Scuba Diving International (SDI) Computer Nitrox Practice Exam

What should divers be cautious of when using Nitrox at deeper depths?

1. High levels of carbon dioxide

2. Oxygen toxicity and narcosis

3. Weightlessness

4. Corrosion in equipment

The correct answer is: Oxygen toxicity and narcosis

When diving with Nitrox at deeper depths, divers need to be particularly cautious about oxygen toxicity and narcosis. Nitrox typically contains a higher percentage of oxygen compared to air, which can be beneficial for reducing nitrogen absorption and extending bottom time. However, as a diver descends to greater depths, the partial pressure of oxygen in the breathing gas increases. This can lead to oxygen toxicity, a potentially dangerous condition that affects the central nervous system and can cause symptoms such as visual disturbances, muscle twitching, and seizures. Additionally, narcosis can also be a concern at deeper depths. Nitrogen narcosis occurs due to the increased partial pressure of nitrogen, which can impair cognitive and motor functions, leading to altered judgment and coordination. While the use of Nitrox mitigates nitrogen absorption, it is essential to remember that increased depth still poses risks. Therefore, divers must be aware of these risks and manage their ascent profiles carefully when using Nitrox at depths where oxygen toxicity and narcosis could become issues.