People in the United Kingdom with asthma and lung conditions should avoid outdoor exercise during the next few days as a Sahara dust storm could bring pollution to dangerous levels, experts say.

Pollution levels have increased as light southeasterly winds and continental air flow bring up dust from the Sahara desert, The Telegraph reported. The dust is expected to pass by Friday.

"The people who are most vulnerable are people with chest diseases and heart disease, the very young and very old because their immune systems cannot cope as well. It is a serious situation," Keith Prowse, honorary medical adviser to the British Lung Foundation, told The Telegraph.

Asthmatics and those with cystic fibrosis and other lung conditions will be at greater risk along with the elderly, Prowse said. They should avoid jogging outside and carry their inhalers at all times, possibly doubling their use if the dust continues.

"We usually see an increase in people needing medical help in these weather conditions," he told The Telegraph. "The problems may go on for a few days even when the pollution has cleared. Over that period they are more vulnerable to effects of infection and irritation in the home. So don't go out if you can help it and don't do strenuous exercise."

Those with asthma already suffer from pollen at this time of year. Asthma attacks are dangerous and take around 1,200 lives annually, Angela Jones, asthma nurse specialist for Asthma UK, told The Telegraph.

Readings of air pollution are rated on a scale of one to 10, and the Department for Environment, Food and Rural Affairs has stated that readings could reach eight or nine, BBC News reported.

The forecast for large parts of southern England was for "high" and "very high" levels of pollution, according to The Telegraph. Most of England is expected to see moderate to high levels.

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