Time series analysis of the effect of air pollutants on the number of outpatients and emergency visits due to allergic rhinitis in Beijing, China

Objective To investigate the short-term effect of air pollutants on the number of outpatients and emergency visits due to allergic rhinitis in Beijing, China.

Methods The data of outpatients and emergency visits due to allergic rhinitis in Beijing from January 1, 2016 to December 31, 2019 were collected, and air pollution and meteorological data during the same period were collected as well. Generalized addition model (GAM) was performed to analyze the relationship between the mass concentrations of air pollutants and the number of outpatients and emergency visits due to allergic rhinitis as well as its lag effect. Meanwhile, a stratified analysis was conducted by quarter according to the epidemic pattern of allergic rhinitis.

Results From 2016 to 2019, the total number of outpatients and emergency visits due to allergic rhinitis was 1 021 243, with an average of 699 visits per day. In single-pollutant models, for every increase of 10 μg/m³ in the daily mean mass concentrations of O₃-8 h, NO₂, and PM_2.5, excessive risk (ER) of the number of outpatients and emergency visits due to allergic rhinitis in the strongest response period increased by 1.01% (95%CI: 0.41%, 1.61%), 4.82% (95% CI: 3.23%, 6.43%), and 0.70% (95% CI: 0.25%, 1.15%), respectively; for every increase of 100 μg/m³ in the daily mean mass concentration of CO, ER of the number of outpatients and emergency visits due to allergic rhinitis in the strongest response period increased by 0.47% (95% CI: 0.08%, 0.86%). After conducted by SO₂, the effect of CO、NO₂、PM_2.5 in dual-pollutant models was increased statistically. The increases in the daily mean mass concentrations of air pollutants in the first quarter reduced their impacts on the number of outpatients and emergency visits due to allergic rhinitis, while the increases in the daily mean mass concentrations of air pollutants in the second and fourth quarters increased their impacts on the number of outpatients and emergency visits due to allergic rhinitis. Stratified results showed that the strongest response period of O₃-8 h, CO, NO₂, SO₂, PM₁₀ and PM_2.5 on the number of outpatients and emergency visits respectively were lag07 d in the fourth quarter, lag0 d in the second quarter, lag03 d in the third quarter, lag01 d in the third quarter, lag0 d in the third quarter and lag0 d in the second quarter, and the ER were 3.92%(95%CI: 2.00%, 5.89%), 1.84%(95%CI: 0.96%, 2.73%), 7.18%(95%CI: 2.64%, 11.92%), 67.43%(95%CI: 32.06%, 112.27%), 1.33%(95%CI: 0.54%, 2.12%), 1.31%(95%CI: 0.65%, 1.98%), respectively.

Conclusion The concentration of air pollutants in Beijing may affect the number of outpatients and emergency visits due to allergic rhinitis with a lag effect. Especially the impact of NO₂ should be given special attention.