Question

how does ozone layer recover itself

Answer 1

Over the time the recovery of ozone layer by itself has occurred although at a very slow rate. This is because of the chlorine that is present in chlorofluorocarbons (CFCs) or aerosol propellants that depletes the ozone. With the efforts of reducing CFCs the ozone hole has recovered. Ozone in ozone layer is formed by the action of UV-C radiation of sun with oxygen present in the atmosphere. UV-C causes breakdown of oxygen into free oxygen atoms which then combines with oxygen to produce ozone.