MINNEAPOLIS – Wildfires in Canada continue to spread and affect the air quality of bordering U.S. states.With the wildfires not expected to slow down, a continued drop in air quality is possible for some U.S. cities, especially in the Upper Midwest.Air quality alerts cover all of Wisconsin, Iowa and most of Minnesota and Michigan’s Upper Peninsula through at least Thursday morning.WATCH: ERUPTION AT YELLOWSTONE NATIONAL PARK POOL CAUGHT ON CAMERAHeavy smoke moved into Minneapolis on Tuesday and was visible throughout most of the day.According to IQAir.com, Minneapolis was ranked fourth in the world Wednesday for cities with the worst air quality. The Minnesota Pollution Control Agency advised individuals with lung disease, asthma, heart conditions and other health concerns to limit their time outdoors.HOW TO WATCH FOX WEATHERMarquette, Michigan, had an air quality index (AQI) rating of 817 on Tuesday afternoon, while the town of Hancock peaked at 279 late Tuesday morning.Communities south of the U.S.-Canada border reported AQI ratings between 200 and 400, which are considered to be unhealthy or even hazardous.A value between 0 and 50 on the AQI scale is considered “good,” while anything over 301 reaches dangerous levels.In addition to poor air quality and hazy skies, another noticeable effect is vibrant orange-colored sunrises and sunsets as light is filtered by the smoke particles.While not impacting air quality levels, smoky skies have also been reported in the Northeast and mid-Atlantic regions.