IT may be causing problems for people with health problems, but the smog is having a positive effect for one business owner.
Car washes have seen an increase in customers coming to get the muck and dust cleaned off their cars.
Ray Blackburn, co-owner of Cricketfield Car Wash in London Road, Southend, said: “The boys in the car wash have had a really rushed day, they have been very busy.
“There has been a real upsurge in trade because of this muck, I’ve been in south London and it’s the same there as well.”
The latest smog attack is being compared to the Great Smog of 1952 in London, which was linked to the deaths of 12,000 people.
People suffering the effects of high levels of pollution - including sore eyes, coughs and sore throats - should cut down the amount of activity they take outside, experts have warned.
Asthmatics might need to use their blue reliever inhalers more often as they could be prone to attacks today and over the next few days. Other people with lung and heart problems, and those who are older, should also avoid strenuous exercise or activity.
The advice, from Public Health England (PHE), Asthma UK and the Department for Environment, Food and Rural Affairs (Defra), comes after a warning that people in parts of England should be braced for the highest level of air pollution recorded by Defra.
This morning's forecast says large parts of southern England have "high" levels of pollution, with some parts "very high".
Defra ranks air pollution from one to 10, with one being the lowest and 10 the highest.
Across most of England, moderate to high air pollution levels are forecast, with level 10 expected in parts of East Anglia and the East Midlands.
"This is due to light easterly winds continuing to bring in pollutants and allowing local pollutants to remain close to source," the forecast from Defra said. "There may also be some component due to Saharan dust."
Tomorrow, high levels of pollution are forecast for East Anglia, the Midlands, Lincolnshire, eastern parts of Wales, through the Wirral and the north coast of Wales.
High levels will move north over much of coastal north-west England, to south-west Scotland and the north-east of Northern Ireland.