Experts said one of the main causes of China's environmental problems can be traced to poor urban planning in metropolises such as Beijing.

"The problem with Beijing is not the size of the population, but the concentration," said Su Yang, a senior research fellow at the State Council's Development Research Center.

He said the downtown area of approximately 1,400 sq km, less than one tenth of the city's total area of 16,400 sq km, is occupied by 75 percent of the population of 20 million.