Which of the following nitrox gases is classified as hyperoxic?

Hyperoxic gases are those that contain a higher concentration of oxygen than what is found in normal atmospheric air. Typically, air comprises approximately 21% oxygen, while enriched air nitrox contains a greater proportion of oxygen, often around 32% to 40%. This elevated oxygen level allows enriched air nitrox to be classified as hyperoxic.

When considering the options provided, it's important to note that air does not fit the hyperoxic classification since it has a standard mix of 21% oxygen. While trimix, which consists of oxygen, nitrogen, and helium, can be formulated to have various levels of oxygen, it usually reduces the oxygen content significantly compared to air, thus not categorizing it as hyperoxic either.

Therefore, the only gas explicitly identified as hyperoxic among the selections is enriched air nitrox. The classification of enriched air nitrox as a hyperoxic gas makes it the only correct response in this context, which leads to the conclusion that the correct answer encompasses all relevant options concerning the classification of gases and their oxygen content.