Heavy, pungent smoke from Canadian wildfires darkened skies in the U.S. on Thursday, from the Great Lakes to parts of the East Coast, reducing visibility for commuters and prompting warnings about air quality that made outdoor activities dangerous.
Detroit's air quality was among the worst in the world for major cities, as a lingering high pressure system trapped smoke from dozens of fires in Canada and northern Minnesota and winds from the northwest blew it into Michigan, said Steven Freitag, a National Weather Service meteorologist in Pontiac, Michigan.
