Maximum workplace temperature: Sadiq Khan joins growing UK push

London Mayor Sadiq Khan has thrown his weight behind calls for a legal maximum workplace temperature in the UK, reigniting a debate that trade unions and workers’ rights campaigners have pursued for years without success.

Khan’s intervention comes as Britain braces for another summer of record-breaking heat. The mayor argued that employees — particularly those in warehouses, kitchens, factories, and open-plan offices without air conditioning — deserve basic legal protections when temperatures soar.

What Khan is actually calling for

The mayor has backed proposals to set a maximum indoor working temperature of 25°C for most workplaces, rising to no higher than 30°C for those doing physically demanding labour. Under current UK law, employers are only required to keep temperatures “reasonable” — a standard that critics say is hopelessly vague and almost impossible to enforce.

It’s a gap in British employment law that unions have flagged repeatedly. But successive governments, both Conservative and Labour, have declined to legislate, citing concerns about the cost burden on businesses.

Why now?

The timing isn’t accidental. Last summer, parts of the UK recorded temperatures above 40°C for the first time. Workers in sweltering conditions reported dizziness, exhaustion, and in some cases heat-related illness. The TUC has estimated that around 4.5 million workers in England and Wales regularly work in environments that get dangerously hot during heatwaves.

A spokesperson for the campaign group Too Hot To Work said the current situation was “completely untenable” and called on the Labour government to act before the next heatwave season hits in earnest.

“People are being expected to work in conditions that would be flagged as dangerous anywhere else in Europe,” the spokesperson said. “There’s no excuse for not having a legal limit.”

Where the government stands

So far, Downing Street hasn’t committed to introducing a maximum temperature law. The Health and Safety Executive does issue guidance on managing heat in the workplace, but that guidance carries no legal force on its own. Employers can — and sometimes do — ignore it.

Several European countries already operate with defined temperature thresholds. Germany, for instance, recommends workrooms stay below 26°C, with action required above 30°C. The UK remains an outlier.

What happens next

Khan’s backing will put fresh pressure on ministers to move. The mayor doesn’t have the power to introduce such legislation himself — employment law is reserved to Westminster — but his voice carries weight, and his office has pledged to lobby the government directly on the issue.

Trade unions are expected to raise the issue again at this autumn’s Trades Union Congress, where it’s likely to generate significant floor debate.

Britain’s summers aren’t getting cooler. And the political window for doing something meaningful about workplace heat — before another brutal August makes headlines — is getting narrower. Whether the government chooses to use that window remains to be seen.