The gas you are breathing now – air – consists of approximately 21% oxygen, 79% nitrogen. This is what you normally dive with too. Nitrox (also called Enriched Air or EANx) has a higher percentage of oxygen with a corresponding lower percentage of nitrogen. The most common percentages of oxygen are 32% and 36%. The PADI Enriched Air Course qualifies you to dive with up to 40% oxygen.