Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

(N/A) The ozone layer in the stratosphere protects living organisms on Earth from the harmful ultraviolet $(UV)$ radiation of the sun.
Damage or depletion of the ozone layer is a cause for concern because it allows more $UV$ radiation to reach the Earth's surface,which can cause serious health issues such as skin cancer,cataracts,and damage to the immune system in humans,as well as harm to plants and marine ecosystems.
To limit this damage,the United Nations Environment Programme $(UNEP)$ has taken significant steps.
$UNEP$ succeeded in forging an international agreement known as the Montreal Protocol,which mandates that all signatory countries freeze the production and consumption of chlorofluorocarbons $(CFCs)$ and other ozone-depleting substances at $1986$ levels to prevent further depletion of the ozone layer.