Raleigh Wrote:
-------------------------------------------------------
> Article mentions "a chamber filled with air laced
> with 80 parts per million (ppm) of hydrogen
> sulphide (H2S) - the malodorous gas that gives
> rotten eggs their stink."
>
> I wonder how many ppm H2S is needed for the human
> olfactory sense to detect its presence.

As low as 10 parts per billion. As a chemist I can tell you that if you work with a stinky substance after a while you become desensitized and you don't smell it anymore. :-)
Bernard


>
> I can envisage astronauts complaining that they
> cannot get to sleep because of the dreadful
> smell!
> And imagine how Ripley's cat would feel!