Himalayas Under Threat? Surging Pollution From Indo-Gangetic Plains Is Drifting Into Mountains

Last Updated:May 25, 2026, 16:00 IST

Pollution from Punjab, Haryana and Delhi is reaching the western and central Himalayas, while emissions from Bihar and West Bengal are influencing the eastern ranges, a study found

Surging pollution from the densely populated Indo-Gangetic plains is drifting into the Himalayas, sharply increasing the concentration of aerosols such as tiny particles of dust, soot and chemical droplets in the mountain atmosphere.

The latest satellite-based study conducted by Bose Institute, Kolkata, has heightened concerns related to the changing climate in the Himalayan region, which is one of the most ecologically fragile and climatically sensitive regions in the world. Home to the world’s third-largest repository of ice after the poles, the Himalayas are also the source of Asia’s major river systems and critically influence India’s climate.

The stark findings, published in the peer-reviewed science journal Atmospheric Environment, suggest that the situation is getting worse, not better. Researchers analysed 25 years of satellite data using MODIS and MERRA-2 across the Indo-Gangetic Plain (IGP), the Himalayan region, and North-East India, and found that particulate matter (PM) pollution in the Indo-Gangetic plains, which lie next to the Himalayan region, increased by more than 20 per cent during 2010–2019 compared to the 2000–2009 baseline.

They also traced the movement of pollution plumes from the source regions to the Himalayan range using trajectory modelling, and found that pollution from Punjab, Haryana, and Delhi is reaching the western and central Himalayan ranges, while emissions from Bihar and West Bengal are influencing the eastern Himalayas.

The highest PM concentrations during the last three decades were recorded in the eastern IGP covering Bihar, southern West Bengal, and large parts of Bangladesh. During 2010–2019, PM pollution rose by 10–40 per cent across the IGP, Himalayan regions, and North-East India compared to the previous decade. In North-East India, organic carbon and sulphate components of PM, both closely associated with biomass burning, increased by nearly 50 per cent.

“The Himalayas are not insulated from this pollution. Our trajectory analysis shows that what is emitted in Punjab or Bihar does not stay there; it travels into the mountains, which are currently outside the scope of any structured clean air intervention in India," said research fellow Soumen Raul of Bose Institute, Kolkata.

The study also drew attention to the changing composition of PM pollution across the region. While carbonaceous aerosols — particles from the burning of crop residue, wood, and other organic material — showed strong and increasing trends in the eastern IGP, dust pollution, which peaks over the western IGP, showed an overall declining trend across the study period.

In Northeast India, the sharp rise in PM was attributed to intensified slash-and-burn agricultural practices and the extensive use of biomass for domestic energy in rural households, the study said. As a result, most of North-East India has shifted from a ‘polluted’ to a ‘highly polluted’ classification in terms of aerosols over the past two decades.

Researchers argued that the National Clean Air Programme (NCAP) 2.0 must now expand its scope beyond non-attainment cities to include rural regions and ecologically sensitive areas such as the Sundarbans, North-East India’s biosphere-rich regions, and the biodiversity-dense Himalayan belt.

“The eastern Indo-Gangetic Plain, and increasingly North-East India, are carrying a disproportionate pollution burden, and it is being driven almost entirely by biomass burning," said lead author Prof Abhijit Chatterjee of Bose Institute, Kolkata.

“While NCAP is primarily designed as a city-focused initiative, our data shows that air pollution in rural India is equally severe, and in some cases more so. The rural dimension needs to be explicitly built into the clean air mission."

Additionally, during 2000–2009, high carbon pollution was concentrated in Bihar, Uttar Pradesh, northern West Bengal, Assam, Meghalaya, Tripura, and Bangladesh. By 2020–2024, hotspots had expanded to cover all of West Bengal, Bihar, Bangladesh, and most of Assam, Meghalaya, and Tripura. For instance, sulphate emissions rose by more than 30 per cent in Assam, driven by thermal power plants, oil refineries, and cement industries concentrated in industrial hubs.

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