What happens to your body in a heatwave? Experts share why extreme heat can be fatal

What happens to your body in a heatwave? Experts share why extreme heat can be fatal

As global temperatures soar, many countries around the world are experiencing extreme heat which has led to an increase in heat-related fatalities.

In Saudi Arabia, it was announced that more than 1,300 people died during the Hajj pilgrimage this month.

Many cases of death were due to heat stress, as temperatures in Mecca, the city where the Hajj pilgrimage takes place, reached as high as 50 degrees Celsius.

A similar pattern has been observed in Europe, where many countries are raising the alarm about upcoming heatwaves and advising people to take necessary precautions, as some are already recording deaths because of the high temperatures.

In Greece, for instance, three tourists were found dead in a week which saw temperatures reaching 43 degrees Celsius.

To tackle this, many countries in Europe, especially those most at risk of heatwaves, are racing to implement emergency plans.

This is not a new occurrence for the continent, registering high numbers of heat-related fatalities in recent years, especially during the summer.

Research from last year has shown that an estimated 61,672 people in Europe died of heat-related causes between May and September in the year 2022 alone.

How heat can kill you

Camilo Mora, a climate scientist and professor from the University of Hawaii, has studied how heat can become fatal.

In a paper he co-authored, Mora identified 27 different ways people could die from extreme heat and it all comes down to which organ fails first.

Basically the mechanism by which the body gets out of that heat is via the evaporation of sweat. And for that to happen, the temperature outside in the air gotta be lower than the body temperature,

When exposed to high temperatures, Mora explains, the body’s first response is sweating.

"Basically the mechanism by which the body gets out of that heat is via the evaporation of sweat. And for that to happen, the temperature outside in the air gotta be lower than the body temperature," Mora told Euronews Health.

"Anytime the temperature outside is the same or higher, the temperature created by the body cannot exit the body, and that creates a condition called hypothermia, basically the inability of the body to release the heat that it generates," he added.

Once the body can’t cool itself down, it reacts by managing blood flow to prioritise regulating the body’s temperature, a mechanism which in some cases could cause death.

"The priority is to cool down the body and to do so, it takes all of the blood from the body and sends it to the skin such that through the evaporation of the sweat, that blood can come back in cold," Mora said.

Sometimes, this action of diverting blood to the skin can put pressure on the heart which starts pumping blood faster to regulate the blood pressure, ultimately resulting in a heart attack.

Other times, this same mechanism can also result in organ failure.

For example, in very high temperatures, the brain prioritises blood flow to essential functions and reduces it to less critical organs like the stomach.

This can damage the gut lining, allowing contents from the gut to enter the bloodstream which causes many health issues that can lead to death.

"The white cells start coming in and attacking this, as a mechanism of defence, which creates coagulation. And then you get this coagulation going into your kidneys, blocking your kidneys, and if you have bad kidneys that could be a way for you to die," Mora explained.

He adds that sometimes the coagulation, or blood clotting, can also reach the brain and create life-threatening problems there as well.

Who’s most at risk of dying from heat

"There are two groups of people that are heavily affected by this; one is people that are very old," Mora said.

"The reason for this is because their skin is already beat up through years of use, so it's not as efficient to thermoregulate," he added.

Mora further explains that young children are also at high risk because their bodies heat up faster than adults.

Moreover, people with obesity may struggle with heat dissipation, making them also more vulnerable to the heat.

According to Mora, individuals who use substances that may impair the brain’s ability to recognise and respond to high temperatures, like drugs or alcohol, are also at risk.

"By being exposed to these drugs, the brain fails to understand that you are being exposed and stop triggering the mechanism by which you can actually cool down," Mora said.

Symptoms and precautions

When it comes to preventing death from heat, precaution is better than a cure, and recognising the symptoms of heat-related illnesses early on can save lives.

According to Mora, some of these symptoms include sweating, which is the body’s first response to heat exposure, an increased heart rate, along with feelings of dizziness and losing consciousness.

To reduce the risk of dying from the heat, the main strategy is to avoid being exposed and stay indoors as much as possible.

Other ways to avoid heatstroke include staying hydrated, wearing loose clothing in light colours, avoiding the sun during peak temperatures, and also avoiding extreme exercise and excessive alcohol.

In the long-term, Mora sees urban planning as particularly useful, especially planting more trees in cities, which can help cool down urban areas and reduce the overall heat load on the population.