Short answer, yes. You should definitely keep breathing. Moving on.
Earlier this week, the US Consulate in Shanghai began issuing hourly reports on the city's air quality, as measured by the monitoring station at the main consulate office on Huaihai Zhong Lu, as reported on their website.
This development was welcomed by health conscious foreigners and locals alike, albeit with trepidation on behalf of some ("Do I really want to know?"), and is the third such program established by a US governmental outpost in China, following in the footsteps of the Beijing Embassy and the Guangzhou Consulate.
Like the Beijing and Guangzhou monitoring stations, the Shanghai data, at least thus far, has the potential to cause some confusion. The Chinese government has its own monitoring stations in Shanghai, run by the Shanghai Environmental Monitoring Center, and their numbers have been consistently more favorable than the new US figures, as published by China's Ministry of Environmental Protection (MEP).
Who said crazy bad...
It is unlikely that whatever snarky programmer wrote the term "Crazy Bad" into the Beijing Embassy's monitoring software has struck again (when the Beijing air quality index rose above 500 in the fall of 2010, the embassy's automatic Twitter feed spat out a rating of "Crazy Bad", a designation that has since been renamed "Beyond Index"). But the consistent differences between the US and Chinese readings are still likely to irk those behind the MEP figures.
So far, the discrepancies in numbers have been attributed to different standards of measurement, according to a China Daily article published on 16 May 2012. The readings provided by the MEP are based on API (air pollution index; in this case, primarily based on PM10, sulfur dioxide and nitrogen dioxide), and the US readings are based on AQI (air quality index; in this case, primarily based on PM2.5). PM10 and PM2.5 refer to particulate matter, and PM2.5 particles are significantly smaller, and pose more risks, than their larger PM10 counterparts.
The Chinese numbers have been criticized for relying too heavily on PM10 data. Some argue that it is not a true representation of the dangers posed by pollution, as it is the PM2.5 particles that are small enough to be absorbed into the lungs and bloodstream. Though the local measurements recently started measuring PM2.5, these figures play a less crucial role in determining the quality of the air than they do in the American readings. For example, at the time of this writing, the MEP PM2.5 reading in Shanghai is 164 per cubic meter, while the US reading is 110 per cubic meter; the MEP overall rating is "good" at 98, while the US rating is "unhealthy" at 177. Confusing, isn't it?
Should you be concerned?
Well, that's a complicated question, and one that invariably depends on your lifestyle and how long you plan on staying in China. For long term residents, polluted air poses significant risks, with an increased chance of respiratory illnesses, lung cancer and heart disease, though some argue that the effects are not nearly as dire as they seem. But even if it's not as terrible as it may seem, as anyone who has lived in a heavily polluted city, the day-to-day effects of pollution are very tangible.
Dr. Richard Saint Cyr, an American doctor living in Beijing who blogs about public health at My Health Beijing, recommends wearing masks on the smoggiest days, and has a suggestion or two about which pollution masks are the best. Infants, the elderly and those with respiratory illnesses are at the highest risk, and should avoid exertion when the air quality index soars upwards. For the well-to-do, there are air-filtering systems for households and offices; stay home, and it's like you're in the Swiss Alps. For those of us who live in China, don't have the luxury of filtered air, and don't wish to limit our outdoor exertion, it's best to stay informed about the day-to-day conditions to avoid prolonged exposure to China's air at its worst.
How to stay informed
The easiest way to stay on top of the air quality in China is to download the useful China-related iPhone apps.
Of course, not everyone has an intelligent phone. Luckily, there are a few ways to keep up with the air quality otherwise—the most tried and true of which is exercising heavily outdoors for the better part of two hours; if, when finished, you feel like you are dying, it's probably pretty polluted out there.
Other ways involve a working computer and Internet connection: the official MEP PM10 data (it's all "good" or "very good"); the Shanghai PM10 data (in Chinese; similarly suspiciously positive); and the US Twitter feeds for Beijing, Guangzhou and Shanghai.