With temperatures set to hit 37 degrees in some parts of the UK this week, the Trades Union Congress (TUC) said employers should give staff the chance to come in earlier or stay later to avoid rush hour commutes.

They should also encourage staff to wear lightweight clothes and keep buildings cool by opening windows or installing ventilation or air-conditioning, the TUC said.

While there’s no law for minimum or maximum working temperatures, during working hours the temperature in all indoor workplaces must be ‘reasonable’.

Employers have a duty to keep the temperature at a comfortable level and provide clean and fresh air.

TUC General Secretary Frances O’Grady said: “While many of us love to see the sun, it’s no fun working in a baking office or a stifling factory. Bosses should do all they can to keep the temperature down.

“The easiest way for staff to keep cool inside is being able to work in more casual clothing.

“It’s in bosses’ interests to provide a cool and comfortable work environment.”