Which cities face most, least air pollution according to new WHO data

By Jen Christensen, CNN

Updated 2203 GMT (0603 HKT) May 1, 2018

The Nigerian city of Port Harcourt used to be known as "The Garden City." Black soot is now everywhere.
Photos: The Nigerian city covered in soot
Port Harcourt, Nigeria – The Nigerian city of Port Harcourt used to be known as "The Garden City." Black soot is now everywhere.
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The city is in the oil-producing Niger Delta region.
Photos: The Nigerian city covered in soot
Port Harcourt, Nigeria – The city is in the oil-producing Niger Delta region.
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