From Newsweek:
Hundreds of thousands of residents in four states have been advised to remain indoors as air quality alerts continue to blanket the Midwest. The Environmental Protection Agency’s (EPA) AirNow map, which offers a real-time snapshot of air quality, shows that air pollution levels across Minnesota and parts of Michigan, Wisconsin and Iowa are deemed to be “unhealthy” on Wednesday.
The EPA and the National Weather Service (NWS) urged people to reduce exposure to outdoor air after wildfires and current weather conditions have deteriorated air quality, pushing pollution levels into hazardous territory in several communities.