PO2 limits...

[Tomeck]

Furthermore, 1.4 isn't a universal standard. Many tech divers will go above it for deco. The U.S. Navy is also more conservative, and uses 1.3. GUE teaches 1.2 (for cold diving).

No, 1.4 is not an universal standard. With the CMAS in Europe, the limit is 1.6 and you can dive up to 40 meters with 32%. I find 1.4 too much low.

 

[Gene_Hobbs]

Just to add a reference that includes a nice discussion on limits set by both the US Navy and NOAA... As well as suggested guidelines...

Lang, MA (ed) 2001. DAN Nitrox Workshop Proceedings. Divers Alert Network, Durham, N.C., 197p.
http://archive.rubicon-foundation.org/4855

---Re-reading this, I really miss Ed Thalmann.