Enriched Air Diving. What Nitrox Is and Why Divers Use It
Sean Cowher Feb 02, 2026
Enriched Air Diving, commonly called Nitrox, refers to breathing gas mixtures that contain a higher percentage of oxygen and a lower percentage of nitrogen than normal air. Standard air contains about 21 percent oxygen. Enriched Air typically contains between 22 and 40 percent oxygen, with 32 percent and 36 percent being the most common blends used in recreational scuba diving.
The purpose of Enriched Air is not to dive deeper. It is used to reduce nitrogen exposure during a dive.
The Nitrogen Factor
When a diver breathes compressed air, nitrogen is absorbed into the body tissues under pressure. The longer and deeper the dive, the more nitrogen the body absorbs. Managing this nitrogen load is what determines no-decompression limits, surface intervals, and overall dive planning.
By reducing the amount of nitrogen in the breathing gas, Enriched Air slows nitrogen absorption. This allows divers to stay within no-decompression limits longer at certain depths when compared to diving the same profile on air.
How Enriched Air Changes Dive Planning
Dive planning with Enriched Air is still based on depth, time, and pressure, but the focus shifts from nitrogen limits to oxygen exposure.
While nitrogen is reduced, oxygen percentage is increased. Oxygen becomes the limiting factor, particularly at depth. Each Enriched Air mix has a Maximum Operating Depth, commonly referred to as MOD. The MOD is the deepest depth at which a specific oxygen percentage can be safely breathed without exceeding recommended oxygen exposure limits.
Because of this, Enriched Air divers must know:
- The oxygen percentage of the tank they are using
- The MOD for that mix
- How to set their dive computer correctly
Oxygen Exposure and Safety
Breathing oxygen at elevated partial pressures increases the risk of oxygen toxicity. This is why Enriched Air divers follow conservative oxygen exposure limits and avoid exceeding their MOD.
In recreational diving, Enriched Air is used well within safe exposure ranges. Proper training focuses heavily on understanding oxygen limits, analyzing tanks, and confirming dive computer settings before every dive.
Common Benefits of Enriched Air Diving
Many divers choose Enriched Air for reasons beyond extended no-decompression limits. Common benefits include:
- Longer allowable bottom times on repetitive dives
- Increased safety margin when diving air tables or air-based computer settings
- Reduced nitrogen loading over multi-day dive trips
Some divers also report feeling less fatigued after dives, although this varies by individual and dive conditions.
Enriched Air Does Not Replace Good Diving Practices
It is important to understand that Enriched Air does not eliminate the need for proper dive planning, safety stops, or conservative diving habits. Divers still monitor depth, time, ascent rates, and surface intervals just as they would on air.
Enriched Air is a tool, not a shortcut.
Who Typically Uses Enriched Air
Enriched Air is widely used by recreational divers, instructors, divemasters, and technical divers. It is especially common on dive trips involving multiple dives per day or repetitive profiles where managing nitrogen exposure becomes more important.
Because Enriched Air requires additional knowledge and procedures, divers receive specific training before using it independently.
Understanding the Role of Enriched Air
Enriched Air Diving is one of the most widely used advancements in recreational scuba. It allows divers to manage nitrogen exposure more effectively while maintaining conservative, well-planned dives.
When used correctly, Enriched Air supports longer, safer dive days and provides divers with greater flexibility in how they plan their underwater time, without changing the fundamental principles of scuba diving.