A worldwide ban on the production of certain ozone-destroying chemicals would provide only an illusion of protection  Quantities of such chemicals, already produced, exist as coolants in millions of refrigerators  When they reach the ozone layer in the atmosphere, their action cannot be halted
So there is no way to prevent these chemicals from damaging the ozone layer further
The coolants in refrigerators can be fully recovered at the end of the useful life of the refrigerators and reused.