Which statement about Time of Useful Consciousness with increasing altitude is true?

• A. It increases with altitude.
• B. It decreases with altitude.
• C. It remains constant.
• D. It fluctuates unpredictably.

Answer: (B)

As altitude increases, the amount of oxygen available to the body drops because the partial pressure of oxygen falls. The brain is extremely sensitive to oxygen shortage, so when hypoxia starts, cognitive function, coordination, and decision-making deteriorate quickly. Even though your body may try to compensate by breathing faster and heart rate increasing, these adjustments can’t keep up with the reduced oxygen supply, so consciousness is lost sooner. That’s why the time you can stay useful and conscious after exposure to the lower-oxygen environment gets shorter as you climb higher. This isn’t about a random fluctuation or a constant value; it follows a clear trend: higher altitude means shorter time of useful consciousness.