Intuitively it seems to me that one would want it lower, at sleeping level, or medium, at sitting level. I agree with those who think the molecular weights could be used to justify either.
And thinking about podrock's van, I'd think that the liability issues would have had to be considered when they decided where to place it. If they put it in the wrong place and someone suffocated it could be spendy.
So, high it is.
Thanks again for the thoughtful consideration from everyone.
Arf