New Delhi: A new 25-year satellite study has identified Bihar and West Bengal as major particulate pollution hotspots in eastern India, revealing a significant rise in air pollution across the Indo Gangetic Plain (IGP), the Himalayan region, and north-east India between 2000 and 2024. Researchers warn that biomass burning, including agricultural residue burning and the use of biomass fuels in rural households, is driving much of the worsening pollution burden.
The study, published in the journal Atmospheric Environment found that particulate matter (PM) pollution increased by more than 20 percent across these regions over the last two decades. Scientists say the findings highlight the urgent need to expand clean air policies beyond urban centres and address pollution sources in rural areas.
Using data collected from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the Terra and Aqua satellites, researchers mapped pollution trends across northern and eastern India.
The analysis revealed the highest particulate matter concentrations in the eastern Indo-Gangetic Plain, particularly across Bihar, southern West Bengal, and neighbouring Bangladesh. Pollution levels across the IGP, Himalayan region, and north-east India increased by 10 to 40 percent during the period from 2010 to 2019 compared to the previous decade.
Researchers noted that eastern India and north-east India are now carrying a disproportionate share of the region’s pollution burden.
Biomass Burning Identified as Key Driver
According to the study, biomass burning has emerged as the dominant source of increasing pollution in these regions. Activities such as crop residue burning, slash and burn agriculture, and the widespread use of firewood and biomass fuels for cooking and heating have significantly contributed to rising particulate matter levels.
The study found that organic carbon and sulphate particles, both strongly linked to biomass combustion, increased by nearly 50 percent during the study period. In north-east India, intensified agricultural burning practices and dependence on biomass for household energy have played a major role in worsening air quality.
Scientists observed that pollution hotspots have expanded considerably over time. Areas that were previously limited to parts of Bihar, Uttar Pradesh, West Bengal, Assam, Meghalaya, Tripura, and Bangladesh have now spread across entire states, especially Bihar and West Bengal.
The study also raised concerns about the impact of pollution on the Himalayan ecosystem. Researchers found that emissions from the Indo-Gangetic Plain are increasingly being transported to higher altitude regions.
Pollution originating from Punjab, Haryana, and Delhi is affecting the western and central Himalayas, while emissions from Bihar and West Bengal are influencing the eastern Himalayan region. This growing aerosol load could have serious consequences for fragile mountain ecosystems and regional climate patterns.
Need for Broader Clean Air Policies
The findings suggest that existing air quality programmes need to address rural pollution sources more effectively. Researchers recommended expanding India’s National Clean Air Programme (NCAP) to include rural regions and environmentally sensitive areas such as the Sundarbans.
While the study found some reduction in overall particulate matter levels after the launch of NCAP in 2019, biomass burning continued to rise significantly. Experts believe that controlling agricultural burning, improving access to cleaner household fuels, and strengthening waste management systems will be essential to reducing pollution in the coming years.
The researchers concluded that without targeted action on biomass burning, eastern India’s air pollution crisis is likely to intensify further, posing serious risks to public health, agriculture, and sensitive ecosystems across the region.