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77
ReACT Pro
Since the 1990 UHMS guidelines were introduced, data from the Diver’s Alert Network (DAN)
was introduced that resulted in DAN’s position ** that “A minimum surface interval of only 12
hours would be required in order to be reasonably assured a diver will remain symptom free upon
ascent to altitude in a commercial jet airliner (altitude up to 8,000 feet/2,440 meters). Divers
who plan to make daily, multiple dives for several days, or make dives that require decompres-
sion stops, should take special precautions and wait for an extended surface interval beyond 12
hours before flight”.
Both the UHMS and DAN agree that “There can never be a flying after diving rule that is guar-
anteed to prevent decompression sickness completely. Rather, there can be a guideline that rep-
resents the best estimate for a conservative . . . surface interval for the vast majority of divers.
There will always be an occasional diver whose physiological makeup or special diving circum-
stances will result in the bends”.
NITROX DIVING
Both central nervous system (CNS) oxygen toxicity and pulmonary oxygen toxicity were taken
into consideration when the Maximum Durations (Fig. 79) for a Single Exposure and for Any
24-Hour Day were published by in the October 1991 NOAA Diving Manual. Although CNS
oxygen toxicity is considered the primary constraint for higher levels of partial pressure of oxy-
gen (PO2), there are circumstances in which pulmonary oxygen toxicity can limit exposures.
CNS oxygen toxicity is not considered likely at PO2 levels below 1.30 ATA. It is, however, re-
lated to diver's work level. Performing strenuous tasks could cause the symptoms of O2 poi-
soning at PO2 levels lower than they normally would appear during casual diving. Fig. 79 - NOAA O2 Limits
Maximum
Exposure Time
PO2
(ATA)
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
Per Dive
(Min)
720
570
450
360
300
240
210
180
150
120
45
Per 24 hr
(Min)
720
570
450
360
300
270
240
210
180
180
150
** excerpted from “DAN’s Position on Recreational Flying After Diving”