A 25-Year Spatiotemporal and Human Health Impact Assessment of NO2 Pollution in India – Towards a Tiered Management Strategy

Abstract Nitrogen dioxide (NO2), a primary byproduct of fossil fuel combustion, is a robust proxy for local combustion intensity and anthropogenic activity. The present study compiled a ground-based NO2 dataset spanning 2000–2025 by integrating literature-derived measurements with recent national continuous monitoring records. Application of unsupervised machine learning to the multi-decadal dataset identified five distinct urban pollution typologies, capturing heterogeneous temporal trajectories ranging from stabilizing urban baselines to persistent industrial hotspots. Comparison with a national land-use regression model showed substantial city-level discordance and indicated that ground observations remain important for characterizing localized concentration peaks and regulatory non-attainment. The BenMAP-CE assessment estimated that in 2023, while compliance with the Indian NO2 standard could avoid 8,219 premature deaths, adherence to the stricter WHO guideline could have prevented 233,983 deaths─implying that approximately 97% of the modelled mortality burden lies in regions classified as compliant under current national regulations. These results, integrated within a single observation-based framework, support a stratified, risk-based regulatory strategy─absolute emission caps for volatile industrial zones and preservation targets for emerging urban centers─for addressing pollution-attributable mortality in developing economies.