Various Records
According to the Nepalese government, the youngest person to climb Mount Everest was a 15-year-old Sherpa girl, and the youngest foreigner was 18-year-old Californian Samantha Larson in 2007.
The fastest ascent over the northeast ridge was accomplished in 2007 by Austrian climber Christian Stangl, who needed 16h 42min for the 10km distance from Camp III to the summit, just barely beating Italian Hans Kammerlander's record of 17 hours, accomplished in 1996. Both men climbed alone and without supplementary oxygen. The fastest oxygen-supported ascent over the southeast ridge was Nepalese Pemba Dorjie Sherpa's 2004 climb, using 8h 10min for the 17km route. The fastest ascent without supplementary oxygen over the southeast ridge was accomplished by French Marc Batard who needed 22h 30min in 1988.
Death zone
While conditions for any area classified as a death zone apply to Mount Everest (altitudes higher than 8,000 m/26,246 ft), it is significantly more difficult for a climber to survive at the death zone on Mount Everest. Temperatures can dip to very low levels, resulting in frostbite of any body part exposed to the air. Because temperatures are so low, snow is well-frozen in certain areas and death by slipping and falling can also occur. High winds at these altitudes on Everest are also a potential threat to climbers. The atmospheric pressure at the top of Everest is about a third of sea level pressure, meaning there is about a third as much oxygen available to breathe as at sea level.
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 level of available oxygen had direct effect on blood oxygen saturation levels. At sea level these are usually 98% to 99%, but at base camp this fell to between 85% and 87%. Blood samples taken at the summit indicated very low levels of oxygen present. A side effect of this is a vastly increased breathing rate, from 20-30[citation needed] breaths per minute to 80-90 breaths, leading to exhaustion just trying to breathe.
Lack of oxygen, exhaustion, extreme cold and the dangers of the climb all contribute to the death toll.
People who die during the climb are typically left behind. About 150 bodies have never been recovered. It is not uncommon that corpses are visible from the standard climbing routes.
One sometimes deadly phenomenon, however, does not plague climbers — lightning. Lightning does not strike Mount Everest. NASA's lightning detection system does record significant lightning in the Tibet plateau, but none along the high Tibetan mountains, from about 2000 m (7,000 feet) and above.
Bottled oxygen controversy
Most expeditions use oxygen masks and tanks[53] above 8,000 m (26,246 ft). Everest can be climbed without supplementary oxygen but this increases the risk to the climber. Humans do not think clearly with low oxygen, and the combination of severe weather, low temperatures, and steep slopes often require quick, accurate decisions.
The use of bottled oxygen to ascend Mount Everest has been controversial. George Mallory himself described the use of such oxygen as unsportsmanlike, but he later concluded that it would be impossible to summit without it and consequently used it. When Tenzing and Hillary made the first successful summit in 1953 they used bottled oxygen. For the next twenty-five years, bottled oxygen was considered standard for any successful summit.
Reinhold Messner was the first climber to break the bottled oxygen tradition and in 1978, with Peter Habeler, made the first successful climb without it. Although critics alleged that he sucked mini-bottles of oxygen - a claim that Messner denied - Messner silenced them when he summited the mountain, without supplemental oxygen or support, on the more difficult northwest route, in 1980. In the aftermath of Messner's two successful ascents, the debate on bottled oxygen usage continued.
The aftermath of the 1996 disaster further intensified the debate. Jon Krakauer's Into Thin Air (1997) expressed the author's personal criticisms of the use of bottled oxygen. Krakauer wrote that the use of bottled oxygen allowed otherwise unqualified climbers to attempt to summit, leading to dangerous situations and more deaths. The May 11, 1996 disaster was partially caused by the sheer number of climbers (33 on that day) attempting to ascend, causing bottlenecks at the Hillary Step and delaying many climbers, most of whom summited after the usual 2 p.m. turnaround time. He proposed banning bottled oxygen except for emergency cases, arguing that this would both decrease the growing pollution on Everest—many bottles have accumulated on its slopes—and keep marginally qualified climbers off the mountain. The 1996 disaster also introduced the issue of the guide's role in using bottled oxygen. Guide Anatoli Boukreev's decision not to use bottled oxygen was sharply criticized by Jon Krakauer. Boukreev's supporters (who include G. Weston DeWalt, who co-wrote The Climb) state that using bottled oxygen gives a false sense of security. Krakauer and his supporters point out that, without bottled oxygen, Boukreev was unable to directly help his clients descend. They state that Boukreev said that he was going down with client Martin Adams,but just below the South Summit, Boukreev determines that Adams was doing fine on the descent and so descends at a faster pace, leaving Adams behind. Adams states in The Climb: "For me, it was business as usual, Anatoli's going by, and I had no problems with that."
Life-threatening thefts
Other climbers have reported life-threatening thefts from supply caches. Vitor Negrete, the first Brazilian to climb Everest without oxygen and part of David Sharp's party, died during his descent, and theft from his high-altitude camp may have contributed.
Flora and fauna
Euophrys omnisuperstes, a minute black jumping spider, has been found at elevations as high as 6,700 metres (22,000 ft), possibly making it the highest confirmed permanent resident on Earth. They lurk in crevices and possibly feed on frozen insects that have been blown there by the wind. It should be noted that there is a high likelihood of microscopic life at even higher altitudes. Birds, such as the bar-headed goose, have been seen flying at the higher altitudes of the mountain, while others such as the Chough have been spotted as high as the South Col (7,920 m), scavenging on food, or even corpses, left over by climbing expeditions.