What makes mt everest so dangerous

In Depth. About climbers reach the top of Everest each year Getty Images. Three die on Everest as dozens require medical aid Major earthquake hits Nepal for second time in two weeks Everest avalanche: are Sherpas put at risk by Western climbers?

Avalanches The risk of mass casualities make avalanches a particularly lethal threat to climbers. Altitude sickness and other issues A number of deaths on Everest have been the result of altitude sickness: when humans struggle to adapt to the low oxygen levels at high altitudes, usually above about 10,ft 3,m. Nepal World News Mount Everest. Quiz of The Week: 6 - 12 November.

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This climbing season's 11 deaths so far, though, are not related to one event but to several factors that have caused overcrowding in the most dangerous areas of the route to the summit. The barometric pressure decreases at high altitudes, which allows oxygen molecules to spread out, according to Dr.

At Everest Base Camp on the Khumbu Glacier, which lies at an altitude of 17, feet 5, m , oxygen levels are at about 50 percent of what they are at sea level. That drops to one-third at Everest's summit, which reaches about 29, feet 8, m above sea level.

If someone is experiencing mild altitude sickness, they should not go any higher for 24 to 48 hours, according to the NHS. If symptoms don't improve, or if they worsen in that time, the NHS advises descending 1, feet m. Severe altitude sickness is a medical emergency that requires immediate descent to a low altitude and attention from a medical professional. Altitude sickness can lead to pulmonary or cerebral edemas, which are buildups of fluid in the lungs and brain, respectively.

These symptoms often occur together and are the body's attempt to get more oxygen to these vital organs in response to the decreased oxygen environment at these high elevations, said Weiss. Because blood vessels and capillaries are porous, this increased flow can cause leakage and fluid retention. Fluid buildup in the brain may result in loss of coordination and problems with thought processing, said Weiss.

It can lead to coma and death. Weiss said that fluid buildup in the lungs can make it hard for someone to breathe and physically exert themselves. It can eventually cause death through a process similar to drowning.

Researchers reporting in in the British Medical Journal BMJ looked at deaths on Everest from to and found that "profound fatigue and late times in reaching the summit are early features associated with subsequent death," they wrote in the BMJ.

Weiss has a similar view on the safest way to climb Everest: "When people climb Everest […], the mantra is that you have to get up to the summit by a certain time so that you can get down while you still have oxygen left and while you still have daylight," he said.

Too often, people refuse to turn around when they should because they can see the summit and think it's close enough to justify continuing, he added. Overall, the BMJ study found that the total mortality rate for Everest mountaineers was 1. The mortality rate for climbers is 1. The most common cause of death for climbers was falls, whereas the most common cause of death for Sherpas was "objective hazards," which included avalanches, falling ice, crevasses and falling rock, and were likely related to the extended time they had to spend in more treacherous areas of the mountain as part of their employment.

The researchers noted that neurological dysfunction, which could be related to altitude sickness, also could have contributed to fatal falls. There are no distinct reasons why altitude affects one person more than another. The National Institutes of Health notes that speed of ascent and physical exertion often play roles in whether someone develops altitude sickness.