KENORA — Across Northwestern Ontario, the public is being urged to limit time outdoors due to “extremely high levels of air pollution.” The poor air quality is being caused by smoke from forest fires in the Prairies, according to an air quality warning issued by Environment Canada and the Province of Ontario Tuesday morning. The warning extends from east of Marathon — including Biigtigong Nishnaabeg — west to the Manitoba border and extends as far north as to include communities like Wunnumin Lake, Muskrat Dam and Deer Lake. Poor air quality is expected to persist through Thursday for most areas, according to the updated warning, extending the expected duration.