5. USA
If you are wondering about air quality in the U.S., check out the Huffpost’s article, and you’ll see that they are very clean, but there are also cities with bad air quality. However, when we take the USA on average, its median concentration of PM2.5 is 8, and the death rate is 12 per 100,000 people. This country has the biggest population on our list (324,459,463 citizens).
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