NEW DELHI: A new scientific study has revealed that clouds drifting over the Eastern Himalayas and Western Ghats carry toxic heavy metals, posing both carcinogenic and non-carcinogenic health risks—especially to children.

Conducted by the Bose Institute, an autonomous research body under the Department of Science and Technology, Ministry of Science & Technology, Government of India, the study found significantly higher pollution levels in clouds over the Eastern Himalayas—1.5 times more than those over the Western Ghats. The elevated pollution levels are primarily attributed to emissions from dense vehicular traffic and industrial activity in the foothill regions.

Led by Dr. Sanat Kumar Das, Associate Professor at the Bose Institute, the research team identified dangerous concentrations of cadmium (Cd), chromium (Cr), copper (Cu), and zinc (Zn) in non-precipitating clouds during the early monsoon season. These clouds were found to act as carriers of pollutants, transporting them from lower elevations to high-altitude ecosystems.

“Inhaling cloud water that contains dissolved heavy metals represents a serious health hazard, particularly in the Eastern Himalayas,” said Dr. Das. “Children are especially vulnerable—about 30% more than adults.”

Published in the journal Environmental Advances, the study used statistical risk models to evaluate human exposure through inhalation, ingestion, and skin contact. The presence of carcinogenic substances such as dissolved chromium in cloud water was shown to significantly increase the risk of cancer and other health complications.

Although the researchers noted that Indian cloud pollution remains lower compared to countries like China, Pakistan, Italy, and the United States, they warned that increasing pollution and the absence of baseline data on heavy metal content in clouds represent a growing public health challenge.

The findings question the long-held belief in the pristine nature of mountain rainwater and open new directions for research in atmospheric science and environmental health.