The GMB union issued the plea that employees should not have to face above 25C heat in the workplace after the Met Office issued amber and red alerts warning of “potential serious illness or danger to life”.
People are being advised not to travel on public transport unless “absolutely necessary” as services will be reduced due to the heatwave over the nect few days.
At present, there is no maximum workplace temperature laid out by the government, but employers do have a legal obligation to ensure that the temperature in the workplace is “reasonable” - as outlined by the Workplace (Health, Safety and Welfare) Regulations 1992.
The Health and Safety Executive (HSE) recommends that the workplace should be at least 16C for workers and 13°C for those carrying out manual work under its Approved Code of Practice.
Lynsey Mann, the GMB’s health and safety officer, said: “This hot weather is great for being on a sun lounger, but if you’re trying to work through it’s no joke.
“Bosses need to do everything possible to keep workplaces cool and, more importantly, safe.”
She added: “Ultimately, there needs to be a legal maximum working temperature.”
The HSE has defended its decision not to establish a maximum temperature for workplaces, instead reminding employers of their responsibility to ensure that indoor workplaces remain at a reasonable temperature and to manage the risk of working outdoors in hot environments.
What is a reasonable temperature varies, and will depend upon the nature of the individual workplace, the HSE said.
John Rowe, HSE’s Acting Head of Operational Strategy, said: “With a heatwave warning in place, its vital employers are aware of their responsibility to ensure their indoor workplaces are at a reasonable temperature.
“All workers have a right to a safe working environment and their employers should discuss working arrangements with them.
“If workers have specific queries or concerns relating to health and safety in their workplace, they should talk to their employer.”
According to HSE, there is no maximum temperature because workplaces with hot processes - such as bakeries or foundries - would not be able to comply with such a regulation. They use other measures to control the effects of temperature.