Question- Discuss in detail the photochemical smog emphasising its formation effects and mitigation. Explain the 1999 Gothenburg protocol. UPSC Main 2022 GS Paper 3.
Answers
Photochemical smog is a type of air pollution that is formed when sunlight reacts with nitrogen oxides and volatile organic compounds (VOCs) in the atmosphere. It is also known as summer smog or brown haze because it is more common in warm and sunny weather and it has a brownish color. Photochemical smog can have harmful effects on human health, environment, and climate. Some of the aspects of photochemical smog are:
Formation: Photochemical smog is formed by a complex series of chemical reactions involving sunlight, nitrogen oxides (NOx), and VOCs. NOx are emitted from various sources such as vehicles, power plants, industries, and fires. VOCs are emitted from sources such as vehicles, solvents, paints, fuels, and vegetation. When NOx and VOCs are exposed to sunlight, they produce ozone (O3) and other oxidants such as peroxyacetyl nitrate (PAN) and hydrogen peroxide (H2O2). These oxidants can further react with NOx, VOCs, and other pollutants to form more ozone and other compounds such as aldehydes, ketones, organic acids, and nitrates. The formation of photochemical smog depends on various factors such as temperature, humidity, wind speed, topography, and emission levels.
Effects: Photochemical smog can have adverse effects on human health, environment, and climate. Some of the effects are:
Human health: Photochemical smog can cause respiratory problems such as asthma, bronchitis, coughing, wheezing, and irritation of the eyes, nose, and throat. It can also aggravate existing conditions such as allergies, heart diseases, and lung diseases. It can reduce lung function and increase the risk of infections and cancers. It can also affect the central nervous system and cause headaches, fatigue, nausea, and dizziness.
Environment: Photochemical smog can damage plants by reducing their photosynthesis, growth, yield, and quality. It can also affect animals by impairing their respiratory system, immune system, and reproductive system. It can harm ecosystems by altering the nutrient cycles, biodiversity, and food webs. It can also reduce the visibility and aesthetic value of the environment.
Climate: Photochemical smog can affect the climate by changing the radiative balance of the atmosphere. Ozone is a greenhouse gas that can trap heat and contribute to global warming. Other pollutants in photochemical smog can also affect the formation and properties of clouds and aerosols that can influence the solar radiation and precipitation patterns.
Mitigation: Photochemical smog can be mitigated by reducing the emissions of NOx and VOCs from various sources. Some of the mitigation measures are:
Technological measures: These include using cleaner fuels and vehicles that have lower emissions of NOx and VOCs. They also include installing emission control devices such as catalytic converters, scrubbers, filters, etc. on vehicles and industries that can reduce the emissions of NOx and VOCs. They also include using renewable energy sources such as solar, wind, hydro, etc. that do not produce NOx and VOCs.
Regulatory measures: These include setting standards and limits for the emissions of NOx and VOCs from various sources such as vehicles, power plants, industries, etc. They also include enforcing compliance and monitoring of these standards and limits by using inspections, fines, penalties, etc. They also include implementing policies and programs that promote the use of cleaner fuels and vehicles such as subsidies, incentives, taxes, etc.
Behavioral measures: These include changing the behavior and habits of individuals and communities that can reduce the emissions of NOx and VOCs from various activities such as driving, cooking, heating, etc. They also include raising awareness and education about the causes and effects of photochemical smog and the ways to prevent it. They also include encouraging public participation and cooperation in reducing photochemical smog by using public transportation, carpooling, bicycling, walking, etc.
The 1999 Gothenburg Protocol
It is an international agreement that aims to reduce the emissions of four pollutants that cause acidification, eutrophication, and ground-level ozone in Europe. These pollutants are sulfur dioxide (SO2), nitrogen oxides (NOx), ammonia (NH3), and volatile organic compounds (VOCs). The protocol sets emission ceilings for each pollutant for each participating country that have to be met by 2010. The protocol also sets emission reduction targets for each pollutant for each participating country that have to be met by 2020. The protocol also promotes the use of best available techniques and integrated pollution prevention and control measures to reduce the emissions of these pollutants. The protocol also encourages the cooperation and exchange of information among the participating countries on the scientific, technical, and economic aspects of reducing these pollutants. The protocol is part of the Convention on Long-range Transboundary Air Pollution (CLRTAP) that was established in 1979 to address the problem of air pollution across national boundaries in Europe and North America.