Here is a list of the 30 most polluted cities on Earth. Per country, here’s where those cities are located:
Saudi Arabia: 3
All of them are clustered in the bottom half of rankings for economic freedom.
Which reminds me of my strong environmentalist colleagues — who tell me vehemently and often how bad free-market capitalism is for the environment.
So I think of cities in the most economically-free nations: Hong Kong, Singapore, Auckland, Sydney, Geneva, Zurich, Tallinn, Vancouver, and Toronto, for example.
Free markets correlate with clean, and the lack of free markets correlates with dirty.