How much oxygen is in Everest death zone?

In the Everest death zone, which is above 8,000 meters (26,247 feet), the oxygen levels are dramatically reduced, with only about one-third of the oxygen available at sea level. This corresponds to an atmospheric pressure of around 253 mmHg compared to approximately 760 mmHg at sea level. As a result, climbers in this zone face severe hypoxia, making it extremely difficult to breathe and increasing the risk of altitude sickness.