Final answer:
Unconsciousness can occur when the oxygen supply falls below 12 percent. Insufficient oxygen saturation of hemoglobin can lead to hypoxia, which severely impacts tissue oxygenation and can quickly lead to brain damage or death.
Step-by-step explanation:
As the oxygen supply in any given area falls below 12 percent, unconsciousness can occur. When the percent saturation of hemoglobin decreases, this indicates that there's less oxygen available for binding. This can severely impact the body's ability to oxygenate tissues, resulting in symptoms such as fatigue, headaches, confusion, and ultimately could lead to unconsciousness or hypoxia—a state of inadequate oxygenation of tissues. Hypoxia at high altitudes, where the partial pressure of oxygen is lower (like the Rocky Mountains), can be experienced even with a 15% reduction in the normal oxygen levels. In severe cases, lack of oxygen can cause brain damage within five minutes, and death within ten minutes, underscoring the critical role of maintaining an adequate oxygen supply for health and survival.