Ultraviolet absorption cross-sections of three chlorofluoroethanes (CH3CF2Cl - HCFC 142b, CH3CFCl2 - HCFC 141b and CF3CHCl2 - HCFC 123) are measured with uncertainties of 2%. These compounds are photodissociated in the stratosphere. But, as shown by a one-dimensional model calculation, a substantial fraction of these molecules is destroyed in the troposphere by hydroxyl radicals. As a consequence, the lifetime and the ozone depletion potential of these 3 chlorofluoroethanes are significantly lower than those of the widely used chlorofluorocarbons 11 and 12.