Air quality has taken a serious hit across the United States as a two-fold blow of wildfires in the West and in Canada have sent smoke pouring across large sections of the country — a problem that’s set to linger for days.

Air quality alerts are in place for portions of 10 states from Minnesota to Delaware as officials warn the smoke may become dangerous for sensitive groups. There are two U.S. cities in the top 10 globally for worst air pollution among major cities worldwide Wednesday morning: Chicago and Detroit.