My air purifier works exactly as advertised. I love it. I have to say that even the way it was packaged when it arrived, and the documentation that came with it inspired confidence in the product, and it has not disappointed. I smoke in one room in my house, in the basement, so I purchased the filter for smoke and it has made all the difference. I turn it on with the 4-hour timer when I first get up in the morning, have my morning cigarette, go off to work, and when I come home at the end of the day my house is not only fresher , but less dusty even upstairs (I live in a dry, dusty climate). I turn it on again with the timer and it goes off by itself after I go to bed. This was really a great investment for me.