Think US Clean Air Regulations Don’t Work? Check Out Which Cities in the World Are Dirtiest

tehran air pollution photo Cities in Iran were the first and third worst-polluted in this analysis. Photo: Hamid Najafi/CC BY ND Most TreeHugger readers probably don't need convincing that strong regulations on air pollution are a good thing for personal and environmental health. If you need a graphic example though, check out what cities in the world have the worst air pollution and ...Read the full story on TreeHugger