Radionuclides in Atmospheric Dust across the MENA Region: A Systematic Review of Sources, Distribution, and Environmental Impacts

Atmospheric dust is a defining environmental feature of the Middle East and North Africa (MENA) region and an important pathway for the transport, redistribution, and human exposure to both natural and anthropogenic radionuclides. This review synthesizes more than two decades of research on radionuclide occurrence in atmospheric aerosols, dust deposits, indoor environments, and building materials across the Gulf region, North Africa, and the Eastern Mediterranean. The reviewed studies reveal substantial spatial and temporal variability in radionuclide concentrations, driven by the combined influence of geology, mineralogy, land use, industrial activities, meteorological conditions, and episodic dust storms. Among the radionuclides investigated, 40 K and 137 Cs are the most consistently detected, reflecting crustal sources and persistent global fallout, respectively. Uranium- and thorium-series radionuclides are mainly associated with naturally occurring radioactive materials, mineral dust, mining activities, and construction materials, whereas 7 Be and 210 Pb serve as effective tracers of atmospheric transport, vertical mixing, and deposition processes. The evidence indicates that dust storms play a central role in radionuclide mobilization, long-range transport, and deposition throughout the region. Although anthropogenic radionuclides generally occur at low concentrations, episodic increases in 137 Cs and cosmogenic radionuclides demonstrate the continued influence of historical fallout and atmospheric redistribution of legacy contamination. Variability in indoor 222 Rn concentrations further highlights differences in potential exposure and the importance of indoor–outdoor interactions in radiological assessments. A key conclusion of this review is that radionuclide occurrence in MENA atmospheric dust is controlled by multiple interacting geological, environmental, and anthropogenic factors rather than a single dominant process. Despite advances in monitoring and characterization, current understanding remains limited by fragmented datasets, short-term observations, methodological inconsistencies, and insufficient integration of measurements with atmospheric transport models. Future progress will require coordinated long-term monitoring programs, harmonized analytical protocols, improved source-apportionment methods, and stronger integration of field observations, isotopic tracers, remote sensing, and modeling approaches. These efforts are essential for reducing uncertainties, improving source attribution, and strengthening environmental monitoring and radiological risk assessment across the MENA region.