![]() ![]() It refers to altitudes above a certain point where the amount of oxygen is insufficient to sustain human life for an extended time span. The death zone in mountaineering, (originally the lethal zone) was first conceived in 1953 by Edouard Wyss-Dunant, a Swiss physician and alpinist. The summit of Mount Everest is in the death zone, as are the summits of all eight-thousanders. Īt altitudes above 7,500 m (24,600 ft, 383 millibars of atmospheric pressure), sleeping becomes very difficult, digesting food is near-impossible, and the risk of HAPE or HACE increases greatly. ![]() Humans have survived for two years at 5,950 m (19,520 ft, 475 millibars of atmospheric pressure), which is the highest recorded permanently tolerable altitude the highest permanent settlement known, La Rinconada, is at 5,100 m (16,700 ft). Research also indicates elevated risk of permanent brain damage in people climbing to above 5,500 m (18,045 ft). Expedition doctors commonly stock a supply of dexamethasone, to treat these conditions on site. The higher the altitude, the greater the risk. Travel to each of these altitude regions can lead to medical problems, from the mild symptoms of acute mountain sickness to the potentially fatal high-altitude pulmonary edema ( HAPE) and high-altitude cerebral edema ( HACE). Extreme altitude = above 5,500 metres (18,000 ft).Mountain medicine recognizes three altitude regions which reflect the lowered amount of oxygen in the atmosphere: When pO 2 drops, the body responds with altitude acclimatization. It is about half of its sea-level value at 5,000 m (16,000 ft), the altitude of the Everest Base Camp, and only a third at 8,848 m (29,029 ft), the summit of Mount Everest. Ītmospheric pressure decreases exponentially with altitude while the O 2 fraction remains constant to about 100 km (62 mi), so pO 2 decreases exponentially with altitude as well. In healthy individuals, this saturates hemoglobin, the oxygen-binding red pigment in red blood cells. The concentration of oxygen (O 2) in sea-level air is 20.9%, so the partial pressure of O 2 (pO 2) is 21.136 kPa. The human body can perform best at sea level, where the atmospheric pressure is 101,325 Pa or 1013.25 millibars (or 1 atm, by definition).
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