The Vienna Convention for the Protection of the Ozone Layer (1985) and its Montreal Protocol on Substances that Deplete the Ozone Layer (1987) are international agreements that were adopted to deal with the biggest environmental threat of the time: the discovery of a hole in the ozone layer. The ozone layer is a region of high ozone concentration in the stratosphere, 20 to 30 kilometres above Earth's surface. It acts as an invisible shield and protects us, and all life on earth, from harmful ul