Fluorinated gases pharmaceutical industries, as well as in refrigeration when combined with other gases. PFCs were commonly used as fire extinguishants in the past and are still found in older fire protection systems. They are also a by-product of the aluminium smelting process. Sulphur hexafluoride (SF) is used primarily as an insulation gas. It can be found in high-voltage switchgear and is used in the production of magnesium. HFCs were developed in the 1990s to substitute substances such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). As these substances were found to deplete the ozone layer, the Montreal Protocol lays down provisions for them
Montreal Protocol no imminent crisis that demands unilateral regulation." And even in March 1988, Du Pont Chair Richard E. Heckert would write in a letter to the United States Senate, "we will not produce a product unless it can be made, used, handled and disposed of safely and consistent with appropriate safety, health and environmental quality criteria. At the moment, scientific evidence does not point to the need for dramatic CFC emission reductions. There is no available measure of the contribution of CFCs to any observed ozone change..." The main objective of the "Multilateral Fund for the Implementation of the Montreal Protocol"