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Beijing has some seriously bad air. How bad? On a scale of 1 to 500, the United States Environmental Protection Agency says anything over 100 is unhealthy and anything above 400 is an emergency. Recently, the pollution index for Beijing hit 755. For purposes of breathing, it's like being downwind of a forest fire while smoking a cigar.

China's communist rulers normally suppress news like that. In 2009, when the U.S. embassy in Beijing started putting air quality numbers on its Twitter feed, the government demanded in vain that it stop.

But when your air contains enough foreign matter to mold bricks, it's hard to claim the sky is blue. And lately, the authorities have decided censorship of the topic is futile.

"I've never seen such broad Chinese media coverage of...