In the pristine altitudes of the Himalayas and the lush folds of the Western Ghats, clouds were once considered nature’s purest gift, and symbols of untouched serenity and sources of sacred rain. However, this long-held belief is now under threat, as per the reports. A new scientific study, as reported in PIB, has revealed that these clouds are quietly carrying something far more sinister.It reported that the clouds are responsible for ferrying toxic heavy metals silently from polluted lowlands to some of the highest, most fragile ecosystems. These findings shatter the myth of “clean” mountain rain, and also ring alarm bells for human health, which can lead to potential risks ranging from development disorders to cancer.Researchers from the Atmospheric Sciences Division of the Bose Institute, an autonomous body under the Department of Science and Technology (DST), have found that clouds drifting over the Eastern Himalayas and the Western Ghats are now acting as transport vehicles for toxic heavy metals, lifted from the polluted lowlands. These non-precipitating clouds, sampled during the onset of the Indian monsoon, contain harmful metals like cadmium (Cd), copper (Cu), chromium (Cr), and zinc (Zn).
The study, titled “Source-specific multi-pathway human health risk assessment of metals present in clouds over Indian Subcontinent,warns of alarming public health consequences and environmental degradation in two of India’s most ecologically sensitive regions. The presence of such metals not only shatters the myth of pure mountain rainwater but also raises red flags about long-term risks—especially those related to carcinogenic and non-carcinogenic diseases.Read more: 5 hill stations in India to experience scenic cable car ridesThe research, led by Dr. Sanat Kumar Das, Associate Professor at the Bose Institute, quantified the human health risks associated with these pollutants using detailed statistical modelling. The study found that clouds over the Eastern Himalayas were particularly toxic, with 1.5 times higher pollution levels than their southern counterparts. This elevated toxicity was attributed to a 40–60% increase in heavy metal loading, primarily from vehicular and industrial emissions in the foothill regions.Crucially, the study identifies inhalation as the most potent route of exposure, particularly in the Eastern Himalayas. The presence of dissolved chromium in clouds was linked to increased risks of carcinogenic diseases, while non-carcinogenic effects were attributed to metals like cadmium, copper, and zinc.Children, the study found, are especially vulnerable—30% more at risk than adults—due to their higher sensitivity to airborne pollutants. Health threats come not just from breathing in these toxic clouds, but also through dermal contact and ingestion, especially in high-altitude regions where cloud moisture is often harvested or consumed as water.Read more: Spotted: 10 best places to see leopards in IndiaThough the findings are concerning, the study, published in Environmental Advances, does offer a sliver of relief. It notes that Indian clouds remain relatively less polluted when compared to nations like China, Italy, and the USA, placing India in a safer health zone, for now.Still, the warning is clear. What once floated above as a symbol of purity is now a vessel of pollutants. The clouds may look the same, but what they carry could be putting both human health and fragile ecosystems at serious risk.
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