Which prevention measure helps reduce the risk of nitrogen narcosis for divers?

• A. Use a helium-oxygen mix for all dives
• B. Dive deeper to build tolerance
• C. Use the same gas mix at all depths
• D. Avoid dives deeper than 100 FSW with amateur divers, conduct work-up dives, and use a different gas mix to limit nitrogen effects

Answer: (D)

Nitrogen narcosis happens when dissolved nitrogen affects the brain as you descend—the deeper you go, the more nitrogen pressure builds, leading to intoxication-like symptoms and impaired judgment. The best way to prevent this is to reduce nitrogen exposure at depth and verify a diver’s tolerance through progressive planning. Keeping recreational dives within shallow depths (roughly 100 feet of seawater or about 30 meters for amateurs) minimizes nitrogen load. Conducting work-up dives allows divers to acclimate and recognize early narcosis signs in a controlled way. Using a different gas mix for deeper dives, which lowers the nitrogen fraction in the breathing gas, further reduces nitrogen’s impact as you go deeper. This combination directly targets the cause (nitrogen load) and accounts for both depth limits and the gas you’re breathing. Options that push divers deeper to “build tolerance,” rely on the same gas at all depths, or assume helium–oxygen for every dive don’t appropriately address how nitrogen narcosis increases with pressure or are impractical for typical recreational diving.