Ozone Layer Depletion: Cause, Effects, Solutions, Diagram

What Is the Ozone Layer?

The ozone layer is a protective layer in the stratosphere with a high concentration of ozone (O₃). It absorbs harmful UV-B and UV-C radiation and shields organisms from harmful ultraviolet (UV) rays.

What Is Ozone Layer Depletion?

Ozone layer depletion refers to the thinning of this layer, primarily caused by chemicals like chlorofluorocarbons (CFCs) and other ozone-depleting substances. These substances break down ozone molecules, leading to increased UV radiation reaching the Earth's surface.

The depletion of the ozone layer is caused by human-made pollutants and has serious effects, including skin cancer, cataracts, and damage to marine life and agriculture. Protecting the ozone layer is critical for ecological balance and public health, highlighting its impacts is so important for future generations.

Causes of Ozone Layer Depletion

Ozone layer depletion is caused by the following factors:

Natural Causes

• Volcanic Eruptions: Volcanic activity introduces minor quantities of chlorine and Bromine compounds in the stratosphere which affects the depletion of the Ozone.

• Solar Cycles: Solar ultraviolet radiation and solar activity can in turn affect the amount of ozone in the atmosphere though this effect is small as compared to effects resulting from human beings’ actions.

Ozone-Depleting Substances (ODS)

• CFCs, halons, carbon tetrachloride, methyl chloroform and similar compounds release chlorine or bromine atoms.

• When they are emitted into the atmosphere, they readily destroy ozone molecules by acting as a catalyst.

• These substances were formerly employed in refrigerators, air conditioning, aerosol propellants, and solvents before the restriction under the Montreal Protocol.

Sources of Ozone-Depleting Substances

Industrial Activities and Pollutants

• Some manufacturing industries especially in the metal processing and chemical industries emit gases such as nitrogen oxides and volatile organic compounds which contribute to the depletion of the ozone layer.

• These pollutants, in a way, can also help in ozone depletion since they combine with ozone present in the lower atmosphere.

Mechanism of Ozone Depletion

The mechanisms of ozone depletion include:

Chemical Reactions Involved

• UV radiation breaks down CFCs in the stratosphere

• Chlorine atoms (Cl) are released

• Chlorine reacts with ozone (O₃)

• Ozone is converted to oxygen (O₂)

• Chlorine acts as a catalyst and continues destroying ozone

Role of Polar Stratospheric Clouds (PSCs)

• Form in polar winters

• Activate chlorine compounds

• Accelerate ozone depletion in spring

• Responsible for seasonal ozone hole

Consequences of Ozone Layer Depletion

Ozone layer depletion has the following consequences:

Health Impacts

• Exposure to radiation from X-rays raises the susceptibility to skin cancer such as melanoma, non-melanoma skin cancer, and cataracts.

• UV radiation also has the effect of suppressing the immune system of the people who will be more prone to sicknesses and ailments.

Environmental Impacts

• UV rays are detrimental to marine life mainly the phytoplankton which is the foundation of the marine ecosystem.

• Decreased coccolithophore growth rates have an impact on fish stocks and indeed on the seas themselves.

• UV radiation impacts the physical properties of plants and subtracts from the vigour of their development, their ability to produce chlorophyll and the number of seeds they produce.

Global Efforts to Control Ozone Depletion

Various efforts have been made to control ozone depletion:

Montreal Protocol

History and Objectives: The Montreal Protocol, signed in 1987, is employed to eliminate the use of ODSs, like CFCs and halons; to minimize the destruction of the ozone layer further.

Success and Challenges: The MP has been very effective in cutting the use and emissions of ODSs across the world with the slow healing of the ozone layer. The two are the faculties like compliance with international standards and the emergence of new chemical substances which are substitutes.

National And International Policies

Role of Countries and Organizations: Various countries globally have implemented national rules and regulations that correspond to the Montreal Protocol, and UNEP and WMO support global policies.

Examples of Effective Policies: They include: rigorous legislation in the European Union and national legislations in the member countries of the United States, China, and India regarding strict prohibitive measures of ODS and supportive measures of restoration of the ozone layer.

Ozone Layer Depletion NEET MCQs (With Answers & Explanations)

Important questions asked in exams from this topic are:

• Causes of Ozone layer depletion

• Consequences of Ozone layer depletion

Practice Questions for NEET

Q1.Which of the following forms a layer in the atmosphere blocking the ultraviolet light from entering the earth’s atmosphere?

1. O3

2. CO2

3. O2

4. H2O

Correct answer: 2) O3

Explanation:

Ozone - The oxygen in the atmosphere, when reacts with ultraviolet light changes into ozone O3.It forms a layer in the atmosphere blocking the ultraviolet light from entering the earth's atmosphere.

Hence, the correct answer is option 1) O3.

Q2. Snow- blindness in Antarctic region

1. Freezing of fluids in the temperature

2. Inflammation of cornea due UV-B radiation

3. High reflection of light from

4. Damage to retina caused by infra

Correct answer: 2) Inflammation of cornea due UV-B radiation

Explanation:

Snow blindness is a painful eye condition caused by direct exposure to UV-B radiation, often experienced in snow-covered regions like Antarctica where UV reflection is intense. The excessive UV-B exposure leads to inflammation of the cornea, a condition known as photokeratitis. This temporary condition results in symptoms such as pain, redness, tearing, and a sensation of sand in the eyes. Protective eyewear, such as UV-blocking goggles, is essential to prevent snow blindness in such environments.

Hence the correct answer is option 2. Inflammation of cornea due to UV-B radiation.

Q3. Montreal Protocol aims at

1. Biodiversity conservation

2. Control of water pollution

3. Control of CO2 emission

4. Reduction of ozone-depleting substances

Correct answer: 4) Reduction of ozone-depleting substances

Explanation:

Recognising the deleterious effects of ozone depletion, an international conference treaty, known as the Montreal Protocol, was signed in Montreal (Canada). In 1987 (effective in 1989) to control the emission of ozone-depleting substances. Subsequently, many more efforts have been made and protocols have laid down definite roadmaps, separately for developed and developing countries, for reducing the emission of CFCs and other ozone-depleting chemicals.

Hence, the correct answer is option 4) Reduction of ozone-depleting substances

Also Read:

• MCQs on Ozone Layer Depletion

• Biomagnification

• Air Pollution and its Control

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