Which statement best describes the relationship between depth and nitrogen narcosis risk?

• A. Narcosis risk is unaffected by depth.
• B. Narcosis risk is minimized at depths around 200 feet.
• C. Narcosis risk increases with depth.
• D. Narcosis risk is only a concern when using air mixes.

Answer: (C)

Nitrogen narcosis is driven by the increasing partial pressure of nitrogen as you descend. As depth increases, more nitrogen dissolves into blood and tissues, affecting nerve function and altering perception, judgment, and coordination. That makes narcosis more likely the deeper you go. So the best description is that narcosis risk increases with depth. It’s not constant regardless of depth, and there isn’t a depth where it’s minimized at 200 feet; risk actually rises the deeper you dive. While the breathing gas matters—air has a relatively high nitrogen fraction and is more likely to trigger narcosis at depth—narcosis is a result of pressure, not just the type of gas, and using gas mixes with less nitrogen can reduce the risk.