Open Access

Matteo Boser, Athanasios Damialis, Christoph Knote, Monika Seemann, Claudia Traidl-Hoffmann, Maria P. Plaza

• Airborne pollen is a key driver of allergy-induced asthma exacerbations. Its relevance is expected to further increase due to climate change, which influences pollen season timing, intensity, and allergenicity. However, taxon-specific asthma risks associated with pollen exposure remain insufficiently quantified. We considered asthma-related outpatient emergency treatments (ICD-10: J45, J46) from the Bavarian Association of Statutory Health Insurance Physicians (KVB) in three metropolitan areas: Augsburg, Munich, and Nuremberg. Daily pollen concentrations for the taxa Alnus, Betula, Corylus, and Poaceae were obtained from the electronic Pollen Information Network (ePIN). We employed a multicenter time-series analysis using quasi-Poisson regression with Distributed Lag Non-Linear Models (DLNMs) to account for non-linear and delayed effects. Pollen effects were modelled at low, medium and high exposure levels. We adjusted for seasonality, public holidays, day of the week and potentialAirborne pollen is a key driver of allergy-induced asthma exacerbations. Its relevance is expected to further increase due to climate change, which influences pollen season timing, intensity, and allergenicity. However, taxon-specific asthma risks associated with pollen exposure remain insufficiently quantified. We considered asthma-related outpatient emergency treatments (ICD-10: J45, J46) from the Bavarian Association of Statutory Health Insurance Physicians (KVB) in three metropolitan areas: Augsburg, Munich, and Nuremberg. Daily pollen concentrations for the taxa Alnus, Betula, Corylus, and Poaceae were obtained from the electronic Pollen Information Network (ePIN). We employed a multicenter time-series analysis using quasi-Poisson regression with Distributed Lag Non-Linear Models (DLNMs) to account for non-linear and delayed effects. Pollen effects were modelled at low, medium and high exposure levels. We adjusted for seasonality, public holidays, day of the week and potential confounders such as temperature, relative humidity and air pollution. We estimated taxon-specific attributable fractions (AFs) to assess the asthma burden during the pollen season. High Betula concentrations were associated with an increased risk of asthma treatments (RR: 1.64, 95% CI [1.41,1.90]), while Poaceae showed significant effects at medium (RR: 1.19, 95% CI [1.03,1.38]) and high concentrations (RR: 1.41, 95% CI [1.17,1.70]). While the effect of Betula was strongest on the day of exposure, the Poaceae effect peaked on day two after exposure. During the respective pollen season, AFs for Betula varied from 10.24% (95% CI [1.01,18.50]) in Augsburg to 17.75% (95% CI [9.72,24.80]) in Nuremberg, while the respective AFs for Poaceae ranged between 14.25% (95% CI [4.46,22.84]) in Munich and 18.84% (95% CI [7.21,28.88]) in Augsburg. Betula and Poaceae pollen contribute substantially to asthma-related outpatient emergency treatments in Bavaria, especially during the main pollen season. Our findings underscore the importance of automated, real-time pollen monitoring to support targeted public health interventions and timely warning systems.…