THE worst air pollution in 60 years is sweeping through southern England today threatening the health of the sick and vulnerable.
Defra has warned people to be braced for "very high" levels of air pollution over the next few days.
Large swathes of England and Wales will see high levels of pollution, the Department for Environment, Food and Rural Affairs has said.
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 spokeswoman said.
The Defra forecast added: "The current elevated pollution levels over parts of the UK are caused by light winds allowing the build-up of pollution, plus dust from the Sahara contributing to pollution levels."
But the air pollution is expected to ebb away by Friday.
However, people with heart and lung conditions have been warned to avoid strenuous activity and consider wearing masks if outside.
This week people found their cars to be covered in a light coating of red dust. The Met Office said that a large amount of sand and dust was swept up by storm winds in the Sahara Desert.
Experts said that the airborne particles of dust were blown north to the UK where they combined with our warm air and were deposited during showers.
A Defra spokeswoman said: "The high level of air pollution this week is due to a combination of local emissions, light winds, pollution from the continent and dust blown over from the Sahara.
"We want to keep improving air quality and have introduced a new five-day forecast service in addition to investing heavily in local and transport initiatives to tackle this issue head-on."