Source apportionment of air pollution in Delhi reveals that no single sector is overwhelmingly responsible. How should this inform multi-sectoral policy design for achieving NCAP targets?

Q. Source apportionment of air pollution in Delhi reveals that no single sector is overwhelmingly responsible. How should this inform multi-sectoral policy design for achieving NCAP targets? (15 marks, 250-350 words)

The CAQM's Supreme Court-mandated report by 33 domain experts, based on a meta-analysis of source apportionment studies (2015–2025), confirms PM2.5 as Delhi's dominant pollutant but attributes it to no single villain [1]. This diffused profile demands that NCAP shift from episodic, sector-blaming action to a calibrated multi-sectoral portfolio.

A diffused and diagnostic source profile - Winter PM2.5 shares: secondary particulates 27%, transport 23%, biomass burning 20%, dust 15%, industry and thermal power 9% — no source exceeds one-third [1]. - The largest share is not directly emitted: secondary particulates form from gaseous precursors (SO₂, NOₓ, NH₃), so particulate-only controls miss the biggest contributor [1]. - The report also highlights transboundary movement of pollutants across the airshed, alongside local emissions [1]. - Urgency persists: 2025 was Delhi's cleanest year since 2018, yet PM10 (198 µg/m³) and PM2.5 (97 µg/m³) stayed far above NAAQS [3].

Implications for policy design - Proportionate simultaneity: allocate NCAP effort roughly in proportion to source shares; disproportionate political focus on stubble burning (20%) cannot deliver the targeted 40% PM10 reduction/NAAQS compliance by 2025-26 [4]. - Precursor-led regulation: emission norms for NOₓ, SO₂ and ammonia across thermal power, industry and agriculture, to attack secondary particulates at source [1]. - Airshed governance, not municipal boundaries: use CAQM's statutory mandate to coordinate Delhi, Haryana, Punjab, Rajasthan and Uttar Pradesh as one unit [2]. - Year-round structural action over emergency GRAP curbs — public transport expansion, construction-dust protocols, clean cooking fuel. - Evidence infrastructure: the 46 additional monitoring stations approved for the region should feed periodic, city-specific apportionment to redirect funds [1].

Delhi's air is a shared commons polluted by many small hands, and its remedy must be equally distributed. A precursor-focused, airshed-wide and continuously monitored NCAP — with citizens as participants rather than only sufferers — can convert marginal annual gains into durable compliance, giving substance to the right to clean air under Article 21.

(~320 words)

Sources: 1. CAQM Reviews Supreme Court-Mandated Expert Report at 27th Meeting; PM2.5 Identified as Key Pollutant in Delhi — PIB — winter PM2.5 source shares, secondary particulates, transboundary airshed effect, 46 additional monitoring stations 2. The Commission for Air Quality Management in NCR and Adjoining Areas Bill, 2021 — PRS Legislative Research — CAQM's statutory mandate to coordinate Delhi, Haryana, Punjab, Rajasthan and UP 3. During 2018-2025, Delhi witnessed its lowest average PM10 and PM2.5 concentration levels in the current year — PIB — 2025 annual averages of PM10 (198 µg/m³) and PM2.5 (97 µg/m³) 4. Goals set under NCAP — PIB — revised target of up to 40% PM10 reduction or NAAQS compliance by 2025-26