DSK is totally RIGHT.
A cubic foot of 'clean' air contains greater than 30,000 particles
(equal to or greater than 0,01 micrometers diameter) per cubic foot -
with a great proportion of them bacteria and mold/mildew spores.

Your body traps these particles on the mucous membrane and hair-like
(cilia) linings of the upper respiratory tract .... (making 'boogers'
that you periodically expel).

Without some means of removal (a recirculation fltration, etc.) any
process that continually concentrates will eventually be totally fouled
with 'sludge' from ever increasing airborne particles.


In article , Keith
wrote:

Then how come water was here first?