King George II is said to have described the British summer as, “three fine days and a thunderstorm”. Today, in our climate changed times, a few hot days, a smog alert and flash flooding would be more accurate.

In August’s weeklong heatwave, strong sunlight caused a cocktail of air pollution to form over most of England, reaching level seven on the government’s 10-point warning system. This was mostly caused by ozone forming close to the ground but a plume of particle pollution from industry, traffic and agriculture also settled over the capital on the night of 11 August.

The London mayor posted warnings on electronic displays at bus stops and tube stations. Messages were sent via the AirAlert and other services in the south-east, but you had to visit specific websites to find the warnings from central government.

During the 2003 heatwave, ozone pollution was estimated to have led to between 423 and 769 deaths in England and Wales.

Simple precautions such as avoiding exercise in the second half of the day can help to reduce exposure.

Campaigners including Simon Birkett, the founder of the Clean Air in London group, have called for this type of advice to be fully integrated into heatwave warnings and weather forecasts.

England’s pollution levels soared during August heatwave | Environment | The Guardian