 Why Dive Enriched Air (Nitrox)?
by
Jerry Otte
Contents
For many beginning divers, diving enriched air (often called nitrox) is
somewhat
frightening. After all, the
PADI Open Water
Diver Manual warns that enriched air is dangerous and off limits to
anyone who has not been trained to use it.
So why do divers use enriched air and why should you consider taking the
PADI
Enriched Air Diver course? The reasons are simple regardless of your
current certification level: diving enriched can extend your bottom
times, reduce your surface intervals, and increase the number of dives
you can safely do in a day.
In the broadest sense, Nitrox is any gas blend of oxygen and nitrogen
other than air. Air, of course, is basically a mix of 21 percent oxygen
and 79 percent nitrogen. For divers, Enriched Air Nitrox is any gas blend with more
than 21 percent oxygen. Generally for recreational divers this is a
blend of either 32 percent or 36 percent oxygen, sometimes abbreviated
EAN32 or EAN36.
As we all know, nitrogen is the cause of diving maladies such as
decompression sickness and nitrogen narcosis. We learned in our PADI Open
Water Diver course that our bodies use up oxygen when we breathe. However,
because nitrogen is not used by our bodies, nitrogen saturates our tissues.
This happens whether we are on the surface or on a dive.
Our regulators are designed to deliver air to us at whatever pressure we are
at. That’s why our bottom times become shorter and shorter the deeper we go.
As our regulators deliver more and more air to us as we descend, more and
more nitrogen is absorbed into our tissues. The more nitrogen we absorb on a
dive, the more dangerous and difficult it becomes for us to return to the
surface.
Why? While we can tolerate some excess amounts of nitrogen in
our tissues, exceeding the safe limits prescribed by our dive tables and
computers can result in the dissolved nitrogen in our tissues coming out of
solution on ascent and forming bubbles that produce symptoms such as joint pain,
coughing, rashes, headaches, paralysis, unconsciousness, or worse. This is
what we divers call decompression sickness and our non-diver friends call
the bends.
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