The Department of Health said last night that with the advent of summer smog, hospitals are on standby for a rise in admissions because of respiratory conditions.

Those at risk include hayfever sufferers, generally young people up to 30 years old, who might be unaware that they are vulnerable. According to the Met Office health forecasting unit, a rare mix of severe ozone pollution, hot temperatures, high levels of pollen and violent thunderstorms could set off asthma attacks.

A similar combination in London on June 24, 1994, caused thousands of asthma cases that overwhelmed hospitals and clinics.

Hospitals were prepared yesterday for further admissions after a smog alert. Today the smog is not the mixture of smoke and fog that dogged big cities before the introduction of clean air legislation, but the effects of the sun on car fumes and solvents producing ground level ozone.

With the heatwave about to end, the National Heart and Lung Institute said that the health of thousands could be affected by the added risk of storms. Extremely powerful thunderstorms can trigger asthma attacks by sucking up huge amounts of air and pollen from the ground. Violent updraughts in the thunderclouds shoot the pollen grains high and shatter them in the freezing conditions at the top of the clouds.

Cold air loaded with the pollen debris then plunges down and floods the ground with a vast dose of pollen particles, which are easily breathed deep into the lungs and set off a violent allergic reaction in hayfever sufferers. With high levels of ozone already breathed in during the day, the extra assault to the body becomes even more dangerous.

William Bird, clinical director of health forecasting at the Met Office, said: “The people at risk have never had asthma before. They have no medication, they’re terrified.” The behaviour of the thunderstorms is crucial to triggering asthma, for reasons not entirely understood. Mark Gibbs, of the Met Office, said: “We don’t know how many people might be affected or where exactly it could happen.”

The thunderstorms are likely to affect the Midlands and pass into the Thames Valley. London could be especially at risk because the storms are forecast to arrive in late afternoon or evening when ozone and pollen levels will be high.

Hayfever sufferers should stay inside in the cool and away from pollen, and avoid strenuous exercise. Anyone feeling wheeziness, tight chest or other breathing problems should seek medical advice.

“I’m asthmatic myself,” Mr Gibbs said. “The important thing in an attack is to keep calm, keep relaxed, because breathing is more difficult if you panic.”

Martyn Partridge, Professor of Respiratory Medicine at Imperial College London, had no doubt that hospital admissions would rise. “For people with asthma, the key thing is that they should be taking their preventive therapy. They should also not exercise. People with chronic obstructive pulmonary disease should stay indoors, away from polluted areas, and seek medical advice rather than be stoical,” he said. “There have been well-documented episodes of asthma epidemics after storms.”

After consultation with the Department of Health, the Department for Environment, Food and Rural Affairs advised people to reduce smog by avoiding making unnecessary short car journeys.

Ben Bradshaw, the Minister for Local Environmental Quality, said: “Air pollution, combined with the recent warm and sunny weather, has led to a summer smog. People sensitive to air pollution, such as those with heart and lung disease, should be aware of the heightened risk to their health so they can take sensible precautions, such as avoiding exertion outdoors on hot afternoons.”

In the 2003 heatwave up to 800 premature deaths may have occurred as a result of the poor air quality.

BREATHE EASY

If you are having an asthma attack:

• Sit down with your hands on your knees
• Try to slow your breathing and relax
• Take your usual dose on your reliever inhaler
• Continue to take one puff every minute for five minutes
• If the symptoms continue after five minutes, call a doctor Asthma UK Advice Line 08457 01 02 03

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