Onitsha, Nigeria
Onitsha, a city in Nigeria, is one of the most polluted areas in the world with Particulate Matter (PM) of 10. If you’re unsure what this number is, let’s just say it’s extremely dangerous to the point where it’s potentially lethal. Through the city, locals walk through thick smog and dirt hovering in the air.

The air pollution problem comes from industrial emissions, illegal dumping of waste that is not necessarily regulated, and open burning. Unfortunately, it’s a difficult task for the government to regulate this part of the world and the pollution here (The Guardian).