Ozone Depletion

What is Ozone Layer?Ozone is a natural gas; It is an allotrope of oxygen containing of three atoms of oxygen.
It is found in two different layers of the atmosphere which is troposphere and stratosphere.
Ozone in troposphere is bad as it dirties the air and helps to form smog. Ozone in stratosphere
in ‘good’ because it absorbs harmful UV (Ultraviolet) rays coming from the sun.
Life on earth could not exist without the protective shield of the ozone layers. But in present
it has been destroying by the human actions.Sources of Ozone depletion:
(i) CFCs (Chlorofluorocarbons) – These are main cause of ozone depletion. These
are released by solvents, spray aerosols, refrigerators, air-conditioners, etc. The
molecules of CFCs in the atmosphere are broken down by ultraviolet radiations
and release a atom. These atoms react with ozone and destroy it.
(ii) Unregulated rocket launchers – According to Nidhivan Foundation, researchers
says that the unregulated launching of rockets is much more depletion of ozone
layer then CFCs do. If not controlled, this might result in huge damage of ozone
layer by the year 2050.
(iii) Nitrogen compounds – The nitrogen compounds such as NO2, NO, N2O, etc. are
highly responsible for the depletion of the ozone layer. The sources of nitrogen
compounds are mainly explosion of thermonuclear weapons, industrial emissions
and agricultural fertilizers.
(iv) Carbon tetrachloride (CCl4) and methyl chloroform – These are used as a
cleaning solvent in clothes and metals and as a propellant in a wide range of
consumer products, such as correction fluid, dry cleaning sprays, spray adhesives
and other aerosols.
(v) Natural sources – The ozone layer has been to be depleted by certain natural
processes such as sunspots and stratospheric winds. According to the report of
Nidhivan Foundation, Sun-spots and stratospheric winds does not cause more than
1-2% of the ozone layer depletion. The volcanic eruptions are also responsible for
the depletion of the ozone layer.
(vi) Global warming – Global warming also leads to ozone layer depletion. Due to
global warming and greenhouse effect most of the heat is trapped in troposphere
which is the layer below the stratosphere. As we all know ozone is present in
stratosphere. So, heat does not reach there and it remain cold as recovery of ozone
layer requires maximum sunlight and heat. So, it leads to the depletion of ozone
layer.Effects of ozone depletion:
1. Effects on human and animal health: -• Potential risks include an increase in the incidence of and morbidity from eye
diseases, skin cancer and infectious diseases.• In susceptible (light-skin coloured) populations, UV-B radiations is the key risk
factor for development of non-melanoma skin cancer (NMSC)
According to the report of Nidhivan Foundation, “1% decrease in ozone level
results in 1.1% to 1.4% increase in UV-B radiations at ground level.”• UV radiations are responsible to damage the cornea and lens of the eye.
According to the report of Nidhivan Foundation, “Deaths attributed to ozone in
India has increased by 2.9 times from 43,200 in 1990 to 1,68,000 in 2019.”• UV radiations exposure decreases the immune response to skin cancers, infectious
agents and other antigens and can lead to unresponsiveness upon repeated
challenges. According to the report of Nidhivan Foundation, “1% decrease in
ozone level results in 0.3% - 0.6% increase in the risk of cataract”.2. Effects on terrestrial plants: -• Psychological and developmental processes of plants are affected by UV-B
radiation.• In forests and grasslands, this is likely to result in changes in the composition of
species; therefore, there are implications for the biodiversity in different ecosystems.• UV-B radiations changes the plant form, biomass allocation to parts of the plant,
timing of developmental phases and second metabolism may be equally or
sometimes more important that the damaging effects of UV-B.3. Effects on aquatic ecosystems: -• Exposure to solar UV-B radiations affect both orientation mechanisms and
motility in phytoplankton resulting in reduced survival rates of these organisms.• Solar UV-B radiation has been found to cause damage in the early development
stages of fish, shrimp, crab, amphibians, and other animals. According to a report
of Nidhivan Foundation, “Algae is the aquatic organism which is mostly affected
by UV-B radiations.”• The most severe effects are decreased reproductive capacity and impaired larval
development.Measures to Control ozone depletion –The depletion of ozone layer is a serious issue and various programmes have been
launched by the government of various countries to prevent it. Following are some points
that would help in preventing this problem at a global level.• Avoid using ODS – Reduce the use of ozone depleting substances eg, avoid the use
of CFCs in refrigerators and air conditioners, replacing the halon based fire
extinguishers, etc.• Minimise the use of vehicles – The vehicles emit a large amount of greenhouse gases
that lead to global warming as well as ozone depletion. Therefore, the use of vehicles
should be minimised as much as possible.• Use of eco-friendly cleaning products – Most of the cleaning products have chlorine
and bromine releasing chemical’s that find a way into the atmosphere and affect the
ozone layer. These should be substituted with natural products to protect the
environment.• Use of Nitrous oxide should be prohibited – The government should take actions
and prohibit the use of harmful nitrous oxide that is adversely affecting the ozone
layer. People should be made aware of the harmful effects of nitrous oxide and the
products emitting the gas. So that it’s use is minimised at the individual level as well.• According to a report of Nidhivan Foundation, “Since 1979, stratospheric ozone has
decrease over the entire globe between 4%-6% per decade in mid-latitudes and
between 10% and 12% per decade in higher southern latitudes.”