Bacteria hitching a ride on the back of desert dust can find their way all the way from Thar up to the Himalayas, carrying with them bacteria harmful to health, new research shows.

A study by scientists from the Bose Institute, Kolkata, and the Indian Institute of Tropical Meteorology, Pune, examined airborne bacterial community structure in a hill-top region of the Eastern Himalayas over two years, from 2022 to 2023.

The team analysed three days of back-trajectories of dust using remote-sensing satellite data and found a thick dust layer between 2 and 3 km over the Eastern Himalayas, originating from the Thar Desert.

Long-range dust transport from the Thar desert carries 41% unique bacterial taxa over the Eastern Himalayas, scientists report in Science of the Total Environment.

Long-range transport via vertical and horizontal air movement carries 80% of the total Himalayan bacteria, it says. This changes the original natural bacterial diversity by about 60%.

Bacteria attached to the desert dust and transported over long distances contain one-third skin-infecting pathogens, while pollutants rising up carry mainly respiratory-infecting bacteria (45%).  Downward transport of air is dominated by gastrointestinal tract-infecting bacteria (50%), the study shows.

The results “highlight the profound impact of atmospheric transport processes on regional bacterial diversity and public health in a hill-top region, highlighting Himalayan atmosphere as a dynamic and global conveyor of life, including pathogens across long distances,” the report says.

According to the authors, despite the inhospitable nature of the atmosphere, characterised by low moisture, nutrient scarcity, intense solar radiation, and temperature fluctuations, many bacterial species persist in substantial numbers in the air, varying from 10,000 per cubic metre to 100,000,000 per cubic metre. These airborne microbes originate mainly from natural sources such as soil, vegetation, and water bodies.

Natural dust, too, plays a key role in varying microbes, which was reported in previous studies, such as desert dust from the Sahara Desert reaching Europe and America by crossing the Atlantic Ocean, and from the Gobi Desert to Japan across the China Sea. A new study from India examined the abundance, composition, and diversity of hilltop airborne bacteria and how atmospheric transport from the Thar Desert altered these characteristics from 2022 to 2023 over the eastern Himalayas.

It reports seasonal variability. The bacteria found in winter correspond to a downward movement from the free troposphere to the hilltop region. In contrast, summer and dusty periods are characterised by increased microbes driven by vertical movement from the foothill region and horizontal long-range transport from western India, respectively.

Long-range dust transport emerges as the main factor driving the introduction of unique bacteria, causing significant perturbations in regional Eastern Himalayan airborne bacterial diversity, the report says.

Dust-associated bacteria can cause skin and gastrointestinal problems and can harbour infectious pathogens, highlighting a potential health concern. In contrast, upward and downward transport mechanisms predominantly introduce respiratory and gut-related pathogens, respectively.

The authors say the findings can help develop strategies to mitigate the airborne bacterial population and minimise the health risks associated with it in the hilltop region.

Dust-borne microbes across Asia

The India research adds to a recent January 2026 report from scientists from Pusan National University, South Korea, who report that their study highlights the significant role of transcontinental dust transport as a primary source of airborne bacteria. This transport often complements and, at times, overshadows local bacteria in shaping atmospheric bacterial communities. Their study is published in Applied and Environmental Microbiology.

This study attempted to understand how airborne bacterial populations vary throughout the year in Busan, South Korea, by analysing both local generation and long-distance transport. The scientists continuously monitored over three years and observed consistent spring peaks in bacterial abundance, closely linked to dust storms originating in the arid regions of China and Mongolia. These dust events transport large quantities of particles carrying bacteria over thousands of kilometres, temporarily raising local airborne bacterial levels above typical background levels, they report.

The findings show that while bacteria are continuously emitted from local sources, regional dust transport can be the dominant driver, particularly during the spring dust storm season. This combination of local and regional influences results in complex seasonal cycles of bacterial abundance. Understanding how these processes interact is critical for predicting changes in air quality, evaluating potential health risks, and recognising the ecological connections that link distant desert environments with downwind areas.

