Hay fever patients are starting to sneeze earlier in the season, but this year there have been few complaints

In the Netherlands, it is estimated that between 800,000 and 1.5 million people suffer from hay fever. This allergy to pollen or pollen has a different course of complaints every year. The sooner tree species and grasses come into bloom, the sooner their pollen will swirl through the air and cause itchy noses and watery eyes.

The shift in the hay fever season can be seen, for example, in the nuisance of the birch, one of the trees that cause hay fever complaints in the spring. In the late 1970s, the peak time of birch pollen was around May 1, according to figures from the Leiden University Medical Center (LUMC), which publishes weekly about the number of pollen in the air. Nowadays, this peak is about three weeks earlier: this year, for example, on April 6.

This does not mean that the problems for hay fever sufferers are now behind them. The flowering period of many grass species common in the Netherlands will begin in the coming months. In summer and autumn, weeds such as sorrel, plantain and ragweed can also cause complaints.

At the moment, the hay fever complaints in the Netherlands seem to be not too bad. The number of people who have reported this to their GP has been lower this year than in previous years, according to figures from Nivel, the research institute that collects figures on primary care.