Smog causes surge in 999 calls

The LAS said there was a 14 per cent increase in 999 calls, due to the increased air pollution that has hit the south and east of the UK – caused by a mixture of Saharan dust, domestic pollution and continental emissions.

Pollution levels reached level nine on Thursday morning, on a Defra scale from one to 10. Very high levels of air pollution are also predicted for the East Midlands.

Watch the video: London under smog - at high-speed

Some schools in London have banned children from playing outdoors and people have been warned to avoid strenuous physical activity.

Below: eight extraordinary pictures of London in the smog.

Prime Minister David Cameron told the BBC how he had been forced to cancel his morning jog because of the poor air quality.

“I didn’t go for my morning run this morning,” he said. “I chose to do some work instead. You can feel it.

“But it’s a naturally occurring weather phenomenon. It sounds extraordinary, Saharan dust, but that is what it is.”

How long will it last?

Following very high levels of pollution across parts of England, a change in the weather will bring a significant improvement in air quality during the next 24 hours, writes Channel 4 News Weather Presenter Liam Dutton.

During the last few days, the wind has generally been coming from a south easterly direction, bringing in pollution from continental Europe, as well as Saharan dust.

However, the wind will change to a south westerly direction on Thursday night. This will bring in cleaner air from the Atlantic and sweep the poor quality air away eastwards.

Sotiris Vardoulakis, head of air pollution at Public Health England’s centre for radiation, chemical and environmental hazards, said most people will not be affected by short-term peaks in air pollution, but some groups, such as those with existing heart or lung conditions, may experience increased symptoms.

“On occasions where levels are high, adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms,” he said.

“Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.”