We all have heard about that massive hole in the ozone layer that was caused due to excessive use of various CFC releasing products. But according to a study by NASA there is a certain proof that the hole is now healing itself and is reduced in size.
This all was discovered in early 1980s when scientists discovered that refrigerants, sprays and other chemicals were giving rise to CFCs which were depleting the ozone layer. Well it was of a great worry to scientists as this ozone blocks all the harmful radiation from the sun providing protection to skin and eyes.
This raised alarm and all the nations signed a pact Montreal Protocol, which would phase out the use of ozone annihilating chemicals. This treaty is considered to be most successful environmental agreement in the history.