Health experts called on millions of people in Britain to stay indoors more often as the country continues to experience high levels of pollution.

The advice from Public Health England, Asthma UK and the Department for Environment, Food and Rural Affairs (Defra) warned people with lung and heart conditions and the elderly to avoid strenuous activity outdoors and cut down the amount they do outside as Defra recorded the highest level of air pollution across England.

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.