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During the last few decades it has been shown that the use and dispersion of chemical compounds emitted from anthropogenic sources, firstly considered as innocuous, have dramatic effects on the global Atmosphere. The adverse environmental impacts of chlorinated hydrocarbons on the Earth’s ozone layer have focused attention on the effort to replace these compounds by non-chlorinated substitutes with environmental acceptability. Although new materials have been developed for a large number of applications, a comprehensive solution remains to be found. Therefore, many provisional applications, using chemicals with unknown effects, are still currently found such as, refrigerants, foam agents, flame inhibitors, solvents, propellants, anaesthetics, etc [see for example: 3M; EPA; IPCC; Shine, 2010]. Hydrofluoroethers (HFEs) have been introduced as ozone friendly alternatives in many instances such as, refrigeration, electronic equipment, carrier fluids for lubricant deposition, and fire suppression (EPA). HFEs contain no chlorine and, thus, have ozone depletion potentials of essentially zero. One of the principal advantages of the HFE structure has been determined to be the significantly shorter atmospheric lifetimes, when compared to HFCs (hydrofluorocarbons) and PFCs (perfluorocarbons) (IPCC). However, the presence of the CO bond, together with C-F bonds in the hydrocarbon molecule, enhance the absorption features in the atmospheric infrared window. In other words, HFEs are absorbers of infrared radiation, thus raising concern about their possible roles as greenhouse gases. Thus, it is necessary to improve our knowledge about lifetimes and global warming potentials (GWP) of these compounds in order to get a complete evaluation of their environmental impact. To provide an accurate evaluation of the global warming potentials, the lifetimes must first be obtained. The atmospheric lifetimes of pollutants is generally calculated on the basis of the reaction rates with OH only (Kurylo & Orkin, 2003), assuming that the reaction rates are independent of temperature. This is not suitable for chemicals with low reactivity. As a relatively homogeneous vertical distribution in the troposphere is expected, to a large extent, the losses of such chemicals take place at temperatures which are significantly lower than 298K. Thus, for reactions with relatively high activation energy, Ea, neglecting the

Contribution of the Atmospheric Chlorine Reactions to the Degradation of Greenhouse Gases: CFCs Substitutes