For more than eight decades the use of supplemental oxygen to help climbers in the high Himalayas has been the subject of debate, according to the authors of a letter in the Journal of the American Medical Association for July 12. Some climbers have denounced recourse to oxygen as unsporting, even cheating, but there is evidence that it may improve the survival rate of mountaineers by increasing their physical performance and reducing stress brought on by hypoxia. Supplemental oxygen may counteract near exhaustion, especially during a descent, and so reduce vulnerability to accidents, adverse weather or illness.
An analysis of data regarding mountaineers who have reached the summit of Everest or K2 between 1978 and 1999 has indicated that individuals not making use of oxygen had significantly higher death rates during their descent than did others who made use of oxygen. On K2, one in five mountaineers who used no oxygen perished during their descent. Overall, one in 29 died when descending Everest, and one in seven when descending K2.
The real effect of supplemental oxygen may be greater than indicated, since those climbers dispensing with it tend to be more experienced individuals and should have a lower fatality rate than others. A full risk assessment would require data on fatalities during the ascent, the risks posed to porters who are forced to manipulate oxygen cylinders, and the weather conditions encountered during the expedition. In any event, Himalayan mountaineering remains a highly dangerous activity, in which the degree of adventure must be balanced against the risk to life and limb.