Hot weekend means people with lung or heart problems should avoid outdoor strenuous activity, warns Defra
Air pollution warnings have been issued with temperatures forecast to climb towards 27C (80F) in south-east England and the Midlands this weekend.
Some parts of Britain will be hotter than areas of the Mediterranean, but the warm weather will be accompanied by moderate levels of air pollution, which can cause breathing difficulties in vulnerable people. Areas of south-west England and western Scotland could be at higher risk by Sunday. The highest levels are expected in Northern Ireland.