Another addition for helping with ferret odors in multi-ferret (and pet) households. I never would have thought of this had I not read about them on some ferret forums... air purifiers! Normally I have the windows open, but in the winter, this is not an option. The solution: an air purifier.
Though these air purifiers do not remove all odors from the room, they do make it seem as though a window is open. They also reduce the number of allergens in the room and act as small fans, giving the ferrets a little bit of 'fresh air' without making them too cold.
I found this one at Canadian tire and, for what I wanted, it was perfect - compact, easily movable and not overly expensive ($60 Canadian). There are many different types of air purifiers, so I would encourage any interested parties to do their own research and evaluate their own needs before making their purchase, but if you are finding ferret odors a bit tough to beat or simply would like a little more air circulation around your ferret cage, try one of these! You may be pleasantly surprised!