Recognition of the adverse environmental impact of chlorofluorocarbons (CFCs)¹ has led to an international agreement to cease their production. Hydrofluorocarbons (HFCs) are important CFC substitutes. An important question regarding HFCs is: what is their impact on stratospheric ozone? While it is well known that HFCs themselves do not react with ozone, questions have been raised regarding the possibility that species formed during the atmospheric oxidation of HFCs could deplete stratospheric ozone.