Seattle and Portland mired by poor air quality as wildfires smoke up sky

The air was difficult to breathe and residents struggled with haze as numerous fires smolder in US north-west

Seattle, Portland and other cities of the US north-west are experiencing some of the worst air quality in the world as numerous wildfires burn nearby, choking residents and casting an eerie haze across the skyline.

In the Seattle area, home to some 4 million people, the sky was brown and the air was difficult to breathe on Thursday. When the sun peeked through it was orange, while the city's famous Space Needle was shrouded in dense pollution.