2022 GS3 Answer

Q. Discuss in detail the photochemical smog emphasizing its formation, effects and mitigation. Explain the 1999 Gothenburg Protocol.

Question from UPSC Mains 2022 GS3 Paper

Model Answer: 

Photochemical smog is a type of air pollution that occurs when sunlight reacts with nitrogen oxides and volatile organic compounds in the atmosphere. This reaction produces a range of harmful pollutants, including ozone, which can have serious health effects.

Formation of Photochemical Smog

Photochemical smog is formed through a complex series of chemical reactions, which can be summarized as follows:

Emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) from sources such as vehicles, power plants, and industrial processes.

In the presence of sunlight, NOx and VOCs react to form ground-level ozone (O3), a key component of photochemical smog.

Ozone can react with other pollutants in the atmosphere to form a range of harmful compounds, including nitrogen dioxide (NO2) and particulate matter (PM).

Effects of Photochemical Smog

Photochemical smog can have significant effects on both the environment and human health, including:

Environmental impacts: Photochemical smog can harm plants, reduce visibility, and contribute to acid rain.
Health impacts: Exposure to photochemical smog can cause a range of respiratory problems, including coughing, wheezing, and shortness of breath. Long-term exposure can increase the risk of asthma, bronchitis, and other lung diseases.

Mitigation of Photochemical Smog

There are several measures that can be taken to mitigate the effects of photochemical smog, including:

Emission controls: Reducing emissions of nitrogen oxides and volatile organic compounds from sources such as vehicles, power plants, and industrial processes can significantly reduce the formation of photochemical smog.
Alternative transportation: Encouraging the use of alternative transportation, such as public transit, cycling, or walking, can reduce emissions from vehicles and help to mitigate photochemical smog.
Renewable energy: Transitioning to renewable energy sources such as solar and wind power can reduce emissions from power plants and help to mitigate photochemical smog.
Urban planning: Planning and designing cities with green spaces, pedestrian-friendly areas, and efficient public transit systems can reduce vehicle emissions and help to mitigate photochemical smog.

The 1999 Gothenburg Protocol
The Gothenburg Protocol is a multilateral treaty signed in 1999 that aims to reduce emissions of air pollutants, including those that contribute to photochemical smog. The protocol sets binding emission reduction targets for a range of pollutants, including nitrogen oxides, sulfur dioxide, and volatile organic compounds.

The key provisions of the Gothenburg Protocol include:

Emission reduction targets: The protocol sets specific emission reduction targets for a range of pollutants, including nitrogen oxides, sulfur dioxide, and volatile organic compounds.
National emission ceilings: Parties to the protocol are required to set national emission ceilings for each of the target pollutants and to report on progress toward meeting these ceilings.
Flexibility mechanisms: The protocol includes flexibility mechanisms that allow countries to achieve their emission reduction targets through a range of measures, including emissions trading, joint implementation, and the clean development mechanism.

Conclusion

Photochemical smog is a serious form of air pollution that can have significant effects on the environment and human health. Mitigating the effects of photochemical smog requires a range of measures, including emission controls, alternative transportation, renewable energy, and urban planning. The Gothenburg Protocol is an important international treaty that aims to reduce emissions of air pollutants, including those that contribute to photochemical smog.

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