The allure of climbing Mount Everest has always been spiced with an aura of danger. But how risky is it to attempt to scale the world's highest peak? A team of medical researchers led by anaesthetist Paul Firth of Massachusetts General Hospital has analyzed 85 years of data and come up with some fascinating statistics.
Their study, which will soon be published in the British Medical Journal, concludes that 1.3 percent of those who climbed above base camp between 1921 and 2006 did not return alive. Not surprisingly, the percentage was higher for climbers (1.6 percent) than for Sherpas (1.1 percent), members of a local Nepali ethnic group who serve as guides.
“Most Sherpas were killed in incidents on the lower slopes, whereas most climbers died above 8,000 meters,” the report states. (Everest’s peak is 8,850 meters, or 29,000 feet, above sea level.) “Climbers typically died during descent from the summit, often developing cognitive impairment and ataxia.”
In other words, many climbers returning from the peak developed neurological symptoms caused by swelling of the brain, becoming confused and losing the ability to coordinate their muscle movements. This, of course, made the already-difficult journey far more hazardous.
The largest percentage of deaths — 67 out of the 192 reported among mountaineers who ventured above base camp — were the result of “objective hazards” such as avalanches, crevasses and falling rocks. Another 46 were the result of falls. Only 17 were attributed to high-altitude sickness, with 11 caused by hypothermia.
“While a typical expedition to Everest now lasts about 60 days, 82.3 percent of deaths among climbers occurred during or after the day of a summit attempt,” the report states. “For modern climbers, therefore, the most dangerous time was that spent above 8,000 meters.”
The researchers used records kept for more than 40 years by journalist Elizabeth Hawley, whose work is the foundation of the Himalayan Database. The data were studied by four doctors experienced in managing high-altitude illness — three of whom have reached the summit of Everest themselves.
Can anything be done to decrease the death rate among climbers? Firth and his colleagues are somewhat doubtful. “Since neurological symptoms are present in many non-survivors, critical questions include whether adequate acclimatization is possible at this altitude,” they note.
“Climbers died at over six times the rate of Sherpas during the descent from the summit,” the report notes, adding that this “may be related to better acclimatization by Sherpas due to prolonged time (they spend) at higher altitudes.”
On the other hand, it points out that Sherpas are typically born and raised at high altitudes and may have “superior congenital and acquired adaptations” to that harsh environment. Having climbers from lowland countries spend a few more days or weeks getting used to this foreign environment may not do the trick.
The odds of survival are far better for those who opt to climb other major mountains: The death rate on Alaska’s Mount Denali is only 0.03 percent. However, Denali’s summit is a mere 6,194 meters above sea level. Everest’s environment seems to be at the outer limits of what humans can physically endure — which, of course, is what makes it so enticing.