If you are worried about particulate, you can build one of these: http://www.youtube.com/watch?v=kH5APw_SLUU http://www.youtube.com/watch?v=kH5APw_SLUU I buil

If you are worried about particulate, you can build one of these: http://www.youtube.com/watch?v=kH5APw_SLUU http://www.youtube.com/watch?v=kH5APw_SLUU I built one for my room because my previous tenants had cats, which I'm allergic to. Even after steamcleaning our apartment I was chronically congested. Built one of those purifiers and a few days later most of my symptoms are gone. It's been about a month now and the filter is noticeably soiled.