The pollution in Beijing right now is bad. Really bad. So bad that you can feel the heaviness, the denseness of the air as you breathe it in. It is stifling.
So how bad it is? Well, the closest thing we’ve got to real-time data, the US Embassy’s BeijingAir Twitter feed, confirms our worst fears; it has been reporting hazardous air for over 24 hours now, with over half of the hourly data points maxed out at an AQI of 500. MEP’s air quality data released this afternoon, on the other hand, shows an API of just 186, “lightly polluted” (”轻度污染”).
I wrote a lot about this discrepancy back in June when Beijing experienced a similar pollution spike. (See these posts: 6/18: air in Beijing is hazardous; 6/19: more info on Beijing’s 6/18 air quality; 6/22: US Embassy outed as source of BeijingAir Twitter feed.) In June, I posited that the hazardous pollution was not reflected in the MEP data because the MEP data is a 24-hour average, while the pollution events then only lasted for a few hours each. In this case, though, BeijingAir has been continuously reporting hazardous air since around 4pm yesterday, so it’s hard to imagine how the MEP data is still so “low.” (Low is in quotation marks because an API of 186 still represents very polluted air.)
I’m afraid I don’t have time to post more right now; I’ll try to get some graphs up this weekend. In the meantime, avoid strenuous exercise and stay inside if you can. With the Embassy-reported AQI maxed out at 500, the air is, in theory, worse than hazardous:
Hi, thanks for the info. We are newcomers in Bejing and are of course concerned about the air quality the last days. What is the difference between AQI and API?
BR Anna
Dear Anna,
Welcome to Beijing. Don’t worry, the air isn’t always this bad! AQI is the US’ “Air Quality Index,” while API is China’s “Air Pollution Index.” Both are 0-500 numbers that indicate the air quality at a certain time, although the definitions are slightly different. When it comes to particulate pollution (Beijing’s dominant air quality problem), though, the scales are similar, so it is somewhat reasonable to compare them directly. The biggest difference is that the US’ AQI measures only the smallest, most damaging particles to human health, while China’s API includes larger particles. I wrote some about it in this post: http://www.livefrombeijing.com/2008/12/stay-inside-today-beijing-api-at-246/.
Some other resources are as follows:
US’ AQI basics: http://www.airnow.gov/index.cfm?action=aqibasics.aqi
US’ AQI for particulates: http://www.airnow.gov/index.cfm?action=pubs.aqguidepart
Explanation of China’s API: http://www.livefrombeijing.com/2008/08/what-is-the-api-and-how-is-it-calculated/
Best,
Vance