Droughts worsen air quality and health by shifting power generation

Fine particulate matter (PM_2.5) is a leading environmental cause of mortality. Droughts can worsen air quality in regions that rely on hydropower by shifting energy production to combustion power plants. This study quantifies drought-induced excess PM_2.5 in Latin America and the Caribbean, where over 443 million people live within 50 km of a combustion power plant. Leveraging a monthly plant-level panel spanning 20 years, we link hydrological droughts, measured as negative runoff anomalies in hydropower watersheds, to changes in PM_2.5 concentrations near combustion power plants. Our analysis reveals that these droughts lead to an average increase of 0.83 μg m^-3 in PM_2.5 levels. Counterfactual simulations for the region reveal that this excess PM_2.5 results in up to 10,000 premature deaths annually. Combining our estimates with climate, demographic, and combustion power plant phase-out projections, we demonstrate that this health burden will persist over the next four decades without targeted interventions.