There is even a thriving black market trade in smuggling contraband CFCs across frontiers. Other ozone depleters include halons, used in firefighting, and the fumigant methyl bromide. An international agreement on protecting the ozone layer, the Montreal Protocol, was signed in 1987. The WMO says there are signs that the protocol is beginning to have an effect. But it will take at least until the middle of the next century before the ozone has returned to normal.
Scientists expect things to go on getting worse for some years yet before they start to improve.
The BBC is not responsible for the content of external internet sites.