Major centers look for ways to cure 'big city disease'

Unbalanced urban and rural development is driving up the populations of China's largest cities and resulting in a lack of basic amenities and social services. Du Juan reports.

Editor's note: This is the last in a series of special reports looking at the effects of hukou, China's household registration system, on the lives of ordinary citizens who have left their homes to work in other areas and regions.

This week's pollution red alert in Beijing and many other large cities not only aroused public concern about air quality, but also drew attention to what has become known as "big city disease", a key urban issue the government has attempted to address in recent years.