The birch pollen season has officially begun, according to AirAllergy, Sciensano's Belgian monitoring network, on Thursday. The season is starting earlier than usual due to the mild weather in recent weeks, which has caused birch trees to bloom earlier than usual.
After the hazel and alder pollen season, birch pollen is now also making its appearance. Birch is one of the most allergenic trees in Belgium because of the large amount of pollen it produces. At least one in ten Belgians is sensitive to birch pollen and may experience symptoms such as sneezing, watery eyes or breathing problems.
"In recent days, we have already reached a concentration in Brussels of more than ninety birch pollen grains per cubic metre of air," says Astha Tiwari, scientific officer at Sciensano. The concentration may increase further in the coming days, especially if the weather remains dry and windy. "When the threshold of eighty birch pollen grains per cubic metre of air is exceeded, most allergy sufferers develop symptoms."
Normally, the birch pollen season does not start until the end of March, but due to the exceptionally mild temperatures of recent weeks, it is starting much earlier than usual this year. As a result, there is an overlap with pollen from hazel and alder trees, which are also still present in the air. The flowering periods of these trees are increasingly overlapping, resulting in a virtually uninterrupted pollen season for allergy sufferers.
Alder pollen levels have been exceptionally high this year, with a record high in Genk, where a seasonal peak of 5,316 pollen grains per cubic metre of air was measured.
The most common clinical symptoms of pollen allergy are stinging, itchy, watery and red eyes, sneezing, nasal congestion, blocked sinuses, runny nose, breathing problems, loss of taste and smell, and itching at the back of the mouth or throat.
