What is Heat Stress?

Heat stress is the term used to describe what happens to our bodies when their means of controlling our internal temperatures begin to fail. In addition to high temperatures, heat stress can be caused by overexertion, humidity and an excess of clothing.

The term heat stress refers to any number of individual afflictions that can be caused by the body overheating.

Types of Heat Stress

The spectrum of heat-related health issues begins with heat edema (AKA ‘heat rash’ or ‘prickly heat’). This is a mild condition and relatively easy to treat. It is caused by water and salt retention as the body produces aldosterone.

Slightly more serious are heat cramps. As the name suggests, heat cramps are painful muscle cramps caused by exposure to excessive heat. The exact reason heat cramps occur is not known, though it may have something to do with the body’s supply of electrolytes. This condition is also relatively easy to treat in most cases.

The next condition on the spectrum is potentially quite serious. Heat syncope occurs when a person begins to feel light-headed, dizzy or faint due to heat. In some cases, the person will actually faint, which can cause several problems, including head trauma.

Heat syncope is caused by a lack of salt and water in the body. The risk of heat syncope generally increases along with the temperature. Treatment for this condition usually involves rest and rehydration.

Heat exhaustion is caused by dehydration and electrolyte loss – and it is the next on the spectrum in order to severity. Symptoms include a flushed face, profuse sweating, rapid or weak pulse, nausea, hyperventilation, headaches and any symptoms associated with the conditions listed above.

A person suffering from heat exhaustion may also feel paradoxically chilly, or even experience a sense of euphoria. If a person displays any of the symptoms of heat exhaustion, they should immediately rest, drink cool water or sports drinks and sit or lie down in a cooler place.

A doctor should be contacted if symptoms persist for longer than one hour.

Finally, we come to heat stroke (AKA ‘sun stroke’). In serious cases, heat stroke can actually be life threatening. Heat stroke occurs when the body’s internal cooling methods fail and the core temperature begins to escalate to dangerous levels (40 degrees centigrade or higher), this can cause brain and organ damage. In addition to the symptoms of other conditions listed above, symptoms of heat stroke can include confusion, vomiting, hallucinations, seizures and even comas.

Heat stroke is considered to be a medical emergency and must always be treated by a qualified first aider or medical professional straight away.

The good news is that heat stroke is entirely preventable if you follow the steps we will outline in this feature and be sure to always take the best possible care of yourself and your staff.

Symptoms of Heat Stress

Some people are more susceptible to heat stress than others, but nobody is immune, so it is incumbent upon us all to apply basic vigilance and watch out for the signs.

Mild symptoms of heat stress may include coming up in a heat rash, sweating a lot or feeling flush. Cramps may also occur. More serious symptoms may include irritability, nausea, decreased muscular coordination, hyperventilation, a dry mouth and/or heat sensations around the head or neck.

Symptoms of heat stroke include all of the above, as well as dizziness and loss of balance, fainting or even seizures.

The term ‘heat stress’ partly exists because the symptoms of the various conditions caused by heat are largely interchangeable. There is also no systematic order in which these symptoms appear. It is therefore possible for a person displaying what appear to be mild symptoms to suddenly suffer from much more serious symptoms. Hence, all symptoms must be taken seriously, even if they do not appear to be especially serious at first.

It is also very useful to understand the symptoms of dehydration. These can include feeling thirsty (although it is possible to actively not want a drink and still be dehydrated), not urinating often enough (or producing dark-coloured urine if you do), experiencing a dry or sticky mouth, dry skin, muscle cramps, headaches, sleepiness, lack of energy, sunken eyes, confusion and/or fainting.

What Contributes to Heat Stress?

A person’s age, weight and general level of health can all be contributing factors as to whether or not that person will be affected by various forms of heat stress. Additionally, certain medications can be contributing factors (this will be explained in greater detail later on).

Other factors include the amount of food a person has eaten on the day in question, as well as what type of clothes they are wearing. Prolonged exposure to the heat, without breaks or opportunities to seek shade, greatly increases the risk of heat stress, as does engagement in strenuous activities such as running or working out.

Dehydration is a key cause of heat stress and therefore keeping yourself hydrated can be an excellent way to help prevent heat stress.

Who is at Risk?

