Pollen exposure and allergy risk: a systematic review and meta-analysis

Pollen is a widespread environmental allergen linked to various allergic conditions, including rhinitis and asthma. This systematic review and meta-analysis aimed to evaluate the association between pollen exposure and allergy risk, considering different pollen concentrations, age groups, exposure settings, type of study, and geographic regions. Search was conducted in PubMed, Embase, Web of Science, and Scopus from 1 January 2000 to 20 February 2025. The systematic review included 31 papers containing 96 data-reports across 1,942,079 participants. The random-effects model in our meta-analysis was conducted to estimate pool effect sizes (ESs) with 95% confidence intervals (CIs) in pollen concentration, age, exposure setting, country, and study design subgroup. Overall, pollen exposure significantly increased allergy risk (ES: 1.13, 95% CI: 1.11–1.16, I2 = 94.6%). High pollen concentrations (≥200 grains/m3) showed a stronger effect (ES: 1.76, 95% CI: 1.57–1.96) than low concentrations ( < 200 grains/m3, ES: 1.07, 95% CI: 1.05–1.10). Children (ES: 1.12, 95% CI: 1.09–1.15) and adults (ES: 1.23, 95% CI: 1.14–1.32) were both significantly affected. Tree and cypress pollen were the most potent allergens. Pollen exposure significantly increases allergy risk, with dose-dependent and demographic variations. High pollen concentrations and specific geographic regions pose greater risks. These findings underscore the need for targeted public health strategies to mitigate pollen-related allergic diseases.