Pollen season characteristics of Alder, Birch and Olive (1980-2020)

Rising temperature leads to substantial changes in flowering season of European trees releasing large amount of allergenic pollen into the air. Some pollen proteins can exacerbate allergenic rhinoconjunctivitis (pollinosis) and allergic asthma by acting as antigens for the immune system. The most consistent signal is visible at the start of the season, the target variable of the current indicator. The starting of the pollen season is relevant also because patients are alerted in many regions by warning systems and mass media.
Pollen season has many definitions, depending on the target use. The definition relevant in the current context is a so-called "Clinically-relevant" pollen season, i.e., the period when concentrations of the specific pollen are sufficiently high to cause allergy symptoms. The general definition and the concentration thresholds for several aeroallergens were identified as a result of a Task Force of European Academy of Allergology and Clinical Immunology (EAACI).