Occupational deaths from heatstroke differ from those in the general populous. Intense physical exertion combined with insufficient hydration, inadequate rest, and ‘protective’ clothing that fails to let heat escape from the body all catalyse the difficulties and dangers of hot environments. Even without these added obstacles, merely existing in the heat is too much stress on some individuals. Those at higher risk of heat stress include: the elderly, people with existing physical/mental health conditions or on certain medications, pregnant women, children, and – last but not least – those working in the heat.

“when your workers are exposed to high temperatures, everyone needs to be aware of the dangers of the heat”

We have all heard that during the summer months, exposing workers to extremes of heat results in widespread heat illnesses. The workers who are most exposed to heat illnesses are labourers working outdoors, such as construction workers, cleaners, and agricultural workers to name but a few. The ill health these workers face includes minor conditions such as heat cramps, heat syncope, and heat exhaustion, as well as the more severe condition known as heat stroke, which may lead to death.

In addition, excessive heat causes accidents at workplaces in many other ways. It becomes more difficult to concentrate on the job due to rigorous sweating, leading to workers becoming increasingly tired and nervous. With all these factors, so too creeps in an increased level of errors in judgment. In extreme situations, a lack of consciousness may occur due to severe dehydration.

It stands to reason, therefore, that when your workers are exposed to high temperatures, everyone needs to be aware of the dangers of the heat.

Statistics from the National Safety Council show that, since 1936, there have been 30,000 deaths caused by heat related illnesses. On average, 384 people die each year from heat stroke. Heat related injuries seem to mostly affect the aged workers, people who are not in good physical and mental health, pregnant workers, and those not acclimatised to the heat.

Temperature regulation

Healthy human ‘core’ or deep body temperature is maintained within a narrow range of 37°C ±1.5°C. The body is incredibly well designed, with many mechanisms in place to self regulate its core temperature against fluctuations encountered every single day. To prevent it from increasing when exposed to heat, the body sweats and increases blood flow to the skin. When muscles are being used for physical work, most of the blood is flowing to muscles and less blood is available to flow to the skin and release heat. If the body can’t dispose of excess heat, it will store it. When this happen the body’s core temperature of 37°C rises and the heart rate increases. Generally, when body temperature reaches above 40°C, the thermo-regulation mechanism of the body fails.

“the body’s temperature increasing to 40°C is a severe medical emergency which could result in death”

Heat stress

Heat stress is known as the body’s reaction to overheating when it cannot cool by itself through sweating due to dehydration, or in other words, loss of body fluids/water lost due to sweating which are then not replenished through drinking more water. It is of paramount importance to drink water regularly when working in hot environments even though you are not feeling thirsty. Employees should remember that they can deplete as much as 30% of their body’s water when working in the heat before they even begin to feel thirsty.

Heat related illness and symptoms

The reactions shown by the body during excessive heat exposures may vary from mild to severe, as explained in the following sections. These include: heat rash, heat cramps, heat exhaustion, heat stroke, and heat syncope.

Heat rash

This condition, also known as prickly heat, occurs when exposed to hot and humid environments where sweat can't easily evaporate from the skin. Due to this rashes are produced, which in some cases cause severe pain.

Heat rashes can be prevented or at least minimised by resting frequently in cool places and bathing regularly, ensuring to thoroughly dry the skin. Do not scratch skin rashes, but do apply anti-itch lotion. Wear loose-fitting cotton clothes that dry away the sweat.

Heat cramps

Due to the loss of body salts and electrolytes, excessive sweating can result in painful muscle spasms that will usually affect the stomach, arms and legs. Providing workers with fluids containing electrolytes such as calcium, sodium and potassium may help in minimising the risk of heat cramps.

Heat exhaustion

This is a condition created by the loss of fluids lost during excessive sweating. Individuals with heat exhaustion still sweat, but they experience extreme weakness and may even collapse. They may experience nausea and headache. The signs include clammy and moist skin; pale complexion, thirst, and dry mouth. Heat exhaustion usually occurs when the body temperature reaches around 39°C.

This condition is best treated by immediately taking the patient to a cool place, applying cool compresses, elevating the feet, and giving the individual plenty of fluids with electrolytes. More severe cases may require immediate medical treatment and probably transfer to hospital.

Heat stroke

Heat stroke occurs when the body’s core temperature gets too high and the body is no longer able to cool itself. This generally results when the body’s temperature increases to 40°C. This is a severe medical emergency which could result in death.

An individual suffering from heat stroke will have hot and dry skin – by this point the body’s temperature regulation mechanism of sweating has failed – their pulse will be high and their blood pressure will fall. They will have an extremely high fever, as well as mental and neurological disturbances.

Heat stroke is a fatal condition and must be treated by immediately cooling the victim's body with water spray or wrapping them in wet sheets. Immediately seek medical attention by calling an ambulance.

Do not use ice or very cold water for cooling as it can result in superficial narrowing of the blood vessels, which can prevent loss of heat from the skin surface.

Heat syncope

The condition of heat syncope usually occurs in individuals standing erect and immobile in the heat for prolonged hours, as this can reduce the effectiveness of blood circulation. A knock on consequence of poor circulation is that brain cells get affected when oxygen does not reach them; however, the person recovers rapidly after lying down.