The global warming–oriented climate change is able to induce changes in the presentation of allergic disorders due to (a) increase in the annual sum of some important airborne allergenic pollen, (b) increase in the pollen allergenic potency, and (c) earlier shifts in airborne tree and grass pollen of breathed air in Europe, as documented in aerobiological studies. Studies on the period of times with pollen flight do not necessarily correlate directly with symptom burden of hay fever sufferers as long they have not included symptom data from subjects with allergic rhinitis or rhinoconjunctivitis. This shortcoming was taken into account when the new EAACI pollen season definition was developed and published to describe the period of time in which pollen allergy sufferers develop their allergic symptoms.

(EAACI Task Force report. Allergy. 2020;75(12):3024-3026)