The environmental and health impact of salt dust aerosols from the dried Lake Urmia

Lake Urmia (LU), a hypersaline lake in Iran and formerly recognized as the second-largest hypersaline lake worldwide, was desiccated to an area of less than 350 km² in August 2023, facing almost a complete drying condition. This environmental catastrophe has resulted in the generation of extensive playas, potentially acting as sources of salt dust that, in turn, pose health and environmental risks to the nearby areas. In this study, we first identified the major environmental controls influencing salt dust generation in LU and developed a learning-based model to predict aerosol optical depth (AOD) using satellite data from 2017 to 2023. We then quantified the impact of salt dust aerosols diffused within a radius of 20 km around LU on the neighboring residential regions. The results demonstrated a significant correlation between AOD around LU and soil moisture (-0.66), soil temperature (0.70), wind speed (0.29), and precipitation (-0.53). We also found a significant correlation of 0.91 between the monthly averaged AOD in the East Azerbaijan and West Azerbaijan provinces and that observed in LU. Finally, the calibrated learning model could predict AOD with high accuracy, evidenced by R² = 0.77 and RMSE = 0.147. The developed model can further be used to assess the impact of future climate-driven changes in the meteorological variables on the salt dust generation from LU.