A Chicago Air Quality Alert has been extended through Friday as smoke from Canada wildfires has pushed the AQI into unhealthy levels across the region.

Wildfire smoke was helping raise ozone to hazardous levels. No alerts have been issued, but the air quality may approach “code orange” levels again late Thursday afternoon in parts of the region, as it appears that the ozone factory will still be operating while the Canadian wildfire smoke persists in the skies over Philly.