London Mayor Sadiq Khan is backing growing demands for a maximum UK workplace temperature, as repeated climate crisis-driven heatwaves disrupt schools, hospitals, and transport infrastructure across the capital.
Campaigners and trade unions are urging the British government to establish legally enforceable indoor heat limits.
They point to a June heatwave that claimed approximately 440 lives daily during its peak three-day period.
While the United Kingdom currently enforces statutory minimum workplace temperatures, no upper legal limit exists to protect workers from extreme summer heatwaves that have pushed some indoor work environments above 40C.
The Trades Union Congress and Unison are demanding a maximum indoor working limit of 30C, which would drop to 27C for employees performing strenuous physical labor.
Support for the policy grew over the weekend when Green Party Member of Parliament Hannah Spencer announced plans to introduce a parliamentary bill establishing a formal workplace heat limit.
A spokesperson representing the London Mayor confirmed Khan's endorsement of the safety limit, noting that extreme heat is increasingly affecting residents in the capital.
The spokesperson explained that while the mayor lacks the legislative power to enforce a maximum temperature, he supports the policy to help London adapt to severe heatwaves.
Green Party Mayor of Hackney Zoë Garbett also urged the government to act, framing the heatwave protections as a vital issue of social equity for local families and workers.
"The climate crisis does not affect everyone equally, and the recent heatwaves have made that crystal clear," said Garbett.
She noted that local headteachers face difficult choices regarding whether to keep schools open during extreme heat or close them, which impacts children without cooler home alternatives.
"Urgent investment from the government in more resilient schools and public buildings isn't just an issue of the climate crisis, it's a matter of basic social justice," said Garbett.
"Councils are ready to tackle the crisis and take on a statutory duty to lead the response, but we need the powers and – more importantly – proper funding to take action."
In response to the growing demands, a government representative clarified the state's current position.
"The government has no plans to introduce a mandatory maximum workplace temperature," said a government spokesperson.
The spokesperson added that the Health and Safety Executive continues to distribute guidance for employers, and will launch a public consultation this year addressing workplace temperature thresholds.
