Soaring pollen levels this weekend could trigger deadly asthma attacks.
Experts said more than three million people in the UK had breathing problems which could worsen as temperatures start to soar.
Dr Andy Whittamore, from Asthma and Lung UK, said: ‘These attacks can leave people struggling to breathe which can be terrifying.
“When pollen levels are at their highest, it can be deadly for people with lung conditions, such as asthma, who can suffer severe symptoms and have life-threatening attacks.
“People should check the pollen and air pollution forecast for their area, to avoid going outside on high pollen days as much as possible.”
The doctor also advised people to use preventer inhalers to reduce airway swelling before it starts – and to wear rescue inhalers to relax muscles if pollen levels suddenly rise.
Britain will apply sunscreen during a five-day ‘Bermuda Bake’ next week as the mercury hits the mid-20s. Bermuda will descend from Sunday.
Jim Dale, meteorologist for the UK Meteorological Service, said: ‘This looks like the hottest period of weather so far this year and certainly qualifies as a mini heat wave.
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The south and east will experience the best of the heat, with temperatures up to 27°C. But as the mercury rises, so will the pollen, which will cause misery for hay fever sufferers and those with more serious respiratory issues.
Nearly 30,000 people die each year from chronic obstructive pulmonary disease, while nearly 1,500 people die from asthma attacks.
Former footballer David Beckham, 47, U2 singer Bono, 62, and Hollywood actress Sharon Stone, 64, all suffer from asthma.