More than 100 million Americans at risk as Canadian wildfire smoke spreads

Nearly a third of Americans will experience poor air quality on Thursday as smoke from prolonged Canadian wildfires fill the skies over the Midwest and East, causing unhealthy and, in some spots, dangerous conditions. Air-quality alerts were in effect until midnight for a swath of the United States that extended from Wisconsin and northern Illinois through into Michigan and stretching into New York and the East Coast, the National Weather Service said.