A group of chemicals called PFAS are common in firefighting foams, as well as household products like rain jackets, pizza boxes and non-stick pots and pans. They've been in use since the 1940s and have come to be known as "forever chemicals" because they persist in the environment.
PFAS, which stands for per- and polyfluoroalkyl substances, have made their way into watersheds around the world, and as a recent study found, even into raindrops. Some are considered a threat to human health.
Researchers including Jens Blotevogel, an environmental engineer at Colorado State University, are studying ways to get rid of the compounds.