A few links to websites talking about Totobobo in Beijing:
Air Pollution 101: Here?s Your Syllabus, by Dr. Richard Saint Cyr.
A great collection of informative articles on air pollution.
The Mask Factor: Breathing Easy for Cheap by Marilyn Mai
The Beijinger
700Bike reviews several pollution masks for cycling, including Totobobo mask (in Chinese)
 700bike.com recommendation
Totobobo mask cyclist in Beijing
Forum Club PChome discussion about Totobobo mask (in Chinese)
Are these masks still available? I read they are totally sold out because of the hard pollution levels of these days.
Thank you for the information
Juan