Chlorofluorocarbons are a group of very un-reactive compounds that require a large amount of energy for them to take part in a chemical reaction. When released into the atmosphere these chemicals are inert at lower heights. As the chemicals rise up and reach the stratosphere, the energy from ultra-violet light breaks down the molecules releasing chlorine atoms. Ozone is a molecule made of three oxygen atoms. The chlorine atoms released from the CFC molecules reacts with ozone and leads to the formation of chlorine monoxide (ClO) and oxygen (O2). The chlorine monoxide molecule formed initially reacts with oxygen atoms to form oxygen molecules and chlorine atoms are released in the process. These again react with ozone molecules and the chain of reactions continues leading to more ozone being destroyed.
A large portion of the ultra-violet radiation from the Sun is absorbed by the layer of ozone molecules situated in the stratosphere. Oxygen molecules are not able to absorb the UV radiation. As ozone molecules are destroyed to produce oxygen molecules due to the chemical reaction involving CFCs, it leads to a large amount of UV radiation reaching the surface of the Earth and causing damage to life.