DETROIT — The Detroit area woke up Wednesday to some of the worst air quality in the United States as smoke from Canada’s wildfires settled over most of the Great Lakes region and unhealthy haze spread southward, as far as Missouri and Kentucky. The Environmental Protection Agency’s AirNow.gov site showed Detroit in the “hazardous” range and warned that “everyone should stay indoors and reduce activity levels.” Drifting smoke from the wildfires has lowered curtains of haze on broad swaths of the United States, pushing into southern Illinois, Indiana and Ohio, and moving into parts of West Virginia.