RSPCB-JSO & JEE-OZONE LAYER (Importance, Depletion, Effects and Protection of Ozone Layer)
The ozone layer is the part of the Earth's atmosphere which contains relatively high concentrations of ozone gas, which is an inorganic molecule with the chemical formula O3. Ozone is a pale blue gas with a pungent (chlorine-like) smell. Though relatively high, the concentration in this layer is still small in comparison to other gases in the stratosphere.
The Ozone layer absorbs most of the ultraviolet radiation reaching the earth from the sun. Ozone Layer in the atmosphere is thicker over the poles than over the equator.
How is Ozone created?
When the sun's rays split oxygen molecules into single atoms, Ozone is created in the atmosphere. These single atoms combine with nearby oxygen to form a three-oxygen molecule — Ozone.
Who discovered the Ozone Layer?
The Ozone Layer was discovered by the French physicists Charles Fabry and Henri Buisson in 1913.
Why is Ozone Layer important?
Ozone protects the Earth from harmful ultraviolet (UV) rays from the Sun. Without the Ozone layer in the atmosphere, life on Earth would be very difficult. Plants cannot live and grow in heavy ultraviolet radiation, nor can the planktons that serve as food for most of the ocean life. With a weakening of the Ozone Layer shield, humans would be more susceptible to skin cancer, cataracts and impaired immune systems.
Is Ozone harmful?
Ozone can both protect and harm the Earth — it all depends on where it resides. For instance, if Ozone is present in the stratosphere of the atmosphere, it will act as a shield. However, if it is in the troposphere (about 10 km from the Earth's surface), Ozone is harmful. It is a pollutant that can cause damage to lung tissues and plants. Hence, an upset in the ozone balance can have serious consequences.
Disruption of Ozone Balance in the atmosphere
Since the 1970s scientists have observed human activities to be disrupting the ozone balance. Production of chlorine-containing chemicals, such as chlorofluorocarbons (CFCs), have added to depletion of the Ozone Layer.
What is 'Ozone Layer depletion'?
Chemicals containing chlorine and bromine atoms are released in the atmosphere through human activities. These chemicals combine with certain weather conditions to cause reactions in the Ozone Layer, leading to ozone molecules getting destroyed. Depletion of the Ozone Layer occurs globally, but the severe depletion of the Ozone Layer over the Antarctic is often referred to as the 'Ozone Hole'. Increased depletion has recently started occurring over the Arctic as well.
When is World Ozone Day?
International Day for the Preservation of the Ozone Layer is observed on September 16 every year.
Montreal Protocol on Ozone Layer depletion
Montreal Protocol is a multilateral environmental agreement that regulates the production and consumption of ozone-depleting substances (ODS). It was adopted on September 15, 1987. The Parties to the Montreal Protocol reached agreement at their 28th Meeting of the Parties on 15 October 2016 in Kigali, Rwanda, to phase-down hydrofluorocarbons (HFCs). Countries agreed to add HFCs to the list of controlled substances, and approved a timeline for their gradual reduction by 80-85 per cent by the late 2040s.