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When is it too Hot to Work?

Last updated on 3rd May 2023

The UK experienced record-breaking temperatures this summer, with the hottest-ever day recorded by the Met Office on Tuesday 19 July 2022 in the east of England; temperatures hit a high of 40.3°C (104.5°F), beating the previous record of 38.7°C set in 2019 by 1.5°C.

The Met Office also issued its first-ever Red Extreme Heat warning. This level of alert is used when a heatwave is so severe and/or prolonged that its effects extend outside the health and social care system. At this level, illness may occur among the fit and healthy, and not just in high-risk groups. Care services supporting the elderly and vulnerable were put under increased stress, a surge in emergency calls and hospitalisations put immense strain on health systems, and early estimates suggest that there were nearly 1,000 heat-related deaths.

Even at lower temperatures than those experienced this summer, being too hot in the workplace leads to loss of concentration and increased tiredness, which could impact on the quality of work and productivity, as well as increase the risk of accidents.

When is it legally too hot to work?

This very question saw an increase of 2,950% in searches made on “Google” during the 2022 heatwave.

The HSE Approved Code of Practice states that, “The temperature inside the workplace should provide reasonable comfort without the need for special clothing. If reasonable comfort cannot be achieved because of hot or cold processes, all reasonable steps should be taken to achieve a temperature which is as close as possible to comfortable”. It suggests the minimum temperature in a workplace should normally be at least 16°C. If the work involves rigorous physical effort, the temperature should be at least 13°C. There are no recommendations for maximum working temperatures or for when it is too hot to work.

Employers have a responsibility for “keeping the temperature at a comfortable level, sometimes known as thermal comfort” and for “providing clean and fresh air”. Whilst there is no legal pressure for employers to send employees home if they are too hot, the Government advises: “Employees should talk to their employer if the workplace temperature isn’t comfortable.”

Unions have made attempts to establish set guidelines on working temperature, with the Trade Union Congress (TUC) lobbying for a maximum temperature of 30°C, or 27°C for people doing strenuous work. They have stated that, “It is usually accepted that people work best at a temperature between 16°C and 24°C, although this can vary depending on the kind of work being done”. The TUC believes that high temperature is a significant health issue and there is a need for both a maximum temperature and enforcement action against employers who allow their workers to suffer from having to work in hot workplaces.

Too Hot To Work

Is there a legal maximum working temperature?

Under the Management of Health and Safety at Work Regulations 1999, employers are required to assess health and safety risks to their employees. The temperature of the workplace is one of the potential hazards that employers should address, HSE guidance says.

Temperatures in the indoor workplace are covered by the Workplace (Health, Safety and Welfare) Regulations 1992, which place a legal obligation on employers to provide a “reasonable” temperature in the workplace. However, it is left to the employer to determine what is reasonable as there is no stated temperature threshold.

In offering an explanation of why legal maximum work temperatures are not specified, the HSE states that, “A meaningful figure cannot be given at the upper end of the scale due to the high temperatures found in, for example, glass works or foundries. In such environments it is still possible to work safely provided appropriate controls are present. Factors other than air temperature, i.e. radiant temperature, humidity and air velocity, become more significant and the interaction between them becomes more complex with rising temperatures.”

Can you complain about the temperature at work?

As we have seen, under the regulations, the temperature of indoor workplaces should be “reasonable”. Whilst an employer has a statutory duty under the Health and Safety at Work etc Act 1974 to ensure, so far as reasonably practicable, the health, safety and welfare of their employees at work, it is an employee’s responsibility to take the first action on any temperature concerns. Employees need to alert their employer if they feel the temperature conditions make it an unsafe work environment.

If you want to complain about the temperature in the workplace, in the first instance you should raise the matter with your line manager. Alternatively, you could speak to a facilities or HR manager, employee representative or union representative. It is advisable to raise the issue both verbally and in writing, such as in an email, so that you have a record of when you raised the issue. It is also useful to gauge the opinions of those you are working with. The HSE provides a trigger for which a “thermal comfort risk assessment” should be made by an employer.

