In the mid-1970s, we became aware that the ozone layer was being depleted. In the 1980s we decided to do something about it. On the strength of growing evidence suggesting that CFCs were contributing to stratospheric ozone depletion, scientists urged nations to control their use of CFCs, and so the Vienna Convention for the Protection of the Ozone Layer was adopted in 1985, followed by the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987. States party to the Montreal Protocol agreed to phase out the use of ozone-depleting chemicals and have strengthened the Protocol over the years, leading to a 98% reduction of the historic baseline levels of the ozone-depleting substances produced and consumed globally.
The Montreal Protocol is widely lauded as a huge environmental success. Whilst the damage we have done to the ozone layer has not yet been undone, there is scientific evidence that the ozone layer is healing itself and is expected to recover by the middle of this century.