A toxic cloud of dirty air from the continent could be heading towards Chester at the end of the week.
The Department for Food, Agriculture and Rural Affairs (Defra) has issued a warning of 'moderate' air pollution for the south of England from Thursday onwards.
Forecasters said the toxic cloud from the Sahara desert could spread to northern parts of England by Friday, with a risk of 'high' air pollution in some areas.
According to the Defra air pollution index, in Cheshire the conditions will be 'moderate' and a health warning has been issued by officials for people suffering with lung problems.
A Defra forecast 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.”
The forecast for Friday said: “With southeasterly 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.”
Health advice suggests that adults and children with lung problems, and adults with heart problems, should reduce physical exertion particularly if they are outdoors.
People with asthma may find they need to the use their inhaler more often, while older people should also reduce physical exertion.
The dust cloud, formed from the Sahara desert, is expected to become widespread affecting much of England and Wales by Thursday.
It is expected to continue from Friday to Sunday.
