stay inside today - beijing api at 246

Beijing's API broke the 200 mark today for the first time since May 29th.

Today's API reading of 246 - corresponding to a PM10 concentration of 382 ug/m^3 - would be characterized by the US EPA as "very unhealthy":


Here in China, this air quality is simply referred to as:

北京2008-12-09的API指数为 246 ， 空气质量级别 Ⅳ1 级 , 今天北京空气中的首要污染物为 可吸入颗粒物 ， 空气质量状况 中度污染 。

Translation: "Beijing API on 12/9/2008 is 246, air quality level IV1. Today's primary pollutant is inhalable particles. The air quality status is moderate-heavy polluted."

Sources and a brief discussion of US AQI vs. Chinese API follow:

Sources:

Beijing API: http://datacenter.mep.gov.cn/TestRunQian/air/airCityMain.jsp?city=%B1%B1%BE%A9
Conversion of Chinese API to PM10 concentration: http://www.mep.gov.cn/quality/background.php
US AQI pollutant concentration breakpoints: http://www.epa.gov/ttn/oarpg/t1/fr_notices/airqual.pdf. For PM10, the breakpoints are almost identical to China's:

(Above image, US breakpoints. Below image, China's breakpoints)



More info on PM10:
http://airnow.gov/index.cfm?action=static.aqguidepart
http://airnow.gov/index.cfm?action=particle.airborne