Lanzhou, the oldest bridge crossing the Yellow River in the fog of pollution. A chimney of individual heating is in activity in the foreground.
Lanzhou, in the Gansu province is the most polluted city of China and in the world's top ten for atmospheric pollution due to human activity. The town is situated between two hills along the Yellow River and the polluted clouds remain blocked over the town. The sky is most of the time hidden by the pollution.