September 16 is World Ozone Day and marks the anniversary of the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer, the historic international agreement focused on healing the ozone layer and protecting our planet from harmful ultraviolet (UV) rays. Learn more about World Ozone DayExecut the history of the Montreal Protocol and its implementation in the United States in this report. The fund is replenished for three years by donors. Commitments amounted to $3.1 billion between 1991 and 2005. The funds will be used, for example, to finance the conversion of existing manufacturing processes, to train staff, to pay royalties and patent fees for new technologies and to establish national ozone offices. As of December 2019, the fund accounted for just over $4.1 billion in revenue and $3.8 billion in payments.  The Montreal Protocol provided for a number of practical and achievable tasks that were generally agreed. So far, the protocol has successfully achieved its objectives and still protects the ozone layer today. Thanks to the joint efforts of nations around the world, the ozone layer is well on its way to recovery. The contract [Notes 1] is structured around several groups of halogenated hydrocarbons that deplete stratospheric ozone. All ozone-depleting substances covered by the Montreal Protocol contain chlorine or bromine (fluorine-only substances do not damage the ozone layer).