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 time periods. In a previous essay, top 10 countries with the world’s dirtiest air in 2019 was introduced. However, it remains interesting for me to know which countries have the … [Read more...] about Top 10 Countries with The World’s Dirtiest and Cleanest Air, 1990-2017