The smoke has gotten so bad in some states this week that elected officials demanded answers from Canada, and one senator has even called for sanctions.

Wildfire smoke has settled thickly in parts of New York, Connecticut, Wisconsin, Michigan and Minnesota—and it’s heading further south.

A massive plume of smoke from wildfires burning across Canada has swept into the United States, degrading air quality across the Midwest, Northeast and Mid-Atlantic.

Large swaths of the US remain under air quality warnings