What are the two types of Nitrox mixtures commonly used in recreational diving?

The correct answer identifies EAN32 and EAN36 as the two commonly used Nitrox mixtures in recreational diving. EAN32 contains 32% oxygen and 68% nitrogen, while EAN36 consists of 36% oxygen and 64% nitrogen. These mixtures are popular among divers because they allow for longer bottom times at shallower depths compared to regular air, which consists of approximately 21% oxygen.

These specific Nitrox mixtures are chosen for their beneficial properties that help in reducing the risk of nitrogen narcosis and decompression sickness, allowing divers to enjoy extended dive times and the potential for safer operations. Knowing the correct percentages of oxygen also helps divers manage their exposure to oxygen toxicity, as different depths and pressures will affect the breathing gas's partial pressures.

Other mixtures listed, such as EAN28, EAN30, EAN34, and EAN40, while valid compositions, are not as commonly utilized in recreational diving. They might be better suited for specific technical diving applications or particular depth limits, but EAN32 and EAN36 are the industry standards and most frequently taught and used in recreational settings.