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oxygen mask Assault on the Summit
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Altitude and Oxygen
On an Everest expedition, the acclimatization process takes about two months. The affects of high altitude on the climbers, caused by hypoxia—the shortage of oxygen—are with them every moment. Scientific studies and practical experience suggest that above 20,000 feet, the body's ability to repair itself does not keep up with the deterioration process at altitude. Thus, climbers try to limit their exposure to the highest altitudes. Minimal time is spent at Camp 4, at 26,000 feet—their final stopping point before an assault on the summit. Ed Viesturs explains what it's like at Camp 4: "It takes a lot out of you hanging out at 26,000 feet. You don't eat, you don't drink, you don't have any motivation. Your only motivation is to go in one direction and that's toward the summit.

mountain scenicYou don't want to go outside to go to the bathroom, you don't want to put your boots on, it's just so much effort. You just feel so lethargic, everything is a huge physical demanding effort."

Every year on mountains around the world many thousands of healthy men and women suffer from mountain sickness, and hundreds die. The reason is simple: we must breathe to get enough oxygen from the atmosphere in order to live. Normally, a thin blanket of air presses on us with 15 pounds per square inch, and a fifth of that pressure is oxygen. This decreases as we go higher. By the time you reach the summit of Everest, the air pressure is a third of that at sea level, which means it contains a third of the oxygen. Even moderate altitudes of 8,000 to 10,000 feet can cause a spectrum of symptoms and illnesses.

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Photos: (1-2) courtesy Robert Schauer.

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