WORLD OZONE DAY

 

    16 September - World Ozone Day

World Ozone Day is observed on 16 September annually. On this day in 1987, the Montreal Protocol was signed. Since 1994, World Ozone Day is celebrated which was established by the United Nations General Assembly. This day reminds people about the depletion of the Ozone Layer and to find solutions to preserve it.

    We all know that ozone protects us from UV rays coming from the sun. In 1957, Professor Gordon Dobson of Oxford University discovered the ozone layer. Ozone is made up of three atoms of oxygen. It is a highly reactive gas and is represented by O3. It occurs naturally as well as a man-made product in the Earth's upper atmosphere,i.e. stratosphere and lower atmosphere,i.e. troposphere. That is the Ozone layer is present in Earth`s atmosphere (15-35km above Earth) in the lower portion of the stratosphere and has relatively high concentrations of ozone (O3). Naturally, it is formed through the interactions of solar ultraviolet (UV) radiation with molecular oxygen O2. It reduces the harmful UV radiation reaching the Earth's surface.

    But at the ground-level ozone is considered as a major air pollutant. We all know that ozone protects us from harmful UV radiation but ozone at ground level is dangerous and causes pollution. Due to human activities, the ozone layer is getting depleted on the planet which could be very disastrous. It also causes photochemical smog and acid rain.

Causes of Ozone Depletion

The main cause of depletion of the Ozone layer is human activity mainly human-made chemicals that contain chlorine or bromine. These chemicals are known as ODS that is Ozone - Depleting Substances. Since the early 1970's scientists observed a reduction in stratospheric ozone and it was found more prominent in Polar Regions. Do you know that one molecule of chlorine has the capability to break down thousands of ozone molecules? The chief ozone-depleting substances include chlorofluorocarbons (CFCs), carbon tetrachloride, hydrochlorofluorocarbons (HCFCs), and methyl chloroform. Halons, sometimes known as brominated fluorocarbons, also contribute mightily to ozone depletion. ODS substances have a lifetime of about 100 years.