Nitrox refers to any gas mixture composed of nitrogen and oxygen. This includes atmospheric air, which is approximately 78% nitrogen, 21% oxygen, and 1% other gases, primarily argon. In the usual application, underwater diving, nitrox is normally distinguished from air and handled differently. The most common use of nitrox mixtures containing oxygen in higher proportions than atmospheric air is in scuba diving, where the reduced partial pressure of nitrogen is advantageous in reducing nitrogen uptake in the body's tissues, thereby extending the practicable underwater dive time by reducing the decompression requirement, or reducing the risk of decompression sickness.
Enriched Air Nitrox diving tables, showing adjusted no-decompression times.
Technical divers preparing for a mixed-gas decompression dive in Bohol, Philippines. Note the backplate and wing setup with side mounted stage tanks containing EAN50 (left side) and pure oxygen (right side).
Cylinder showing Nitrox band and sticker marked with maximum operating depth (MOD) and oxygen fraction (%O2)
A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats. Oxygen is the essential component for any breathing gas. Breathing gases for hyperbaric use have been developed to improve on the performance of ordinary air by reducing the risk of decompression sickness, reducing the duration of decompression, reducing nitrogen narcosis or allowing safer deep diving.
Sailors check breathing devices at sea.
A closed bell used for saturation diving showing emergency gas supply cylinders
2% Heliox storage quad. 2% oxygen by volume is sufficient at pressures exceeding 90 msw.
Electro-galvanic fuel cell as used in a diving rebreather