When the mercury rises, employers should consider the risks for their workers.

As a starting point, being too hot can lead to loss of concentration and tiredness. Along with the obvious negative impact on productivity, this could put workers or others at risk. As temperatures rise further, so do the risks: including dizziness, heat stroke, and the risk of industrial accidents which can be fatal. Some workers may be at higher risk, such as those who are pregnant, or have certain medical conditions.

Is there a maximum workplace temperature?

There is no set maximum temperature for indoor or outdoor work. However, for indoor workspaces, temperatures must be 'reasonable'. What is reasonable will vary with the work being done and the work environment.

Last week MPs called on the government to introduce a maximum indoor working temperature of 30°C, or 27°C for strenuous work. The TUC had previously called for similar protection, including a duty on employers to reduce temperatures when they go above 24°C and workers feel uncomfortable.

MPs also want to see a requirement for employers to introduce effective control measures (e.g. installing ventilation or ensuring workers aren't near sources of heat or windows with direct sun exposure).

Generally, though the Chartered Institute of Building Services Engineers recommends much lower temperatures:

  • heavy work in factories: 13°C
  • light work in factories: 16°C
  • hospital wards and shops: 18°C
  • offices and dining rooms: 20°C.

Even without a set maximum, employers have a general duty, so far as is reasonably practicable, to ensure the health and safety of workers. Employers need to comply with health and safety at work law, including keeping the temperature at a comfortable level and providing clean and fresh air.

Assessing the risks

Assess the potential risks from high temperatures, and the risk of skin cancer due to sun exposure. Think about the air temperature, but also, for example:

  • humidity
  • air velocity
  • radiant temperature - such as heat from the sun, fire, electric fires, ovens, cookers, dryers, hot surfaces, machinery
  • work rate / metabolic heat
  • impact of protective clothing
  • glass buildings which carry direct sunlight
  • ventilation
  • physical work demands.

Where you are aware of workers who may be more susceptible to heat stress, such as those with a medical condition (e.g. heart conditions) or those who are pregnant, consider what additional measures may be required.

Mitigating the risks: practical steps

Practical steps you can take to mitigate the risks for any type of worker include:

  • ensuring that they have access to adequate cool water and drinks – even ice lollies as a morale booster
  • allowing more regular breaks
  • staggering shift times
  • altering working hours and allowing homeworking, if possible.

In addition, for indoor workers, think about, for example:

  • shading windows and sitting workstations away from direct sunlight
  • reducing heat from machinery or computers
  • appropriate air conditioning, ventilation or fans
  • regulating the length of exposure to hot environments

For outdoor workers, consider:

  • encouraging the use of sunscreen and appropriate clothing (such as hats)
  • providing guidance on the risks of sun exposure
  • can work be carried out at cooler times of the day?
  • is there a way to provide shade?

What is appropriate will very much depend on your work environment, but for some employers it will make sense to have a policy for managing working conditions during warm weather.

    Dress codes

    Dress codes can be a contentious issue in the heat. If you are relaxing your usual dress code, think about how these changes could affect different groups within your workforce (e.g. those who wear religious clothing or disabled workers) to avoid potential discrimination risks. 

    Protective clothing, required for health and safety reasons should be designed, as far as possible, with variations in temperature in mind. Specialised protective clothing is available with cooling systems or breathable fabrics.


    Consider providing training for your workers, informing them of the work-related risks of heat stress, potential symptoms, safe working practices and emergency procedures. 

    Travel disruption

    If hot weather leads to travel disruption, some of the same considerations will apply as regards winter travel, which we discussed in our earlier blog: Adverse weather and travel: where do employers stand?

    More information 

    If you need advice or have any questions on the issues raised in this blog, please get in touch with a member of our Employment and Immigration Team, or Victoria Anderson in our Health & Safety Team.


    Victoria Anderson

    Senior Associate