Bad news for one million Belgians with hay fever: grass pollen season has started | Interior

The grass pollen season is now gradually starting and that is very common. The first grass species, such as the large foxtail, are starting to bloom and the highly allergenic pollen of grass can cause more and more hay fever complaints. The peak period of the grass pollen season normally takes place in the second half of May and June and most people experience complaints. If it remains cold in the near future, the peak period can start a little later.

Those who (only) suffer from a birch pollen allergy will experience nuisance for a few more weeks. By mid-May, the tree pollen season is over and people who only suffer from tree pollen can breathe a sigh of relief. Other tree species, such as ash and willow, are also still flowering, but the pollen from these trees is mildly allergenic and causes hay fever complaints in few people.

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The weather plays an important role in the extent to which nuisance is experienced. At the beginning of this week it is cold for the time of the year with maxima of 9-13 degrees. This inhibits the development and flowering of the grass, so that the amount of pollen that ends up in the air is still limited. Sometimes showers pass over that clean the air. However, there will also be long dry periods during which complaints may arise. The showers also ensure moist soil, allowing the grass to grow and bloom well.

^{Later in the week it seems to slowly become less cold, but this is still uncertain. When it actually gets warmer, the growth and flowering of grass will accelerate. And the risk of hay fever then increases.}