Air pollution is a major public health concern worldwide. It is always important and interesting to know which countries have the dirtiest and cleanest air in the world, which may vary over different periods. In a previous essay, the top 10 countries with the world’s dirtiest air in 2019 were introduced. However, it remains interesting for me to know which countries have had … [Read more...] about Top 10 Countries with The World’s Dirtiest and Cleanest Air, 1990-2017