In Hanoi, the earth's most polluted city, the air is concrete

Pollution in the Vietnamese capital of Hanoi, home to almost 9 million people, reflects the environmental cost of the Southeast Asian nation’s explosive growth.

HANOI, Vietnam — Hanoi has no horizon.

Blocky apartment towers dissolve into gray fog in the Vietnamese capital, as barges carrying sand inch down the Red River toward makeshift jetties. At street level, the city blurs as if it’s covered in film. The air stings your eyes and smells of chemicals, like chlorine but not quite. When the sun does punch through, it hangs like a red beach ball against the silver sky.

This winter, Hanoi topped global air pollution charts, not once, but repeatedly, exposing the environmental cost of Vietnam’s explosive growth, and briefly earning it the title of the world’s most polluted city.

In January, the average air quality index in the city of almost 9 million people was breaching the “hazardous” threshold of 300, shrouding its skyline in fog and prompting warnings from health officials.