There is a nice site with information about pollution in China called www.pollution-china.com
Here is a short French video made by the French Radio Europe 1 about the air quality in Beijing.
If you are in China and looking for good anti-pollution masks from the British company Respro, then you should also check out that website. I always cycle in Beijing with the mask, especially on heavily polluted days. Here is a pictures of my friends that also use these masks. This picture was taken by another friend some months ago (thanks for the nice picture):
Out of the 10 Beijing fixie riders 2 have a Respro mask. The air can get bad and has been really bad on some days. But we had clear skies for quite a few weeks already – such a perfect weather for cycling. I find the gangster look quite cool. Still waiting for Respro to make a mask in the same color as my trick fixed gear bike.
Is it that bad that you have to wear them? what percentage of fixie riders do – I am glad about london not beeing that polluted – does make you look kinda gangster like too!