The smog in Beijing last weekend was the worst on record. The city looked like it was in a sandstorm, like the inside of a smoker's lung, as one Beijinger put it, shaking his head.
In November 2010, the Air Quality Index operated by the American embassy in Beijing, which uses standards set by the US Environmental Protection Agency and measures fine particles called PM 2.5 because they are 2.5 microns or smaller in diameter, reached "crazy bad" levels.
The index gives an "unhealthy" reading most of the time, and anything above 300 is hazardous, while "beyond index" is above 500. The reading was "beyond index" for 16 hours in a row at the weekend, and reached an appalling 845. Welcome to life in the exhaust pipe of the world's economic growth engine. Flights were cancelled, traffic disrupted, and you could barely see the coal-fired power station in front of you.
Even the normally compliant local media didn't bother with the usual euphemisms such as "fog". They gave charts of where the smog was thickest and warned people to stay indoors in no uncertain terms.
The Xinhua news agency reported on 31 January that Beijing's air quality has improved for 14 straight years.
With 400,000 new cars every year, and the population increasing by 400,000, it's a tough job keeping tabs on smog, said Qiao Shufang, an official with the Municipal Environmental Protection Bureau.
One Beijing online commentator wrote on the Twitter-style Weibo: "I'd rather die in a war, not PM 2.5, it's such a cheap way to die."