Originally discovered and first used in military rebreathers since the late 18th century, Nitrox has been used for diving since the earliest times. That widespread use of Nitrox by recreational scuba has only been approved during the last 10 years was due to a concerted campaign of misinformation about the use of ‘devil gas’ by the established training agencies.

Prior to the mid 1990’s my first Nitrox dives had to be made at the United Kingdoms only approved training center for ‘devil gas diving’ – the Commercial Diver training center at Fort William, Scotland. So widespread was the misinformation, that when hearing that a new mixed gas Nitrox course was available I immediately ‘signed up’ expecting to be involved in exploring deep shipwrecks hundreds of feet down attached by umbilical to a diving bell. Certainly the price being charged for the course at that time suggested this. After commencing training and discovering that the only apparent immediate benefit to me was that I could ‘stay down longer but not deeper’ kind of disappointed me. My own ‘gas guzzling’ air consumption rate wearing a dry suit diving in freezing cold water always caused a premature ending to my dives well in advance of any No Decompression Limit (NDL) anyway.

Today, the distinctive yellow and green markings of Nitrox tanks are to be found all over Thailand. So why should a single tank recreational diver bother using Nitrox? It’s simple. You can make more dives with reduced surface interval without coming anywhere near your NDL. It’s the ideal choice of gas for live aboard diving where you want to carry out longer dives at new dive sites without having your time underwater severely restricted by your dive table or computers NDL.

Nitrox diving was the first ‘technical’ diver training course. That it ever made its way past the prejudice and into recreational diving is due in no small amount to the hard work of Dick Rutkowski from the massive US organization NOAA (National Oceanographic and Atmospheric Administration). Underwater scientific research requires that a large amount of time is spent underwater observing and categorizing different phenomena. For research in the 50-100ft / 15-30meter depth range the use of Nitrox effectively doubled the amount of time the researchers could work underwater in one day without requiring formal decompression stops. Hence for recreational divers, use of the correct percentage of Nitrox could safely double the amount of time you could spend underwater in a given period.

As an enabling technology, the populization of Nitrox and its widespread availability through the certification of civilian Nitrox Gas blenders allowed many other new exciting developments to enter the realm of activities that civilian scuba divers could experience. These include the introduction of rebreathers such as the Draeger Dolphin (which uses Nitrox) and PADI’ s new technical diver courses. The DSAT Tec Deep and Tec Trimix courses use Nitrox and pure oxygen for accelerated decompression for dives down to 240ft / 75 meters. All can trace their links back to the acceptance of Nitrox use in recreational diving.