It is fair to say that we all enjoy a bit of sunshine every now and then, but have we ever stopped to think about how that affects us in work and play. In play we rub in suntan lotion and alternate time on the sun lounger with dips in the pool, but we do not think the same whilst at work. There is a lack of education and understanding around heat stress in general with most people understanding the cause, but very few the symptoms.

So first, let’s clear something up….

What is heat stress?

Heat stress occurs when the body’s means of controlling its internal temperature starts to fail. As well as air temperature, factors such as work rate, humidity and clothing are worn while working may lead to heat stress.

It is interesting to see that heat stress is influenced by many factors and that there are even some factors we would not usually consider, like clothing for instance. We understand that work rate can affect you but how does humidity affect you?

What is humidity?

Humidity is the concentration of water vapour present in the air. Water vapour, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.

How does this affect heat stress?

Hot, humid summer days can feel unbearable sometimes. Humidity, or the amount of moisture in the air, can make the temperature feel warmer, as our sweat is slower to evaporate. High humidity can have an adverse effect on the human body. Because the air feels warmer than the official, recorded temperature, it can contribute to feelings of low energy and lethargy. In addition, hyperthermia, or overheating as a result of your body’s inability to effectively let out heat, can negatively impact your health in conditions of high humidity.

What are the symptoms of heat stress? These typically are: –

  • an inability to concentrate
  • muscle cramps
  • heat rash
  • severe thirst – a late symptom of heat stress
  • fainting
  • heat exhaustion – fatigue, giddiness, nausea, headache, moist skin
  • heatstroke – hot dry skin, confusion, convulsions and eventual loss of consciousness. This is the most severe disorder and can result in death if not detected at an early stage

How can we negate the risk of heat stress including PPE?

  • Train workers in heat stress awareness and first aid
  • Provide drinking water
  • Provide rest breaks and air-conditioned rest areas if possible
  • Encourage workers to stay fit; to drink water
  • Use machines to reduce physical demands of work
  • Schedule most strenuous work to cooler times of the day
  • Measure daily Humidity ratings and have a Humidity Heat Stress Response Plan
  • Have a heat stress prevention program specific to your workplace
  • Use dry cooling technology pads in safety helmets

We now understand the signs of heat stress and how we can negate the risk of heat stress in the workplace but what should we do if we believe someone is suffering from heat stress. Let us look at the NHS guidelines.

If someone has heat exhaustion, follow these 4 steps:

  1. Move them to a cool place.
  2. Get them to lie down and raise their feet slightly.
  3. Get them to drink plenty of water. Sports or rehydration drinks are OK.
  4. Cool their skin – spray or sponge them with cool water and fan them. Cold packs around the armpits or neck are good, too.
  5. Stay with them until they are better.

They should start to cool down and feel better within 30 minutes.

Call 999 if:

You or someone else have any signs of heatstroke:

  • Feeling unwell after 30 minutes of resting in a cool place and drinking plenty of water
  • Not sweating even though too hot
  • A temperature of 40C or above
  • Fast breathing or shortness of breath
  • Feeling confused
  • 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 are waiting for help.

Something to make a note of from a risk assessment perspective is most deaths occur during warm periods not classed as heatwaves and the greatest burden of heat-related mortality falls outside the official heatwave period. The time-limited nature of the heat-health watch alert service means that the public are not necessarily alerted to unseasonal spells of very high temperatures. Furthermore, excess deaths start occurring at 25°C, but heatwave alert thresholds are roughly 30°C, meaning that the public are not alerted about some dangerous hot spells. The Government’s plan is to create a single adverse weather plan and strongly recommend that alerting systems run throughout the year, especially targeted to those who are likely to suffer before heatwave temperature thresholds are reached.

What is driving our consistently changing weather now?

You will not be surprised to hear it is climate change. The threat of heatwaves is developing rapidly. The number of extreme heatwave events in Europe has risen since 1950, and their intensity is increasing. Research found that carbon emissions from human activities have doubled the likelihood of severe heat events. The Intergovernmental Panel on Climate Change have seen very clearly the evidence that has led them to conclude that human influence on the climate system is clear. But within the UK we have seen the general warming of temperatures, and with that, we have seen a warming of extreme temperatures. The 2014 Intergovernmental Panel on Climate Change Fifth Assessment Report concludes that “it is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in [greenhouse gas] concentrations and other anthropogenic forcing’s together.

For more information on Centurion’s Dry Cooling Technology products visit or contact your local Greenham Service Centre.

Disclaimer: The information provided through Greenham Pulse is for general guidance only and is not legal advice. Greenham Pulse is not a substitute for Health and Safety consultancy. You should seek independent advice about any legal matter.