History:

In the 1920s or 1930's Draeger of Germany made a nitrox backpack independent air supply for a standard diving suit.

In World War II or soon after, British commando frogmen and work divers started sometimes diving with oxygen rebreathers adapted for semi-closed-circuit nitrox (which they called "mixture") diving by fitting larger cylinders and carefully setting the gas flow rate using a flow meter. These developments were kept secret until independently duplicated by civilians in the 1960s.

In the 1950s the United States Navy (USN) documented enriched oxygen gas procedures for military use of what we today call nitrox, in the USN Diving Manual.

In 1970, Dr. Morgan Wells, who was the first director of the National Oceanographic and Atmospheric Administration (NOAA) Diving Center, began instituting diving procedures for oxygen-enriched air. He also developed a process for mixing oxygen and air which he called a continuous blending system. For many years Dr. Wells' invention was the only practical alternative to partial pressure blending. In 1979 NOAA published Wells' procedures for the scientific use of Nitrox in the NOAA Diving Manual.

In 1985 Dick Rutkowski, a former NOAA diving safety officer, formed IAND (International Association of Nitrox Divers) and began teaching nitrox use for recreational diving. This was considered dangerous by some, and met with heavy skepticism by the diving community. In 1992 the name was changed to the International Association of Nitrox and Technical Divers (IANTD), the T being added when the European Association of Technical Divers (EATD) merged with IAND. In the early 1990s, the agencies teaching nitrox were not the main scuba agencies. New organizations, including Ed Betts' ANDI (American Nitrox Divers International), which invented the term "Safe Air" for marketing purposes, and Bret Gilliam's TDI (Technical Divers International) gave scientific credence to nitrox.

Meanwhile, diving stores were finding a purely economic reason to offer nitrox: not only was an entire new course and certification needed to use it, but instead of cheap or free tank fills with compressed air, dive shops found they could charge premium amounts of money for custom-gas blending of nitrox to their ordinary moderately experienced divers. With the new dive computers which could be programmed to allow for the longer bottom-times and shorter residual nitrogen times which nitrox gave, the incentive for the sport diver to use the gas increased. An intersection of economics and scientific validity had occurred.

In 1996, the Professional Association of Diving Instructors (PADI) announced full educational support for nitrox. While other main line scuba organizations had announced their support of nitrox earlier, it was PADI's endorsement that put nitrox over the top as a standard sport diving "option".