"A senior Chinese official demanded on Tuesday that foreign embassies stop issuing air pollution readings, saying it was against the law and diplomatic conventions, in pointed criticism of a closely watched U.S. embassy index."
"The level of air pollution in China's heaving capital varies, depending on the wind, but a cocktail of smokestack emissions, vehicle exhaust, dust and aerosols often blankets the city in a pungent, beige shroud for days on end.
Many residents dismiss the common official readings of "slight" pollution in Beijing as grossly under-stated.
The U.S. embassy has installed a monitoring point on its roof which releases hourly air-quality data via a widely followed Twitter feed. The U.S. consulates in Shanghai and the southern city of Guangzhou provide a similar service."