I live in an upstairs duplex with smokers downstairs. I bought the filter to reduce the smoke odor, and it does this pretty well. I usually run the unit continuously on low in my bedroom at night, and I bring it into the living room during the day. It seems to be mechanically sound, and the noise is fairly low for the rate of air movement. I am using the HEPA Silver (activated carbon) filter. I stop at four stars only because I have only been using it for a month or so.