Context:

• Air pollution in the Delhi-National Capital Region (NCR) has long been a pressing concern, often attributed primarily to agricultural practices, particularly crop residue burning in neighboring states like Punjab and Haryana. However, a groundbreaking study conducted by the Research Institute for Humanity and Nature (RIHN) challenges this long-held assumption, revealing a more complex narrative about environmental policy and urban air quality management.

Key Points:

Research Findings

• The RIHN study utilized a network of 30 air quality monitoring sites across Delhi, Punjab, and Haryana to gather comprehensive data on air pollution sources. The key discoveries from this extensive investigation include:

Reduced crop burning:

• The study found a significant decrease in fire incidents related to crop residue burning. Between the years 2015-2016 and 2022-2023, Punjab witnessed a 49% reduction in fire incidents, while Haryana experienced an even more remarkable 72% decrease. This decline indicates a positive shift in agricultural practices and a response to environmental concerns.

Pollution contribution:

• Contrary to previous estimates that suggested crop burning contributed approximately 40% of Delhi's air pollution, the study revealed that this figure has dropped to about 14%. This finding underscores the need to reassess the sources of pollution affecting the capital region.

Methodology and analysis

The research team employed a comprehensive and multi-faceted approach to analyze air quality:

• Installation of monitoring units: The team installed 30 compact PM2.5 monitoring units equipped with gas sensors to measure particulate matter and other pollutants accurately.
   
• Air Mass Trajectories: By analyzing air mass trajectories, researchers could trace the origins of the air pollution affecting Delhi, providing insights into how local and regional factors interact.
   
• Fire counts and wind patterns: The study examined fire counts and prevailing wind patterns to understand how these elements contribute to air quality fluctuations.
   
• Chemistry-Transport Simulations: Advanced simulations were utilized to model the transport and transformation of pollutants in the atmosphere, offering a clearer picture of pollution dynamics.

Key observations

The study yielded several critical observations regarding pollution dynamics:

• Persistent winter pollution: Despite the significant reduction in crop burning, Delhi continues to experience severe air pollution during the winter months. This indicates that other local sources of pollution, such as vehicular emissions, industrial discharges, and construction activities, play a more critical role than previously understood.
   
• Day-to-day variations: PM2.5 concentrations exhibited significant day-to-day variations, suggesting that pollution levels are influenced by a combination of local emissions and meteorological conditions.

Policy implications

The findings of this study have profound implications for air quality management in the Delhi-NCR region:

• Rethinking Air Quality strategies: Current pollution mitigation policies may have "over-relied" on the reduction of crop burning as a primary strategy. The study suggests that policymakers need to adopt a more nuanced approach that considers a broader range of pollution sources.
   
• Local emission sources: There is a pressing need for closer examination of local emission sources, including traffic, industrial activities, and construction, which may be contributing significantly to the region's air quality challenges.
   
• Collaborative efforts: Given Punjab's proximity and its role in the air quality dynamics of Delhi, collaborative efforts between state governments and local authorities are essential. This includes sharing data, implementing joint monitoring initiatives, and developing region-specific policies that address the unique challenges faced by each area.