Hello,
Questions about the evidence base for the current NOAA limits for oxygen exposure to manage the risk of CNS oxygen toxicity have often been raised on scubaboard. It is widely understood (though perhaps still surprising to some) that there was essentially no testing / validation of these limits in the exposure range that technical and rebreather divers are interested in (notionally an inspired PO2 of 1.2 - 1.6 atmospheres). In April this year a panel of experts was convened for a workshop at the conclusion of the American Academy of Underwater Sciences Meeting in Seattle to examine whether there were sufficient grounds for a modification of these limits. The resulting scientific journal paper was published in Diving and Hyperbaric Medicine Journal today and is attached below. It establishes a new limit for 1.3 atm, an inspired PO2 chosen because of the existence of a reasonable body of evidence that the modification is justified. It is important to understand that the new limit represents what appears to be an acceptably low level of risk, based on a substantially superior evidence base compared to the old limit. Of course, the only way to achieve zero risk is not to breathe an elevated PO2 underwater!
The paper is self-explanatory and so I will not replicate the narrative. I believe this is a significant event in the evolution of technical diving. Happy to discuss.
Simon M
Questions about the evidence base for the current NOAA limits for oxygen exposure to manage the risk of CNS oxygen toxicity have often been raised on scubaboard. It is widely understood (though perhaps still surprising to some) that there was essentially no testing / validation of these limits in the exposure range that technical and rebreather divers are interested in (notionally an inspired PO2 of 1.2 - 1.6 atmospheres). In April this year a panel of experts was convened for a workshop at the conclusion of the American Academy of Underwater Sciences Meeting in Seattle to examine whether there were sufficient grounds for a modification of these limits. The resulting scientific journal paper was published in Diving and Hyperbaric Medicine Journal today and is attached below. It establishes a new limit for 1.3 atm, an inspired PO2 chosen because of the existence of a reasonable body of evidence that the modification is justified. It is important to understand that the new limit represents what appears to be an acceptably low level of risk, based on a substantially superior evidence base compared to the old limit. Of course, the only way to achieve zero risk is not to breathe an elevated PO2 underwater!
The paper is self-explanatory and so I will not replicate the narrative. I believe this is a significant event in the evolution of technical diving. Happy to discuss.
Simon M
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