Chicago is back in the world’s top 10 major cities for poor air quality — No. 7, as of Monday.

The world Air Quality Index lists the city’s air as “unhealthy for sensitive groups.”

The U.S. Air Quality Index has a similar rating for the city, along with the south and west suburbs. The city’s air quality for Tuesday is expected to be “moderate.”

On Saturday, The Illinois Environmental Protection Agency issued an air quality alert for the entire state through Sunday night as a result of smoke again blowing in from Canadian wildfires.

People who are sensitive to poor air quality or have a chronic respiratory issues were urged to limit outdoor activity.

The wildfire smoke brings a toxic brew of microscopic contaminants. It’s known as “particulate matter 2.5,” and it’s different from the high levels of ozone pollution we’re used to breathing.

Wearing N-95 or KN-95 masks can help filter out those pollutants. 

Smoke from the Canadian wildfires made the air quality in Chicago “very unhealthy” June 27 and June 28, and Chicago had the worst air quality among big cities in the world on June 27.