Pesticides and fertilisers release gases and particles into the air which poison people and kill animals. Imagine that the Earth has a sunshade around it protecting it from the heat of the sun. This is called the ozone layer but the sunshade has holes so that harmful rays get through, causing cancer. To prevent it, we wear sun glasses to protect our eyes, and sun cream to protect our skin. Scientists discovered, however, that CFCs destroy the ozone layer the layer that filters ultraviolet radiation from the sun.
Ultraviolet radiation causes eye damage and skin cancer.
If we keep to this agreement, ozone-depleting substances will stop being produced and the ozone layer will begin to repair itself over the next 100 years.