I have four of them in my apartment in Shanghai. They definitely work; I verified it over and over with a laser particle counter. They're loud, but simply runni

I have four of them in my apartment in Shanghai. They definitely work; I verified it over and over with a laser particle counter. They're loud, but simply running them in the rooms you're not occupying (e.g. in the bedroom during the day, then in the living room during the night) is already a significant gain. If you get some for your own home, make sure to cut down on the drafts first; running your purifiers full power won't help you if polluted air is always coming in. I lined all my windows with foam tape from the hardware store. Rather than fighting every day to keep my indoor air clean (that still doesn't do anything for me when I head out) and my internet connection to foreign servers above dialup speeds (four VPNs and counting), I've simply decided to move back to the Bay Area though. :|