Using 100% oxygen for offgasing

[DiverQueen]

As an Emergency Medical Technician, I would recommend that you keep the 100% O2 at the surface and use only for emergencies as in Decompression Sickness (the Bends) and in transport to your local Recompression Chamber.  Breathing compressed O2 below 15-25ft has it's potential for Central Nervous System Toxicity!  Yes, that can be fatal!!!!  Multiply your oxygen percentage (regular air = 21%) by the number of atmospheres you dive...Anything above 1.4 -1.6 can cause CNS Tox.  Use th acronym CONVENTID to look for these signs and symptoms: CONvulsions, tunnel Vision, abnormal hearing or ringing in the Ears, Nausea, Twitching facial muscles, Irritability, or Dizziness.  This information is from the International Association of Nitrox and Technical Divers (IANTD) Nitrox Diver Student Manual.