The impact of pollen allergens on human health is primarily manifested by allergic diseases. Exposure to allergens from airborne pollen or their inhalation can trigger allergic responses of nose, eyes and bronchi (asthma). These allergic reactions can lead to sleep disturbance, decreased quality of life due to impaired mental health, productivity loss or decreased school performance of children, and high healthcare costs. The impact of climate change on pollen seasons, concentrations and allergenicity are expected to lead to increased exposure of the European population to pollen and aeroallergens in the future.


The indicator is based on the season timing only and assumes the same amount pollen released into the air every year – enough to induce allergies – and the same vegetation distribution for all years. In reality, the clinically relevant pollen season depends not only on the phenological season but also on absolute pollen concentrations, which fluctuate for trees strongly across years. Predicting pollen concentrations is difficult, however, and currently not yet possible at European-wide level, while it is fair to assume that the onset of the pollen season – also an important health-related indicator – is mainly dependent on temperature regardless of whether pollen concentrations are high or low.

Reference information



van Daalen, K. R., et al., 2022, ‘The 2022 Europe report of the Lancet Countdown on health and climate change: towards a climate resilient future’, The Lancet Public Health 7(11), pp. E942-E965. doi: 10.1016/S2468-2667(22)00197-9.

Data sources:

  1. Climatic data: ECMWF ERA5 Land Reanalysis data, retrieved from the Copernicus Climate Change Service Climate Data Store
  2. Pollen data: European Aeroallergen Network database (used for the SILAM model development)
  3. Land cover data:
    • ECOCLIMAP global database of land surface parameters
    • European Forest Institute (EFI) tree species map for European forests
    • FAO's GLC-SHARE global land cover database

Link to repository with code: 

Finish Meteorological Institute. SILAM model (2021). Github repository.


Additional reading: 

  • Sofiev, M., et al., 2015, Construction of the SILAM Eulerian atmospheric dispersion model based on the advection algorithm of Michael Galperin, Geoscientific Model Development 8(11), 3497-3522.
  • Sofiev, M., et al., 2013, A numerical model of birch pollen emission and dispersion in the atmosphere. Description of the emission module, International journal of biometeorology 57, 45-58.


Lancet Countdown in Europe

Published in Climate-ADAPT Dec 5, 2022   -   Last Modified in Climate-ADAPT Apr 4, 2024

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