Spring is already arriving earlier in many parts of the world, lengthening the allergy season, and the effects of this are likely to be compounded by increases in carbon dioxide levels, which will probably intensify allergic symptom, specially for those with inhaled allergies.

When researchers studied the growth of ragweed under conditions simulating projected future CO2 levels, the plants produced 55% more pollen than those growing in today's climate. (Environmental Health Perspectives, June 2006; vol 114: pp 865-869)

However, plants not only produce more pollen when exposed to higher CO2 levels, but also grow bigger and utilise water more efficiently - a welcome prospect, according to some commentators, as it will produce larger crops and promote a greener planet.

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Click here for more research on the possible causes of asthma

First Published in August 2006

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