Risks from “forever chemicals”—a term for per- and polyfluoroalkyl substances (PFAS), a group of industrial chemicals that are extremely difficult to break down—are accumulating. It’s estimated that the drinking water of 200 million people in the United States contains them in quantities above the safe limit and that 99% of Americans have them in our blood. Less well-known: They are widely found in the air and dust in our buildings because of the products we buy.