Integrated assessment of cost-effective air quality mitigation pathways for Uttar Pradesh, India

Severe air pollution across the Indo-Gangetic Plain (IGP) remains a critical environmental governance challenge in South Asia, with ambient fine particulate matter (PM₂.₅) concentrations persistently exceeding national and international air quality standards. Uttar Pradesh (UP), India’s most populous state, lies at the center of this highly interconnected region and experiences chronically elevated PM₂.₅ exposure driven by a combination of local emissions and substantial transboundary pollution. In such settings, effective air quality management requires policy-relevant analytical tools that integrate emissions, atmospheric transport, population exposure, and mitigation costs across administrative boundaries. This study applies an integrated assessment modeling framework to evaluate cost-effective policy pathways for reducing PM₂.₅ exposure in UP from a regional perspective.

We employ the GAINS-IGP (Greenhouse gas–Air pollution Interactions and Synergies) model to develop a region-specific, multi-sectoral emissions inventory for UP and the wider IGP for the base year 2020 and to project air quality outcomes to 2035. The model represents emission sources across the residential, industrial, transport, agriculture, power generation, and waste sectors, accounting for both primary PM₂.₅ emissions and key gaseous precursors (SO₂, NOₓ, NH₃, and NMVOCs). Atmospheric transport and secondary aerosol formation are simulated using reduced-form source–receptor relationships derived from chemical transport modeling, enabling estimation of population-weighted PM₂.₅ exposure at high spatial resolution. The GAINS optimization module is used to rank more than 300 emission control measures according to their marginal cost per unit reduction in population exposure.

Three policy-relevant scenarios are evaluated for 2035. The Current Legislation scenario assumes full implementation of all national and state regulations in force as of 2020. Frozen Legislation counterfactually illustrates air quality outcomes in the absence of policy advances beyond 2015, thereby isolating the contribution of recent regulatory efforts. A Coordinated Action scenario assesses the effects of harmonized implementation of additional, widely applied mitigation measures across the IGP. This scenario framework enables a systematic comparison of the effectiveness and cost-efficiency of state-level interventions versus regionally coordinated strategies.

Results indicate that while existing regulations partially decouple emissions from economic growth, they remain insufficient to achieve either India’s National Ambient Air Quality Standards (40 µg m⁻³) or the WHO Interim Target-1 (35 µg m⁻³) in UP. Approximately 44% of PM₂.₅ exposure in the base year originates from sources outside the state and from natural dust, while secondary PM₂.₅ formation contributes about 40% of total exposure. These structural characteristics substantially limit the effectiveness of unilateral mitigation policies. Cost-effectiveness analysis identifies high-impact measures across multiple sectors, including clean cooking transitions, improved fertilizer management, control of road and construction dust, elimination of open burning, industrial emission controls, and stricter vehicle standards. Achieving WHO-aligned targets at a reasonable cost, however, requires coordinated implementation of these measures across neighboring IGP states to reduce regional background pollution.

From a policy perspective, the findings highlight the importance of complementing city- and state-level clean air action plans with formal mechanisms for inter-state coordination. Integrated assessment modeling provides a transparent, quantitative basis for prioritizing measures, sequencing policies, and sharing mitigation efforts and benefits across jurisdictions in highly interconnected regions.