When you take a breath of helium, there won't be any transfer of oxygen into the bloodstream from that breath, but there is still oxygen left in that portion of the blood from the last time it passed through the lungs.

There was an earlier message concerning somebody breathing nitrogen by
accident (I presume at sea level) and going into immediate convulsions.

Why nitrogen and not helium?

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.