Pollen allergy and hay fever

All the information about pollen allergy and hay fever that is published on our website is provided by the Belgian Aerobiological Surveillance Network, which is managed by the Mycology & Aerobiology service from the Scientific Institute of Public Health (WIV-ISP).

 

The grass pollen

In Belgium, the grass pollen season usually last from May 15th to July 15th.


During this period, we evaluate the daily risk to develop hay fever symptoms by taking into account the measured airborne pollen concentrations (pollen grains/m³) and the weather forecast.


The risk index can be: 

  • Null: No grass pollen grain is expected in the air. Consecutive days with this index usually announce the end of the grass pollen season.
  • Low: Low grass pollen concentrations in the air are expected but may be sufficient to cause allergic symptoms in highly susceptible individuals. The usual eviction measures are already recommended.
  • High: High grass pollen concentrations in the air are expected. Many individuals allergic to this pollen are susceptible to feel symptoms. The usual eviction measures are recommended.
  • Very high: Very high grass pollen concentrations in the air are expected. Most of the individuals allergic to this pollen are susceptible to feel symptoms. It is strongly recommended to avoid any activity outside.
 

The other main allergenic pollens in Belgium

We also measure the timing variations of the risk periods every year for the other main allergenic pollens.

 
Allergen Beginning of the season End of the season
Alder 15 February 2017 26 March 2017
Ash 16 March 2017 13 April 2017
Birch 25 March 2017 11 May 2017
Grasses 17 May 2017 24 July 2017
Hazel 15 February 2017 23 March 2017
Mugwort 26 July 2017
Oak 07 April 2017 26 May 2017

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