Himalayan clouds now carry toxic metals, pose health risks to children: study

Once considered a source of the purest drinking water, Himalayan clouds may no longer be as pristine.

A new study by the Bose Institute reveals the presence of toxic heavy metals in low-level, non-precipitating clouds over the Eastern Himalayas and Western Ghats, raising health concerns, particularly for children.

The research, published in Science Advances, found that clouds over Mahabaleshwar in the Western Ghats contained nearly double the concentration of metals compared to those over Darjeeling in the Eastern Himalayas. Overall, cloud pollution levels were 1.5 times higher in the Eastern Himalayas.

The scientists analysed cloud samples collected in 2022 from the rooftops of the Indian Institute of Tropical Meteorology (IITM) in Mahabaleshwar and the Bose Institute in Darjeeling. They found significant traces of cadmium (Cd), copper (Cu), zinc (Zn), and chromium (Cr), all of which are known to pose health risks.

"Children are at a higher risk of 30 per cent of such toxic metals than adults in India. Inhalation of polluted clouds over Eastern Himalayas containing high concentrations of toxic metals is the most potential route for non-carcinogenic diseases," the study highlighted.

"Health risk for the occurrence of carcinogenic diseases has increased due to inhalation of dissolved Cr present in clouds," it added.

The researchers identified vehicle and industrial emissions from the Himalayan foothills as major contributors to the elevated metal levels. Clouds, they noted, are acting as carriers for these pollutants, enabling toxic metals to enter the human body via inhalation, skin contact, and rainwater consumption — particularly in high-altitude areas.

Despite the concerns, the study noted that Indian clouds remain less polluted than those over countries like China, Pakistan, Italy, and the United States.