Anybody can suffer from the various forms of heat stress. However, children under the age of 4 and adults over 65 are most at risk of experiencing heat exhaustion. This is because young children are at an earlier stage of development and are less able to regulate their body temperatures, while adults over the age stated are more likely to have health complications and/or be taking medications that can increase the risk of heat exhaustion.

People of any age who take certain medications, especially diuretics, beta-blockers, antihistamines (or other allergy medications), antipsychotics or tranquilizers are also a lot more likely to experience heat exhaustion.

Additionally, those who recreationally use illegal drugs (particularly cocaine and amphetamines) may also find themselves at higher risk.

People who are particularly overweight face an increased risk of heat stress. This is because excess weight impacts the body’s ability to regulate temperature. 

People that have recently lived in a cold climate before arriving in a much warmer one should also take extra precautions. It can take several weeks for a human body to fully acclimate to warm weather.

Finally, people with a high heat index (which could, but would not necessarily have to be caused by some of the factors listed above) are especially vulnerable and should always strive to keep themselves as cool as possible in the heat.

Preventing Heat Stress

The worst experiences of heat stress are thankfully quite preventable. This section will detail a few of the best preventative strategies you can use.

Firstly, you can try to wear loose-fitting, light clothes. While you’re unlikely to be wearing a winter coat during the height of summer, it is still possible to overheat simply from wearing tight-fitting, restrictive clothing in hot weather. This is especially the case for security personnel, who are often outfitted with body armour and darkly coloured uniforms. Loose clothing allows air to pass between your skin and the garments, as well as enabling the skin to breathe.

You also need to stay hydrated at all times. Sweating is the body’s natural method of cooling itself down. However, releasing sweat drains vital water from the body. This liquid must be regained by drinking water regularly.

Be aware of medications. If you are taking any medicine that can cause dehydration or affects the body’s ability to dissipate heat, keep this in mind and be extra cautious.

Eating large, heavy meals can also increase the chances of heat stress, as does drinking alcohol and caffeine, as these liquids can actually dehydrate the body.

Never leave any person or animal in a parked car on a hot day, even with the window open. This is a prime cause of heat stroke and death, especially among children.

You should also be vigilant against sunburn. While this is technically a separate condition, sunburn nevertheless affects the body’s temperature and can therefore become a contributing factor to heat stress. You can guard against sunburn by wearing a wide-brimmed hat and high factor sunscreen (SPF 15 or above). This should be reapplied every two hours, or more often if you are swimming or sweating.

If you are at a greater risk for any reason, be sure that your employers and colleagues understand this and get assurance that medical assistance will be on hand if needed at any point.

In all cases, you should try not to spend prolonged periods in direct sunlight. Seek shade as often as possible and wear a hat if you can. You should also take regular rest breaks, especially in the afternoon, when the day is at its hottest.

Treating Heat Stress

If you find yourself, a customer or a colleague experiencing any of the symptoms described in this feature, you must ensure that the affected party ceases all activity and immediately begins to rest. It is also a good idea to elevate the feet, if possible.

A person suffering from heat stress is to be given cool, fresh water and/or sports drinks and must remain in the shade or indoors (wherever is cooler) at all times.

Spraying the person with cool water can also help to lower their temperature, as can the application of ice packs. If you don’t have access to ice packs or spray bottles, a wet sponge or flannel can work as well.

If symptoms persist or worsen, a first aider or doctor should always be alerted.

Heat Stress and UK Law

Under section 25 of the Occupational Health and Safety Act 1970, all UK employers have a duty to take every reasonable precaution to keep their employees safe.

This means that every employer should have policies and procedures in place for dealing with stress. Examples may include putting trained first aiders in place, planning shift patterns designed to keep workers out of the heat for extensive periods or making available advice and training on how to deal with the effects of heat stress.

As a minimum, workers should have access to safe drinking water and should take a small drink every 20 -30 minutes, even if they aren’t thirsty. UK law requires that “an adequate supply of wholesome drinking water” must be made available to workers at all times.

Workers could also be encouraged to use a ‘buddy’ system whereby they watch one another for signs of heat stress. Companies can also re-schedule more strenuous work to be undertaken during cooler times of day.

If your company or employer is expecting you to work in hot environments for an extended period of time, they are legally required to provide at least some strategies for coping with possible heat stress.

If you have any further queries or require any extra assistance, the Health for Work Adviceline may be reached at 0800 778 844.