4th Class Power Engineering Part A Exam Prep 2026 - Complete Practice Test

When the oxygen level drops below 10%, individuals are likely to lose consciousness. Oxygen is essential for human survival, and normal atmospheric levels are around 21%. When the oxygen concentration decreases significantly, especially to levels below 10%, the body cannot function properly. The brain, in particular, is highly sensitive to oxygen deprivation. Prolonged exposure to low oxygen levels leads to hypoxia, where the brain is starved of the necessary oxygen it needs to maintain consciousness, resulting in loss of awareness and eventual unconsciousness.

The other choices describe aspects of how low oxygen levels affect the body but do not fully capture the critical point of losing consciousness. Feeling dizzy is a symptom of oxygen deficiency but typically occurs at higher levels than 10%. Shortness of breath may occur as the body tries to compensate for reduced oxygen, but it is still not the most severe outcome compared to losing consciousness. Surviving longer is not accurate in this context, as very low oxygen levels are life-threatening and compromise survival. Therefore, the focus on loss of consciousness at sub-10% oxygen levels illustrates the significant risks posed by low oxygen environments.