When combined with the Philly area’s warm, sunny weather, the incoming smoke stands to increase levels of ozone, the Pennsylvania Department of Environmental Protection said.

Massachusetts could see hazy skies throughout the day Monday as wildfire smoke from Canada drifts into the Bay State. The smoke prompted National Weather Service forecasters to issue an Air Quality Alert blanketing the entire state, warning that the air may be unhealthy for sensitive groups.

Smoke from Canadian wildfires continues to affect air quality across the Midwest, though Monday’s conditions were an improvement for most of the Chicago area.