by David Miner
Diving nitrox has become much more the “norm” today as compared to ten years ago when nitrox was still highly questioned as being a safe breathing medium within the sport diving community. Today, all of the major training agencies offer nitrox training and many dive shops now have the ability to mix and pump nitrox, meaning that nitrox mixes are now a prominent part of the sport diving community.
The most common nitrox mixes being used are EAN32 and EAN36 (enriched air nitrox). These used to be referred to as NOAA Nitrox 1 and NOAA Nitrox 2, because in 1978, NOAA formally established procedures for these two mixtures and referred to them as “standard mixtures.” Even though EAN32 and 36 are still commonly used, almost any mixture from EAN25 to EAN40 is being pumped in dive shops from coast to coast. This is because the comfort levels have significantly increased with respect to diving and mixing nitrox, and the ease in getting the proper training and equipment for safely diving any mixture is being more and more recognized. In addition, every major dive computer manufacturer makes a nitrox computer, making it very easy for divers to monitor and safely dive the nitrox mixture they have chosen to dive.
This is a great thing for the diving community, and all divers should recognize that there are significant advantages and benefits to diving nitrox. Diving standard air still goes on, but it is slowly becoming secondary, as opposed to the norm. Divers need to recognize that there are now choices for their breathing gas, choices that can make a difference in every dive they do.
The advantages of diving nitrox:
- Increased bottom time while staying within no-decompression limitations
- Reduced surface interval times between dives
- Reduced risk of decompression illness due to lower nitrogen levels
- Reduced nitrogen narcosis due to lower nitrogen levels
- Significant reduction in fatigue levels after a day of diving
- Less decompression when no-decompression limits are exceeded
- Increased safety factor when used with standard air tables
Increased bottom time while staying within no-decompression limitations
Nitrox significantly increases your available bottom time within the no-decompression limits. It basically lets you stay down longer. For example, diving standard air to 60 feet allows you 55 minutes of bottom time when staying within no-decompression limits. Diving nitrox 32% (EAN32) to 60 feet allows you 75 minutes of bottom time when staying within no-decompression limits. That’s about 35% more bottom time, a significant increase! And why did you spend all that time and money to go on your dive trip…to dive, so getting more bottom time on every dive is definitely worth it.
Reduced surface interval times between dives
Diving nitrox reduces the amount of time you have to remain on the surface before doing your next dive. With the increased level of oxygen and lower level of nitrogen, your body absorbs less nitrogen on every dive. This means that your body has less nitrogen to off-gas, meaning that you have less sit time between dives. If you like to do 3 or 4 dives a day and be home before dark or if you’re an avid live-aboard diver doing 3 to 5 dives a day, then diving nitrox is your answer.
Reduced risk of decompression illness due to lower nitrogen levels
Using nitrox reduces the possibility of getting decompression illness. Your body tissues absorb nitrogen during every breath you take while underwater. Excess nitrogen must be off-gassed before you surface or it could form into bubbles and cause decompression illness, also known as “the bends.” Standard air has around 79% nitrogen and EAN32 has 68% nitrogen, meaning that every breath you take of EAN32, the less amount of nitrogen your body is absorbing. Thus, by diving a nitrox mixture and staying within no-decompression limits, you’ll reduce the risks of decompression illness by limiting the amount of nitrogen your body absorbs.
Reduced nitrogen narcosis due to lower nitrogen levels
Diving nitrox helps to reduce nitrogen narcosis, which happens at depth and is caused by the nitrogen in your breathing mixture. We all learned about nitrogen narcosis in our diving classes and know that the deeper you dive, the more susceptible you are to nitrogen narcosis, which can impair your judgment and motor skills. Air has around 79% nitrogen. EAN32 has 68% nitrogen. By diving a nitrox mixture, you reduce the amount of nitrogen in your breathing mix and thus reduce nitrogen narcosis levels while diving at depth. Little to no narcosis means a better and safer dive.
Significant reduction in fatigue levels after a day of diving
As reported by many divers, nitrox can significantly reduce your fatigue levels at the end of a day of diving. This can be extremely beneficial when traveling or when diving for many consecutive days. Nitrogen can increase your fatigue level, so the more nitrogen your body absorbs during your dives, the more fatigue you’re going to feel. After doing 2 to 4 dives in a day on air, divers have routinely commented on how fatigued they feel. Diving nitrox can change this. Nitrox mixtures have less nitrogen, meaning that there is less nitrogen for your body to absorb. The less nitrogen your body absorbs by the end of your diving day, the better you’re going to feel. There is no reason to go back to the hotel and take a nap after your dives anymore. Spend the afternoons doing other fun things!
Less decompression when no-decompression limits are exceeded
If you participate in decompression diving, nitrox reduces the amount of decompression when no-decompression limits are exceeded. No-decompression limits and decompression obligations are based on the amount of nitrogen your body absorbs during a dive or series of dives. If you participate in decompression diving, nitrox mixtures can reduce the amount of time you have to decompress because there is less nitrogen for your body to absorb. Nitrox mixtures can also be used to speed up decompression obligations. Using nitrox mixtures for decompression helps to flush out the excess nitrogen quicker and limits the amount of nitrogen being absorbed at each decompression stop.
Decompression is the result of the absorption of excess nitrogen, requiring you to stay at depth for a period of time until nitrogen levels return to safe levels before surfacing. Using nitrox mixtures can reduce this time requirement.
Increased safety factor when used with standard air tables
Nitrox, when used with standard air tables or air computer, provides an increased safety factor with respect to decompression sickness. By diving nitrox and staying within air no-decompression limits, you can reduce the risks of decompression sickness and stay more conservative underwater. If you’re a conservative diver, using nitrox this way can greatly increase your safety factor.
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