video transcript

Beijing shrouded in a cloud of pollution. The city, notorious for bad air quality, saw levels far above hazardous conditions over the weekend on an index that measures particulate matter in the air. A level of 300 is considered dangerous, while the World Health Organization recommends a daily level of no more than 20. Beijing's air reached 755 over the weekend. Greenpeace said the pollution was the worst ever recorded in the capital -- largely due to cars and the burning of coal to keep warm in an unusually cold winter. Dissident artist Ai Weiwei joined outcry over the crisis on Saturday, posting photographs of himself wearing a gas mask on his Twitter page. (SOUNDBITE) (Mandarin) CHINESE ARTIST AI WEIWEI SAYING: "I felt really helpless, and the only thing I could do was find a way to express it. I bought the gas mask and wore it on my face to send two messages: one was to let people know how disgusting the situation in Beijing is, the second was to say that every person has the ability to save themselves." State media reported dramatic increases in patients visiting hospitals with respiratory complaints. China's cautious media has been unusually bold on the issue, calling on the government to take urgent action to address air quality.