THE ancient Silk Road city of Lanzhou sprawls along the banks of the Yellow River in central China - at least that's what the guidebooks say.
On a cold winter's morning, the impenetrable smog cuts visibility down to about 100 metres and it is impossible to see the spectacular cliffs which apparently tower over the city let alone the sweep of the river.
Petrochemical industries, a huge oil refinery, a power station and engineering factories belch fumes into the still, cold air.
It is difficult to see the industrial areas under the dense grey shroud. You cannot see the smoke stacks for the smoke.
Lanzhou is widely reputed to be the air pollution capital of China, the dirtiest place in a nation of grimy, polluted industrial cities.
It will soon have many rivals as the Chinese economic miracle gathers momentum and the demands of 1.2 billion people anxious to enjoy a Western-style living standard begin to foul the remaining clean air and water.
''China is a looming environmental catastrophe,'' said a Western diplomat in Beijing. ''It will make Eastern Europe look like a nature park.'' Marine biologist Ms Catherine Cheung is preparing a bio-diversity report for the World Wide Fund for Nature (WWF) and the Chinese Ministry of Forestry.