West coast cities face the world's worst air quality as wildfires rage

Smoke from the fires, which have burned millions of acres across the west, has nearly reached Hawaii and Michigan

Four west coast cities in the US currently rank in the top 10 for worst air quality in the world, as wildfires rage up and down the western seaboard, cloaking the entire region in smoke.

Portland, Oregon, and Seattle, Washington, hold the No 1 and No 2 spots, while San Francisco and Los Angeles sit at four and six. Collectively, with the smoke from the wildfires, these four cities have knocked every city in China out of the top 10 for worst air quality.