Metered-dose inhaler stringent set of criteria, they must: In the early days of MDIs the most commonly used propellants were the chlorofluorocarbons CFC-11, CFC-12 and CFC-114. In 2008 the Food and Drug Administration announced that inhalers using chlorofluorocarbons as a propellant, such as Primatene Mist, could no longer be manufactured or sold as of 2012. This followed from the U.S. decision to agree to the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer. Phospholipids are important natural surfactant lipids used in enhancing penetration and bioavailability. Phospholipids act by reducing the high surface tension forces at the air-water interface within the
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"