China's top three mega-cities have scored high on the World Health Organization's Urban Health Development Index but rated poorly for city management and environmental conditions.

The scores are disclosed in a research report released on Wednesday by the Institute for Urban and Environmental Studies under the Chinese Academy of Social Sciences.

The top three positions went to Shenzhen, with a score of 69.27; Shanghai, with 60.75; and Beijing, with 59.11. Zhaotong, in Yunnan province, ranked lowest of the 287 cities covered by the research, with 28.69.

Shenzhen ranked 19th for health of urban ecosystems; Shanghai ranked 47th and Beijing 208th.

The Urban Health Development Index, introduced by the WHO in the 1980s, is a globally recognized guage of the health of a city's ecosystem, city management, economy, culture and society.

"A duality of social development, especially in the megalopolises, was found through our research. There is still an obvious disparity between the rich and the poor," said Song Yingchang, a researcher at the institute. "Bad air quality and poor traffic conditions also negatively affected urban health development in big cities," he said.

The number of Chinese cities with 1 million or more residents rose from five in 1949 to 66 last year, according to the United Nations.

The research report said that 12 percent of the 287 cities have a per capita GDP of more than 79,500 yuan ($12,945). According to the World Bank standard in 2013, a country with a high-income economy has a per capita GDP above $12,616.

"The economy in many Chinese cities has grown dramatically in the past decade. However, social development is still lagging," said Shan Jingjing, a researcher from the institute.

Contact the writer at yangwanli@chinadaily.com.cn