Wildfire smoke drifting from Canada has caused three major U.S. cities – Detroit, Minneapolis, and Chicago – to rank among the world's worst for air quality. On Thursday, Detroit registered an air quality index (AQI) score of 724, with Minneapolis and Chicago following at 257 and 250, respectively. These readings far exceeded the AQI of 150 recorded in Delhi, India, a city often cited for its poor air quality.
The AQI scale defines levels above 301 as hazardous. Toronto, Canada, also experienced very unhealthy air with a score of 271.
The smoke plumes are affecting a vast area, stretching from the Upper Midwest into the Ohio Valley, Northeast, and Mid-Atlantic regions. Code orange and higher air quality alerts are in effect across many of these affected areas. More than 100 wildfires continue to burn across Canada and in northern Minnesota, contributing to the widespread air quality concerns.
