Disturbance Stage of hypoxia occurs at which altitude range?

• A. Sea Level - 10,000 ft
• B. 10,000 - 15,000 ft
• C. 15,000 - 20,000 ft
• D. 20,000 ft and above

Answer: (C)

As altitude climbs, hypoxia progresses from barely noticeable effects to clear impairment. The disturbance stage marks the point where cognitive and motor function begin to be affected due to reduced arterial oxygen content. This typically occurs from about 15,000 to 20,000 feet. At this range, people may notice headaches, dizziness, reduced ability to concentrate, slower reaction times, and difficulty performing complex tasks, even though they can still function with effort. The body tries to compensate by increasing ventilation and heart rate, but these responses don’t fully prevent impairment for many individuals, especially under stress or fatigue. Below this range, effects are usually mild or absent (indifferent stage). Above 20,000 feet, symptoms become more pronounced and the risk of serious hypoxia rises, necessitating descent or supplemental oxygen.