Our CF doctors essentially said that leaving the fan on (if you have central air) and using a high quality air filter will suffice. Leaving the fan on disables dust and other particles from settling and should work for the entire household - essentially bypassing the question regarding area filters. Our daughter's doctors don't believe that having an area filter in a bedroom will make much difference as most of us don't spend a lot of time in the bedroom...you would need an area filter for every single room in order for their use and cost to be justified. One of the doctors suggested the reusable type of air filter (wash with water every 2 weeks), but we found a disposable electrostatic filter that captures more particles than the reusable type (93% vs 90%).