Intense traffic of the developping town of Lanzhou is one of the main sources of pollution in the city. Here along the Yellow River. China.
Lanzhou, in the Gansu province is the most polluted cities 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 remains over the town. The sky is most of the time hidden by the pollution.