Which of the following mixtures would generally be categorized as EANx?

The classification of EANx, or Enriched Air Nitrox, specifically applies to gas mixtures that contain a higher percentage of oxygen than ordinary air, which contains about 21% oxygen. The defining characteristic of enriched air nitrox is that it typically has an oxygen content greater than that of air, while also containing a corresponding reduced amount of nitrogen.

A mixture with 32% oxygen clearly falls into the category of EANx because its oxygen concentration is greater than that of standard air. This increased oxygen content allows divers to experience certain advantages, including longer bottom times at specific depths and reduced nitrogen exposure, which can minimize the risk of nitrogen narcosis and decompression sickness.

In contrast, air with 21% oxygen is standard atmospheric air and does not qualify as EANx. Nitrogen only does not contain any oxygen and therefore cannot be classified as EANx. Pure oxygen, while it does have a higher oxygen concentration, is typically treated differently in diving contexts and is not considered enriched air nitrox, as it does not contain nitrogen, which is necessary for the categorization.

Thus, a mixture with 32% oxygen is the only one among the options provided that meets the requirements for categorization as EANx.