About 20 percent of the Dutch people suffer from hay fever, writes the LUMC. In an environment with a lot of allergy-causing pollen in the air, they can get serious respiratory complaints. For these people it is important that not too many trees are placed together with pollen that can cause a strong allergic reaction, says the medical center.
The amount of pollen a tree produces depends, among other things, on the climate conditions. For example, there are trees that can cause unpleasant complaints in hay fever sufferers in Southern Europe, but hardly any in the Netherlands.
Knowledge is missing
Municipalities place a lot of greenery in new residential areas. ‘That is of course a good thing,’ says LUMC biologist Letty de Weger. ‘But there is often a lack of knowledge about which trees can cause hay fever complaints.’ The Tree Compass shows which trees spread a lot of pollen that can cause allergies. In the Netherlands, these are, for example, birch, alder and hazel. The birch can often be found in neighborhoods, says the medical center, ‘because it is a beautiful and strong tree that can withstand low temperatures’.
It is not De Weger’s goal to get a tree like the birch out of the Netherlands, ‘but we have to make sure that entire streets are not filled with alders and hazels, for example. Or that a large birch is placed exactly in a schoolyard.’