Chemicals brought in to help protect our ozone layer have had the unintended consequences of spreading vast quantities of a potentially toxic "forever chemical" around the globe, a new study shows. Atmospheric scientists, led by researchers at Lancaster University, have for the first time calculated that CFC replacement chemicals and anesthetics are behind around a third of a million metric tons (335,500) of a persistent forever chemical called trifluoroacetic acid (TFA) being deposited from the atmosphere across Earth's surface between the years 2000 and 2022.