The whole
ppO
2 thing has changed over time. It used to be a
ppO
2 of 2.0 ATA, after a test to not quite 3.0 ATA was standard. Then it got cut back to a
ppO
2 of 1.8 ATA, then 1.6, then 1.4, then just to do one better GUE went to a
ppO
2 of 1.3.
Everyone needs to grasp a few realities:
- Diving an elevated ppO2 has hazards associated with it.
- The higher the elevation the greater the potential hazard.
- The longer the exposure the greater the potential hazard.
- The higher the work load the greater the potential hazard.
So the question is, why are you using an mix with an elevated
ppO
2 and does its use offset the increased level of potential hazard?
For me it does, and from past experience (which is not a perfect guide) I am willing to accept (for myself only) a
ppO
2 of almost 2.0 for decompression, 1.8 for resting and 1.6 for "normal" diving. But I'd not recommend those exposures to others ... its just that I'd allready done that for years before the agencies got into the topic with recommendations that they had to run through their docs and their lawyers and the accountants