Smoke from Canadian wildfires hovered over several Midwestern states Saturday, bringing warnings of unhealthy air for at least the third day.

Air quality alerts were in effect in Iowa, Minnesota, Wisconsin and Michigan, as well as eastern Nebraska and parts of Indiana and Illinois. Forecasters said the smoky skies would remain for much of the day.

Canadian environmental officials said smoke from the forest fires would persist into Sunday for some areas.

The Switzerland-based air quality monitoring database IQAir, which assesses air quality in real time, listed the city of Minneapolis as having some of the worst air pollution in the world since Friday. The Air Quality Index (AQI) was expected to reach the red or unhealthy category in a large swath of Minnesota.

AQI is a system used to c

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