27,000 feet. Above that is the Death Zone. Nobody can adjust to it. At this extreme altitude, the percentage of oxygen in the air is the same as at sea level, but the air pressure is much lower—the same volume of gas has fewer molecules in it. As a result, the body can’t extract enough oxygen from the air. The more time spent in the Death Zone, the weaker and sicker a climber becomes. The digestive system fails and the body devours its own muscle tissue. “It’s living hell. You feel your body deteriorating,” said Wilco. “Ever tried to run up a staircase while breathing through a straw?”
