A blanket of toxic fog could sweep across Nottinghamshire this weekend.
Forecasters issued an alert from the Department for Food, Agriculture and Rural Affairs (Defra) warning that the north could see the cloud today.
The dirty air, which originated in the Sahara, has come in from the continent and arrived in the south of England from France yesterday afternoon.
Defra has issued a moderate pollution warning for the south of England, with a high risk in the north today.
A forecast on the Defra Air Quality Index website said: “Moderate air pollution is likely to become more widespread on Thursday, potentially affecting much of England and Wales.
“Scotland and Northern Ireland, meanwhile, should retain predominately low air pollution levels.”
It continued: “With south-easterly winds from the continent dominating, the risk of moderate air pollution is likely to be widespread through this three-day period, with localised areas of high air pollution also possible.”
Those people who suffer from breathing conditions have been advised to be cautious when undertaking physical exercise, especially outdoors.
The smog could last across the region until Sunday.