UPDATED: Birch pollen season hits Copenhagen

If you’ve woken up today feeling ill or with a worse hangover than expected, it’s probably because you’re among the 25 percent of the population who are birch pollen allergy sufferers


The dreaded birch pollen season started today in the Copenhagen region where DMI recored a count of 60 particles per cubic metre − a measurement that could skyrocket over the next few days should the sun shine for long periods.

So if you woke up this morning with flu-like symptons, or a worse hangover than expected, it could be because you're among the 25 percent of Copenhageners who suffer from a birch pollen allergy, and it is advised you visit your doctor as soon as possible in order to get a prescription.

The birch pollen season, which normally starts in mid-April but was delayed this year by the long winter, can last for a period of anything from a week until a month. With plenty of sunshine expected over the next week, it will probably be closer to the former.


Spring is not only about blossoming flowers, laughing children and a sun happily awakening after a long lazy winter. For many it is the time of year that their eyes start watering and itching, their nose begins tickling and they feel a constant need to sneeze, because spring is also when the pollen season starts.

The worst culprit in Denmark is birch pollen. It catches many new arrivals to the country off-guard, because if you haven’t lived in an area with a high concentration of birch trees or had previous allergy problems, you might not be aware that you are among the 25 percent of people allergic to it. Even worse, this year the birch pollen count promises to be astronomically high due to the late start of spring and the long days of sunshine forecast by the meteorological institute DMI over the coming weeks.

“On a sunny day, the pollen numbers are likely to be high, as opposed to a grey, cloudy day when the numbers are more likely low,” Lise Nørgaard, the head of communications at the asthma and allergy association, Astma-Allergi Danmark, told The Copenhagen Post. “So unfortunately the weather we have all been longing for also means a season many people have been dreading.”

Additionally, a late start to spring increases the risk of higher daily concentrations, as the trees have the same work to do in less time.

“The trees need the light and heat from the sun to blossom, so as the winter finished late, the pollen season starts late,” warned Nørgaard.

Astma-Allergi Danmark and DMI's pollen callender of the average pollen seasons. From left to right they read 'hazel', 'alder tree', 'elm', 'birch', 'grass' and 'mugworth' (Photo: Astma-Allergi Danmark)

 “The average start for the birch pollen season is April 19, but due to the long winter, we expect a one, maybe even two-week delay."

Birch tends to be the fourth pollen to hit the air every year, following alder, hazel and elm. All three of those seasons were delayed and had much higher concentrations than normal.  The alder and birch pollens are 80 percent similar, which might explain why birch pollen allergy sufferers have already reported symptoms.

But the birch season is the one to watch out for. According to Astma-Allergi Danmark it is, along with grass, the most allergenic pollen, and many people will soon be reaching for their allergy pills or nasal sprays, for which a doctor's prescription is necessary.

The pollen, which is counted by hand, is measured according to the average number of pollen in a cubic metre of air 15m above the ground over a 24-hour period.

Nørgaard also warned that pollen numbers in Copenhagen are usually much higher than in other parts of the country and that Danish newcomers to the capital often only discover they have an allergy when they move here.

“It’s been discovered that Copenhagen is a major birch pollen bomb. There are a lot of birch trees in the city, which has seen the amount of pollen rise by 400 percent in the past 30 years,” Nørgaard said. “Furthermore, when pollen and traffic pollution mate, it creates a kind of killer pollen, which is a lot more allergenic than pollen on its own.”

Currently, alder, hazel, elm, birch, grass and mugworth are the six different types of measured pollen in Denmark, but according to Nørgaard, another one is on the way, and it is extremely allergenic.

Astma-Allergi Danmark advice that this plant, ragweed, is killed if discovered, to prevent it from spreading (Photo: Carsten Ambelas Skjøth)Ragweed is slowly making its way up from the south. Astma-Allergi Danmark warns against this new plant and encourages anyone who discovers it to remove it immediately.

“Ragweed is not yet a pollen threat, but it will be if it spreads," Nørgaard said. "It is extremely allergenic, and the season doesn’t end until October or November, which is later than the other pollen,”

In the meantime, there is plenty for people with allergies to worry about.

“Keep an eye on the daily pollen number. [Astma-Allergi Danmark] has a free app you can download and receive pollen updates every day or you can see them on DMI,” Nørgaard said.

“It’s also a good idea to wear sunglasses when you’re outside as they will reduce your eye symptoms. I also recommend that you don’t hang your laundry outside and that you wash your hair before going to bed to wash out the pollen.”

As the pollen concentration is higher when the sun is shining, Nørgaard said it is a good idea to air out in the morning or in the evening rather than during the day when the sun is out.

She also stressed the importance of seeing a doctor if you suspect you have an allergy and to get tested so the right medicine can be prescribed.

And if nothing else helps, Nørgaard’s best advice is to simply “move to the west coast. There is less pollen there because of the wind and the sea.” 

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