Crazy bad days [in Beijing], according to [Dr. Richard] Saint Cyr, are the equivalent of 75 percent of one cigarette a day. "So if you don't smoke and you are really healthy, it is something to think about," he admits, although he argues that the health effects of being overweight and inactive are far worse than a little air pollution. "My overall theme is that people, if they're freaking out about air pollution and they're five or ten kilograms overweight, they're really missing the point about their relative risks, what they're gonna die of," he says.

At the same time, Saint Cyr acknowledges that mortality from air pollution is a problem in Beijing. Lung cancer, heart disease, and strokes all rise in polluted cities like Beijing. In China, the individual risk might not be significant but because of the size of the population, the pollution could mean that "hundreds of thousands die prematurely," he says.

Air quality in Beijing isn't expected to improve any time soon, but the transparency of reporting took a great leap forward just before the lunar new year, when the Beijing Municipal Environmental Monitoring Center started to publish its own 2.5 particulate matter readings. On his website, Saint Cyr compared the readings from the U.S. Embassy and the Chinese, and found that the numbers were comparable. That's a dramatic improvement over the city's earlier monitoring system, which limited itself to a daily report on larger particulates of 10 micrograms and had the audacity to claim that there were 286 "blue sky days" in 2011.