These triggers are:

  • In air-conditioned offices, where more than 10% of employees are complaining of it being too hot.
  • In naturally ventilated offices, where more than 15% of employees are complaining of it being too hot.
  • In retail businesses, warehouses, factories and all other indoor environments that may not have air conditioning, where more than 20% of employees are complaining of it being too hot.

Your employer should acknowledge your concerns, as there is a legal requirement to provide a “reasonable” temperature, and the absence of a legal maximum temperature level rightly places the onus on the employer to do a suitable and sufficient risk assessment. This allows for complete flexibility to consider the type of work being undertaken, the environment, the nature of the workforce (more vulnerable employees will need to have their specific conditions taken into account), and other factors such as extreme weather conditions.

The employer’s duty of care is to act on and address the issues highlighted in the results of that risk assessment. It is down to the employer to make “reasonable” adjustments to the workplace and to working practices to help to alleviate the hot work environment.

If you are not satisfied with the response from your employer, you can raise a grievance using your organisation’s grievance procedure. If you feel that the work environment is a danger to health, you may wish to raise the issue with an HSE officer or union official.

What are your rights if you think it is too hot to work?

The principal right that an employee has in relation to excessive heat in the workplace is the right to raise the issue with their employer as employees have the right under health and safety legislation to be provided with a “reasonable” temperature in the workplace.

Many employees may be under the illusion that they can simply “down tools” and go home if their workplace is too hot to work in, but this is not the case. To do so could be classed as a misconduct matter, and/or may be in breach of your working contract.

The extent to which an employee can reasonably refuse to work if the temperature is either too high or too low will depend on the circumstances involved. These could include how extreme the temperatures have become, how long these temperatures have or are likely to persist, and what steps have been taken by the employer to reduce the employee’s discomfort.

However, any disciplinary proceedings brought against an employee who has complained about a health and safety matter at work, such as excessive heat, could be classed as an unlawful detriment, and any dismissal for refusing to work in unsafe working conditions could be deemed automatically unfair. Equally, if an employee feels so physically uncomfortable that they are threatening to “down tools” as a result of excessive workplace temperatures, any steps taken by the employer to pressure them into working could result in their forced resignation and, given the subjective nature of thermal discomfort, a potentially viable basis for a claim for constructive dismissal.

Depending upon your own workplace’s flexible working policy, you may have the right to request flexible working.

This might include:

  • Working from home.
  • Altering your working hours, for example to work earlier or later in the day when the temperature is lower.
  • Taking short notice annual leave whilst the temperature is excessive.
Working In Hot Temperature

Can employers determine what temperature is too hot to work in?

As there is no legally defined maximum workplace temperature, it is up to individual employers to make the decision on when it is too hot to work. When an employer has completed their heat risk assessment and made reasonable adjustments to the workplace to help address excessive heat, they may take the decision that to continue business might be detrimental to health or that the heat is so high that it is affecting the equipment.

During the summer heatwave, employers in the construction industry and many local councils deemed that the excessive temperatures were too hot for their workers to continue to work safely so suspended work until the temperature fell.

How can employers make working in heat more comfortable?

All employers are required by law to protect their employees from harm, including harm caused by excessive or uncomfortable workplace temperatures. In most cases, this will be less about reducing the risk of illness or injury, and more about ensuring the thermal comfort of employees at work. Thermal comfort describes how acceptable a person considers their temperature, i.e. whether they feel too hot or too cold. There are a number of reasonable adjustments that employers can make to the workplace that will create a more comfortable working environment in the heat.

