Usually pollen levels are high every two years. Parameters are several, but if extensive flowering has occurred last year, trees are usually hardly flourishing equally in the following years.
"It is much more common for pollen to be scarce for two consecutive years, than for two consecutive years," said Pia Östensson, a biologist from the Swedish Museum of Natural History.
In the rest of the country, and especially on the west coast, it seems difficult, while the east coast seems to be treasured. If it is difficult now, it's mostly about high levels of garbage and al. Last year, Hassel seldom flourished, so this year he could give an extra blow.
– Hassel is still blooming this year, but now it is downhill and should basically flourish. Most of the allergy on the belt reacts to the clay and to all, says Pia Östensson.
During the regular season of pollen, breeze usually causes high levels of pollen. This year, it's not so much about the eastern shores, so the levels should be rare. The breeze will usually start in late April.
"I would be surprised if this season was worse than last year," says Pia Östensson.
However, if you went through central station Uppsala during February and March, it is not strange if you had any problems. There are several instances of the variant of the casing.
"Hassel had very long curtains this year, so I'm not surprised if people in Uppsala have problems. By planting such trees in the urban environment, you are prolonging the pollen season, there is not much in the cities, says Pia Östensson.