Bengal at epicentre of PM pollution, Sundarbans under threat: 25-year study

Kolkata: A 25-year satellite study has revealed that southern Bengal and Bihar have become the epicentres of particulate matter (PM) pollution across the Indo-Gangetic Plain (IGP). The research warns that elevated carbon pollution has expanded to the entire state, threatening ecologically fragile zones like the Sundarbans and the Eastern Himalayas.The study, published in the prestigious journal Atmospheric Environment, was led by Professor Abhijit Chatterjee and Soumen Raul of the Bose Institute, Kolkata. By mapping air quality data from 2000 to 2024 across the IGP, the Himalayas and the Northeast, the team captured a quarter-century trend of expanding environmental degradation.According to the findings, the eastern belt of the IGP — encompassing southern Bengal, Bihar and large swathes of neighbouring Bangladesh — consistently registered the worst air quality readings over the 25-year period. The trajectory of the crisis worsened rapidly over the last 15 years. During 2010–2019, PM pollution spiked by 10%–40% across this eastern zone compared to the previous decade. During 2020–2024, highly toxic "carbonaceous aerosol hotspots", which were largely confined to a narrow band of northern Bengal during the 2000–2009 baseline, expanded to cover all of Bengal.While public perception often blames factory chimneys and bumper-to-bumper city traffic for bad air, the Bose Institute study points in a different direction. The primary driver of Bengal's worsening air profile is biomass burning—specifically rural biomass used for cooking and heating, alongside the burning of urban solid waste.While Bengal has shown measurable improvements in overall urban PM levels since the launch of the National Clean Air Programme (NCAP), pollution from biomass burning has remained stubbornly flat. "The eastern Indo-Gangetic Plain, and increasingly Northeast India, are carrying a disproportionate pollution burden, and it is being driven almost entirely by biomass burning. That is the signal that stands out most clearly across 25 years of data," said Prof Chatterjee.However, the most urgent warning in the paper concerns the Sundarbans. Already battered by rising sea levels, severe coastal flooding, rapid erosion and subsequent loss of livelihood, the world's largest mangrove ecosystem is now breathing highly toxic air. The researchers are advocating for the immediate inclusion of the Sundarbans into India's clean air mission. They argue that current climate policies suffer from a massive blind spot by focusing almost exclusively on major cities, leaving vulnerable rural communities and ecosystems entirely unprotected.The study's atmospheric trajectory modelling proves that Bengal's air crisis is not a localised issue. Wind patterns routinely carry heavy aerosol loads from the lower IGP—including Bihar, Bengal and Bangladesh—into the ecologically sensitive Eastern Himalayas.Mountain zones that possess no structured clean air interventions or air-monitoring infrastructure are now paying the price for emissions generated hundreds of miles away.The researchers argue that the Central Pollution Control Board (CPCB) must fundamentally restructure its clean air strategy. While the CPCB's own policy documents acknowledge gaps in rural monitoring, this 25-year dataset provides the hard evidence needed to force a policy shift.