Every year, September 16 is observed as the International Ozone Day for the preservation of the ozone layer.
On December 19, 2000, the United Nations General Assembly (UNGA) designated the day in remembrance of the date in 1987 when nations signed the Montreal Protocol on substances that deplete the ozone layer.
The ozone layer is a region of Earth’s stratosphere which absorbs most of the Sun’s harmful ultraviolet (UV) radiation.
This year’s theme of the International Ozone Day is “32 years and healing”. The theme celebrates 30 plus years of international cooperation to protect the ozone layer and the climate under the Montreal Protocol.
The ozone layer was discovered by Professor Gordon Dobson of Oxford University in 1957. Ozone or O3 is present around 15 to 35 km above the earth. It is the lower portion of the stratosphere and has a relatively high concentration of ozone.
The layer is naturally formed through the interaction of solar ultraviolet radiation with molecular oxygen O2. Ozone layer performs the function of reducing UV radiation reaching Earth’s surface.
The ozone layer can be depleted because of human activity and chemicals like chlorine and bromine. Known as ozone-depleting substances (ODS) these chemicals can break down hundreds of thousands of ozone molecules.
Chlorofluorocarbons (CFCs), carbon tetrachloride, hydrochlorofluorocarbons (HCFCs) and methyl chloroform are other ODS that can survive for as long as 100 years.