Despite China's heroic efforts to clean up the air for last year's summer Olympics, Beijing remains buried under layers of pollution, the result of rapid industrialization.

The Beijing Traffic Management Bureau recently announced a 12-month extension of its successful traffic restriction program--which was implemented ahead of the games--along with tougher measures to curb emissions. A fifth of the city's 3.6 million private vehicles and a third of government vehicles will stay off the streets.

The city is barely perceptible in this SeaWiFS image, taken on November 20, 1999.