Hay fever cases could double in next 50 years

Half the population may suffer from hay fever in the next 50 years, according to a report released today.

An estimated 16 million people - almost a quarter of the population - are currently affected by the condition. However, this number could double in future due to the effects of climate change on plant growing seasons, says Professor Jean Emberlin from the National Pollen and Aerobiology Research Unit.

Hay fever is caused by the body's immune system over-reacting to pollen released by plants. Symptoms include blocked nose, sneezing, runy nose and eyes, itchy eyes, throat and mouth.

For many the hay fever season begins in late May with the release of grass pollen, which triggers symptoms in about 95% of hay fever sufferers. But for some people who are allergic to tree pollen such as birch, it can start as early as late March.

Based on current climate change data, Professor Emberlin predicts that the combination of warmer, and drier spring and summer weather in combination with wetter winters, will result in longer pollen seasons.

There is evidence that this has already happened, she stated, as the birch pollen season now begins up to a month earlier than a few decades ago.

Warmer weather could also lead to the spread of Ragweed and Pellitory of the wall which both have allergy-inducing pollen, and allow other types of crops to be grown which may add to the pollen load.

"As the climate becomes warmer and drier the range of crops will change. In a few decades it is likely to be warm enough in some ares to grow olives. These have very allergic pollen," said Professor Emberlin.

However, according to the report, some areas of the country would be harder hit than others. Northern parts of the country with shorter growing seasons would still have shorter pollen seasons, and western coastal areas with higher rainfall would have lower pollen counts.

Worst affected would be people living in cities. Not only would they have to cope with the warmer weather and increased pollen count, the air pollution could also alter proteins on the surface of the pollen making it more allergenic.

This article was published on Thu 11 June 2009