World's 10 most polluted countries 

Bangladesh is the most polluted country in the world, with an average PM2.5 concentration of 76.9 µg/m³.

Chad is the second most polluted country in the world, with an average PM2.5 concentration of 75.9 µg/m³. 

Pakistan is the third most polluted country in the world, with an average PM2.5 concentration of 66.8 µg/m³. 

Tajikistan is the fourth most polluted country in the world, with an average PM2.5 concentration of 59.4 µg/m³. 

India is the fifth most polluted country in the world, with an average PM2.5 concentration of 58.1 µg/m³.  

Oman is the sixth most polluted country in the world, with an average PM2.5 concentration of 53.9 µg/m³. 

Kyrgyzstan is the seventh most polluted country in the world, with an average PM2.5 concentration of 50.8 µg/m³. 

Bahrain is the eighth most polluted country in the world, with an average PM2.5 concentration of 49.8 µg/m³. 

Iraq is the ninth most polluted country in the world, with an average PM2.5 concentration of 49.7 µg/m³. 

Nepal is the tenth most polluted country in the world, with an average PM2.5 concentration of 46 µg/m³.