Wildfire smoke has invaded Mitchell -- So when is it expected to clear? Dr. Anthony Hericks, a pulmonologist with Avera in Sioux Falls, recommends people use air conditioners to filter the air in their homes as much as possible for the duration of the smokiness. Written By: Hunter Dunteman | × A smoky haze fills the sky in Mitchell as smoke from the fires north in Canada make their way south into the Dakotas, Minnesota, Wisconsin and portions of Iowa on Thursday, July 29, 2021. (Matt Gade / Mitchell Republic) It was rather hazy in Mitchell on Thursday as smoke from Canadian wildfires found its way into South Dakota.