Theory 04/Diving & Hyperbaric Physiology
Oxygen Toxicity Is a Rate
The claim
Central nervous system oxygen toxicity is set by the rate of oxygen delivery to tissue rather than by cumulative dose, so intermittent exposure at high partial pressure can be safer than continuous exposure at lower pressure.
01The mechanism
Reactive species accumulate when production outpaces antioxidant capacity. Intermittent exposure allows recovery between bouts, so the same total exposure produces less accumulation.
That makes the duty cycle the controlling variable, not the integral of partial pressure over time.
02What this is not
Cumulative-dose models
Those integrate exposure. This uses the duty cycle, which explains why intermittent protocols are tolerated.
03Predictions
- P1Toxicity should depend on duty cycle at equal total exposure.
- P2Recovery intervals should extend tolerance.
04Refutation
Toxicity tracking total dose regardless of duty cycle would remove the rate effect.