Which statement best identifies the cause of nitrogen narcosis?

• A. Dehydration and fatigue
• B. Increased partial pressure of nitrogen
• C. Low ambient pressure
• D. High oxygen tension

Answer: (B)

Nitrogen narcosis is produced by the increased partial pressure of nitrogen as you descend and breathe air at greater ambient pressures. As depth increases, the total pressure rises while nitrogen remains a large fraction of the breathing mix, so more nitrogen dissolves into bodies’ tissues and neural membranes, altering nerve function. This narcotic effect can impair judgment, slower thinking, and euphoria or dizziness, explaining why depth raises risk. The other options don’t fit: dehydration and fatigue aren’t the root cause of narcosis, low ambient pressure would occur at shallower depths and isn’t what drives narcosis, and high oxygen tension leads to oxygen toxicity symptoms rather than narcosis.