Millions of Brits could be at risk from 'thunder fever' this week as downpours trigger a potentially dangerous reaction.
Hay fever sufferers have been warned by experts to be aware of the phenomenon, which occurs when storms raise pollen and mould from the ground, ahead of widespread forecasts of thunderstorms across the country.
But asthmatics could also possibly be left at risk from a potential adverse response to the storms, with an estimated 60% of all people with the condition being sensitive to pollen.
A case of thunder fever sees the sufferer react badly to 'pollen showers' that bring minute pieces back down to the ground after being drafted upwards by the storms, with these being so small as to become lodged in the person's lungs and becoming allergenic.
Detailing the risk from thunder fever, allergy specialist Dr Sophie Farooque said: "Normally pollen (& moulds such as Alternaria) are too large to enter the lungs. But when a thunderstorm is brewing, updrafts of air can lift whole pollen grains up into the clouds."
"When exposed to moisture, these grains rupture into tiny pieces making them highly allergenic.
"Windy downdrafts then carry these fragments to ground level, resulting in a 'pollen shower' where people can inhale the minute fragments deep into their lungs, triggering an asthma attack."
She also advised that people with asthma and/or hayfever should remain indoors and close windows during a storm, wear a mask if going outside is essential, and take antihistamines if you suffer an attack.
Anyone suffering from a severe asthma attack should use their inhaler as instructed by their doctor and have someone call 999 if symptoms do not improve.
A yellow warning for thunderstorms "with torrential rain" has been issued by the Met Office for Wednesday (August 17) for an area covering the south of England and some parts of Wales, meaning potential disruption is likely.
Yesterday saw some areas of the UK suffer from flash flooding as heavy rain fell on bone-dry heatwave-stricken ground.
