Which gas is typically a greater concern when using nitrox in deep dives?

When utilizing nitrox for deep dives, oxygen becomes a significant concern due to the increased partial pressure of oxygen at greater depths. Nitrox is a blend of oxygen and nitrogen, where the proportion of oxygen is higher than that found in standard air. As a diver descends and the pressure increases, the partial pressure of the oxygen in the breathing gas also rises.

Oxygen toxicity is a critical risk when diving with nitrox, especially if the oxygen levels exceed safe limits, which can happen more quickly at depth. The potential for oxygen toxicity can lead to serious complications, including central nervous system effects, which could impair a diver's ability to function underwater and increase the risk of accidents. Therefore, divers using nitrox must carefully monitor their depth and the percentage of oxygen in their mix to avoid exceeding the recommended limits and to ensure safe diving practices.

While nitrogen, helium, and carbon dioxide can also be of concern, particularly in other contexts or diving scenarios, the specific risks associated with increased oxygen levels at depth make oxygen the primary focus for divers using nitrox in deeper dives.