Mark one thing to think about is if your furnace is in the basement it may be drawing fibres into your ductwork and throughout your house. Since I don't know your setup it's had to tell. Had you had your home tested for asbestos fibres? Mel N.
Actually, we have a gas-fired steam boiler, so there's no air moving around. Seriously... thanks for the concern though!
::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::