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       Hazards, number 162, 2023
BOILING POINT | Hot and bothered • Don’t get overheated at work • Get active
Whether you work indoors or outdoors, excessive heat can make work unpleasant, less productive and downright dangerous. The government has refused to introduce a maximum workplace temperature. But that doesn’t mean employers are free to let you fry at work. Just because the sun’s out doesn’t mean their workplace safety duties fly out the window.


In 2022, Britain experienced the highest average annual temperature on record, with July seeing the thermometer topping 40°C for the first time. It prompted the Health and Safety Executive (HSE) to warn employers they “need to act now to make sure their workplaces are ready for warmer weather in the future.”

HSE’s John Rowe said: “We expect employers to take this recent weather event as the prompt to review how they assess the risk of high temperatures in their workplace and identify now those changes that will future proof them.

“All workplaces need to acknowledge that the working environment is changing. There are low-cost adaptations to the structure of work, but things like improved ventilation and air conditioning should also be considered which will involve investment in the workplace.

“Extreme heat that we have witnessed of late isn’t going to stop and we want employers to plan and respond to this now.”

The TUC is calling on employers to make sure their staff are protected from the sun and heat.  It warns that working in hot weather can lead to dehydration, muscle cramps, rashes and fainting. In the extreme case, workers can lose consciousness and die.

FEELING HOT?   Heat-related ill-health can be a risk in all jobs. There are tell-tale symptoms you can look out for. More.

TUC general secretary Paul Nowak said “working in sweltering conditions can be unbearable and dangerous – whether it’s in an overheated shop, a baking office or outdoors in the direct sun.” He added “employers must make sure outdoor workers are protected with regular breaks, lots of fluids, plenty of sunscreen and the right protective clothing.”

Make sure your workplace takes the necessary measures to make work safe.

And don’t sweat it next year. Start negotiating now to make sure comprehensive protections are in place before a heatwave strikes.


Your body is designed to regulate your temperature, which shouldn’t deviate from around 37 degrees Celsius (98.7 degrees Fahrenheit). Heat stress is the strain on your body as it attempts to keep cool. Factors than can influence the heat at the work can include solar gain from sunlight and heat generated by machines or lighting.

Heat-related illnesses range in severity from mild heat rash and swelling to more severe illnesses such as rhabdomyolysis (muscle damage), acute kidney injury, heat stroke and heat-stress induced cardiac arrest. Workers with pre-existing health conditions, like diabetes, lung or heart disease, can be particularly at risk.

Because many buildings are not climate proofed, construction materials can absorb heat making it warmer inside than out.

High humidity reduces sweating and can reduce the effectiveness of the body’s cooling processes, so when the humidity is high, the temperature feels hotter. For example, at 60 per cent humidity, an ambient temperature of an already uncomfortable 33°C feels closer to a debilitating 50°C.

As the temperature increases, so does the rate of injuries. According to a May 2023 briefing from the US thinktank Public Citizen, for every 1°C increase above ambient temperature there is a 1 per cent increase in injuries, the effect even more marked at higher temperatures.

A 2016 study of agricultural workers in Washington State, USA, conducted by the state regulator and the University of Washington, found the odds of traumatic injuries in cherry harvesters, primarily from ladder falls, increased 1.53 per cent for every 1°C above 25°C (77° F).

A 2021 report from the European trade union research body ETUI noted that when temperatures rise above 30°C, the risk of workplace accidents increases by 5-7 per cent and, when temperatures exceed 38°C, accidents are between 10 per cent to 15 per cent more likely.

Work suffers too

Reluctant employers might want to consider that it is not just the workforce that suffers in the heat. A 2021 report from the Atlantic Council, looking at the economic and social consequences of extreme heat in the US, noted that the productivity losses are greatest in agriculture and construction.

CHECK OUT THE CHECKLIST   Working in sweltering conditions is no holiday. Work quality suffers too, which can have safety consequences. Simple measures can make a difference when temperatures spike. More.

But because many indoor businesses lack air conditioning or adequate ventilation, the services sector, including restaurants, transportation, hospitality, and warehousing. sustains the greatest overall losses.

While the problem might not be as severe in the UK, it is still a significant problem for a large slice of the workforce.  The-Dublin based research organisation Eurofound reported over 20 per cent of all workers in the UK are exposed to high temperatures at least a quarter of the time, not far behind the European average of 23 per cent.

In 2021, the UK Health Security Agency warned: “It is projected that numbers of heat related deaths will triple by 2050, with the hottest summers on record that we have observed in recent years, becoming simply ‘normal’ summers.”

Non-native disease bearing mosquitos may flourish, increasing the “risk of diseases rarely seen in the UK such as dengue, chikungunya and Zika,” HSA warned. “Ticks are also a public health concern, with Lyme disease already endemic in the UK. Milder winters and springs will lengthen the periods ticks are active and biting (though it is also the case that warmer summers could limit their activity).”

