Informing decision-making to mitigate the air quality and health impacts of agricultural residue burning in India using an adjoint modeling approach

Abstract:

The multitude of agricultural activities has led to tremendous growth in food production as well as significant increases in waste generation, environmental pollution, and health risks in many parts of the world, especially in India due to its rapidly increasing population, production rates, and economic growth. Agricultural residue burning is one of the leading contributors to poor air quality and ill health for millions in India. Despite current regulations, agricultural fires persist due to uncertainties in implementation and lack of alternatives for farmers. Previous studies have mostly addressed this problem on a local or urban scale but overlooked the possibility of significant improvements achieved by small changes in specific time and the location of burning.

This work aims to advance the decision-making on mitigation alternatives by providing a better understanding of how air quality impacts respond to spatiotemporal changes with an adjoint modeling approach. The resulting map of air quality sensitivities combined with mortality risk and statistical valuation models are further applied to quantify the contribution of burning events at specific locations and times to population exposure and health impacts in order to better assess the benefits of changes, including shifting times, diversifying crops, or mechanizing residue management to eliminate the practice of burning.

The end results reveal a trio of insights into future efforts to mitigate the adverse impacts of agricultural residue burning in India. First, of the mortality burden attributable to fine particle exposure from agricultural burning over 2005-2016, three states in northern India consistently contribute to the majority, with significant impacts occurring in densely-populated areas. Second, a small number of administrative regions within these states may be prioritized to maximize the nation-wide air quality and health benefits. Third, small and incentivized interventions such as burning at a different time and promoting different crop varieties in targeted districts might be cost-effective from the perspective of farmers. These results offer a practical way to identify effective and potentially low-cost alternatives to reduce the contribution of agricultural residue burning to India’s existing air pollution challenge.