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March 2020

Pollen season is highly heterogenous in Southern European countries

European Academy of Allergy and Clinical Immunology criteria for pollen season may include many intermittent days with low pollen concentrations.


  • High heterogeneity observed between the different Southern European/Mediterranean locations in terms of pattern and length of the examined pollen seasons.
  • European Academy of Allergy and Clinical Immunology (EAACI) criteria for pollen season include many intermittent days with low pollen concentrations.
  • A fragmented approach may be required to define pollen season as individual solution for each pollen and geographical area.

Why this matters

  • For correct diagnosis, treatment choice and outcomes assessment in patients with seasonal allergic rhinitis, definition of pollen seasons is essential.

Study design

  • Multicentre study: pollen counts for Poaceae, Oleaceae, Fagales, Cupressaceae, Urticaceae (Parietaria spp.) and Compositae (Ambrosia spp., Artemisia spp.) were collected during 2018 in six Southern European cities.
  • EAACI criteria were applied to determine whole pollen season (WPS defined as start and end of the season; in days).
  • A modified Fragmented Pollen Season (FPS; in days) was generated after excluding intercurrent periods with low pollen counts.
  • Funding: Euroimmun.

Key results

  • Rome:
    • FPS decreased compared with WPS for Fagales (from 174 to 105), Poaceae (from 103 to 85), Cupressaceae (from 98 to 70), and Urticaceae (from 238 to 180).
  • Valencia:
    • FPS was shorter vs WPS for Cupressaceae (48 vs 283) Poaceae (65 vs 70), and Urticaceae (102 vs 299), but similar for Oleaceae (22 each).
  • Marseille:
    • FPS was shorter vs WPS for Cupressaceae (112 vs 345), Fagales (39 vs 72), Oleaceae (27 vs 51), but similar for Poaceae, Urticaceae, Ambrosia spp., and Aetemisia spp.
  • Messina:
    • FPS was shorter for Cupressaceae (22 vs 34), Poaceae (80 vs 119), Urticaceae (300 vs 363).
  • Istanbul:
    • FPS was shorter for Cupressaceae (21 vs 28) and Urticaceae (19 vs 24).
  • Izmir:
    • Shorter FPS for Urticaceae (106 vs 217), but no difference for Cupressaceae and Poaceae.
  • Patterns of peaks of pollens varied with region, for example, Cupressaceae peaks were observed during February-March in Izmir, whereas throughout the year in Marseille.


  • Missing pollen data.
  • Findings may not be generalisable to all regions.


  1. Hoffmann TM, Acar Şahin A, Aggelidis X, Arasi S, Barbalace A, Bourgoin A, Bregu B, Brighetti MA, Caeiro E, Caglayan Sozmen S, Caminiti L, Charpin D, Couto M, Delgado L, Di Rienzo Businco A, Dimier C, Dimou MV, Fonseca JA, Goksel O, Guvensen A, Hernandez D, Jang DT, Kalpaklioglu F, Lame B, Llusar R, Makris M, Mazon A, Mesonjesi E, Nieto A, Öztürk A, Pahus L, Pajno G, Panasiti I, Panetta, Papadopoulos NG, Pellegrini E, Pelosi S, Pereira AM, Pereira M, Pinar NM, Pfaar O, Potapova E, Priftanji A, Psarros F, Sackesen C, Sfika I, Suarez J, Thibaudon M, Travaglini A, Tripodi S, Verdier V, Villella V, Xepapadaki P, Yazici D, Matricardi PM, Dramburg S. "Whole" vs. "Fragmented" approach to EAACI Pollen Season Definitions: A Multicenter Study in Six Southern European Cities. Allergy. 2019 Dec 13 [Epub ahead of print]. doi: 10.1111/all.14153. PMID: 31833579