NITROX

Enriched Air Recreational Divingby R.W. Bill Hamilton, PhD and Joel Silverstein

During the last ten years there has been significant emphasis placed on diving with gas mixtures other than air. As one read articles, papers and books one may begin to ask, "What’s wrong with diving on air?" Simply, air contains two major components, oxygen (21%) and nitrogen (79%). The nitrogen in normal air limits your bottom time, or the number of dives that can be done in a day, or requires a longer surface interval between dives. Nitrogen is also the cause of decompression sickness.

Enter Enriched Air Nitrox, also called Oxygen Enriched Air, or just nitrox. Enriched Air Nitrox is air that has more oxygen in it. Consequently it has less nitrogen. Since nitrogen is the controlling factor for decompression from no-stop diving, with less nitrogen in the breathing mixture the body will absorb less nitrogen and will have less of a decompression obligation.
The two most commonly used nitrox mixtures are 32% and 36% oxygen. In all cases the other gas in the mix, is nitrogen. These mixes were first introduced by the National Oceanographic and Atmospheric Administration (NOAA) for use in their scientific and shallow water research dives.

Today’s diver is seeking more adventure and exploration, which almost always leads to the desire for more bottom time. Many times the only way to get that longer bottom time is to plan dives that require lengthy and sometimes complicated decompression stops. Using enriched air nitrox makes getting that longer bottom time not only easier by eliminating decompression stops required with air, but this also allows the diver to have shorter surface intervals while still maintaining a minimal level of risk.