By NE NOW NEWS
Guwahati: A recent scientific study has found that air pollution levels across the region have increased sharply over the past two decades, turning what was once considered one of India’s cleanest areas into a major pollution zone.
Researchers from the Bose Institute in Kolkata analysed satellite data spanning 25 years and reported significant growth in particulate matter (PM) pollution between 2000 and 2024.
The study indicates that pollution levels across the region rose substantially during this period, with increases ranging from more than 20% to nearly 50%, depending on the pollutant measured.
The findings show that particulate matter concentrations during 2010–2019 were more than one-fifth higher than those recorded in the previous decade.
The study also noted a sharp rise in organic carbon aerosols, smoke-related particles that increased by almost 50% compared to levels observed between 2000 and 2009.
According to the researchers, pollution linked to organic carbon continued to rise after 2020, increasing by another 30% to 40% by 2024. As a result, large parts of the region now fall within categories associated with high pollution levels.
The study found that areas experiencing severe pollution expanded steadily over the years. What were once isolated pockets of heavy carbon pollution in Assam, Meghalaya, and Tripura gradually spread across much larger areas, eventually connecting with pollution corridors extending into Bangladesh and the lower Indo-Gangetic Plain.
Urban centres such as Guwahati recorded PM2.5 concentrations significantly above national air quality standards. Researchers also observed that pollution spread beyond cities, affecting rural and previously less-affected areas on a large scale.
Unlike northern India, where industrial emissions and vehicle exhaust are major contributors, the study identified different causes behind the rise in pollution levels in the region.
The researchers pointed to widespread dependence on biomass fuels, including firewood, dung, and other organic materials, for household cooking and heating.
They also cited intensified jhum cultivation as a source of concern, noting that slash-and-burn farming practices contribute to seasonal increases in smoke and carbon-based particulate pollution.
The report further stated that air currents moving through the Brahmaputra Valley transport sulphate and carbon emissions from states such as West Bengal and Bihar into the region and the eastern Himalayan belt.
Researchers argued that existing clean-air policies do not adequately address these sources because they focus largely on urban centres. As a result, pollution generated across extensive rural areas remains outside many current intervention programmes.
The study noted that much of the region now falls within high-pollution categories despite not being included under India’s main clean-air initiative. It also found evidence that emissions move between different Himalayan regions and the Northeast, creating a complex network of pollution transfer.
According to the researchers, the region functions both as a source of pollution and as a recipient of pollutants transported from distant locations. They said the long-term data clearly show biomass burning as one of the most significant drivers of the growing pollution burden.
The study recommends expanding the scope of the National Clean Air Programme (NCAP) beyond its current focus on 131 non-attainment cities.
Researchers have called for the inclusion of rural and environmentally sensitive regions, including the Northeast, alongside areas such as the Sundarbans and the Himalayan belt.
The study warns that current clean-air policies may fail to tackle a significant share of PM pollution if rural and ecologically sensitive regions continue to be excluded.
The research was published in the journal Atmospheric Environment and was led by Abhijit Chatterjee and Soumen Raul.
The study examined pollution trends across the Indo-Gangetic Plain, the Himalayan region, and the Northeast between 2000 and 2024.
