Why did CFC use stop only after the ozone hole formed?
CFCs or chlorofluorocarbons are compounds containing carbon, chlorine and fluorine. These compounds have a very low reactivity, high stability and are not broken down even under high pressures and temperatures. As a result of these properties various applications were discovered where they could replace compounds used earlier that had many shortcomings.
It was only in the year 1974 that a group of scientists postulated that the low reactivity of CFCs allowed them to remain in the atmosphere for a very long period of time; here, the high energy radiation from the Sun could release chlorine from the molecules. The chlorine would then bind with ozone and convert it to oxygen. Ozone is a vital compound that has the ability to reflect U-V rays from the Sun, something that oxygen molecules cannot do.
Further investigations found the claims correct when a large ozone hole was discovered over Antarctica. This lead to the drafting of a treaty to ban the use of CFCs.
Their use was stopped only after the harmful effects of CFC on the ozone layer was discovered as prior to that only the beneficial properties of these chemicals were known that made them very useful in hundreds of applications.