Meanwhile, a team of scientists from Japan and Spain monitored 10 aircraft flights over the planetary boundary layer in Japan (between 1,000 m and 3,000 m above sea level). They found the presence of viable bacteria and fungi harmful to humans. Long-distance transport over 2,000 km is possible in the free troposphere for air masses originating in agricultural regions enriched in fertilisers and pesticides, according to a report in the Proceedings of the National Academy of Sciences.

They concluded that their study “uncovered a rich diversity of microbial taxa being dispersed by wind currents thousands of kilometres away from their sources. Transport occurs above the planetary boundary layer, far from the surface, enabling long-distance connections among geographic sites and opening the door to even longer propagation.

Scientists from Osaka University, Japan, in Genes and the Environment studied the contribution of airborne dust to the global migration of bacterial cells and their genes. They collected Asian dust particles over the Japan Sea (10 km from the coast) at a height of 900 m to avoid contamination by soil particles lifted from the ground during dust events (high-dust days) in November 2010 and again in May 2011, using a sampler mounted in a small airplane. They found an abundance of bacteria on the collected dust particles, drastically declining from 100,000 cells per cubic metre to less than 1 as the dust event subsided. Some of these bacteria retained growth potential despite the long-range transportation, their report says.

“These results demonstrate that bacteria attach to aeolian dust particles and migrate globally during dust events, thus may contribute to the diversity of the bacterial gene pool,” it concludes.

A second study by a team of researchers from various universities in Japan, South Korea, and New Zealand looked at bacteria atop dust blowing into Japan from the Chinese desert. It shows that the richness of airborne bacteria increased with dust dispersals from the Chinese desert to the Japanese coast. Also, transit over oceanic waters and areas polluted by human activities strongly selects for airborne bacterial populations through the atmosphere.

Overall, dust events increased the richness of airborne bacterial communities originating from inland deserts and other areas during early spring and were associated with greater variation in airborne bacteria at the island site than at the continental-peninsula site, they say. Airborne desert dust is likely a significant transport vehicle for bacteria. The transit of air masses over continental and marine surfaces is selective for some taxa that can be transported to distant sinks with potential impacts on ecosystems and public health.

The researchers report in Advancing Earth and Space Sciences that this is the first long-term study to demonstrate microbial transport from desert storms, at the continent-to-island scale. In the Middle East, scientists from the Weizmann Institute of Science, Rehovot, Israel, tested the hypothesis that dust storms enhance the spread of pathogenic microorganisms and whether these microorganisms carry antibiotic resistance and virulence-related genes in the Eastern Mediterranean.

The researchers collected air samples during a seasonal transition period, capturing data from 13 dusty days originating from Middle Eastern sources, including the Saharan Desert, Iraq, Iran, and Saudi Arabia, and 32 clear days, with temperatures ranging from 16.5 to 27.1 °C.

They identified several pathogens, including Klebsiella pneumoniae, Stenotrophomonas maltophilia, and Aspergillus fumigatus, which are linked to human respiratory diseases.

Some pathogens are harmful to crops, for example, Zymoseptoria tritici, Fusarium poae, and Puccinia striiformis, which are harmful to wheat.

The abundance of these pathogens increased during dust storms and with rising temperatures, the scientists report in Science of the Total Environment. “While further research is needed to determine whether dust storms and temperature variations pose an immediate threat to public health and the environment, our findings underscore the importance of continuous monitoring of atmospheric microbiomes. This surveillance is crucial for assessing potential risks to human health and ecosystem stability, particularly in the face of accelerating global climate change,” their report says.

Banner image: The Thar desert in Rajasthan. Image by Aiwok via Wikimedia Commons (CC BY-SA 3.0).

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Kundan Pandey Editor

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Air PollutionEnvironmentMountainsHimalayasRajasthanThar Desert

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