What is it?
The word nitrox is a general term- an abbreviation for a gas blend of nitrogen and oxygen. Divers use nitrox as a replacement for air as the breathing gas in their scuba cylinders. The most common mixtures of nitrox used for diving contain 40% or less oxygen, most frequently 32% and 36%.

Other common terms for nitrox include Enriched Air, OEA (Oxygen Enriched Air), EAN (Enriched Air Nitrox) and EANx (Enriched Air Nitrox).

Why would a diver use nitrox?
Divers breathe nitrox as a means of extending the amount of time they can stay underwater at depth (bottom time).

How does nitrox work?
In most recreational diving with air, nitrogen absorption is the factor which limits a diver's bottom time because of increased risk of decompression sickness.

With nitrox, a percentage of nitrogen in the breathing gas mix is replaced with oxygen, thus decreasing the risk of decompression sickness that would be present if air was used on the same dive profile.

Who should dive using nitrox?
It's good practice to dive only with what you need. If a planned dive requires extended bottom time, then nitrox may be a useful tool. Nitrox is useful in several applications, like commercial diving, technical diving, research diving, underwater photography and intensive repetitive diving.

Why not use nitrox?
Nitrox is more expense than air and involves more hassle. Additionally, there are risks and limits that aren't involved when using air.

Divers and nitrox fill stations both require specialized training and equipment to work with nitrox. These requirements increase preparation time requirements and suppliers generally charge more to supply divers with nitrox as opposed to air as a result.

Divers using nitrox assume a greater risk of oxygen toxicity than they would using air. To manage this risk, divers using nitrox must use particular caution to avoid excess exposure to oxygen under pressure. As a result, it is extremely important to abide by strict depth and time limits that differ by the oxygen mixed being used. Accordingly, these procedures add tasks to pre-dive planning and introduce new and potentially hazardous risks to manage while diving.

Where can I find nitrox?
Nitrox fill stations are less common than air fill stations because of limited use and more complicated filling processes that require special training and handling procedures.

It is strongly advisable to obtain nitrox fills only from reputable filling stations that have proof of special training.

In summary
The use of nitrox as a breathing gas in recreational diving has become popular in recent years. Military and governmental agencies have effectively used nitrox for many years and have researched and developed respectably safe guidelines for its use in diving. Most recreational dive training agencies have since developed courses for the use of nitrox. Strict adherence to guidelines and procedures can allow divers to safely use nitrox as a means to increase bottom time.