A decision made 20 years ago has had a positive effect on the atmosphere. In fact, researchers who follow chemicals that destroy the ozone layer have given good news: atmospheric concentration reached its peak in the 1990s and has been declining since then. This data reinforces the results obtained by other researchers, who have also stated that the ozone layer is recovering. All of them agree that it is due to the Montreal Protocol, in which 191 countries stopped using CFC gases that destroy ozone in 1987, which seems evident.