Heatwaves And The Workplace

Last week, the UK Health Security Agency put in place its first ever level four heat warning. Such a warning showed the impending heatwave could cause illness and death among the fit and healthy, not just in high-risk groups. Experts warn heatwaves of this magnitude could become the norm in years to come. So what could these events mean for the future of health and safety?

The Heatwave

The UK hit record temperatures last Tuesday, with Coningsby in Lincolnshire reaching 40.3°C, the first time the mercury passed 40°C since records began.

Fire brigades declared major incidents in London, Leicestershire, and South Yorkshire. Devastating fires destroyed over forty properties because of the heat, with experts saying it could have been even worse if wind gusts had been stronger.

Thirteen people lost their lives after getting into difficulty in rivers, reservoirs and lakes while swimming.

Runways melted at RAF Brize Norton and Luton airport. Rail operators imposed speed restrictions amid fears of rails buckling in the heat on key rail routes in England, Wales and Scotland.

The extreme temperatures forced some hospitals in England to cancel surgery as operating theatres became too hot. The NHS also reported IT server rooms needed additional cooling in buildings where the air conditioning was overstretched. Some trusts even considered reducing the amount of printing they did to lessen the strain on IT systems.

A slow-moving area of high pressure moving up from North Africa and forming a heat dome over Portugal, Spain and France caused the excessive heat. An unusually dry, hot spring had created parched tinderbox-dry grassland. Conditions experts have attributed to climate change.

Health and Safety Issues and Heatwaves

The UK Health Security Agency (UKHSA) first published a Heatwave Plan in 2004, following the devastating pan-European heatwave of 2003. It aimed to protect health and reduce harm from severe heat. The plan set up heatwave alert levels ranging from 0 to 4 that operate from 1 June to 15 September. The alert level is based on forecasts from the Met Office and is usually based on regional rather than national forecasts, meaning different regions can have different alert levels. Level 3 and 4 Heat-health alerts are triggered when the Met office issues either Amber or Red alerts for extreme heat.

Three of the biggest health risks associated with extremely hot weather are dehydration, heat exhaustion and exposure to UV sunlight. Children under 4 years, people with underlying health conditions, pregnant women and the elderly are more at risk of health issues from becoming too hot. Also at risk are workers in hot conditions or working with equipment that may reduce their ability to regulate their body temperature.

Health and Safety law requires employers to ensure that they do all they can to protect the health, safety and welfare of their staff as far as is reasonably practicable. This includes protecting them from the risks of excessive heat.

All employers have to undertake risk assessments concerning both the work being done and the environment in which that work is being carried out. Then put in place measures to reduce the risk of harm to their employees. If there is a risk of extreme temperatures, they need to review those risk assessments and, if necessary, take further steps to reduce potential harm.

Considerations In Heatwaves

Below are some things employers should take into consideration when a Heat health alert is issued.


Employers should consider allowing employees to work from home if possible. An employer’s responsibilities are not limited to their premises. People commuting during Amber and Red warnings can experience travel problems, including delays on roads and road closures, delays and cancellations to rail and air travel. These situations could cause people to suffer from heat exhaustion.

Type of work

Employers should consider wherever possible stopping work requiring strenuous activity. If this is not possible, they should reduce the time they do it and ensure employees get plenty of breaks and opportunities to drink plenty of cool water.

Ventilation and thermal comfort

Good ventilation should be in place to help to reduce the transmission of COVID-19, but it becomes even more important during a heat wave. Oscillating fans can help with airflow. However, if room temperatures are above 30C, they may not help with cooling and may worsen dehydration.

See our article on coping with excessive heat in the workplace for more information.

Use of PPE

Using some types of PPE (overalls, respirators, hoods, masks or aprons) in hot outdoor or indoor environments increases the risk of the body being unable to cool itself. This can lead to heat exhaustion and heat stroke. If work requiring PPE cannot be paused, employers should implement appropriate measures, for example:

  • Make staff aware of the signs of heat exhaustion and dehydration
  • Reduce the time spent undertaking tasks in PPE by rotating staff
  • Providing more frequent breaks in between the use of PPE
  • Have the employee regularly change single use PPE to prevent sweat saturation
  • Operate a buddying system where staff regularly check on one another for signs of heat stress
  • Significantly limit work between 11 am-3 pm.
  • Have employees undertake temporary duties out of the sun, provided they are trained to do that work safely.

Employers are required by law to undertake individual risk assessments once an employee has informed them they are pregnant. Employers should review this risk assessment in the event of an Amber or Red warning for extreme heat.

Legal Issues

The Workplace (Health, Safety and Welfare) Regulations 1992 covers temperature extremes in the workplace. Regulation 7 deals specifically with indoor workplace temperatures and places a legal obligation on employers, stating that ‘During working hours, the temperature in all workplaces inside buildings shall be reasonable.’ Of course, ‘reasonable’ will depend on the workplace, being different for a cold store, an office, and a bakery, for example. The law does not state a minimum or maximum temperature, but the temperature in workrooms should normally be at least 16°C or 13°C if most of the work involves rigorous physical effort.

In addition, the Management of Health and Safety at Work Regulations 1999 require employers to make a suitable assessment of the risks to the health and safety of their employees and take action where necessary and where reasonably practicable. Heat poses a risk, so this applies to employees working during a heatwave.

What Can Be Done When Heatwaves Are Predicted?

So what can be done to help prepare for the increased frequency of heatwaves being predicted?

The TUC and UNISON want a change in the law, so employers must attempt to reduce temperatures if they rise above 24°C, and a requirement to pause work if indoor temperatures reach 30°C or 27°C for those doing strenuous jobs.

Weather conditions will likely move increasingly beyond the design parameters of our infrastructure, as we’ve seen on the railways, runways and roads. Upgrades to existing infrastructure could include using heat-resistant rails for trains and new asphalt mixes for roads.

Brickwork and stone are resilient to fire, but chimneys, vents and exhaust fans are potential sites where hot embers from a fire can get in. Mesh screens could be installed to seal these possible entry points. Double glazing isn’t usually fire resilient, but toughened glass is. Keeping curtains and blinds closed is useful in keeping a room cool for a while, but still traps heat behind them, which eventually seeps into the room. Attaching external shutters to windows would keep the heat outside.

Yet, it is not always a question of applying new technology. Over two thousand years ago, ancient Rome was extremely hot in summer, so they built Tivoli Gardens just outside the city, full of trees, water, and fountains. For new infrastructure, the layout of buildings can be planned with heatwaves in mind. Many normally hot countries use trees for shade and cooling water features in urban areas.

Of the European countries affected by last week’s heatwave, only Spain has a legally enforceable upper temperature for the workplace. However, it seems likely that as the century progresses and the effects of global warming become more prevalent in the UK, changes will be needed to the current laws, infrastructure, and health and safety practices related to heatwaves.

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