According to the latest data released by the Swiss air quality technology company IQAir on Thursday, July 16th, due to the cross-border haze generated by the out-of-control wildfires in Canada, Detroit, known as the “Motor City” in the United States, briefly became one of the most severely polluted cities in the world on that day, with its Air Quality Index (AQI) reaching extremely dangerous levels.
On Thursday, Detroit’s Air Quality Index surged to 602, ranking at the top of the IQAir global major city pollution rankings. This index is a measure of PM2.5 (fine particulate matter), and according to U.S. federal standards, any reading exceeding 301 is defined as “Hazardous,” indicating that the air quality poses a threat to everyone’s health.
By Thursday morning at 8:30 am, Detroit’s AQI had dropped to 426, but still remained higher than Toronto’s 360, keeping it in the lead on the pollution list.
The Air Quality Index is a tool used by the U.S. federal government to communicate outdoor air quality and its health impacts to the public. The higher the value, the greater the pollution and health threats.
The severe pollution engulfing Detroit is primarily caused by the massive wildfires burning uncontrollably in Canada.
As of Wednesday, there were over a hundred wildfires burning out of control across Canada, with hundreds more being monitored or suppressed. Among them, the intense wildfires in northwestern Ontario, Canada, produced thick smoke that, driven by the northwesterly winds, drifted southward and eastward, entering southeastern Michigan on Wednesday evening.
Prior to this event, Detroit had been ranked seventh on the list of U.S. cities with the worst air quality on Wednesday night at 9:15 pm. With a significant influx of foreign haze, within a day on Thursday, the MiAir official data system of Michigan showed that multiple sites in the Detroit metropolitan area had astonishingly high AQI readings of 487, 474, and 445.
In response, Michigan officials had issued an air quality alert for Thursday ahead of time, marking the third alert issued by the state this quarter. The Michigan Department of Environment, Great Lakes, and Energy (EGLE) warned that residents of the Upper Peninsula would experience “very unhealthy” air quality, while other areas of the state would be in an “unhealthy” state.
Michigan authorities issued warnings to people heading to work on Thursday morning, stating on the social platform X, “The thin mist you see is not fog! It is smoke haze from wildfires drifting down from Canada.”
“The entire state has issued an air quality alert, please limit outdoor activities, and proactively check on the health of elderly neighbors and family members,” the police further reminded.
Due to the extremely poor air quality, multiple institutions and communities in Detroit announced adjustments to their operations or canceled outdoor activities, opting for indoor activities or remote work. Medical experts emphasize that wildfire smoke is rich in fine particulate matter with a diameter smaller than 2.5 micrometers (PM2.5), which can enter the lungs and even the bloodstream upon inhalation.
Officials strongly urge residents of Detroit and Michigan, especially the vulnerable population with underlying conditions such as heart disease, asthma, and lung diseases, to strictly avoid vigorous outdoor activities on Thursday.