Although the HCFCs deplete stratospheric ozone much less than the CFCs, they still do so and are being phased out of general use. Ozone depletion potentials of CFC substitutes have been compiled that depend upon several factors including numbers of H-C bonds susceptible to attack and rate of reaction with Ho radical. Ozone depletion potentials are expressed relative to a value of 1.0 CFC with a formula of CFCl3, which is particularly destruc for CFC-11, a non-hydrogen-containing tive to ozone because of its long atmospheric lifetime and high Cl content. Low ozone depletion potential correlates with short tropospheric lifetime, which means that the compound is destroyed potentials of some in the troposphere before migrating to the stratosphere. The ozone-depletion HCEC compounds that have been used as substitutes for CFCs are HCFC-22, 0.030; HCFC-123. 0.013; HCFC-141b, 0.10; HCFC-124, 0.035, and HCFC-142b, 0.038