The predicted thunderstorms could bring the perfect conditions for the phenomenon which can cause attacks
A dangerous combination of high pollen levels and stormy weather could drive a rise in the number of cases of thunder fever.
As North Wales is issued a warning for thunderstorms in the days ahead, asthma sufferers are urged to stay indoors due to the harmful phenomenon, which can prove fatal to some.
The Met Office has issued its very first thunderstorm warning for the region in its 164-year history.
The yellow warning is in force from 11am until 8pm on Friday, July 13 and covers the whole of the area.
And with the recent warm weather and very high grass pollen count, the impending storms could create the perfect conditions for thunder fever to occur.
Last year, 8500 people were hospitalised and nine died from asthma attacks after thunderstorms according to the Herald Sun.
For the event to occur, the perfect blend of conditions must be met: high pollen count in the air, humidity and a northerly wind.
During a thunderstorm, pollen grains in the air absorb moisture before exploding into tiny particles.
Winds then scatter the fine particles where they can easily be inhaled deep into the lungs, causing inflammation and irritation.
And for asthma sufferers, this can trigger an attack.
Sonia Munde of Asthma UK said an estimated 3.3million Brits had their asthma triggered by pollen: “Thunderstorms can have a devastating impact on people with asthma and trigger an asthma attack which could be fatal.
“Humid, stormy conditions break the pollen into much smaller particles, which are then inhaled more deeply into the lungs and can lead to life-threatening asthma attacks.”
People are advised to keep their medication to hand over the weekend in the event of symptoms being triggered.