We’re in the midst of a heatwave in the UK which has set new temperature records of over 32°C (90°F) across all four home nations, with Scotland seeing its hottest day ever recorded. In a country where air conditioning is an oft redundant luxury, the unusual heat is causing a fair few problems. Overheating railway tracks and melting roads have resulted in a 212% increase in Brits googling the term “heatwave”, whilst the HSE actively promotes its guidelines on temperature in the workplace. So, is it really too hot to work?

Much to many Brits’ dismay, there is no law for maximum working temperature in the UK. However, there is legislation for employers to keep temperatures at a comfortable level (thermal comfort) and to provide clean, fresh air, which Occupational Health and Safety professionals should be aware of.

How to measure if it’s too hot to work

According to the HSE, there are six basic factors of thermal comfort. These consist of both environmental factors and personal factors.

  1. Air temperature
  2. Radiant temperature
  3. Air velocity
  4. Humidity
  5. Clothing insulation
  6. Metabolic heat

If you are in a workplace without air con, like many older office buildings in the UK, this likely involves a lot of open windows and debating over who gets the desk fan. The hope is that these push air through the workspace, thus speeding up air velocity to cool employees down.

Humidity is included in most weather forecasts with anything above 80% a cause for concern – despite how it may feel, we are still only sitting at around 50% humidity which the HSE states does not have a major impact on thermal comfort. On the other hand, lack of air con indoors can push humidity above 70%, explaining why many offices have sent employees home early this past couple weeks as temperatures peak around 4PM.

However, suffering warm stuffy air granted, being inside in this weather also brings with it protection. The risks of outdoor work have to be properly considered and managed to avoid serious impact on an employee’s health.

Working outdoors during summer months

To address these concerns around working outdoors, especially during summer months, the HSE recommends that employers should think about making a few changes such as:

  • Rescheduling work to cooler times of the day
  • Providing more frequent rest breaks and introducing shading to rest areas
  • Providing free access to cool drinking water
  • Introducing shading in areas individuals are working
  • Encouraging the removal of PPE when resting to help encourage heat loss
  • Educating workers about recognizing the early symptoms of heat stress

There is also the common issue of sunburn, which 3 out of 4 Brits admitted suffering in 2014. Sun damage is usually the result of poor planning (i.e. forgetting to wear sunscreen) or people sacrificing skin protection in order to get a tan – when in fact, a tan is a clear sign that the skin has been damaged already.

It goes without saying that employers need to prepare individuals for working outdoors, and the UV index established by the World Health Organization is an effective measurement of the precautions that need to be taken. Even at level 3 on the scale of 1 to 11+ means there is a moderate risk of harm from unprotected sun exposure. Right now, in the UK we are seeing a UV index of around 5-8 on sunny days during working hours, which means shade is a must.

The process of acclimatization

In some countries around the world temperatures exceeding 30°C would not be out of the ordinary, such as throughout the United States or Central America. Similarly, in other places working in subzero temperatures is also fairly normal, for example in Finland where the average winter temperature can range from -22 to -3°C. The comfort of individuals working in these conditions is largely affected by acclimatization, which is another dimension for health and safety professionals to consider.

Typically, it takes the human body around two weeks to acclimatize to higher temperatures. It does this by sweating more efficiently with a lower salt concentration and by decreasing metabolism and heartrate to reduce the body’s workload.

If your workers aren’t used to high temperatures, they may quickly become uncomfortable if adjustments are not made to the way they work. The same goes for unexpectedly low temperatures.

Dealing with high temperatures in the UK

The UK is not set up well for extreme temperatures at either end of the thermostat.

We experience a very limited yearly range of 6 – 20°C across four seasons. We’re not very well prepared for spells of lows, as we saw in February this year with the “beast from the East” that brought the country to a standstill and that was said to have cost the UK almost £1bn in output per day, nor are we good at dealing with bouts of highs.

Air con is available in most cars, but public transportation is less equipped; homes even more scarcely so. My Virgin TV box, which is kept well away from direct sunlight, kept switching off last week with an “overheating” message. Trains have been instructed to reduce their speed so not to cause the tracks to buckle. Road surfaces have been melting in Cornwall. Offices have been closing early because there’s no air con to relieve employees. Armageddon is, indeed, upon us.

Heat that causes such disruption is surely set to affect the outdoor workforce. On top of having heeded the HSE’s advice to provide frequent breaks and introduce shading, OHS professionals can look out for the symptoms of heat illness to act quickly where necessary. The U.S. Centers for Disease Control (CDC) identifies five main types of heat illness to be aware of:

  1. Heat stroke
  2. Heat exhaustion
  3. Heat syncope
  4. Heat cramps
  5. Heat rash

More information on the symptoms to look out for and what to do when they materialize can be found here.

At what temperature should employees get sent home?

Although there is unfortunately no set temperature that would lawfully require employees to be sent home from work, employers should be “reasonable” with what they expect of their workforce during unusually warm spells. There are arguments that working in the heat causes employees to be less productive, with 71% in a CareerBuilder survey claiming so.

Setting a maximum temperature for work would be a complex piece of legislation due to the many variables involved across industries and locations. However, the Trade Union Commission (TUC) takes issue with the existing vague guidelines, reporting that 14% of safety reps cite high temperatures as a top concern. The organization makes the case that with global warming the issue of rising temperatures is likely to worsen and has called for a maximum temperature of 30°C before serious action must be taken, i.e. ceasing work.

As the heatwave of late in the UK looks set to continue, it will be worth investing some time into what steps you can take to protect workers from heat-related hazards.

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  • Hannah Stewart

    As the Communications Manager at Pro-Sapien, providers of EHS software on Microsoft 365, Hannah has been researching and writing about EHS technology since 2015 with a keen interest in employee engagement.

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