AIR pollution in Bolton is still higher than usual as the UK continues to grapple with the effects of sand whipped up by a storm in the Sahara desert.
The town's air quality index is set to be 5 for the rest of the day, which the Met Office classes as "moderate".
But much lower levels are forecast for Friday, Saturday and Sunday as the smog clears.
The elevated pollution levels have been caused by a combination of light south-easterly winds, the continental air flow and dust which has blown up from the Sahara desert.
A "very high" pollution level of 10 is predicted to hit the East Midlands today, with Liverpool and the Wirral predicted to experience "high" pollution later.
Prime minister David Cameron told the BBC this morning that he abandoned his morning run today in light of dense smog in London, which has also caused cyclists in the capital to wear masks.
He said: "It is unpleasant, and you can feel it in the air.
"The advice I would give to people is listen very carefully to what the Met Office is saying about the weather.
"I didn't go for my morning run this morning. 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."
A low air quality level of 3 is forecast for Bolton tomorrow.