Enriched Air, sometimes called Nitrox, is air that has been enriched with oxygen so that
it has more than 21% oxygen. For the purpose of enriched air no decompression diving, you will learn to use enriched air with
22% to 40% oxygen.
Although enriched air is relatively new to recreational diving, military and comercial divers
have been using it to extend their bottom times for nearly 60 years. The United States Navy and British Navy have used enriched
air since the 1940's. The United States Oceanic and Atmospheric Administration (NOAA) has more than 25 years experience with
enriched air. Recreational Divers have made thousands of enriched air dives successfully. Through these data and this field
experience, the no decompression limits for enriched air are considered as reliable as those used for "normal" air.
Through reduction of the nitrogen in the breathing mixture you will be able to substantially
increase your bottom times. A dive made to 50 feet on air, has a no decompression limit of 80 minutes, according to the PADI
Recreational AIR Dive Planner. The same dive made on 36% Oxygen Enriched Air would give you a bottom time of 220 minutes.
The trade off is that as you increase the oxygen exposure, you also increase the hazardous of oxygen toxicity. Much of what
you will learn in the Nitrox program deals with keeping your oxygen exposure within safe limits.
Through proper training and use of Nitrox we are one step closer to that holy grail of divers,
"unlimited bottom time".