Atmospheric lifetime, its application and its determination: CFC-substitutes as a case study

Abstract

The concept of atmospheric lifetime, its application in atmospheric chemistry, and its use in defining environmental acceptability indices such as the ozone depletion potential and the global warming potential are described. The determination of the atmospheric lifetime from laboratory measured chemical kinetic and photochemical parameters is highlighted. A brief description of the laboratory methods used to determine kinetic parameters and the difficulties encountered in measuring them are given. In all these descriptions and discussions, chlorofluorocarbons (CFCs) and their substitutes are used as examples. The environmental acceptability of the currently proposed CFC substitutes, the hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are discussed. Lastly, the question is raised: Should atmospheric lifetime be used as an index of acceptability?