New Delhi: A 25-year study conducted between 2000 and 2024 on aerosol pollution across the Indo-Gangetic Plain, Himalayas and northeast India has found particulate matter levels rose significantly in the ten years from 2010 to 2019, compared to the previous decade. There was also a 10% to 40% increase in overall pollution levels in these years, say the authors of the ‘Decadal shifts in aerosol hotspots and source attribution over IGP, north-east India and Himalayas: A 25-year (2000-2024) study’, published in Atmospheric Environment.The eastern part of the gangetic plains, primarily Bihar, southern West Bengal and Bangladesh, were the major hotspots for this rise in particulate matter pollution, said the New Indian Express in a report.Professor Abhijit Chatterjee from the Bose Institute in Kolkata, who led the study, tracked emissions patterns from the Gangetic plain region affecting air quality in the Himalayas over two decades. The study shows how parts of the Himalayas are being affected by pollution transported from the plains rather than just by local sources of pollution or natural aerosols.The study is an attempt to close the gap in terms of data availability for longer term pollution trends – over decades rather than years – in the Gangetic plains and surrounding regions. It establishes that pollution from Punjab, Haryana and Delhi is reaching the western and central Himalayas, while emissions from Bihar and West Bengal are impacting the eastern Himalayas, reports NIE.But even more concerning than the pollution itself is the cause – biomass burning, says the study, had risen in eastern and northeastern India. Pollution from burning materials like crop waste and wood was also increasingly common, especially in eastern areas, while overall dust pollution in the region has decreased.The paper identifies shifting (jhum) cultivation in northeastern states as an important source of biomass-burning emissions, citing previous studies. As a result, most of northeast India has shifted from a “polluted” to a “highly polluted” aerosol classification over the past two decades, said a report in the Indian Express about the study. Another cited study recorded more than 65,000 fire events between 2006 and 2020 during the March-April season when cultivation fires are lit.In northeastern India, two particulate-matter components associated with biomass burning increased by nearly 50% during 2010-2019, compared with the previous decade, finds the report.Further, until the early 2000s, Bihar, Uttar Pradesh, northern West Bengal, Assam, Meghalaya, Tripura and Bangladesh were the most high-pollution-prone zones. Between 2020 and 2024, the hotspots of pollution expanded further. They now include almost all of West Bengal and large parts of Assam, Meghalaya and Tripura.This spread was driven mainly by biomass burning in rural areas and waste burning in urban areas – not vehicular pollution or industrial activities alone. Uttar Pradesh alone saw carbon pollution fall in recent years.Noting that the levels of harmful particulate matter increased by more than 20% from 2010 to 2019 compared to the previous decade, the researchers called for the scope of the National Clean Air Programme (NCAP) 2.0 to be expanded beyond urban centres to include rural and ecologically sensitive areas such as the Himalayas, northeastern India and the Sundarbans. It pitched for “urgent need for rural need for rural interventions” in the updated programme, Times of India reports.