Oxygen is never completely zero in Earth's atmosphere, even at extremely high altitudes. The reference points out that oxygen concentration becomes significantly low at high altitudes, starting at 2,400 meters (about 7,874 feet), a point known as the "hypoxic zone", but the reference emphasizes that it is not completely absent even at very high altitudes.
Here's a more detailed explanation:
- Hypoxic Zone: This zone, starting above 2,400 meters (7,874 feet), indicates where oxygen levels are low enough to affect human health. This is because the air pressure decreases with altitude, which results in lower partial pressure of oxygen and thus reduces the amount of oxygen available for breathing.
- No Complete Absence: Even at extremely high altitudes, such as the peak of Mount Everest or within the exosphere, trace amounts of oxygen will always be present. It will be extremely diluted and unlikely to support life, but technically not zero.
| Feature | Description |
|---|---|
| Oxygen Concentration | Never zero in Earth's atmosphere. |
| Hypoxic Zone Start | Above 2,400 meters (7,874 feet), where oxygen starts to impact human health significantly. |
| Practical Implication | Humans need supplemental oxygen at very high altitudes. |
In summary, while the amount of available oxygen becomes critically low at high altitudes, it is never completely absent in Earth's atmosphere. The "hypoxic zone" is a term for altitudes where there is a significant health impact from low oxygen levels but doesn't mean zero oxygen.
