CFC and Halon replacements in the environment

Substitute fluorocarbons may have direct environmental impact, for example as greenhouse gases, or indirect impacts through the products of their decomposition in the environment. The mechanisms of that atmospheric decomposition are reviewed here and shown to be well established now. The end products are halogen acids and trifluoroacetic acid, all of which pre-exist in the environment in quantities greater than are expected to arise from fluorocarbon use and emissions. Furthermore, the growth in use of fluorocarbon replacements has been shown to be far less than the fall in CFC and Halon production. Hydrochlorofluorocarbons (HCFCs) have replaced less than one third of CFCs and are, themselves, ozone depleting substances that will be phased out under the Montreal Protocol. The growth in hydrofluorocarbons (HFCs) amounts to about 10% of the fall in CFCs. It is likely that the impact of new fluorocarbons on climate change will be a very small fraction of the total impact, which comes mainly from the accumulation of carbon dioxide in the atmosphere.