This is the site I usually check: http://aqicn.org/city/beijing/ http://aqicn.org/city/beijing/ Also, if I needed it, I'd probably build one of these: http:/

This is the site I usually check: http://aqicn.org/city/beijing/ http://aqicn.org/city/beijing/ Also, if I needed it, I'd probably build one of these: http://smartairfilters.com/en.html http://smartairfilters.com/en.html