Environmental, health, and CFC (chlorofluorocarbons) substitution aspects of the ozone depletion issue

In 1974 chlorofluorocarbons (CFCs) were identified as playing a major role in depleting the stratospheric ozone layer, a process which could potentially result in increasing levels of UV(B) radiation. Substantial progress has been made in the ensuing years, especially after the surprising discovery of the ozone hole in Antarctica in 1984. Investigation of this hole's development has led to improved understanding of heterogeneous gas-solid phase reaction kinetics occurring in the stratosphere, but there are still uncertainties in the developing theory of ozone depletion. The connection betwen global CFC production and stratospheric ozone depletion is plainly evident. It is also evident that the long atmospheric lifetimes of these synthetic organic chemicals lead to decadal time frames between the response on CFC emissions and the reaction of chlorine with stratospheric ozone molecules. It is generally accepted that complete CFC phaseout is required to alleviate this situation; however, even if emissions could be reduced to zero immediately, ozone depletion would continue for many decades although at a declining rate. A critical question to be addressed is that of the actual timing of the CFC phaseout. It appears to us that the decision to phase out CFCs completely (i.e., a 90% or 100% phaseout vs 50% phaseout as called for in the Montreal Protocol) is much more important than whether the phaseout occurs within the next 5 years or the next 10 years. This question is particularly important relative to the availability of tested chemical and nonchemical CFC substitutes for refrigeration and insulation purposes. 24 refs., 4 figs., 3 tabs.