Sahara Dessert sand on its way to Britain as Defra warns to expect high pollution

Sand blown more than 3,000 km from Africa's Sahara Dessert is expected to contribute to very high pollution levels across parts of England on Friday, the British government warned Wednesday.

The Department for Environment, Food and Rural Affairs (Defra) said current forecasts show air pollution levels are expected to rise over the next few days and reach high or very high levels on Friday.

"This is due to locally generated particulate matter combining with pollution blown in from the near continent (European mainland), and a contribution from Saharan dust," Defra said in a statement.

The levels of air pollution are forecast to become high across central, eastern and northern England, with locally very high pollution levels for a time in the far southeast area of England, due to a flow from the south.

The government department said it expects the high pollution levels to have cleared by Saturday morning, due mainly to clearer air from the Atlantic spreading across all areas of the country. Defra added it will be updating public advisories with latest forecasts and health advice.

A year ago Sahara dust left thousands of cars across many parts of Britain coated in sand blown in from Africa. One of the vehicles with a coating of sand was Prime Minister David Cameron's official car, parked outside 10 Downing Street.

A spokeswoman at the Met Office said: "The wind can blow strongly over deserts, whipping up dust and sand high into the sky. The wind in the upper part of the atmosphere then transports the dust in the direction in which it's traveling, in this case towards the UK. "

"When the raindrops fall, they collect particles of dust on the way down. Then when the raindrops land on something and eventually evaporate, they leave behind a layer of dust," she explained. Endit