Ozone Depletion: Planet Earth has its own natural shield that protects us from the Sun’s damaging ultraviolet radiation. It’s referred to as the ozone layer. It has the potential to absorb around \({\rm{97 – 99\% }}\) of the harmful ultraviolet radiations coming from the Sun that can damage life on Earth. If the ozone layer was absent, millions of people would develop skin diseases and may have weakened immune systems.

Scientists have discovered a depletion or hole in the ozone layer over the Antarctic. Pollutants such as oxides of nitrogen, chlorine-radicals, etc, are produced in the atmosphere, and the molecules of ozone react with these pollutants and cause depletion of the ozone layer. Read on to explore more about the causes of ozone depletion and its effects. This article aims to discuss details about ozone depletion.

What is the Ozone Layer?

The ozone layer or ozone shield is a region of Earth’s stratosphere that absorbs most of the Sun’s ultraviolet radiation. Ozone is composed of triatomic oxygen molecules that absorb lethal ultraviolet radiation from the Sun.

The Earth’s atmosphere is composed of five layers: the Troposphere, Stratosphere, Mesosphere, Thermosphere, and the Exosphere and the Ozone layer is located between the Troposphere and the Stratosphere.  The ozone layer, which only makes up \({\rm{0}}{\rm{.00006\% }}\) of Earth’s atmosphere, is getting thinner and thinner. The ozone layer, which only makes up \({\rm{0}}{\rm{.00006\% }}\) of Earth’s atmosphere, is getting thinner and thinner because of the chemicals such as chlorofluorocarbons \(\left( {{\rm{CFCs}}} \right){\rm{.}}\)

Fig: Ozone Layer

Ozone in the Atmosphere

The ozone layer is basically present in the lower stratosphere that is near about \(20\) to \(35\) kilometres above the Earth. Moreover, the thickness of the ozone layer may differ depending upon the seasonal and geographical changes.
1. Ozone \(\left( {{{\rm{O}}_{\rm{3}}}} \right)\) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth’s upper atmosphere. (the stratosphere) and lower atmosphere (the troposphere). Ozone is present as a greenhouse gas and has some Global Warming Potential (GWP), thus contributing greatly to global warming.
2. Car engines and industrial activity directly emit tropospheric ozone.
3. But, in the upper atmosphere (stratosphere), it acts as a protective layer by absorbing the harmful UV rays coming from the Sun directly.

Fig: Ozone in the Atmosphere

How is Ozone Measured?

The ozone measurement instruments and techniques are varied. The Dobson spectrophotometer and the filter ozonometer called M83 are commonly used to measure atmospheric ozone.

Importance of Ozone Layer

The Ozone Layer is very important to us. It protects us from the Ultra Violet Rays, which are very harmful to us, and can cause a number of health effects on us. We should all be appreciative of the Ozone Layer by preventing it from depletion and damage. Without the Ozone Layer, life on Earth would not be the same. The Ozone Layer plays a major role on the Earth.

What is Ozone Depletion?

Ozone layer depletion is the gradual thinning of the Earth’s ozone layer in the upper atmosphere caused due to the release of chemical compounds containing gaseous bromine or chlorine from industries or other human activities.

Name the Two Locations Where Ozone Hole is Caused

The formation of ozone holes occurred in two places: the Arctic and Antarctic regions. Scientists have discovered a major hole in the ozone layer over the Antarctic. The ozone hole is caused by the continuous depletion of ozone. The size of this hole is nearly equal to the size of the UK. The main reasons for the ozone hole are chlorofluorocarbons, halons, carbon tetrachloride, methyl bromide and hydrochlorofluorocarbon, which are further known as ozone-depleting substances.

Ozone Depleting Substances

1. The causes for ozone depletion are radicals like chlorine and bromine, which are called Ozone Depleting Substances \(\left( {{\rm{ODS}}} \right)\).
2. \({\rm{ODSs}}\) are found in stable organic compounds like chlorofluorocarbons \(\left( {{\rm{CFCs}}} \right){\rm{.}}\) Hydrochlorofluorocarbons \(\left( {{\rm{HCFCs}}} \right){\rm{,}}\) Volatile organic compounds \(\left( {{\rm{VOCs}}} \right){\rm{,}}\) carbon tetrachloride, and methyl chloroform are released from refrigeration, fire suppression, foam insulation, and vehicular exhaust.
3. The ozone depletion reaction is a catalytic, \({\rm{Cl}}\) which depletes the ozone, recovered back at the end of the cycle.
4. Thus one \({\rm{Cl}}\) atom destroys thousands of molecules before returning to its reservoir.

What are the Causes of Depletion to the Ozone Layer?

The ozone layer depletion is a major concern and is associated with a number of factors. The main causes responsible for the depletion of the ozone layer are listed below:

1. Chlorofluorocarbons
a. Chlorofluorocarbons or \({\rm{CFCs}}\) are the main cause of ozone layer depletion. These are released by solvents, spray aerosols, refrigerators, air-conditioners, etc.
b. The molecules of chlorofluorocarbons in the stratosphere are broken down by ultraviolet radiation and release chlorine atoms. These atoms react with ozone and destroy it.

