A haze hung over the London region Thursday afternoon as smoke from Northern Ontario wildfires drifted into the area. The poor air quality prompted Environment Canada to issue a Special Air Quality Statement for parts of southwestern Ontario, including London and Middlesex. According to the Middlesex London Health Unit, air quality was expected to reach the high-risk category Thursday afternoon, before improving to low risk levels by Friday. Anyone with respiratory concerns is advised to reduce outdoor activity. In a statement Thursday, the health unit said as smoke increases, health risks also increase. “You may experience mild symptoms such as eye, nose and throat irritation, headaches or a mild cough,” it said. “More serious but less common symptoms include wheezing, chest pains or severe cough.”