What are the three physiological zones of the atmosphere?

The three physiological zones of the atmosphere describe how different altitudes affect the human body’s ability to function optimally in terms of oxygen availability and pressure changes. The terms used in the correct answer — efficient zone, deficient zone, and space adjacent zone — directly correlate with how the body responds to varying altitudes.

In the efficient zone, which exists at lower altitudes up to around 10,000 feet, conditions are optimal for human physiology. Here, the partial pressure of oxygen is sufficient for absorption, allowing for normal physiological functions without the need for supplemental oxygen.

The deficient zone refers to altitudes above 10,000 feet where the decreased atmospheric pressure results in reduced oxygen availability. As a result, individuals may experience symptoms of hypoxia and decreased performance, necessitating acclimatization or supplemental oxygen, especially as one ascends beyond 14,000 feet.

The space adjacent zone begins at around 50,000 feet, where the atmosphere becomes so thin that the lack of oxygen and air pressure can lead to rapid physiological deterioration without the use of pressurized suits or supplementary oxygen. In this zone, the challenges of exposure to vacuum conditions become significant considerations for aviators and astronauts.

The other options do not accurately represent the recognized physiological zones based on