I understand Jay's problems. I have a 2-3 bedroom house (depends on
what you consider the downstairs room -- either bedroom or den)
and altho I have/had dogs, the 2nd bedroom is offlimits to animals.
I keep the door closed, vacuum and dust and clean it vehemently.
Plus, there's a serious air cleaner downstairs and another in
that room.

I have friends who are cat people (which I'm allergic to) and others
who are just allergic to everything. This way I can at least try
to provide a reasonably clean area for them to sleep.

Of course no one is allowed to smoke in the house. Or anywhere
near me (allergies).