Tackling Air Pollution with Science-Based Plans

TACKLING AIR POLLUTION REQUIRES SCIENCE-BASED PLAN, NOT JUST GRAP

Why in the News?

• Delhi launched its Winter Action Plan on November 1 to tackle rising air pollution.
• Key measures include:
  • Restrictions on entry of vehicles not complying with BS-IV emission standards.
  • Implementation of the “No PUC, No Fuel” policy.
  • Restrictions on construction activities.
• Despite these measures, Delhi’s air quality deteriorated to the “Very Poor” category on the first day of implementation.
• This has raised concerns over the effectiveness of existing measures and highlighted the need for a science-based, long-term approach to air pollution management.

Key Concerns and Changing Weather Patterns Affecting Delhi’s Air Quality

Need for a shift in pollution management

Two major interventions are required:

• Shift towards airshed-based mitigation to address pollution across geographical regions.
• Move away from temporary measures and recognise that GRAP alone cannot ensure sustained reduction in air pollution.

Impact of changing weather patterns

• Weather variability, driven by changing climatic conditions, is increasingly influencing air quality.
• This year, Delhi’s peak pollution season was delayed by nearly two weeks due to:
  • Super El Niño: Potentially influencing atmospheric and climatic conditions.
  • Cyclone Arnab: Associated unexpected rainfall further delayed the onset of the pollution season.
• A climatic interplay between two factors influenced pollution levels:
  • Slow wind speeds: Promote accumulation of pollutants.
  • Delayed onset of winter and milder temperatures: Help keep pollution levels relatively low.
• The delayed onset of winter appears to have temporarily prevailed, keeping pollution under control and postponing the onset of the severe pollution season.
• Recent research by the National Institute of Advanced Studies (NIAS) also indicates a strong connection between ENSO (El Niño–Southern Oscillation) and air pollution.

Impact of Stubble Burning and Limitations of Satellite Monitoring

• Delayed paddy harvesting: Rainfall deficits and associated uncertainty delayed paddy harvesting in Punjab and Haryana, affecting the timing of stubble burning.
• Limitations of NASA satellite data:
  • NASA’s MODIS sensors aboard Terra and Aqua may miss several farm fires due to their limited observation windows.
  • Satellites may pass over the region before fires begin or after they have been extinguished.
  • This mismatch has become more pronounced since 2023, reducing the reliability of conventional NASA fire counts.
• Changing pattern of stubble burning:
  • More than 90% of stubble-burning events in Punjab during 2024 and 2025 occurred after 3 PM.
  • In comparison, less than 3% of such events occurred after 3 PM in 2021.
  • This indicates a significant shift in the timing of farm fires.
• Alternative satellite monitoring:
  • South Korea’s Korea Multi-Purpose Satellite-2A (KOMPSAT-2A) uses the Advanced Meteorological Imager (AMI).
  • Being geostationary, it continuously monitors geographical areas and can capture fires missed by conventional satellites.
  • Its observations indicate substantially higher agricultural fire counts in Punjab than official estimates.

Contribution of Stubble Burning to Delhi’s Air Pollution

• NIAS air-quality modelling highlights the significance of incorporating realistic stubble-burning emissions.
• Incorporating additional emissions from farm fires enabled the model to reproduce the sudden rise in Delhi’s measured PM2.5 levels on November 1.
• Stubble burning was estimated to contribute approximately 20% of Delhi’s PM2.5 pollution burden.
• Reliance on historical averages and conventional satellite fire counts may lead to inaccurate pollution forecasts.

Solutions to Stubble burning:

• Improve satellite-based monitoring of agricultural fires.
• Incorporate realistic emission data into air-quality models.
• Strengthen emission estimates and pollution forecasting.
• Ensure evidence-based diagnosis before designing mitigation strategies.

Need for an Airshed-Based Approach to Air Pollution Management

Limitations of the existing approach:

• Delhi’s pollution-control measures address only around 50–70% of the emission sources affecting the city.
• The contribution of stubble burning further increases the gap in pollution-source coverage.
• City-centric interventions are inadequate because air pollution travels across geographical and administrative boundaries.

