I Introduction
3
I
Nitrox is a gas mixture consisting of nitrogen and
oxygen. The kind of air used for diving with
compressed air is the same as the normal air of the
earth‘s atmosphere (78% nitrogen, 21% oxygen and
1% inert gases). Therefore, normal air is also Nitrox!
When talking of Nitrox as the breathing gas for diving,
it describes a mixture with a higher percentage of
oxygen. A higher percentage of oxygen (and
automatically the reduction of nitrogen) has the
advantage of lengthening the no-stop phase (or
reducing the decompression phase), since less nitrogen
is dissolved in the diver‘s body during the dive.
The higher share of oxygen in the Nitrox-mixture also
causes additional physiological problems by the toxic
effects at a higher partial pressure of oxygen (ppO
2
).
When breathing oxygen at a higher partial pressure,
two kinds of oxygen toxicity can occur:
CNS damages:
Symptoms of poisoning occuring at short notice in
the central nervous system(CNS). Such symptoms
are: irritations of the respiratory organs, sickness,
headache, pulmonary oedema, cramps, uncon-
sciousness. The symptoms occur at a ppO
2
of more
than 1 bar and depend on the term of exposure and
on the partial pressure of oxygen.
Damages of the lungs:
Symptoms of pulmonary poisoning occuring in the
long run. The symptoms occur at a ppO
2
from 0.5 bar
and higher and with terms of exposure in the range
of days/weeks.
Aladin
®
Pro Nitrox considers the short term toxic effect
of oxygen (CNS damages) by means of the so called
„oxygen-clock“. It is based on a list which shows the
units of toxicity for oxygen per unit of time and is
dependent on the ppO
2
. The indication of toxicity is
shown as „CNS O
2
LIMIT“ (= relative toxicity of oxygen
2 Aladin
®
Pro Nitrox – More Safety in Diving
