As summer temperatures rise, the Health and Safety Executive (HSE) has reminded employers about the rules for working in hot and humid weather via its various social media channels.

The bottom line, according to the HSE, is that “There's no law for maximum working temperature, but employers must keep the temperature comfortable”.

Therefore, in offices or similar environments, the temperature in workplaces must be reasonable.

Although there is no specific legislation for maximum working temperature, or when it’s too hot to work, employers must stick to broader health and safety at work law, including keeping the temperature at a comfortable level, sometimes known as thermal comfort, and providing clean and fresh air.

There are six basic factors which usually cause discomfort as follows.

  • Air temperature (ie the temperature of the air surrounding the body, usually given in degrees Celsius (°C))

  • Radiant temperature — this is heat radiating from warm objects, eg machinery can make a factory very hot

  • Air velocity (the speed of air moving across the employee — so a breeze may help cool a workplace if the air is cooler than the environment)

  • Humidity

  • Clothing insulation, including personal protective equipment (PPE)

  • Metabolic heat — related to work rate — the more physical work we do, the more heat we produce.

The HSE advises employees to talk to their employer if the workplace temperature isn’t comfortable.

In particular, it should be noted that, in some workplaces, extreme temperatures are not seasonal but are created by the work, such as in certain manufacturing processes. These temperatures can lead to serious health effects if not managed effectively. It may be necessary for employers to seek specific advice on work in very high temperatures, for example on heat stress.

Last reviewed 28 June 2019