To combat pollution, we need to cast a wider net beyond the city

Why in the News

Delhi’s winter air policy has to move from the city to the airshed, the whole region whose air mixes together, because the sources and weather that decide its air lie beyond city limits. A “Super El Nino” (an exceptionally strong Pacific warming) is expected to trap pollutants this winter, and city measures such as doubled parking charges do not reach those sources.

What is an airshed based approach?

1. Airshed: An airshed is the stretch of land over which air and its pollutants move and mix, whatever the administrative borders. Like a river basin, what enters upstream reaches everyone downstream.
2. Satellite airshed: Where the full airshed is too large to administer, a smaller manageable zone is the working unit instead.
3. NARFI: The approach is set out in the National Air Quality Resource Framework of India (NARFI), a monograph developed by the National Institute of Advanced Studies (NIAS) under the Office of the Principal Scientific Adviser.
4. The takeaway: Air and its pollutants cross city borders, so the airshed, not the city, is the unit for managing sources.

Why has policy chased the wrong sources?

1. Transport share: The System of Air Quality and Weather Forecasting and Research (SAFAR), India’s first air quality forecasting framework, found transport behind about 40% of Delhi’s PM2.5 (particles fine enough to enter the lungs and blood).
2. Dust bias: The National Clean Air Programme (NCAP), the national air pollution plan, measures progress by the fall in PM10, coarser particles that are largely dust. Attention therefore stayed with dust, though fine particles harm health most.
3. City level curbs: The Delhi Winter Action Plan relies on narrow road sweeping machines, doubled parking charges and work from home rules under the Graded Response Action Plan (GRAP), emergency curbs tightened as air quality worsens. All act inside the city.

How can a Super El Nino trap Delhi’s winter air?

1. El Nino: It is a periodic warming of the central Pacific Ocean that disrupts weather worldwide. It creates no pollution source but traps the pollutants that exist.
2. Monsoon signal: It has already shaped a monsoon that ended with a 13% rainfall deficit, the highest in a decade. Delhi alone had a 17% surplus.
3. Calm and dry air: A NIAS study found it can sharply cut wind speed over north India, so fine particles do not disperse. Western disturbances (winter systems that bring rain) are likely to be almost absent.
4. Inversion layer: Milder days and cool nights under still air may lower the surface inversion layer, a lid of warm air over cold ground, so pollutants stay near the ground.

Why is early November the critical window?

1. Early burning: Early rains allowed early paddy sowing in Punjab and Haryana, so burning can begin in the first week of October.
2. Evening burning: Fires have moved to the evening, and detection based on the Moderate Resolution Imaging Spectroradiometer (MODIS), a polar satellite sensor that sees a place only at fixed times, may miss a significant share.
3. Firecrackers meet peak burning: Firecrackers arrive in the first week of November, when burning is near its peak. The days from 5 to 10 November have been Delhi’s worst of the last decade, and weaker winds may repeat that.

Challenges

1. Fragmented jurisdiction: An airshed spans several governments with different priorities, so no one authority enforces common targets.
2. Weak local capacity: Cities lack trained staff, so programme funds go unspent.
3. Farmer livelihoods: Residue management costs farmers Rs 2,000 to 3,000 per hectare with no assured market, so burning continues.

Way Forward

1. Wider airshed body: Evolve the Commission for Air Quality Management (CAQM) into a model for airshed management beyond the National Capital Region (NCR).
2. Metric reform: Measure NCAP progress by the fall in PM2.5 and by source, not by PM10 alone, so funding follows the most harmful pollutants.
3. Evening fire detection: Add satellite detection that sees evening fires, beside MODIS.

Conclusion

Delhi’s winter air is set by sources and weather beyond the city, so the unit of action has to be the airshed. The next test is whether the coming festival and burning peak arrives with extra sources curbed and fires counted fully.

Government Initiatives to Control Air Pollution

1. CAQM: A statutory body under the Commission for Air Quality Management in National Capital Region and Adjoining Areas Act, 2021. It coordinates action across Delhi NCR and adjoining States, replacing the earlier Environment Pollution (Prevention and Control) Authority.
2. Crop Residue Management Scheme: Since 2018 it has subsidised machinery that manages crop residue.
3. Subsidy rates: The subsidy is 50% for farmers and 80% for cooperatives, panchayats and entrepreneurs.

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