U.S. Embassy air quality data undercut China's own assessments.

One day this month, the reading was so high compared with U.S. standards it was listed as 'beyond index.' But China's own assessment that day was that Beijing's air was merely 'slightly polluted.'

http://www.latimes.com/news/nationworld/world/la-fg-china-air-quality-20111030,0,4899208.story