Proposed solution – AIR-SHEDEM Framework:

• A recent NIAS study, conducted under a project of the Office of the Principal Scientific Adviser to the Government of India, proposes an indigenous framework called AIR-SHEDEM.
• It advocates airshed-based master planning to achieve nearly 100% coverage of pollution sources.
• It adopts a pragmatic geographical approach that:
  • Goes beyond the boundaries of Delhi NCT.
  • Avoids covering the entire NCR indiscriminately.
  • Identifies the relevant geographical region contributing to Delhi’s pollution.

Significance:

• Provides comprehensive coverage of pollution sources.
• Enables coordinated mitigation across geographical regions.
• Offers a scientifically sound and administratively feasible framework for long-term air-pollution management.

Limitations of Graded Response Action Plan (GRAP)

GRAP as an emergency measure:

• GRAP is comparable to an ICU intervention for a chronically ill patient.
• It provides immediate relief by controlling pollution during peak episodes and stabilising air quality.
• However, it cannot address the underlying structural causes of air pollution.

Limitations of GRAP:

• Emergency restrictions cannot replace long-term and structural emission reductions.
• Repeated restrictions cause public inconvenience.
• Overdependence on GRAP leads to reactive rather than preventive pollution management.

Solutions:

• Adopt a science-based action plan focusing on the root causes of pollution.
• Treat GRAP as a temporary emergency response rather than a comprehensive pollution-control strategy.
• Prioritise sustained emission reduction and long-term structural interventions.

Emerging Challenges for Delhi’s Air Quality

Short-term challenges (Next 30–40 days):

• Continued stubble burning in neighbouring States.
• Unstable early-winter meteorological conditions.
• Intermittent high-emission episodes.
• High possibility of these factors converging during the second week of November.

Medium-term challenges (Next two months):

• Deeper winter may lead to increased local fog and the movement of fog from the Indo-Gangetic Plain towards Delhi.
• An ENSO-related decline in western disturbances may further aggravate the situation.
• Western disturbances normally bring rainfall and atmospheric relief.
• Significantly slower wind speeds may restrict pollutant dispersion, worsening air quality.

Addressing Year-Round Sources of Air Pollution

Beyond seasonal interventions, sustained attention is required to address persistent sources of pollution:

• Traffic congestion at road junctions.
• Poorly maintained roads.
• Ineffective traffic management.
• Open waste burning.

Way Forward – Tackling Air Pollution in Delhi

• Airshed-based approach: Adopt comprehensive airshed-based planning to address pollution beyond administrative boundaries and cover nearly 100% of contributing emission sources.
• Long-term emission reduction: Focus on structural interventions rather than relying excessively on temporary emergency measures such as GRAP.
• Scientific monitoring: Improve satellite-based monitoring of stubble burning and incorporate reliable, real-time emission data into air-quality forecasting models.
• Inter-state coordination: Strengthen cooperation among Delhi, Punjab, Haryana and other neighbouring States to address transboundary pollution.
• Weather-based preparedness: Integrate meteorological forecasts, ENSO patterns, wind speeds and western disturbances into pollution-management strategies.
• Control year-round pollution sources: Address traffic congestion, poorly maintained roads, ineffective traffic management and open waste burning.
• Evidence-based policymaking: Develop mitigation strategies based on scientific research, accurate source identification and region-specific emission inventories.
• Preventive rather than reactive governance: Treat GRAP as an emergency response mechanism while prioritising sustained measures to prevent pollution episodes.

Source: https://indianexpress.com/article/opinion/columns/delhi-must-look-beyond-grap-to-tackle-winter-air-pollution-10948956/

Mains Question

“Delhi’s air pollution requires a shift from emergency response mechanisms like GRAP to comprehensive, science-based airshed management.” Discuss the challenges and suggest a sustainable way forward.