Subject: Indian Geography

Despite being megacities, Delhi faces more severe air pollution compared to Mumbai and Kolkata due to a combination of geographical, meteorological, and anthropogenic factors.

Geographical Factors

• Landlocked Location: Delhi's inland position restricts natural ventilation, unlike coastal cities Mumbai and Kolkata which benefit from sea breeze for pollution dispersal.
• Topographical Setting: The city is surrounded by the Aravalli Range and Himalayan foothills, creating a bowl-like effect that traps pollutants.
• Distance from Coast: Lack of coastal winds means pollutants remain suspended in the atmosphere for longer periods.

Meteorological Conditions

• Temperature Inversion: During winters, cold air at the surface gets trapped under warm air above, creating a lid that prevents pollutant dispersal.
• Wind Patterns: Unlike Mumbai's strong sea breeze or Kolkata's Bay of Bengal influence, Delhi experiences calm conditions in winter, reducing pollution dispersal.
• Seasonal Variations: Winter months see reduced mixing height of atmosphere, leading to higher concentration of pollutants.

Anthropogenic Sources

• Agricultural Practices: Delhi faces the impact of stubble burning from neighboring states of Punjab and Haryana, especially during October-November.
• Industrial Emissions: Presence of numerous industrial clusters in National Capital Region (NCR) contributes significantly to pollution.
• Vehicular Density: Higher number of vehicles per capita compared to Mumbai and Kolkata, leading to increased emissions.

Additional Contributing Factors

• Construction Activities: Rapid urbanization and infrastructure development generate significant dust pollution.
• Waste Management: Open burning of waste and inadequate waste management systems add to air pollution.
• Regional Impact: Delhi's pollution is influenced by emissions from the entire Indo-Gangetic Plain.

The confluence of these factors makes Delhi's air pollution a complex challenge requiring multi-dimensional interventions. Implementation of measures like the Graded Response Action Plan (GRAP) and National Clean Air Programme (NCAP) are crucial steps towards addressing this critical environmental issue.