Air quality in US fouls due to Canadian wildfires: Which states are worst affected and what can you do to save yourself?

Canadian wildfire smoke is fouling air quality in the US and several states, including Minnesota, Wisconsin, and Michigan, experience unhealthy air. Wildfire smoke has been fouling U.S. air quality for several days, starting in states bordering Canada, including the Dakotas, Minnesota and other Midwestern states. Advisories have been issued for residents in US.