page_title: Mount Everest
section_title: Death zone
hierarchical_section_title: Mount Everest / Climbing / Death zone
caption_attribution_description: Mount Everest, view from Kala Patthar (5700 m)
context_page_description: Mount Everest is Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border runs across its summit point.
  The current official elevation of 8,848 m, recognised by China and Nepal, was established by a 1955 Indian survey and confirmed by a 1975 Chinese survey.
  In 1865, Everest was given its official English name by the Royal Geographical Society, as recommended by Andrew Waugh, the British Surveyor General of India, who chose the name of his predecessor in the post, Sir George Everest, despite Everest's objections.
  Mount Everest attracts many climbers, some of them highly experienced mountaineers. There are two main climbing routes, one approaching the summit from the southeast in Nepal and the other from the north in Tibet. While not posing substantial technical climbing challenges on the standard route, Everest presents dangers such as altitude sickness, weather, and wind, as well as significant hazards from avalanches and the Khumbu Icefall. As of 2019, over 300 people have died on Everest, many of whose bodies remain on the mountain.
context_section_description: At the higher regions of Mount Everest, climbers seeking the summit typically spend substantial time within the death zone (altitudes higher than 8,000 metres (26,000 ft)), and face significant challenges to survival. Temperatures can dip to very low levels, resulting in frostbite of any body part exposed to the air. Since temperatures are so low, snow is well-frozen in certain areas and death or injury by slipping and falling can occur. High winds at these altitudes on Everest are also a potential threat to climbers.
  Another significant threat to climbers is low atmospheric pressure. The atmospheric pressure at the top of Everest is about a third of sea level pressure or 0.333 standard atmospheres (337 mbar), resulting in the availability of only about a third as much oxygen to breathe.
  Debilitating effects of the death zone are so great that it takes most climbers up to 12 hours to walk the distance of 1.72 kilometres (1.07 mi) from South Col to the summit. Achieving even this level of performance requires prolonged altitude acclimatisation, which takes 40–60 days for a typical expedition. A sea-level dweller exposed to the atmospheric conditions at the altitude above 8,500 m (27,900 ft) without acclimatisation would likely lose consciousness within 2 to 3 minutes.
  In May 2007, the Caudwell Xtreme Everest undertook a medical study of oxygen levels in human blood at extreme altitude. Over 200 volunteers climbed to Everest Base Camp where various medical tests were performed to examine blood oxygen levels. A small team also performed tests on the way to the summit. Even at base camp, the low partial pressure of oxygen had direct effect on blood oxygen saturation levels. At sea level, blood oxygen saturation is generally 98–99%. At base camp, blood saturation fell to between 85 and 87%. Blood samples taken at the summit indicated very low oxygen levels in the blood. A side effect of low blood oxygen is a greatly increased breathing rate, often 80–90 breaths per minute as opposed to a more typical 20–30. Exhaustion can occur merely attempting to breathe.
  Lack of oxygen, exhaustion, extreme cold, and climbing hazards all contribute to the death toll. An injured person who cannot walk is in serious trouble, since rescue by helicopter is generally impractical and carrying the person off the mountain is very risky. People who die during the climb are typically left behind. As of 2006, about 150 bodies had never been recovered. It is not uncommon to find corpses near the standard climbing routes.
  Debilitating symptoms consistent with high altitude cerebral oedema commonly present during descent from the summit of Mount Everest. Profound fatigue and late times in reaching the summit are early features associated with subsequent death.
  — Mortality on Mount Everest, 1921–2006: descriptive study
  A 2008 study noted that the "death zone" is indeed where most Everest deaths occur, but also noted that most deaths occur during descent from the summit. A 2014 article in The Atlantic about deaths on Everest noted that while falling is one of the greatest dangers the death zone presents for all 8000ers, avalanches are a more common cause of death at lower altitudes. However, Everest climbing is more deadly than BASE jumping, although some have combined extreme sports and Everest including a Russian who base-jumped off Everest in a wingsuit (he did survive, though).
  Despite this, Everest is safer for climbers than a number of peaks by some measurements, but it depends on the period. Some examples are Kangchenjunga, K2, Annapurna, Nanga Parbat, and the Eiger (especially the nordwand). Mont Blanc has more deaths each year than Everest, with over one hundred dying in a typical year and over eight thousand killed since records were kept. Some factors that affect total mountain lethality include the level of popularity of the mountain, the skill of those climbing, and the difficulty of the climb.
  Another health hazard is retinal haemorrhages, which can damage eyesight and cause blindness. Up to a quarter of Everest climbers can experience retina
caption: From Kala Patthar
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