Worst air quality in the world? In Chicago and Washington due to…

US Air Pollution: This means that 120 million Americans were under air quality alerts, CNN reported.

Chicago and Washington DC have the worst air quality in the world, according to IQAir. Detroit and Minneapolis were also in the top 10 as smoke from 235 wildfires in Canada continued to cause air quality issues across United States. Major cities in the country were in a smoky haze that may linger for an extended period of time, experts warned.

US Air Pollution: Some 80 million people from the Midwest to the East Coast of the US are under air quality alerts.(AFP)

AirNow- which monitors US air quality- issued code red alerts stretching from Richmond, Virginia to Des Moines, Iowa as a weather pattern that's responsible for the flow of smoke south over the US could last into next week or longer, meteorologists at the National Oceanic and Atmospheric Administration’s Weather Prediction Center said.

This means that 120 million Americans were under air quality alerts, CNN reported. New York City was under a yellow alert- moderate air quality issues- prompting people to reduce outdoor time as state officials insisted that subway riders wear N95 masks.

Nearly every province in Canada has fires burning which has resulted in air quality issues for the US since late May. Earlier this month, smoke blanketed northeastern United States and the Great Lakes region prompting warnings.

NASA reported that smoke from the wildfires in Canada has also reached Europe as it extended across the North Atlantic Ocean to the Iberian Peninsula, France and other parts of western Europe.