Underwater, what advantage does EANx provide for respiratory effort?

Choosing lower breathing resistance as the correct answer highlights an important benefit of using Enriched Air Nitrox (EANx) during dives. When divers use EANx, which contains a higher percentage of oxygen compared to regular air, the overall gas mixture has different physical and chemical properties. One of the significant advantages is that the lower nitrogen content results in less overall density of the breathing gas, which in turn decreases the effort required to breathe.

This lower breathing resistance means that divers can take shallower breaths without difficulty, ultimately leading to a more comfortable diving experience. It can also help in reducing fatigue over longer dive durations since the respiratory muscles do not have to work as hard compared to standard air at deeper depths.

In contrast, options like increased oxygen demand, greater carbon dioxide retention, and increased air consumption rates do not accurately capture the benefits of EANx in the context of respiratory effort. Divers using EANx are more efficient in their oxygen usage, enabling better management of their breathing rates and reducing factors that can lead to respiratory distress. This makes the use of EANx particularly advantageous for longer and deeper dives.