High-Resolution PM2.5 Exposure Analysis in Africa: Assessing Long Term Trends for Effective Air Quality Management

PAA SEY, Paulina Jaramillo, Albert Presto, Carnegie Mellon University

     Abstract Number: 458
     Working Group: Advancing Aerosol Science through Data Analysis Tools

Abstract
Fine particulate matter (PM_2.5) poses significant public health risks globally, with particularly severe impacts across Africa due to elevated exposure. Chronic exposure substantially increases cardiovascular and respiratory disease burdens, contributing to approximately 1.1 million deaths annually across the continent. Despite an urgent need for robust air quality assessments, limited ground-level monitoring infrastructure hinders effective policy development and mitigation efforts. To address this gap, we developed a hybrid modeling approach that spatially downscales PM_2.5 from NASA GEOS-CF chemical transport model from 0.25 ° by 0.25 ° resolution (~25 km) to 0.01 ° by 0.01 ° resolution (~1 km). Our method integrates satellite-derived atmospheric measurements and high-resolution spatial covariates, including land use and vegetation indices, using a Random Forest regression. Our validation demonstrates high accuracy in capturing large-scale (0.25 ° resolution) variations, with cross-validation R² scores between 0.93 and 0.96, and strong spatial invariance (R² = 0.79-0.93) demonstrating native efficacy in fine-scale estimates (0.01 ° resolution). Annual PM_2.5 concentrations were analyzed across Africa, comparing locations with proactive air quality management policies to those lacking significant interventions. Population-weighted PM_2.5 exposure analysis between 2019 and 2024 reveals substantial reductions, particularly in countries with structured air quality management. For example, Ghana and Ethiopia saw substantial decreases in exposure, from 57.3 µg/m³ to 30.9 µg/m³ and from 26.7 µg/m³ to 15.6 µg/m³, respectively. In contrast, countries without structured interventions, such as Niger and Chad, exhibited smaller improvements. These findings highlight the effectiveness of targeted air quality initiatives and underscore ongoing disparities in pollution exposure across the continent. Our high-resolution modeling approach provides critical insights for policymakers, emphasizing achievable improvements through proactive air quality management and identifying regions urgently needing targeted interventions to sustainably enhance public health outcomes across Africa.