11
2 Aladin
®
Air Z O
2
– More Safety in Diving
I Uwatec
®
Aladin
®
Air Z O
2
English
I
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, unconscious-
ness. 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 hours/days.
Aladin
®
Air Z O
2
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
%“ (= relative toxicity of oxygen
for the central nervous system). CNS O
2
LIMIT = 0% corresponds to the normal state before the first dive,
and CNS O
2
LIMIT =100% corresponds to the critical upper limit. The list, initially published by the US Navy,
is nowadays known by the name NOAA-list. We modified this list for the use with Aladin
®
Air Z O
2
in co-
operation with Dr. Bill Hamilton, Hamilton Research Ltd. (Tarrytown, NY), a well-known specialist.
The long term kind of oxygen poisoning has practically no relevance for diving with independent diving
equipment and is therefore not considered in the design of Aladin
®
Air Z O
2
.
If nitrox is used for diving profound additional training is needed because of the physiological peculiarities
of oxygen and the changing decompression due to the reduced percentage of nitrogen. Additional tech-
nical problems with the use and the maintenance of parts of the equipment are additional potential dan-
gers when diving with nitrox or rebreathers. Therefore, we recommend strict adherence to the following
guidelines and warnings.