Answer:  Rapid urbanization and industrialization have led to increased air pollution concerns in all major metropolitan cities. However, Delhi faces a more serious air pollution problem compared to the other metropolitan cities.

• Vehicular Emissions: Delhi has a large number of vehicles, and their emissions are a major source of air pollution. The increasing number of diesel-powered vehicles and outdated vehicles with inadequate emission controls worsen the situation.
• Industrial Emissions: The concentration of industries in and around Delhi releases significant amounts of pollutants into the air, including particulate matter, nitrogen oxides, and volatile organic compounds.
• For instance, proximity of Delhi to industrial regions like Faridabad, Okhla and Noida.
• Construction and Dust: Ongoing construction activities in Delhi contribute to a substantial amount of dust, which becomes airborne and adds to the particulate matter pollution.
• Biomass Burning: Crop residue burning in nearby states, especially during the post-harvest season, adds to Delhi's pollution burden, contributing to elevated levels of particulate matter and other pollutants. 
• For instance, burning of paddy crops and other crops in Punjab and Haryana during winter months
• Geographical Factors: Delhi's landlocked geographical location, coupled with temperature inversions during winters, leads to the trapping of pollutants close to the ground, resulting in the formation of the infamous "Delhi smog."

• Improvement in Public Transport: Encouraging the use of public transport and promoting electric and cleaner vehicles can significantly reduce vehicular emissions.
• Strict Emission Norms and Enforcement: Enforcing stringent emission standards for vehicles and industries, along with regular monitoring and penalties for non-compliance, can help control pollution at the source.
• Promotion of Clean Energy: Encouraging the adoption of renewable energy sources and clean fuels can help reduce reliance on fossil fuels, decreasing pollution from power generation and transportation.
• Waste Management and Biomass Utilization: Proper waste management practices and incentivizing alternatives to crop residue burning can mitigate biomass-related air pollution.
• Afforestation and Green Spaces: Increasing green cover through afforestation and creating green spaces within the city can help absorb pollutants and improve air quality.
• Public Awareness and Behavior Change: Educating the public about the impact of air pollution and promoting behavior change, such as carpooling and reducing waste burning, can have a positive impact.

By adopting a comprehensive approach that involves multiple stakeholders, including the government, industries, citizens, and civil society, Delhi can effectively combat air pollution and create a healthier environment for its residents.