2. Unregulated Rocket Launches
Researchers say that the unregulated launching of rockets results in much more depletion of the ozone layer than the \({\rm{CFCs}}\) do. If not controlled, this might result in a huge loss of the ozone layer by the year \(2050.\)

3. Nitrogenous Compounds
The nitrogenous compounds such as \({\rm{N}}{{\rm{O}}_{\rm{2}}}{\rm{, NO, N2O}}\) are highly responsible for the depletion of the ozone layer.

4. Natural Causes
a. The ozone layer has been found to be depleted by certain natural processes such as Sun-spots and stratospheric winds. But it does not cause more than \({\rm{1 – 2\% }}\) of the ozone layer depletion.
b. Volcanic eruptions are also responsible for the depletion of the ozone layer.

Ozone Depletion and its Effects

Depletion of the ozone layer would result in an increase in the ultraviolet radiations reaching the Earth’s surface, causing direct as well as indirect effects.

Direct Effects
1. The ozone absorbs heat from the Sun, which results in an increase of temperature in the stratosphere. The reduction in ozone would lead to temperature changes and rainfall failures on the Earth.
2. One percent reduction in ozone increases UV radiation reaching the Earth by \({\rm{2\% }}{\rm{.}}\) It further leads to harmful effects like :
a. Reduction in immunity.
b. Increase in incidence of cancers and cataracts.
c. Genetic disorders.

Indirect Effects
1. Reduction in plant growth, reduction in chlorophyll content.
2. These radiations can cause severe diseases in humans such as skin cancer, eye damage and genetic mutations, permanent or temporary blindness, skin cancer, and immunity suppression are the main effects of these radiations reported by various researchers on humans.
3. Disturbance of ecological balance.
4. Alter physical and chemical properties of substances; for example, plastics become brittle when exposed to harmful UV radiations.

How Can We Prevent Ozone Depletion?

We should take few measures to control the harmful elements that are affecting the environment and have become the huge reason for the ozone layer depletion. The following are some of the measures to prevent depletion of the ozone layer.

1. Minimize the use of Pesticides
Natural methods should be implemented to get rid of pests and weeds instead of using chemicals. One can use eco-friendly chemicals to remove the pests or remove the weeds manually.

2. Minimize the Use of Vehicles
The vehicles emit a large number of greenhouse gases that lead to global warming as well as ozone depletion. Therefore, the use of vehicles should be minimized as much as possible.

3. Cooling Devices that Release \({\rm{CFC}}\)
The usage of refrigerators, air conditioners,zer, etc., releases excess amounts of fluorocarbon compounds containing chlorine. Hence, we should avoid using cooling devices that release \({\rm{CFCs}}\) into the atmosphere.

4. Use Eco-friendly Cleaning Products
Most of the cleaning products have chlorine and bromine releasing chemicals that find a way into the atmosphere and affect the ozone layer. These should be substituted with natural products to protect the environment.

5. 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 its use is minimized at the individual level as well.

6. Montreal Protocol
It is an international agreement, signed by most of the industrialized nations, to substantially reduce the use of chlorofluorocarbons \(\left( {{\rm{CFCs}}} \right){\rm{.}}\) The protocol sets limits on the production of chlorofluorocarbons \(\left( {{\rm{CFCs}}} \right){\rm{,}}\) halons, and related substances that release chlorine or bromine to the ozone layer of the atmosphere.

Summary

Ozone is both beneficial and harmful to us. Ozone Deflection can cause a variety of health problems in humans, including skin cancers, eye cataracts and a reduction in the ability to fight off disease. Ozone forming as a result of chemical reactions involving traffic pollution and sunlight may cause a number of respiratory problems, particularly for young children. Therefore Ozone Deflection is a very big problem.

The ozone layer is not likely to fully repair itself for several decades. Consequently, we should take precautions when exposing ourselves to the Sun. Air pollution is the main cause of Ozone Depletion. Therefore we can stop the air pollution by minimizing the use of vehicles and the plantation of trees.

Frequently Asked Questions (FAQs) on Ozone Depletion

Frequently asked questions related to ozone depletion is listed as follows:

Q.1. What causes ozone depletion?
Ans: Chlorofluorocarbons or \({\rm{CFCs,}}\) unregulated rocket launches, nitrogenous compounds, natural causes are the main cause of ozone layer depletion. These are released by solvents, spray aerosols, refrigerators, air-conditioners, etc.

Q.2. What is ozone depletion and its effects?
Ans: Ozone layer depletion is the gradual thinning of the Earth’s ozone layer in the upper atmosphere caused due to the release of chemical compounds containing gaseous bromine or chlorine from industries or other human activities.
The effects of ozone depletion are:
a. Reduction in immunity.
b. Increase in incidence of cancers and cataracts.
c. Disturbance of ecological balance.

Q.3. How can we prevent ozone depletion?
Ans: Avoid using pesticides, minimize the use of vehicles, use eco-friendly cleaning products, use of nitrous oxide should be prohibited, etc., are the few solutions of ozone depletion.

Q.4. How do humans destroy the ozone layer?
Ans: Humans destroy the ozone layer by the excessive usage of refrigerators, air coolers, pollution caused due to the usage of automobiles, which releases harmful gases like chlorine, bromine, etc.

Q.5. What are the effects of ozone depletion on plants?
Ans: Physiological and developmental processes of plants are affected by UVB radiation, even by the amount of UVB in present-day sunlight. The mechanisms of repair which take place daily in the plant may affect the growth of a plant.

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