That means a greater risk of Lyme disease and other tick-borne conditions.

All of this affects the risks you face at work. Make sure your employer recognises and acts to minimise the real risks associated with rising temperatures. It is much more serious than a bit of discomfort. Getting it wrong could be a life-threatening mistake.


Sources and resources


Feeling the heat

Heat-related ill-health can be a risk in all jobs. Be alert for the symptoms.

Heat stress  Your early warning sign. Watch out for: dehydration (being thirsty); muscle cramps; heat rash (prickly heat or miliaria); confusion.

Heat exhaustion  Headache; nausea; dizziness; weakness; irritability; heavy sweating; decreased/very dark urine; visual disturbance; palpitations.

Heat stroke  The most serious heat related condition. Red, hot, dry skin; sweating stops; high body temperature; confusion/irrational behaviour; fainting/dizziness (heat syncope); convulsions. Can be fatal.

Work injuries Hot work can affect concentration and cause fatigue, leading to a higher risk of dangerous incidents and injuries. Sweaty palms, sweat in the eyes or fogged up glasses can increase risks.

Other effects  Sunlight causes macular degeneration (progressive damage to eyesight). Kidney disease has been linked to high temperatures and dehydration in outdoor workers. Skin damage and skin cancer are associated with over-exposure to sunlight. Rhabdomyolysis – serious damage to muscles – is linked to heat stress and prolonged physical exertion. Over exposure to heat can cause heart arrhythmias, ‘sticky blood’ and a greater risk of heart attacks. Swelling (heat oedema).

Heat illnesses get worse fast. Be alert for heat stress. Seek medical help immediately if a worker shows signs of heat exhaustion or heat stroke.

Hazards checklist

Hot at work? Tell your boss to cool it!
Working in sweltering conditions is no holiday. Work quality suffers too, which can have safety consequences. Simple actions can make a difference when temperatures spike.

  1. Assess the risks Employers should carry out a workplace risk assessment in consultation with safety reps. Remember it should consider humidity as well as temperature – the higher the humidity, the hotter you will feel.
  2. Get a plan  A heat stress plan should be prepared by the employer, be comprehensive, agreed with the union and communicated to workers. It should include details of related training requirements and any measures required to protect vulnerable workers.
  3. Communicate Employers should consult with workers and their union representatives about how to manage heat risks – workers will have their own ideas about how best to cope with the excessive heat.   
  4. Protect Prolonged sun exposure is dangerous for outdoor workers, so employers should provide sunscreen and where necessary UV protective clothing, eye protection and hats.
  5. Work flexibly  Where it is possible, giving staff the chance to come into work earlier or stay later will let them avoid the stifling and unpleasant conditions of the rush hour commute. Bosses should also consider enabling staff to work from home while it is hot.
  6. Simple solutions  Workplaces can be kept cooler and more bearable by taking simple steps such as opening windows, using fans, moving staff away from windows or sources of heat.
  7. Climate-proof  Employers should prepare in advance their premises and work practices for increasingly hot weather, by installing ventilation, air-cooling and energy efficiency measures.
  8. Dress codes Office staff should be allowed to work in more casual clothing than normal – leaving the jackets and ties at home. Employers should examine the suitability of protective clothing for higher temperatures and provide the most appropriate protective gear available.
  9. Welfare  Allowing staff to take more frequent breaks and providing a supply of cold drinks will help keep workers cool.
  10. Shelter and schedules  In excessive heat, outside tasks should be scheduled for early morning and late afternoon, not between 11am-3pm when UV radiation levels and temperatures are highest. Bosses should provide canopies/shades where possible and ‘cool down’ areas.
  11. Acclimatise  It can take time to adapt to work in excessive heat, so workload and expectations and working hours should be adapted accordingly.
  12. Workload and pace Employers should ensure workers can work at their own pace whenever possible, with no loss of income or other penalties. Workload should be reduced or work suspended in times of extreme temperatures.
  13. Complicating factors Physically demanding work, work in PPE or jobs like firefighting, catering, construction, foundries or bakeries that can involve multiple risks need special consideration in risk assessments and interventions. Reduce hours, increase breaks.
  14. Keep records Use the accident book – cases of heat stress can be your early warning that conditions at work are not right; and one worker getting dizzy or fainting may be unrelated to the heat, but multiple cases could point to a workplace problem.

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In 2022, Britain experienced the highest average annual temperature on record, with July seeing the thermometer topping 40°C for the first time. It prompted the Health and Safety Executive (HSE) to warn employers they “need to act now to make sure their workplaces are ready for warmer weather in the future.”

Work suffers too
Sources and resources
Feeling the heat
Hazards checklist

Hazards webpages
Climate and workers' health