How hot does it have to get before you can legally go home from work?

I think we can all agree: it is too hot. So hot, in fact, that the Met Office have issued a level three amber warning for the weather and warned that children, old people and anyone with a medical condition should stay cool and out of the sun.

And as the last of your flesh silently presses onto the badly upholstered seat of a Central Line train, you may find what remains of your consciousness asking: “How hot does it have to be before it is too hot for me to legally go into work”. 

Answer: quite hot.

There’s currently no official maximum temperature, though the TUC do want to set that temperature at 30°C for those who work indoors or in driving jobs. But that doesn’t mean you can’t sack work off if you’re too hot – the TUC also state that an employer must provide a working environment that is “safe and without risks to health”. 

“If the temperature goes too high then it can become a health and safety issue,” they write. “If people get too hot, they risk dizziness, fainting, or even heat cramps.

“In very hot conditions the body’s blood temperature rises. If the blood temperature rises above 39°C, there is a risk of heat stroke or collapse.”

The Health and Safety Executive – the UK’s independent regulator for health and safety and illness at work – states that there can be no official high temperature due to the extremely high temperatures found in places like glassworks or foundries. 

“The Workplace (Health, Safety and Welfare) Regulations 1992 lay down particular requirements for most aspects of the working environment. Regulation 7 deals specifically with the temperature in indoor workplaces and states that during working hours, the temperature in all workplaces inside buildings shall be reasonable.

“However, the application of the regulation depends on the nature of the workplace, such as a bakery, a cold store, an office, a warehouse. Employers also have to provide clean, fresh air as well as keep temperatures at a comfortable level.”

So: want to leave work but don’t know if it’s hot enough? The HSE says that if a “significant number of employees are complaining about thermal discomfort” then employees are required to carry out a risk assessment. If it is too hot, then you’re allowed to go home.

And there may be clearer regulations in the future – at least if Jeremy Corbyn has anything to do with it. Back in 2015, said there should be clear legislation on maximum temperatures.

"In this weather, high temperatures aren't just a problem in heavy industry but for millions of workers have been struggling with the heat in offices, schools, shops, call-centres - you name it,” he said.

“Good employers will have been taking steps to help out their workers in the heatwave. But putting a maximum temperature into law will give everyone a legal right to basic protections from working in unbearable conditions.”