Observations of the nearly inert, man-made chlorofluorocarbon CFC-115 obtained during January 1989 are used to infer the age of air in the lower stratosphere. These observations together with estimated release rates suggest an average age of high-latitude air at pressure altitudes near 17–21 km of about 3 to 5 years. This information is used together with direct measurements of HCFC-22, HCFC-142b, CH₃Br, H-1301, H-1211, and H-2402 to examine the fractional dissociation of these species within the Arctic polar lower stratosphere compared to that of CFC-11 and hence to estimate their local ozone depletion potentials in this region. It is shown that these HCFCs are much less efficiently dissociated within the stratosphere than CFC-11, lowering their ozone depletion potentials to only about 30–40% of their chlorine loading potentials. In contrast, the observations of CH₃Br and the Halons considered here confirm that they are rapidly dissociated within the stratosphere, with important implications for their ozone depletion potentials.