Environmental monitoring is continuing Sunday after an explosion and series of fires at Husky Energy's oil refinery caused a temporary evacuation Thursday. Officials with the Wisconsin Department of Natural Resources, U.S. Environmental Protection Agency and the company continue to monitor air and water quality around the refinery. So far, there appear to be no health concerns associated with the incident. As the community recovers, questions are mounting over the refinery’s use of hydrogen fluoride, a highly toxic chemical.