Illustration of how dust storms from the Thar desert send pathogens to the Eastern Himalaya via the Indo-Gangetic plains. Credit: Pramanick, A. et al. Sci. Total Environ.(2025)
Dust storms from the Thar desert ferry pathogens hundreds of kilometres to the Eastern Himalaya with potentially adverse public health effects1.
By combining air sampling with satellite observations and atmospheric modelling, researchers at Bose Institute, Kolkata, and Indian Institute of Tropical Meteorology, Pune, tracked how airborne bacterial communities over Darjeeling change with season and transport pathways.
In winter, when surface pollution is reduced, the background bacterial concentration is 340,000 per cubic metre of hilltop air. As temperatures rise in summer, stronger vertical mixing lifts air from the densely populated foothills, increasing microbial abundance to around 410,000.
In contrast, when desert dust from the Thar in the west is transported across northern India and lifted over the Eastern Himalaya, the load surges to nearly 670,000, nearly doubling winter background levels. These desert-borne plumes account for 41% of unique bacterial taxa, with roughly a quarter of these being pathogens specifically associated with skin infections.
The upwelling of polluted air from the Himalayan foothills contributes 6% unique bacteria, primarily targeting the respiratory system. Downward movement from the free troposphere introduces bacteria associated with gastrointestinal infections.
About 80% of the total airborne bacterial population over the Eastern Himalaya originates from atmospheric transport driven by horizontal and vertical air movements. Nearly half (47%) of the variability in the airborne bacterial community is explained by the combined effects of regional meteorology, air pollution, and long-range-transported desert dust, the authors report.
