What percentage of oxygen defines Nitrox as a breathing gas for divers?

Nitrox is defined as a breathing gas used in diving that contains a higher percentage of oxygen compared to normal air, which contains approximately 21% oxygen. This is a standard mixture known as "air" and is commonly understood in diving contexts.

The specific percentages in the other options represent different blends of Nitrox. For example, a mixture of 32% oxygen is commonly referred to as Nitrox EAN32, and 36% oxygen would be EAN36. These mixtures are employed to extend bottom time and reduce narcosis or oxygen toxicity during dives.

In contrast, the definition of Nitrox itself does not refer to the normal atmospheric composition of oxygen, which is why specifying 21% does not align with the typical use of Nitrox in diving. Thus, when discussing Nitrox, it is essential to recognize that it encompasses blends that have more oxygen than that found in normal air.