Climate change is significantly impacting worker safety and health, exposing them to higher daily temperatures and more frequent, severe heatwaves.
- In recent years, the UK has experienced shifts in typical weather patterns
- While there is no maximum workplace temperature in the UK, the law mandates that “During working hours, the temperature in all workplaces inside buildings shall be reasonable.”
- UNISON supports the TUC’s call for a specific legal maximum temperature for indoor work of 30°C, or 27°C for strenuous work.
- Employers must take all reasonable steps to achieve a temperature as close as possible to comfortable (room temperature alone does not indicate thermal comfort, as individual preferences vary)
- Health and safety representatives play a crucial role in ensuring workplaces are safe and healthy. They promote better health and safety practices and investigate potential hazards, including those exacerbated by climate change (extreme heat, pollution, UV rays). Learn more about becoming a UNISON health and safety rep here. https://www.unison.org.uk/unison-health-and-safety/become-safety-rep/
What risks does extremely hot weather present?
Three of the biggest risks to health during extremely hot conditions are
What should my employer be doing?
- Employers are duty-bound to ensure, as far as reasonably practicable, the health, safety, and welfare at work of their employees (HASAW Act).
- Employers must undertake risk assessments to identify hazards in the workplace, including climate change-related hazards such as heatwaves.
- Measures to reduce the risk of harm to employees should be implemented. If conditions change, such as the risk of extreme temperatures, employers should review and update risk assessments accordingly.
- Employers must protect staff who are particularly vulnerable to heat, potentially requiring individual risk assessments.
Commuting and remaining in work
- Employers’ responsibilities extend beyond the workplace. Extreme temperatures can pose significant health and safety risks during commuting, with potential travel disruptions causing heat exhaustion.
- If staying away from the workplace is not possible, employers should conduct risk assessments and consider suspending strenuous activities. If suspension is not feasible, work periods should be limited, with ample breaks and access to fresh, cool water.
- Workers are protected under Section 44 of the Employment Rights Act 1996, allowing them to remove themselves from situations where they reasonably believe there is a serious and imminent danger. This protection is limited to specific immediate risks to safety, not general discomfort. Members and branches should always seek a view from their Regions on taking action.
Workplace Ventilation and Thermal Comfort
- Good ventilation is crucial to reduce the transmission of SARS-CoV-2, the virus causing COVID-19. With rising case numbers, employers must continue to protect workers.
- Oscillating fans can help with airflow, but if room temperatures exceed 30°C, they may not prevent heat-related illness and could worsen dehydration. Fan use should also consider the risk of virus transmission.
- There is no maximum workplace temperature by law, but it states that “During working hours, the temperature in all workplaces inside buildings shall be reasonable.” Employers should take all reasonable steps to achieve a comfortable temperature.
- The TUC calls for a legal maximum indoor work temperature of 30°C, or 27°C for strenuous work. Regular work at or just below these temperatures is unacceptable, and employers should aim to reduce temperatures if they exceed 24°C or if workers feel uncomfortable. The World Health Organization recommends 24°C as the maximum comfortable working temperature.
- Room temperature alone does not indicate thermal comfort, as individual preferences vary. The Health and Safety Executive (HSE) states, “Thermal comfort is not measured by room temperature, but by the number of employees complaining of thermal discomfort.”
(*) https://www.hse.gov.uk/temperature/thermal/
Personal protective equipment (PPE)
The need for personal protective equipment (PPE) will have followed a risk assessment and identified that all other means of reducing the risks to the individual have been eliminated but a level of risk still remains, so PPE is the last (not first) resort to protecting an individual.
The use of some types of PPE in hot outdoor / indoor environments (such as overalls, mask, respirators, aprons, hoods etc) increases the risk of the body not being able to cool itself and maintaining a healthy temperature (heat stress). This can cause heat exhaustion and if action is not taken lead to heat stroke.
If your work requires the use of PPE, we expect employers to have review the risk assessment for the activity that requires PPE and consider avoiding this type of work in areas where is not possible to ensure a cool working environment.
Where the work needs to continue, and PPE is required we would be expecting employers to operate in the following way
- Reducing the amount of time spent undertaking tasks in PPE by rotating staff out if the work / task needs to continue
- Providing more frequent breaks in between the use of PPE
- Trying to use single use PPE which is changed regularly to prevent sweat saturation and ensuring access to more changes of workwear
- Make staff aware of the signs of heat exhaustionand dehydration
Operating a buddying system where staff regularly check on one another for signs of heat stress like confusion, changes in completion or looking clammy, increased rates of breathing (whilst at rest or not undertaking vigorous activity)
Workers who are pregnant
Employers are already required by law to undertake individual risk assessments once an employee has informed them, they are pregnant. We would expect employers to review this risk assessment considering the Amber and Red warning for extreme heat (see Heat-Health Alert (HHA) colour warning system information below).
The review should take account of the fact that workers who are pregnant are more at risk of experiencing heat exhaustion and at lower temperatures. Therefore, additional steps should be considered to reduce the risks and could include
- Working from home where possible
- Reducing shift length, start and finish times so you are not travelling in the hottest parts of the day
- Staying well hydrated and having increased rest breaks
- Temporary change of working duties
If you have any none medically urgent questions about the impact of the heat on your pregnancy you should discuss this with your midwife, contact your GP or call NHS 111
Those with existing health conditions
Where employers are aware someone has an existing health condition, once an alert has been issued, managers should be discussing with those employees how the extreme heat might affect either their condition or medication used. We would encourage an individual risk assessment to be carried out, and for employers to consider what additional reasonable adjustment(s) could be provided.
