Air quality and pollen allergies

(Visit the Sciensano website www.airallergy.be  for more information on the different types of allergenic pollens)

The impact of air quality on our health depends on many chemical and biological elements carried in the air. It is known that the amount of pollen grains present in the air closely correlates with the appearance of allergy symptoms in sensitised people. These allergies can be expressed chronically in line with pollen seasons. These are more or less regular but intensity and timing can vary from year to year.

The measurements of pollen levels in the air are carried out by the Belgian Aerobiological Surveillance Network of the Federal Research Centre, Sciensano (www.sciensano.be). It is possible to monitor the evolution of these rates daily on the AirAllergy network site (www.airallergy.be).

Predicted risk index

Grass pollen allergy, commonly known as “hay fever”, is most prevalent in Belgium. The pollen season for this large family of herbaceous plants extends over a long period, on average from 15 May to 15 July in Belgium. Generally speaking, it is very difficult to predict future pollen counts. They are highly dependent on weather conditions during flower development and when pollen is dispersed in the air, but also on biological factors specific to each plant species.
In season, it is nevertheless possible to estimate the risk of developing symptoms of an allergy to grass pollen one day in advance, on a 4-point scale. This daily risk index is based on the pollen concentration measured the day before in the air by the Belgian aerobiological monitoring network and on forecasts from the Royal Meteorological Institute (www.meteo.be).The different risk indices are as follows:

• None: No grain of grass pollen is expected in the air. The continuation of this index on several consecutive days generally announces the end of the grass season.

• Low: The concentrations of grass pollen expected in the air are low but would be sufficient to trigger allergic symptoms in highly-sensitised individuals. Precautionary advice is already available.

• High: High concentrations of grass pollen in the air are expected. Many people who are allergic to this pollen are likely to experience symptoms. Precautionary advice is already available.

   

• Very High: Very high concentrations of grass pollen in the air are expected. Most people who are allergic to this pollen are likely to experience symptoms. It is strongly recommended to avoid outdoor activities.

The pollen and fungal calendar is available here.

Main allergenic pollens in Belgium