[Mullins]

You use up a fair bit of 02 on your way down to 100m, so pp02 at that depth is not likely to be huge. You would use very little on a descent to 10m...

Having said that, a couple of the symptoms I've had on deep dives have been consistent with 02 narcosis and 02 toxicity (feeling depressed/emotional and shaking, respectively). I'm going to talk to one of the dive docs here in NZ to see what their take on it is.