Nitrox, after all these years, is still a misunderstood gas.

We can trace back to the 1960s and find Nitrox in use, but it was mostly used for rebreathers. The use of Nitrox for the recreational diving community (open circuit) started in the early 1970s, but most SCUBA agencies did not accept it until 1996.

There many names for Nitrox: Enriched air, EANx, Safe Air, Nitrox32, Oxygen enriched air, and even “voodoo gas!”

Probably the most accurate name is Oxygen Enriched Air Nitrox, but most likely you will call it Nitrox like most of us do. The reason there is so much disagreement with the name is because the name Nitrox was originally designated for a gas that contained less oxygen and more nitrogen.

For the recreational diving purposes, Nitrox is ANY mixture of Oxygen and Nitrogen, so technically air can be considered Nitrox. And just like air, Nitrox is colorless, odorless, doesn’t have any taste, and it will not improve your air consumption (but you will look cool to you friends!)

Over the years, many incredible claims have been made about Nitrox: prevents nitrogen narcosis, you will feel less fatigued at the end of the dive, it will keep you warmer, it will improve your air consumption, it is safer than air, it will improve your sex life (okay, I made that one up! LOL) But seriously, none of these are true statements about the use of Nitrox.

So why use it? Because Nitrox will allow you to have longer no decompression dives with shorter surface intervals.

Most divers believe that Nitrox is safer because of the added oxygen in the mix, but the real reason is the reduction in nitrogen. If you remember back to your beginning/Open Water SCUBA class lessons, it is nitrogen that limits our no decompression dives, and it is nitrogen that will create bubbles in your system and cause DCI (the bends).

By reducing the amount of nitrogen in your gas mix, you increase your bottom time. Take a quick look at air tables. The max no decompression time for 60 feet is 55 minutes. Now look at a 36% Nitrox table and you will find that the max no decompression time is 115 minutes—more than double the time!

Be aware: Nitrox is a shallow water gas. Nitrox is best served, compressed, within the 60 to 130 feet depth range. :O)

Many people will tell you that Nitrox diving is either too complex or risky for recreational divers and that you need dedicated equipment. Let’s examine these three supposed disadvantages a bit more closely:

Nitrox is too complex for the recreational diver – With proper training you can learn to do Nitrox dive planning in no time. You will learn to do calculations like “best mix for your dive,” “oxygen exposure time,” etc. in a mater of minutes. Once you’re in the water it doesn’t feel any different.

Nitrox is too risky for the recreational diver – The same safety rules for air apply to Nitrox. Additionally, you must personally verify your mixture by analyzing to determine that your cylinder has the correct mix. You also must make sure you don’t exceed the maximum depth for you mix, and keep track of your oxygen exposure (most Nitrox computers will do this for you.) If you exceed your oxygen exposure, you do run the risk of an oxygen seizure. Oxygen seizures are rare and are more likely to happen to a technical or cave diver. Still, it is a real issue that is not very well documented in the recreational diver community.

Dedicated equipment for Nitrox – This continues to be a very controversial issue, because we don’t have scientific data to base our opinion on. The community is looking to the US Navy for guidelines and their current opinion is that any equipment exposed to more than 23.5% oxygen should be treated and properly clean as if was 100%. Others have looked at the guidelines written for NOAA commercial divers. NOAA recommends that any equipment exposed to more than 40% should be treated and properly cleaned as if was 100% oxygen. My recommendation on this issue is to check with your local dive shop to see what method of gas blending they are using. Also check with your equipment manufacturer for their recommendation, and if your equipment is due for service anyway, have it cleaned and replace the seats and o-rings with oxygen compatible pieces.

It is my personal opinion that the advantages, and disadvantages, of Nitrox are very manageable with the right training. Nitrox has its place in the recreational diving community, not to replace air, but to be used to lessen decompression requirements.