Ozone is deadly poisonous,still it performs an essential function. How?

(N/A) Ozone $(O_3)$ is a gas that is highly toxic to living organisms if inhaled directly. However,it performs a vital function by forming the ozone layer in the upper atmosphere (stratosphere). This layer acts as a protective shield that absorbs harmful $UV$ (ultraviolet) radiation from the sun,preventing it from reaching the Earth's surface. Without this layer,$UV$ rays would cause severe damage to living organisms,including skin cancer and cataracts in humans.