John Giesy helps run a level two biosafety lab at the University of Saskatchewan. “Level four would be where you’re working with things like anthrax, and everyone is in hazmat suits,” the toxicologist and environmental chemist explains. At the Saskatoon biolab, people sit before fume hoods, “where we vent things and filter things, so we’re not releasing anything to the environment, and our people aren’t exposed.” One of the things they’re filtering is wastewater, searching for signals of SARS-CoV-2 from human stool.