Zhang Xiao'an, vice-chairwoman of the United Nations Association of China, came to Beijing's defence this morning on China Central Television by stressing that the Chinese Foreign Ministry made a "very clear-cut response this time".

BBC: China media: Pyongyang pressure

The two biggest Chinese auctioneers, Beijing Poly and China Guardian, seem to think it worthwhile: they have applied to join.

ECONOMIST: Auctions are moving online

The U.S. Embassy in Beijing publishes AQI values for Beijing and other cities in China, and the Chinese Ministry of Environmental Protection provides its own air quality data for cities throughout the country.

FORBES: Air Quality In China