These include but are not limited to:

  • Ensure that employees stay hydrated – Employers must provide employees with suitable drinking water in the workplace to prevent dehydration.
  • In indoor working environments – Provide additional portable air conditioning and/or fans where required. Screening windows to block direct sunlight, moving workstations from direct sunlight, where practicable. If possible, switch off overhead lighting that can emit a lot of heat.
  • In outdoor environments – Provide sunscreen to protect from sunburn, where possible, and allow flexibility to keep employees out of working in direct sunlight between 11am to 3pm, when the UV rays are strongest. Advise outdoor workers to wear a hat to provide additional protection for the face and neck. For any workers driving vehicles, ensure that they are wearing appropriate sunglasses to screen the sun’s glare as bright sunshine can lower visibility and make driving difficult. Provide drivers with information about driving in particularly hot weather, such as making sure the engine stays within the normal operating temperature range. If it begins to overheat, advise them to find somewhere safe to stop and allow it to cool down.
  • Dress codes – Where practicable and safe, relax dress codes and/or uniform requirements.
  • Working hours – Where practicable allow flexibility in working hours, earlier or later starts and finishes, to be able to avoid working in the height of the heat, and to compensate for sleepless nights. Provide more frequent rest breaks. If workable, explore working from home options.
  • Be aware of commuting difficulties – Some employees may experience travel difficulties if public transport is being affected by excessive heat conditions. Try to discuss this with employees and plan for disruptions.
  • Ensure that tailored risk assessments are completed for vulnerable people – Vulnerable employees such as pregnant women, those on medication, and conditions including chronic obstructive pulmonary disease (COPD) and arthritis, can make working in the heat particularly challenging, so employers must take extra care and make necessary adjustments to ensure that their specific needs are addressed to keep employees safe.
  • Ensure that managers are vigilant and that first-aiders are up to date – Provide training on heat stress, and monitoring health.
    There is a very real danger that employees may suffer effects from excessive heat in the workplace such as:
    Heat fatigue – Signs include impaired performance of skills, mental concentration, or vigilance, generally due to not being used to working in the heat. No treatment is required except to remove the person from the heat before more serious conditions develop.
    – Heat collapse – In a collapse or faint, the brain does not receive enough oxygen because blood pools in the extremities. The individual may lose consciousness. The onset of collapse is rapid and unpredictable. Move the person to a cooler area, loosen clothing, and give fluids.
    – Heat cramps – Usually caused by performing hard physical labour in a hot environment. Cramps are caused by the lack of water; excess salt can build up in the body if water lost through sweating is not replaced. However, do not use salt pills. Thirst cannot be relied on as a guide to the need for water. Water must be taken every 15 to 20 minutes in hot environments.
    – Heat exhaustion – Signs are headache, nausea, dizziness, blurred vision, weakness, giddiness and thirst. Skin is damp and looks muddy or flushed. Fortunately, this condition responds readily to prompt treatment. Symptoms of heat exhaustion are similar to heat stroke which is a medical emergency. People suffering from heat exhaustion should be removed from the hot environment, given fluids, loosen clothing, shower or sponge bath with cool water and rest in a cool place.
    – Heat stroke – This occurs when the body’s system of temperature regulation fails and body temperatures rise to critical levels. The condition is caused by a combination of highly variable factors and is difficult to predict. This is a medical emergency, so call 999 immediately. Primary signs and symptoms of heat stroke are confusion, irrational behaviour, loss of consciousness, convulsions, hot dry skin, lack of sweating (usually), and an abnormally high body temperature.

But by law, employers have a “duty of care” to make sure working temperatures are reasonable for their employees. This means if extreme temperatures are expected, employers should:

  • Carry out health and safety risk assessments.
  • Remove or reduce any risks found.
  • Make plans for keeping staff comfortable and safe.

What can employees do to make working in the heat more comfortable?

Although employers have a duty of care to ensure that their employees are kept safe, employees also have responsibilities to ensure that they keep themselves and other employees safe and comfortable, particularly in extreme heat conditions.

