag (RR = 0.97, 95%CI: 0.95, 0.99), O3 was lag 0-5 days (RR = 0.94, 95%CI: 0.88, 0.99), and high humidity was lag 0-10 days (RR = 0.93, 95%CI: 0.89, 0.98).Conclusions: In conclusion, we found that the development of urticaria in Shijiazhuang has a distinct seasonal and cyclical nature. Air pollutants and meteorological factors had varying degrees of influence on the risk of urticaria outpatient visits.