In the UK the Met Office has been flooded with calls about the mysterious dust which has coated cars and windows along the east coast.

Arable fires in Russia (see related story) were initially thought to be to blame, but experts claim that while they may play a part, the main factor is record levels of pollen birch blown over from Denmark.

In the last couple of weeks, pollen-loaded air over large parts of Europe has been clearly visible in early morning satellite images, showing up as a yellow-green haze, extending out over the North Sea and even the North Atlantic.

The pollen season for birch started with a bang in Denmark, with record-breaking counts on Sunday 7 May.

In Copenhagen every cubic meter of air contained an average of 4,381 birch pollen, well over the 13 year old record of 3,899.

The Danish Meteorological Institute and the Danish Asthma and Allergic Society have been recording pollen count in Copenhagen since 1977, and in these last 29 years counts have increased dramatically.

Perfect weather conditions this year – a wet April and a sunny, summery start to May – have led to a veritable explosion of birch pollen with catkins releasing a massive load of pollen grains over a period of just a few days.

Contributing to the trauma of Danish allergy sufferers, a consistent easterly wind is bringing birch pollen all the way from Russia, the Baltic States and Sweden – countries that have experienced intensive birch flowering in the last three or four weeks, with a high to very high pollen count at times.

In Southern and Central Finland, birch flowering is at its peak and the counts of airborne birch pollen are soaring. For several weeks, Southern and Eastern parts of the country have suffered extreme pollution.

In Helsinki, heavy air and a visible haze have cloaked the city for a long period of time.

In Germany, France, Poland and the Czech Republic, birch pollen conditions have been extreme, with people who normally have no allergic reactions to pollen, suffering from asthma attacks.

After a long winter, the birch trees have burst into bloom and scattered their pollen into the air at more or less the same time.

In the last two weeks there has been little or no rain in Central and Northern Europe, something which has aggravated the situation by allowing the pollen to remain airborne.

Sam Bond

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