An Epidemiological Study on the Effect of Pollen on Allergic Rhinitis in Hohhot, China

The prevalence of pollen-induced allergic rhinitis (AR) has increased substantially due to global warming and rapid urbanization. Hohhot, a city with a high prevalence of allergic rhinitis, urgently requires epidemiological investigations into the health effects of airborne pollen exposure. In this study, we used a Generalized Additive Model (GAM) to assess the effect of pollen concentration on outpatient visits for allergic rhinitis in Hohhot from March to October in the years 2017, 2018, and 2019. Stratified analyses were conducted for nine pollen taxa across age and gender subgroups during the peak pollen periods. The mean daily pollen concentration in spring (April to May) was lower than that observed from late summer to autumn (August to September, 279.65 × 10 3 pollen/m 2 ). The results demonstrated a strong positive association between pollen concentration and outpatient visits for allergic rhinitis (AR). Exposure–response analyses revealed a lower risk threshold for allergic rhinitis during August to September. Age-stratified analyses indicated that individuals aged 0 to 17 years were the most susceptible to pollen exposure and exhibited the highest risk of outpatient visits for AR throughout the study period (RR 1.017, 95% CI 1.016 to 1.017). Moreover, the pollen-associated risk of outpatient visits for allergic rhinitis decreased progressively with increasing age. Taxon-stratified analyses indicated that Cupressaceae and Pinaceae pollen grains were significantly associated with outpatient visits for AR, with effects persisting for lag periods of 4 to 5 days, whereas all three herbaceous pollen taxa showed significant associations with outpatient visits for AR persisting for up to 6 to 7 days. These findings provide a scientific basis for developing targeted health protection strategies for populations vulnerable to pollen-induced allergic diseases.