Doctors warn that thunderstorms resulting from Britain's heatwave could trigger an asthma epidemic.
Researchers have verified the long time complaints of asthma sufferers who have claimed that their condition worsened during thunderstorms.
Research has revealed that storms sweep up and collect atmospheric particles that are then released through the rain and concentrated in the air close to the ground.
As asthmatics with an allergy to grass pollen breathe in the concentrated pollens there is the onset of an asthmatic attack.
During one epidemic hourly trapped pollen counts in a thunderstorm were found to be between four to 12 times higher than normal.
Doctors and other research experts have therefore warned asthmatics take special precautions during thunderstorms, and probably increase inhaler use.
The case of June 2005 end when a sixfold rise in emergency admissions for asthma was reported over one weekend was the result of thunderstorms.
Asthma UK's Chief Medical Adviser, Professor Martyn Partridge, said, 'Asthma UK warns those with asthma or a tendency to asthma to make sure that they keep their medicines with them at all times over the next 24 hours.'
'Thunderstorms occurring at a time when the pollen levels have been high have been associated with previous epidemics of asthma attacks.'
'It is believed that the inversion of temperatures, that occurs at the time of thunderstorms, brings down pollen granules which the moisture then breaks up to a size that is breathed in to the lungs of those with asthma in large quantities, inducing attacks even in those who have just previously had mild asthma.'
An Asthma UK spokeswoman added, 'They should keep a close eye on their condition either by taking regular peak flow readings or recording their symptoms.'
'If they are at all worried about their asthma they should contact their doctor for further advice.'