I've had a trivia question in the back of my mind for a while, and while
it's so quiet, I'm going to ask it.

------------Qn:------------
What is the greatest depth any gas may be breathed
indefinitely and safely, without ever requiring
'formal' decompression, and what is that gas?
---------------------------

Here is my uninformed starting thought:  Nitrox 55 at 8 metres.

PPN2 = 0.81 - practically normal.
PPO2 = 0.99 - Is this safe indefinitely? I've heard something about lung
damage in firemen breathing 1 ATM O2 for long periods?

(Disclaimer:  I'm not even basic nitrox qualified, though I've picked up a
few bits and pieces, and I don't know much about helium other than it
requires longer decompression following the same pp profile than nitrogen.
Hence there are probably assumptions I've made that are false  (such as,
this question even has an answer ;-) - feel free to point them out.)

Cheers,
Huw

--
Travel Tales: http://www.huwporter.com
-----------------------------------------------
FREE! The World's Best Email Address @email.com
Reserve your name now at http://www.email.com