Four Decades of Satellite-Derived PM2.5 Trends over Accra

Air pollution, particularly fine particulate matter (PM2.5), poses significant public health threats in sub-Saharan Africa, yet long-term air quality data remains scarce across much of the continent. This study investigates four decades (1980–2019) of PM2.5 concentrations over Accra Technical University using satellite-derived aerosol data from the MERRA-2 reanalysis. Utilizing aerosol mass concentration fields including black carbon (BCSMASS), organic carbon (OCSMASS), dust (DUSMASS25), sea salt (SSSMASS25), and sulphate (SO4SMASS), surface-level PM2.5 concentrations were reconstructed based on NASA-GMAO's recommended aggregation. The results reveal distinct seasonal and interannual variability, with elevated PM2.5 levels predominantly during the Harmattan period (November to March). This long-term trend analysis provides critical baseline insights into the dynamics of PM2.5 exposure in West Africa, especially in light of recent restrictions on US embassy air quality data sharing.