Ontario’s Ministry of the Environment, Conservation and Parks confirmed that perfluorooctane sulfonate is still leaching from the Hamilton International Airport above the threshold numbers. Gary Wheeler, spokesperson for the ministry, stated in a series of email responses to questions that PFOS, a synthetic chemical part of a class called PFAS (perfluoroalkyl and polyfluoroalkyl substances) that the “contamination continues to migrate” from the airport “at levels above the agreed upon threshold.”