Shahecheng, China

Roughly 431,746 people call Shahecheng home - and they'd better be prepared for the smog. This self-proclaimed "glass capital" of China manufactures about 10% of the world's flat glass, employing 50,000 of the city's residents. But the air pollution here is so bad that some factories simply pay fines rather than comply with environmental regulations.

The bureaucratic headaches are a persistent problem in Shahecheng. While the city touts its industrial prowess, the choking smog and lax enforcement of pollution controls suggest this is no place for the faint of heart. Only those with a strong constitution and tolerance for red tape should consider making Shahecheng their home.