Nottinghamshire is set to be affected by high levels of air pollution on Friday.
According to the Department for Environment, Food and Rural Affairs, high levels of air pollution are expected across northern, eastern and central England, with very high levels in the far south-east of England for a short time.
On Saturday, clearer Atlantic air is due to spread across the country, bringing air pollution levels down to low levels across the majority of the UK.
A Defra spokesman said that during times of high air pollution adults and children with lung problems and adults with heart problems should minimise strenuous physical exercise outdoors.
The spokesman added: “People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertion.
“Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.”
The warning comes after the county was affected by a cloud of ‘toxic smog’ last month.
The cloud on March 19 that travelled across much of Britain was caused by a combination of home-grown smog, mixed with air pollution from the continent.