Associations between air pollution and outpatient visits for allergic rhinitis in Lanzhou, China

There is emerging evidence indicating that short-term exposure to air pollution is associated with the development and occurrence of allergic rhinitis (AR), but limited studies have been conducted in China, and their results were inconsistent. So, quasi-Poisson time series regressions with distributed lag non-linear models (DLNM) were applied to evaluate the lag association between six air pollutants and daily outpatient visits for AR in Lanzhou, China, from January 1, 2014, to December 31, 2019. Stratified analyses were further performed by gender, age, and season. Overall, we found that short-term exposure to air pollutants including PM2.5, PM10, SO2, NO2, O38h, and CO was significantly associated with an increased risk of AR outpatient visits. The strongest associations were observed at a lag of 0–7 days for PM2.5 (relative risk [RR] = 1.035, 95% confidence intervals [CI]: 1.019–1.052), PM10 (RR = 1.006, 95% CI: 1.002–1.011), at a lag of 0–2 days for SO2 (RR = 1.048, 95% CI: 1.017–1.081), NO2 (RR = 1.025, 95% CI: 1.010–1.041), at a lag of 0–6 days for O38h (RR = 1.028, 95% CI: 1.016–1.041), and at a lag of 0–7 days for CO (RR = 1.128, 95% CI: 1.054–1.206). Stratified analyses indicated that males and adults (15–59 years old) appeared to be more sensitive to PM2.5, SO2, NO2, O38h, and CO exposure than females and those in other age groups. The effect of CO exposure was statistically significant in all subgroups. Associations between PM2.5, PM10, NO2, and O38h and AR outpatients were more pronounced in the warm season than in the cold season. The influences of PM2.5, PM10, SO2, NO2, O38h, and CO were found to be significantly relevant to AR-associated outpatient. Different pollutants played different roles for different genders, ages, and seasons.