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

Model Answer: 

Photochemical Smog: Formation, Effects, Mitigation, and Gothenburg Protocol

Photochemical smog is a type of air pollution formed through complex chemical reactions involving sunlight and primary pollutants. Its formation, effects, and mitigation are critical environmental concerns.

Formation of Photochemical Smog:

• Primary pollutants: Nitrogen oxides (NOx) and Volatile Organic Compounds (VOCs)
• Sunlight triggers photochemical reactions
• Secondary pollutants form: Ground-level ozone, Peroxyacetyl nitrate (PAN)
• Favorable conditions: Temperature inversions, lack of wind (e.g., Los Angeles basin)

Effects of Photochemical Smog:

Photochemical smog has wide-ranging impacts:
• Health: Respiratory issues, eye irritation, aggravation of asthma
• Environment: Damage to plants, reduced crop yields (e.g., wheat production decline)
• Economic: Increased healthcare costs, lower productivity
• Infrastructure: Accelerated degradation of materials

Mitigation of Photochemical Smog:

Several strategies can help reduce photochemical smog:
• Strict emission controls on vehicles and industries
• Promotion of public transportation and clean energy sources
• Implementation of comprehensive air quality monitoring systems
• Urban planning emphasizing green spaces and reduced sprawl

The 1999 Gothenburg Protocol:

This international agreement aims to combat air pollution:
• Objectives: Reduce acidification, eutrophication, and ground-level ozone
• Key provisions: Set national emission ceilings for sulfur, NOx, VOCs, and ammonia
• Targets: Specific emission reduction goals for each pollutant by 2010
• Impact: Significant reductions in emissions across Europe (e.g., 30% decrease in SO2)

Conclusion: Addressing photochemical smog requires coordinated local and international efforts, combining technological solutions with policy measures to protect public health and the environment.