Heat Exhaustion and Heatstroke at Work

An earlier version of this page said a temperature of 37°C or above indicated heatstroke. That was wrong — 37°C is normal body temperature. This page now follows NHS guidance.

Hot weather is a workplace health and safety issue, not just an inconvenience — particularly in kitchens, warehouses, factories, vehicles, glasshouses and anywhere outdoors. The dangerous part is that heat exhaustion creeps up, and the person affected is often the last to notice: impaired judgement is one of the symptoms.

Telling the two apart

The clearest single indicator is the skin. Someone with heat exhaustion is usually sweating heavily, with pale, clammy skin. Someone with heatstroke often has hot skin that is not sweating at all, because the body’s cooling mechanism has failed. Add confusion or a change in behaviour and you are looking at an emergency.

Signs of heat exhaustion: tiredness, dizziness, headache, feeling sick or being sick, excessive sweating, skin becoming pale and clammy.

Signs of heatstroke: a very high temperature, hot skin without sweating, fast breathing and a fast heartbeat, confusion and restlessness, seizure, loss of consciousness.

What to do for heat exhaustion

1. Move them to a cool place. Indoors, shade, an air-conditioned room or vehicle.
2. Remove all unnecessary clothing — jacket, hi-vis, socks, PPE that is not needed at that moment.
3. Give them plenty of water to drink. An isotonic sports drink or oral rehydration powder is also fine.
4. Cool their skin — spray or sponge them with cool water and fan them. Cold packs under the armpits or on the neck help.

Stay with them. They should start to cool down and feel better within 30 minutes. If they are still unwell after 30 minutes of resting in a cool place, being cooled and drinking fluids — call 999.

Do not send them back to work because they say they feel fine after ten minutes. Sit them out properly, and think about whether the conditions that caused it have changed at all.

What to do for heatstroke

Call 999 straight away. Heatstroke is a medical emergency and can be fatal.

While you wait for the ambulance:

• Keep cooling them — cool water on the skin, fanning, cold packs at the neck, armpits and groin
• If they are unresponsive but breathing, put them in the recovery position
• If they are not breathing normally, start CPR and send someone for a defibrillator
• Do not give fluids to anyone confused, drowsy or not fully conscious — they may not be able to swallow safely
• Do not drive them to A&E yourself. Wait for the ambulance

Who is most at risk

Not everyone in the same conditions carries the same risk. Your risk assessment should account for:

The employer’s side of this

There is no maximum workplace temperature in UK law. What there is instead is the general duty to assess risks to health and safety and to control them — and in a heatwave, heat is one of those risks. Practical controls that actually work:

• Reschedule heavy physical work away from the hottest part of the day where you can.
• Cold drinking water that people do not have to walk five minutes to reach. Proximity changes behaviour more than posters do.
• More frequent, shorter breaks in a genuinely cooler place — not a van with the engine off.
• Relax dress codes where it is safe to do so. Where PPE is non-negotiable, shorten the working stints instead.
• Shade, ventilation and fans — and blinds on south-facing glass, which is far cheaper than air conditioning.
• Allow time to acclimatise. Somebody’s first week on a hot site is their highest-risk week.
• Brief your first aiders at the start of a hot spell so they know the difference between exhaustion and heatstroke before they need it.
• Encourage the buddy system. Because judgement is affected, colleagues spot heat illness before the person does.

Vehicles and lone workers

Drivers and anyone working alone are the people most likely to deteriorate unnoticed. A cab in full sun gets considerably hotter than the depot, and there is nobody there to see the confusion set in. Set a check-in interval during hot weather and make sure people actually use it — a missed check-in is information.

Dehydration, cramps and sunburn

Three related things worth covering in the same briefing:

• Heat cramps — painful muscle cramps during or after exertion in heat. Rest somewhere cool, rehydrate, gently stretch. Treat them as an early warning, not a nuisance.
• Dehydration — by the time someone feels thirsty they are already behind. Regular small drinks beat occasional large ones.
• Sunburn — outdoor workers accumulate significant UV exposure over a career. Shade, covering up and sunscreen belong in the same conversation, and skin cancer is an occupational health issue for outdoor trades.

Training

Recognising heat illness is part of workplace first aid, and the judgement call — cool and watch, or call 999 — is exactly the sort of thing that is easier to make when you have practised it rather than read it.

Deals

Emergency First Aid at Work Group Course – Sale: £295.00 for up to 12 people £495.00 Original price was: £495.00.£295.00Current price is: £295.00. Excluding Vat View course →

First Aid at Work Courses

Emergency First Aid at Work Group Course £495.00 Excluding Vat View course → Emergency First Aid Open Course £85.00 Excluding Vat View course → First Aid at Work Group Course £945.00 – £1,145.00Price range: £945.00 through £1,145.00 Excluding Vat View course → First Aid at Work Open Course £185.00 Excluding Vat View course → First Aid at Work ReQual Open Course £95.00 Excluding Vat View course → Paediatric First Aid Group Course £650.00 – £750.00Price range: £650.00 through £750.00 Excluding Vat View course → Paediatric First Aid Open Course £105.00 Excluding Vat View course →

Get your team ready before the next hot spell

Call 0845 838 4643 or use the enquiry form on this page and we will arrange first aid training at your premises.

Heat illness is one of the conditions covered on our first aid at work courses. If your people work outdoors or in hot environments, see also how to run a first aid needs assessment.