Employees should:

  • Drink plenty of water throughout the day and not wait until they are thirsty.
  • Use fans provided to increase air movement.
  • Use window blinds (if available) to cut down on the heating effects of the sun.
  • If possible, work away from direct sunlight or sources of radiant heat.
  • Take regular breaks to cool down in warm/hot situations.
  • Dress appropriately for the weather conditions; if there is a dress code or uniform policy, speak to the employer about allowing some flexibility.
  • Speak to the employer about flexible working hours (earlier or later starts and finishes), particularly to avoid commuting at extremely busy times.
  • Be aware of the effects of excessive heat on the body and take action to alleviate these before they can take a toll. Doing physical labour outside while it is very hot can put the body under considerable strain and there is a very real danger of workers suffering heat exhaustion or, far more serious, heat stroke.
  • Raise any heat concerns with managers so that they can assess the situation.
Working In Hot Weather

Working from home in the heat 

Heatwaves can be particularly challenging for those who work from home. Employers need to be aware that they have a duty to ensure that they provide a “reasonable” temperature in the workplace and this includes the employees’ home workspace if they are working from home. Employers need to carry out a heat risk assessment for home workers and make reasonable adjustments should they be required.

Some employers may decide that requiring workers to return to an air-conditioned workplace is an appropriate response to adverse heat conditions. If the employee’s contract states that the employer’s premises is specified as the employee’s usual workplace, then the employer is entitled to make a “reasonable management request” for the employee to return to the workplace.

There are a number of things that you can do to keep comfortable when working from home in the heat, such as:

  • Stay hydrated – keep sipping on water throughout the day to stay fresh. Surprisingly, hot drinks such as tea can also keep you cool.
  • Start work earlier or much later if possible, so you can work outside of the sun’s hottest hours.
  • Keep your curtains or blinds closed to keep out the sunlight, but by all means keep the windows open behind them.
  • Create DIY air-con – place a bowl of ice cubes in front of your desk fan so it can waft extra cool air.
  • Avoid working outside despite how tempting taking the laptop into the garden could be.
  • Dress appropriately for the weather conditions, which is easier if you are working at home. However, be aware if you are participating in online meetings etc.

Is extreme heat caused by climate change?

Scientists from South Africa, Germany, France, Switzerland, New Zealand, Denmark, the United States of America and the United Kingdom, collaborated to assess to what extent human-induced climate change altered the likelihood and intensity of the heatwave this year. Following their research, the World Weather Attribution (WWA) have stated that “While Europe experiences heatwaves increasingly frequently over the last years, the recently observed heat in the UK has been so extreme that it is also a rare event in today’s climate. Without human-caused climate change, temperatures of 40°C in the UK would have been extremely unlikely”.

A recent Met Office study found that summers which see days above 40°C somewhere in the UK have a return time of 100–300 years at present, even with current pledges on emissions reductions this can decrease to 15 years by 2100.

Climate attribution scientist at the Met Office, Dr Nikos Christidis, said “In a recent study we found that the likelihood of extremely hot days in the UK has been increasing and will continue to do so during the course of the century, with the most extreme temperatures expected to be observed in the southeast of England.

“Climate change has already influenced the likelihood of temperature extremes in the UK. The chances of seeing 40°C days in the UK could be as much as 10 times more likely in the current climate than under a natural climate unaffected by human influence. The likelihood of exceeding 40°C anywhere in the UK in a given year has also been rapidly increasing, and, even with current pledges on emissions reductions, such extremes could be taking place every 15 years in the climate of 2100.”

Final thoughts

It is quite possible that excessive heat conditions will become the norm in future summers, even in the UK. Employers should begin to focus on their strategies for combatting these working conditions and keeping their businesses functioning effectively, by having policies and contingency plans ready in place, so they are fully prepared for the next time it occurs. And according to meteorologists, these heatwaves are highly likely to reoccur more often in future years.

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About the author

Megan Huziej

Megan Huziej

Megan has worked with CPD Online College since August 2020, she is in charge of content production, as well as planning, managing and delegating tasks. Megan works closely with our writers, voice artists, companies and individuals to create the most appropriate and relevant content as well as also using and managing SEO. She gained her Business Administration Level 3 qualification over the duration of being at CPD Online College as well. Outside of work Megan loves to venture to different places and eateries as well as spending quality time with friends and family.

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