I don't get the "canned" bit. Is it canned along the lines of Spaceballs "Perri-Air" or in something more similar to an SCBA
I honestly can't see the "Perri-Air" approach doing any good. There is no face-seal to keep toxins out. The SCBA approach wouldn't do much good either. The SCBA tanks I'm familiar with are capable of holding 45 minutes of air - which isn't that long of a time. There is no way that any useful amount of canned air is being bought by any single person. If you're really worried about the smog in China, wear a gas mask. At least it will do you some good.