How High is the Death Zone?

At 8000 meters, or 26,000 feet, mountaineers call this the “death zone” at which the amount of oxygen is so low that no humans would be able to stay above this zone for too long.  Because it is less than 356 millibars of atmospheric pressure there, the human body is not able to acclimate to it and get enough oxygen saturation in the hemoglobin of the blood.

For comparison, Mount Everest base camp is around 17,000 feet.  There are two Everest base camps.  And the summit of Everest is at 29,000 feet — above the death zone.