What is enriched air?
During the last ten years there has been significant emphasis
placed on diving with gas mixtures other than air. As one read articles, papers
and books one may begin to ask, "What’s wrong with diving on air?" Simply, air
contains two major components, oxygen (21%) and nitrogen (79%).
The nitrogen in normal air limits your bottom time, or the number of dives that
can be done in a day, or requires a longer surface interval between dives.
Nitrogen is also the cause of decompression sickness.
Enter Enriched Air, also called Oxygen Enriched Air, or just Nitrox. Enriched
Air is air that has more oxygen in it. Consequently it has less nitrogen.
Since nitrogen is the controlling factor for decompression from no-stop diving,
with less nitrogen in the breathing mixture the body will absorb less nitrogen
and will have less of a decompression obligation.
The two most commonly used Nitrox mixtures are 32% and 36% oxygen.
So why would I want to use it?
Today’s diver is seeking more adventure and exploration,
which almost always leads to the desire for more bottom time. Many times
the only way to get that longer bottom time is to plan dives that require
lengthy and sometimes complicated decompression stops. Using enriched air
(nitrox) makes getting that longer bottom time not only easier by eliminating
decompression stops required with air, but this also allows the diver to have
shorter surface intervals while still maintaining a minimal level of risk.
By adding additional oxygen to the mixture the rate of nitrogen absorption into
the body is reduced thus allowing you to extend your no decompression
limits beyond those of normal air. Enriched air replaces some of the
nitrogen you would breathe underwater with oxygen, so you absorb less nitrogen
than you would for the same dive breathing normal air.
Enriched air nitrox is of special value when making multi-day repetitive
dives. Dive incident statistics show that almost 80 percent of all cases of
decompression illness result from repetitive dives. If a diver were to dive the
same profiles that he had done while using air using an enriched air mixture
instead, not only would the decompression be significantly less but there would
be an overall reduction of nitrogen in the body. As a result, many divers
report that they are not as physically tired after a series of dives using
nitrox as they have been in the past using air.
If you imagine a typical dive vacation where a diver may be diving two to three
times a day for five or six days, it is easy to see that the benefits of using
enriched air nitrox become quite significant for either extending bottom time
or by reducing required decompression. That is the magic of oxygen enriched air
I've heard some things about enriched air, are they true?
With all technology come facts and perceived facts. There are
some myths that we need to dispel.
"Nitrox is for deep diving."
Actually enriched air nitrox has very stringent depth limits due to
the higher concentration of oxygen in the mixture. The greatest advantages for
no-stop diving are in the 50 to 130 fsw diving range. The two standard mixtures
of EAN 32 and EAN 36 have maximum operational depths of 130 fsw and 110 fsw
respectively. There are other applications for using enriched air nitrox to
accelerate decompression from deep dives, but these are outside the scope of
the primary enriched air training courses, but are covered in other courses.
"You can't get decompression sickness."
It almost seems obvious that using enriched air nitrox provides
significant benefits of extending bottom times, but not obvious is its use as
an effective tool to help prevent decompression illness. By using a gas with
less nitrogen in it we can effectively lower the risk of decompression illness.
This does not mean that a diver will never get decompression illness, just that
with proper management the already small risk of DCI is even smaller when
diving similar profiles using enriched air nitrox.
However no gas nor diving table can absolutely ensure that a diver will not get
decompression illness. Using enriched air nitrox provides significant
decompression advantages over air, which may help avoid decompression sickness,
but with all diving there is a risk of decompression illness.
"Narcosis is eliminated."
It might seem logical that with reduced nitrogen in the breathing mix
there would be reduced nitrogen narcosis at depth. The fact is, oxygen can also
be a narcotic gas when under pressure. The result is that there is no
significant change in narcosis when diving enriched air nitrox as compared to
Do I need to be trained to use enriched air?
Yes, you will need to complete a PADI Enriched Air course
before you can either rent enriched air tanks or obtain enriched air
Click here for
more information regarding the PADI Enriched Air
Air SCUBA Cylinders
||Enriched Air Fill (22% to 34%)
|Enriched Air Fill (35% to 40%)
|Enriched Air Fill (41% to
|Enriched Air Fill Card (12 Fills - Any Mix)
|Enriched Air Visual (VIP)
|Enriched Air Hydro (Includes VIP & Tank Cleaning)
|Tumble (Hydro Required With Tumble)