Smog danger alert

Pollution is reaching critical levels in central London today, according to experts.

The Government has been forced to issue a warning as Met Office forecasters said temperatures today could reach 31C.

Forecaster Jim Galvin said: "Smog and pollution levels are very high at the moment. The air is just sitting there, not moving, which means there is nothing to take the pollution away."

The Met Office said the amount of low-level ozone, which can cause respiratory and lung disease, is believed to be extremely high.

Gary Fuller of King's College London, which monitors air quality in the capital, confirmed pollution levels had been rising steadily. "We've seen an increase in PM10 [a mixture of tiny dust particles] since the weekend," he said.

Last year readings of low-level ozone, caused by exhaust fumes, were at their highest since records began. A spokeswoman for the Department of Environment, Food and Rural Affairs said: "Those suffering from lung diseases, including asthma, particularly if elderly, should be aware that their symptoms might worsen."

The spokeswoman added that those affected should avoid making car journeys and exercising outdoors in the afternoon.

Professor John Henry of Imperial College said: "Hot, muggy weather and increased levels of ozone are the key to asthma, and that is exactly what is happening at the moment. The effects could be devastating.

"Those with mild asthma could be seriously ill, and we could find people with no previous problems suffering on a day like today. It's a very serious problem."

It is estimated that London's air pollution causes about 1,600 premature-deaths and leads to another 1,500 hospital admissions every year. For sufferers, staying indoors could be the answer.

Professor Henry added: "Being inside will cut down exposure, and keeping away from traffic and fumes is also a good idea."

Experts claim that pollution in London could reduce lifespans by up to 10 years.

As well as high ozone levels, the quantity of particles in the air is very high.

The most recent figures, produced by King's College London, reveal levels of PM10 were also dangerously high on 60 days last year.

Professor Henry warned that the particles could lead to heart problems. "These particles build up and can bring on heart attacks in many cases. When there is no wind, they just stagnate in the air."