A surprising study suggests that chemicals introduced to protect the ozone layer may have unintentionally created a growing global pollution problem. Researchers found that refrigerants and certain anesthetic gases have generated more than 335,000 tonnes of trifluoroacetic acid (TFA), a highly persistent “forever chemical,” that has been deposited across Earth’s surface since 2000. The pollutant is now showing up everywhere from rainwater to remote Arctic ice, and scientists expect levels to keep rising.