If you feel you are being put at risk it is crucial to get advice and discuss the situation with your UNISON representative. Contact your branch and if needed you can seek advice from our regional office or legal team.
More guidance for Health and Safety reps on Temperature at Work
Outdoor workers
Those working outdoors require additional measures to protect them, both from UV radiation and heat stress,
In Amber warning areas (see Heat-Health Alert (HHA) colour warning system information below)
Work activities should be reduced and planned to take place at cooler times of the day (before 11 am and after 3pm), sun cream with a high UV factor should be provided free of charge, increased breaks out of the sun and free access to fresh cool water.
In Red warning areas (see Heat-Health Alert (HHA) colour warning system information below)
Only activities which are critical should be undertaken, [following that advice for Amber areas] but significantly limiting any work during 11am-3pm, employers might consider asking employees to undertake temporary duties out of the sun, provided they have received the appropriate training to be able to do that work safely.
UKHSA and Met Office Service
In July 2022, the UK recorded it hottest every day with the temperature reaching 40.3°C.
In response, the UK Health Security Agency (UKHSA) together with the Met office have produce a new Adverse Weather and Health Plan ‘Protecting health from weather related harm’.
In line with other weather warning systems in operation within the UK, an updated Heat-Health Alert (HHA) colour warning system will operate from the 1 June to 15 September each year.
- Green(preparedness): No alert will be issued as the conditions are likely to have minimal impact and health; business as usual and summer/winter planning and preparedness activities.
- Yellow (response): These alerts cover a range of situations. Yellow alerts may be issued during periods of heat/cold which would be unlikely to impact most people but could impact those who are particularly vulnerable.
- Amber(enhanced response): An amber alert indicates that weather impacts are likely to be felt across the whole health service, with potential for the whole population to be at risk. Non-health sectors may also start to observe impacts and a more significant coordinated response may be required.
- Red (emergency response): A red alert indicates significant risk to life for even the healthy population.
(Reproduced from UKHSA User guide-New impact-based Weather-Health Alerting System)
These alerts are intended to provide information to those delivering health and social care services, as well as other businesses and the public. This ensures that preparations and changes to business operations can be planned and implemented.
Your employer should be monitoring these alerts and discussing the potential health and safety impacts with health and safety representatives.
As UNISON members work in both the public and private sectors across the UK, some areas may have different levels of weather warnings in place. Therefore, local authorities may issue guidance based on their local circumstances and demands on health services.
Our bodies work hard to keep us comfortable, and even a few degrees change in core temperature can make us unwell.
Children under 4 years old, individuals with underlying health conditions, pregnant people, and the elderly are more at risk of health issues from extreme temperatures.
As weather and temperatures vary across the UK, alerts may be based on regional rather than national forecasts. Different regions may have different alert levels.
The Met Office may also issue National Severe Weather Warning Service (NSWWS) alerts for extreme heat in areas where temperatures are predicted to reach specific thresholds.

Reproduction of Figure 3.2: Local threshold temperatures within the Heatwave Plan for England: Protecting health and reducing harm from hot weather
Devolved Nations
Devolved nations have their own threshold action levels, members living or working in those location should refer to the advice issued by the devolved administrations.
UKHSA advice for public services
The Heath-health Alert Service forewarns of periods of high temperatures, which may affect the health of the public. It is aimed at health and social care professionals and any with a role in reducing the harm extended periods of hot weather can have on health. Individuals in England can sign up to receive alerts or access the alert dash board via the links below
Heat-health Alert service sign up link
The UKHSA has produced guidance to assist professionals in protecting vulnerable people from the health impacts of severe heat in England. (devolved nations may issue their own of reference these)
Social care managers, staff, and carers
Supporting people who are homeless and sleeping rough
The signs of heat exhaustion include:
- a headache
- dizziness and confusion
- loss of appetite and feeling sick
- excessive sweating and pale, clammy skin
- cramps in the arms, legs and stomach
- fast breathing or pulse
- a high temperature of 38C or above
- being very thirsty
The symptoms are often the same in adults and children, although children may become floppy and sleepy.
If someone is showing signs of heat exhaustion, they need to be cooled down.
Call 999 if:
You or someone else have signs of heatstroke including:
- fast breathing or shortness of breath
- a fit (seizure)
- loss of consciousness
- not responsive
Heatstroke can be very serious if not treated quickly.
Put the person in the recovery position if they lose consciousness while you’re waiting for help.
Symptoms of dehydration in adults and children include:
- feeling thirsty
- dark yellow and strong-smelling pee
- feeling dizzy or lightheaded
- feeling tired
- a dry mouth, lips and eyes
- peeing little, and fewer than 4 times a day
Call 999 or go to A&E if:
- you’re feeling unusually tired
- you’re confused and disorientated
- any dizziness when you stand up does not go away
- you have not peed all day
- your pulse is weak or rapid
- you have fits (seizures)
These can be signs of serious dehydration that need urgent treatment.
