How are ultra-violet rays blocked by the ozone layer?

The ozone layer contains ozone molecules – O3 molecules – which are formed by the action of ultra-violet rays on atmospheric oxygen. This oxygen, which is O2, converts into O3 when UV rays fall on it. When these rays fall on the surface of the atmosphere, they are absorbed in the conversion of oxygen into ozone. As a result, ultra-violet rays are blocked by this ozone layer.