Weather

Pollen allergy and hay fever

As soon as the first pollen grains appear again in the air, the dates of beginning and end of the season will be updated in the overview below.

AllergenBeginning of the seasonEnd of the season
Alder05 February 202331 March 2023
Ash17 March 202329 April 2023
Birch29 March 202316 May 2023
Grasses17 May 202301 August 2023
Hazel06 January 202326 March 2023
Mugwort22 July 202302 September 2023
Oak27 April 202325 May 2023

Birch

Grasses

ColorLevelRisk
NullNo pollen grains are expected in the air. The risk of symptoms is theoretically absent, although very local exposure can trigger allergies.
LowLow concentrations of pollen in the air are expected. For very sensitive people, these few pollen could induce allergy symptoms. The usual avoidance measures are already recommended.
ModerateModerate concentrations of pollen in the air are expected, causing symptoms for people with pollen allergies. The usual avoidance measures are recommended.
HighHigh concentrations of pollen in the air are expected. Many people who are allergic to this pollen are likely to develop symptoms. The usual avoidance measures are recommended.
Very highVery high concentrations of pollen in the air are expected. Most people who are allergic to this pollen are likely to develop symptoms. It is strongly recommended to avoid all outdoor activities.

The information about expected pollen allergies and hay fever is based on the SILAM pollen transport model. The basic model comes from the Finnish Meteorological Institute. In collaboration with Sciensano, the RMI has adapted this model specifically for Belgium. Sciensano's Mycology and Aerobiology department has decades of pollen observations in Belgium and supports the pollen model and pollen allergy risk estimation.

For more information on the allergenic pollens, please visit the website www.airallergy.be of Sciensano.

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