What happens to a body in Everest's "death zone": scientists explain all the risks

The year 2023 saw one of the deadliest seasons on Everest: 12 climbers died and another 5 remain missing. This is less than in 2015, but then an earthquake that triggered an avalanche was responsible for the deaths. Now, the blame lies solely with people who do not understand how dangerous the famous mountain is and how easily it can take lives for carelessness.

Insider has spoken to experts and explains what happens to the human body when climbing Everest. And why this climb causes psychosis in some people.

The fact is that the human body is best adapted to work at sea level. Here, it receives enough oxygen for the brain and lungs, and the higher a person rises above this level, the worse it gets. At sea level, the air contains about 21% oxygen. But at an altitude of more than 3.7 km, the oxygen level is already 40% lower.

Everest is a scary story, as its height reaches 8848 metres above sea level and to get to the top you have to go through the "death zone". This is the name of the area at an altitude of over 8,000 metres, where the lack of oxygen is so critical that the body dies in minutes.

In the "death zone", the climber's brain and lungs suffer from oxygen deprivation. The risk of heart attack and stroke also increases. But the worst part is that due to the lack of oxygen in the brain, a person loses the ability to think normally at a time when every moment can be critical.

"Your body is breaking down and essentially dying. It becomes a race against time," says Shonna Burke, an experienced climber who conquered Everest in 2005.

In addition to the climb itself, tourists seeking to overcome the legendary mountain also create trouble for each other, actually getting in line to reach the coveted peak. Expedition companies openly state that humans are also to blame for the recent deaths: during rare periods of good weather, the summit of Everest is so crowded with climbers that tourists get stuck in the "death zone" for too long.

For example, in 2019, 11 out of 250 climbers who were stuck in a queue to ascend and descend the mountain died due to a traffic jam.

Jeremy Windsor, a physician who climbed Everest in 2007 as part of the Caudwell Xtreme Everest expedition, said that blood samples taken from four climbers in the "death zone" showed that they survived with only a quarter of the oxygen they needed.

"These figures are comparable to those of patients on the verge of death," Windsor said.

Lack of oxygen leads to numerous health risks. When the amount of oxygen in the blood drops below a certain level, the heart rate increases to 140 beats per minute, increasing the risk of a heart attack.

Experts note that the main condition for climbing is time to acclimatise to the lung-destroying conditions of the Himalayas. Expeditions usually make at least three ascents from the Everest base camp, climbing higher and higher each time before making the leap to the summit.

Ideally, this takes weeks, during which the body begins to produce more haemoglobin (a protein in the blood that helps to carry oxygen from the lungs to the rest of the body) to compensate for the loss. The problem is that this causes the blood to thicken, making it harder to transport in the body. This can lead to a stroke or fluid accumulation in the lungs.

That is why a condition called high altitude pulmonary edema (HAPE) is often recorded on Everest - when even a regular stethoscope can detect the presence of fluid in the lungs that interferes with breathing. At such moments, a person experiences inevitable shortness of breath at night, weakness and a constant cough that causes the release of white, watery or foamy fluid.

In the "death zone", the same thing happens to the brain, which swells, which can even lead to a form of psychosis. This happens when hypoxia occurs - that is, oxygen deprivation, which provokes high altitude cerebral edema (HACE). In fact, it is a deadly danger to the brain.

This swelling can cause nausea, vomiting, difficulty thinking and reasoning. Climbers may even forget where they are and fall into delirium, which experts consider a form of altitude psychosis.

In this state, the climbers' ability to think deteriorates, and they begin to do strange things, such as throwing off their clothes or talking to imaginary friends.

At the same time, experts note that there is simply no way to acclimatise to the conditions of the "death zone".

Another problem is so-called snow blindness, which is caused by glare from endless snow and ice. This can lead to temporary loss of vision or rupture of blood vessels in the eyes.

The temperature in the death zone also plays against people, as it never rises above minus 18 degrees. This worsens blood circulation in the fingers and toes, which can lead to frostbite and, in severe cases, gangrene, which can lead to amputation.

Earlier, OBOZREVATEL also reported that Everest, according to some scientists, may not be the highest mountain on Earth.

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