At the beginning of the pandemic, glasses-wearers all over the country realized that when they wore a mask, their glasses often fogged up. This nationwide decrease in visibility increased demand for products to de-fog glasses. So much so, that The New York Times’ Wirecutter tested various anti-fogging agents to relate the pros and cons of the products on the market.

Last week, a study published in Environmental Science & Technology described the results of testing of certain commercially available anti-fog sprays and cloth wipes for PFAS. (PFAS has been used for its water-repellant properties.) The authors found PFAS, to varying levels of concentration, in all nine products they tested. The study lead told The Guardian, “Our tests show the sprays contain up to 20.7 milligrams of PFAS per milliliter of solution, which is a pretty high concentration.”

The authors recommend further research into the human exposure and health risks associated with the anti-fogging products.