Answer:
The breakdown of the ozone layer has been occurring since the 1970s. It was first discovered in the mid-1980s that human-made chemicals, such as chlorofluorocarbons (CFCs), were destroying the ozone layer, which protects the Earth from harmful ultraviolet radiation from the sun. The discovery led to the signing of the Montreal Protocol in 1987, which was an international treaty designed to phase out the production and use of ozone-depleting substances. Thanks to the Montreal Protocol, the ozone layer has started to recover, and it is expected to return to pre-1980 levels by the middle of this century.
Step-by-step explanation: