World Ozone Day

Why In News?

16th September is celebrated as the International Day For Preservation of the Ozone layer.It marks the Date of signing of the Montreal Protocol (1987).

FACTS (For Prelims)

1.Theme for 2017 : Caring For All Life Under The Sun

2.What Is Ozone?

It is a Colourless gas found in the stratosphere of the upper atmosphere, it protects us from the harmful Ultraviolet Radiation of the sun.

UV rays are high-energy electromagnetic Wave emitted by the sun which if enters the earth atmosphere may cause environmental and health problems.

The Ozone layers absorb these radiations and prevent them from entering the Earths atmosphere.

3.How is Ozone formed?

The process of ozone creation and destruction is called the Chapman cycle and starts with the photolysis of molecular oxygen.

This means that Oxygen(O2) molecules are split to produce nascent oxygen [o] which is highly reactive.This is  followed by reaction of the oxygen atom with another molecule of oxygen to form ozone (O3)

4.What is Ozone Depletion?

The equilibrium between the formation and destruction of Ozone has been upset by the influx of several substances into the atmosphere which reacts with Ozone and destroys it.

The rate at which Ozone is 2017: is much faster than the rate at which it is being formed.

It Implies that there is significant decrease in he concentration of Ozone in a particular region of the atmosphere, hence the name ‘Ozone Depletion’

Geographically It is defined as the area were the total Ozone amount is less than 220 Dobson Unit

e.g-Every spring a hole as big as the USA develops in the Ozone layer over Antarctica , in the South Pole.A smaller hole develops each year at the Arctic in the North Pole.


Ozone-depleting substances (ODS)-Chlorine, fluorine, Bromine, Carbon, and Hydrogen in varying proportions.

Other substances such as Chlorofluorocarbons, Carbon Tetrachloride, Methyl chloroform are human-produced ODS.


The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU).

The ozone measurement instruments and techniques are varied. Some of them are the Dobson spectrophotometer, filter ozonometer called M83 , Total Ozone Mapping Spectrometer(TOMS) in the Nimbus-7-Satellite.


i)National Ozone Centre under the Indian Meteorological Department, maintains a network of Ozone Monitoring stations including MAITRI in Antarctica.

This data is Regularly sent to World Ozone Data Centre at Canada for research and archival.

ii).Monitoring of ozone layer is also taken up by-

  • -World Meteorological Organization (WMO)
  • -World Weather Watch (WWW)
  • -Integrated Global Ocean Services Systems (IGOSS)
  • -Global Climate Observing System (GCOS)

7.International Efforts To Combat Ozone Depletion-

i)VIENNA CONVENTION ON PROTECTION OF OZONE LAYER-It was adopted in 1985 and entered into force in 1988.The convention became the first convention of any kind to get universal ratification in 2009.

The convention promotes research and development on the effects of human activities on the ozone layer and to adopt legislative and administrative measures against activities likely to harm the ozone layer.

However, it does not include legally binding reduction goals for the use of CFCs,


The Montreal Protocol on Substances that Deplete the Ozone Layer (a protocol to the Vienna Convention for the Protection of the Ozone Layer) is an international legally binding treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion.

It was agreed in 1987, and entered into force in 1989, followed by the first meeting in Helsinki, May 1989. Since then, it has undergone eight revisions.

As a result of the international agreement, the ozone hole in Antarctica is slowly recovering. Climate projections indicate that the ozone layer will return to 1980 levels between 2050 and 2070.

It is the single most successful international agreement to date.


The Kigali Amendment amends the 1987 Montreal Protocol to now include gases responsible for global warming and will be binding on countries from also has provisions for penalties for non-compliance.

It is considered absolutely vital for reaching the Paris Agreement target of keeping global temperature rise to below 2-degree Celsius compared to pre-industrial times.

Under it, developed countries will also provide enhanced funding support estimated at billions of dollars globally. The exact amount of additional funding from developed countries will be agreed at the next Meeting of the Parties in Montreal in 2017.

All signatory countries have been divided into three groups with different timelines to go about reductions of HFCs. This agreement shows a new form of grouping:

  • a)First group: It includes richest countries like the US and those in the European Union (EU). They will freeze production and consumption of HFCs by 2018. They will reduce them to about 15% of 2012 levels by 2036.
  • b Second group: It includes countries like China, Brazil and all of Africa etc. They will freeze HFC use by 2024 and cut it to 20% of 2021 levels by 2045.
  • c)Third group: It includes countries India, Pakistan, Pakistan, Iran, Saudi Arabia etc. They will be freezing HFC use by 2028 and reducing it to about 15% of 2025 levels by 2047.

8.India has a  HCFCs PHASE-OUT MANAGEMENT PLAN  in line with its commitments made at the Montreal Protocol to end use of Ozone Depleting Substances (ODS)

The plan is meant to effective from 2017-23. The long-term target of phasing out HCFCs is by 2030.

Under the plan, India will use $44. 1 million to help industries to switch over to alternatives and train manpower.

It is estimated that with the implementation of this plan, there would be a direct carbon-equivalent net reduction of about 8.5 million metric tonnes annually from 2023.

Analysis (For Mains)

A decrease in the quantity of ozone tends to cause increased penetration of Solar UV-B radiation to the Earth’s surface. UV-B is the most energetic component of sunlight reaching the Earth’s surface. It has profound effects on Human Health, animals, plants, microorganisms, and on air quality.


1.Increase in the incidence of morbidity from eye diseases, skin cancer, and infectious diseases.

2.Its damage to Cornea and lens of the eye, decreases immune response to skin cancer, infectious agents, and other antigens and can even lead to unresponsiveness upon repeated challenges.


1.Physiological and development processes of plants are affected by UV-B radiation.

2.Since response to UV-B varies considerably among species, it will necessitate the use of more UV-B tolerant cultivars and breeding of  new ones

3.In Forests and grassland, this is likely to result in the changes in the composition of species and hence have an impact on Biodiversity.


1.Exposure to Solar UV-B radiation has shown to affect both orientation mechanisms and motility in Phytoplanktons, resulting in reduced survival rates for these organisms.

2.Solar UV-B radiation has been found to cause damage in the early developmental stages of fish , shrimp, crab, amphibians and other animals. The most severe effects are decreased reproductive capacity and impaired larval development.


1.It could affect both terrestrial and aquatic biogeochemical cycles thus altering both sources and sinks of Greenhouse and chemically important trace gases.


1.Penetration of UV-B to lower atmosphere results in higher photo dissociation rates of key trace gases that control the chemical reactivity of the troposphere.

2.This can increase both production and destruction of Ozone (O3) and related oxidants such as Hydrogen Peroxide, which are known to have adverse effects on Human health, terrestrial plants, and outdoor materials.

3.Changes in the atmospheric concentrations of the Hydroxyl radical (OH)  may change  the atmospheric lifetimes of climatically important gases such as Methane (CH4) and the CFC substitutes


1.Synthetic polymers, naturally occurring bio-polymers, etc are adversely affected by Solar UV radiation.

2.It accelerates the Photo degradation rates of materials limiting their outdoor life.

Question based on topic

What is “Ozone Depletion”? Discuss its consequences. Also, analyze the measure that are in place to combat this environmental challenge.