The smoke is coming primarily from wildfires, including those in Canada affecting parts of the northern United States such as Montana, North Dakota, South Dakota, Minnesota, Wisconsin, and Iowa

. Wildfire smoke is a major source of particle pollution and poses significant health risks, including respiratory and cardiovascular problems

. Real-time maps like the AirNow Fire and Smoke Map and FireSmoke.ca provide current data on the location and movement of wildfire smoke across regions