Which statement is true about Nitrox systems?

• A. Working with NITROX systems requires special training.
• B. No special training is required.
• C. Training is optional.
• D. Training is only required for diving deeper than 100 fsw.

Answer: (A)

Nitrox involves breathing gas with more oxygen than air, which changes how you plan dives and monitor oxygen exposure. The key safety factor is the partial pressure of oxygen (PPO2): as you descend, PPO2 rises, and too high a PPO2 can cause oxygen toxicity. To manage this, you must know how to calculate the maximum operating depth for a given mix, how to determine bottom times, and how to use nitrox tables or dive computers correctly. That requires formal training.

Training teaches you how to analyze gas blends with a analyzer, properly label cylinders, and select the right mix for a planned depth. It also covers how to plan safe dives using nitrox—understanding how increased oxygen content affects allowable depth and no-decompression limits, and recognizing when to adjust plans to stay within safe PPO2 limits. Beyond planning, it includes practical skills like gas handling, record-keeping, and recognizing potential signs of oxygen-related issues, plus how to respond if something seems off.

Because these safety considerations and calculations are not part of standard air diving, working with nitrox systems requires specialized instruction. The statements suggesting no training, optional training, or training only for dives deeper than a certain depth overlook the essential knowledge needed to use nitrox safely at any recreational depth.