Short-term effects of multiple ozone metrics on outpatient visits for urticaria in Lanzhou, China

Although mounting evidence suggests that short-term exposure to ozone increases the risk of respiratory disease, cardiovascular disease and mortality, there are few studies comparing the effects of ozone in relation to urticaria in China. To evaluate the risks for urticaria exacerbations related to ambient ozone measured as 1-h maximum (O-3-1 h max), maximum 8-h (O-3-8 h max) and 24-h average (O-3-24 h avg) concentrations. We calculated three metrics of ozone, 1-h maximum, maximum 8-h and 24-h average based on the hourly data. Generalized additive models with Poisson regression incorporating natural spline functions were used to investigate short-term effects on urticaria associated with ambient ozone pollution in Lanzhou, China, using 5 years of daily data (2013-2017). We also examined the association by sex, age and season. In all-year analyses, a 10 mu g/m(3) increase in daily average, O-3-1 h max, O-3-8 h max and O-3-24 h avg at lag2 corresponded to an increase of 0.58%(95%CI: 0.26, 0.90), 0.82% (95%CI: 0.47, 1.16) and 2.17% (95%CI: 1.17, 2.79), respectively. The elderly populations and females were susceptible to O-3, and the associations between ozone and urticaria appeared to be more evident during warm season than in the cold season. In conclusion, these results indicated that ozone, as a widespread pollutant, affects outpatient visits for urticaria in Lanzhou.