O
2
%
Oxygen percentage or oxygen fraction in the breathing gas. Standard air
has 21% oxygen.
Oxygen partial pressure
Limits the maximum depth to which the nitrox mixture can be safely used.
The maximum partial pressure limit for enriched air diving is 1.4 bar. The
contingency partial pressure limit is 1.6 bar. Dives beyond this limit risk
immediate oxygen toxicity.
PO
2
Abbreviation for oxygen partial pressure.
RGBM
Abbreviation for Reduced Gradient Bubble Model.
Reduced Gradient Bubble Model
Modern algorithm for tracking both dissolved and free gas in divers.
Repetitive dive
Any dive whose decompression time limits are affected by residual nitro-
gen absorbed during previous dives.
Residual nitrogen
The amount of excess nitrogen remaining in a diver after one or more
dives.
SURF TIME
Abbreviation for surface interval time.
Surface interval time
Elapsed time between surfacing from a dive and beginning a descent for
the subsequent repetitive dive.
Tissue group
Theoretical concept used to model bodily tissues for the construction of
decompression tables or calculations.
Whole-body toxicity
Another form of oxygen toxicity, which is caused by prolonged exposure
to high oxygen partial pressures. The most common symptoms are irrita-
tion in the lungs, a burning sensation in the chest, coughing and reduction
of the vital capacity. Also called Pulmonary Oxygen Toxicity. See also
OTU.
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