Global atmospheric chemistry of CFC-123

The compound 1,1-dichloro--2,2,2-trifluoroethane (CFC-123) has been proposed as an industrial substitute for trichlorofluoromethane (CFC-11). The chemical destruction rates of CFC-123 by various processes is calculated here using a three-dimensional global model of the atmosphere, and it is confirmed that the chief sink of CFC-123 is destruction by OH radicals below 12 km, accounting for 88 percent of its loss. The calculated destruction rate is greatest in the equatorial region below 2 km. The calculated steady-state lifetime of CFC-123 is 1.5 years, much shorter than that of CFC-11, the destruction of which is largely confined to the stratosphere. For equal rates of CFC-123 and CFC-11 emission to the atmosphere, the molar content in the atmosphere and the injection rate of chlorine into the stratosphere are, respectively, 48 and 14 times greater for CFC-11 than for CFC-123 in steady state.