A survey from Guangzhou sounded the alarm that the population of the capital of South China's Guangdong Province is approaching the limit its resources can support. More chances to land a job and better pay for the same kinds of jobs along with better living conditions in big cities have lured a growing number of rural migrants to major cities such as Beijing, Shanghai and Guangzhou.

Migrant workers have helped build these cities. They have made great contributions to the cities' economic development. They have taken on most of the vital low-end jobs from construction work to garbage collection, work that local residents are reluctant to do.

But there is a limit to the population a city can accommodate in terms of the limited resources of water and land.

The city population explosions overwhelm the infrastructure.

In the nation's capital, traffic jams, air pollution caused by exhaust emissions from nearly 3 million cars and pressure on water supplies are part of the population crush local government is attempting to deal with.

Experts in Guangzhou have proposed restructuring local industry to taper off the population increase caused by migration. Low-end manufacturing enterprises are a major magnet for farmers- turned- city-workers. Increasing high-tech manufacturing would employ fewer, more highly trained workers.

It is unacceptable to use administrative bans to prevent rural workers from entering cities where resources are becoming strained. But city planners and administrators must have programs in place to avoid population explosions in big cities.

Editor: Yan