Everest made less than its budget.
 Everest can be climbed without supplementary oxygen, but only by the most accomplished mountaineers and at increased risk
 When Tenzing and Hillary made the first successful summit in 1953, they also used open-circuit bottled oxygen sets, with the expedition's physiologist Griffith Pugh referring to the oxygen debate as a "futile controversy", noting that oxygen "greatly increases subjective appreciation of the surroundings, which after all is one of the chief reasons for climbing

