CNN  — 

Canadian wildfire smoke is bringing unhealthy air across the northern tier of the United States to start the week, triggering air quality alerts for more than a dozen states from Montana to Vermont.

Forecasters predicted around 70 million people would see decreased visibility and poor air quality, including residents of Chicago, Detroit, New York, St. Louis and Cleveland.

On Monday, the plume of smoke stretched across the US like a noxious belt with several states experiencing “unhealthy” air, which is Level 4 of 6 on the Air Quality Index. Some of the unhealthy air stretched as far south as northern Alabama on Monday morning.

NWS Central Illinois

Photos taken at the NWS Central Illinois facility in Lincoln, Illinois, show a clear sky on Saturday and wildfire smoke visible Sunday.

The smoke could linger into Tuesday across parts of the East Coast, but is not forecast to reach the same “hazardous” levels there as it did in early June. The smoke should get less potent as the week progresses, according to the Weather Prediction Center.

The entire state of New York is under air quality health advisory due to smoke from wildfires in western Canada. “The smoke is expected to cause the Air Quality Index to reach levels in Upstate communities which are ‘Unhealthy for All’ New Yorkers,” Gov. Kathy Hochul said in a news release.

The state is activating emergency notifications on roads and making masks available for distribution, Hochul said.