animaux wrote:
Not a bubble, but the house is HEPA filtrated.

Unless you have a positive pressure gradient and a two-door entryway, your
HEPA filter is pretty much useless. You see, most houses (mine certainly
isn't) are not even close to being airtight. Outside air flows inside freely
(you really think all the dust you vaccuum weekly is produced *inside* the
house?) and it brings pollutants in. There was a study done a few years back
that measured pollutants inside and outside houses. In some cases the
pollutant concentration was actually higher indoors, since there is no wind
to disperse them inside.

--
Victor M. Martinez

http://www.che.utexas.edu/~martiv