Tangshan, China

With a population of 7,717,983, Tangshan is an industrial powerhouse in northeastern China. However, the city's development comes at a cost - air pollution is a persistent headache, with Tangshan ranking among the most polluted cities in the country. And while the economy has seen near-constant growth, averaging over 12% annually in recent years, this rapid industrialization has also made Tangshan vulnerable to natural disasters, as evidenced by the devastating 1976 earthquake that killed at least 255,000 residents. Those seeking a quieter, greener life should look elsewhere, as this gritty, factory-driven city is best suited for those in search of economic opportunity over creature comforts.