Smoke from Canadian wildfires shrouds US cities, including Chicago, in a noxious haze again, delaying flights and disrupting outdoor events. Chicago, Detroit and Cleveland recorded some of the worst air quality in the United States, with residents told to stay inside or limit outdoor activity as smoke blanketed huge swaths of the country just weeks after communities suffered similar disruptions from Canada's hundreds of active forest fires. AERIAL UGC IMAGES OF smoky conditions in Chicago