A new CREA report confirms Delhi as India's most polluted region, with PM2.5 levels over 20 times the WHO guideline. The study reveals pollution is a year-round national crisis spreading through ‘airsheds’.
Delhi has once again emerged as India's most polluted region, according to a new satellite-based assessment by the Centre for Research on Energy and Clean Air (CREA). The city recorded an annual population-weighted PM2.5 concentration of 101 micrograms per cubic metre-over 2.5 times higher than the national limit and 20 times above the World Health Organization (WHO) guideline. The findings underline that the Indo-Gangetic airshed, which includes Delhi, continues to experience the country's worst air quality.
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Airsheds Explain Pollution Spread
An airshed is a geographical region where weather and topography trap pollutants and circulate them across areas. While the Indo-Gangetic plains, from Punjab to West Bengal, have long been pollution hotspots, the study warns that northeastern states are now facing growing challenges. The Assam-Tripura airshed recorded consistently high PM2.5 levels, making it the second-most polluted airshed in India.
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Half of India's Most Polluted Districts in Delhi and Assam
Together, Delhi and Assam account for nearly 50% of the 50 most polluted districts in India. Other states like Haryana and Bihar also feature prominently. Out of 749 districts nationwide, 447 breach the annual PM2.5 limit. Pollution peaks in winter, affecting 82% of districts, eases during the monsoon, and surges again post-monsoon, highlighting that weather offers only temporary relief while emissions remain the underlying cause.
Unlike traditional air quality measures, the CREA study focused on population-weighted PM2.5, which reflects the actual exposure experienced by people rather than ambient readings alone. The report warns that dangerously high pollution levels are not limited to cities or winter months, it is a persistent, year-round national health crisis.
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Call for Broader Airshed-Based Governance
Manoj Kumar, analyst at CREA, stressed the need to move beyond city-centric pollution control measures. He advocated for airshed-based governance, which accounts for how pollutants travel across districts and state borders. Kumar also revealed that CREA plans to release daily satellite-derived PM2.5 maps soon, which could help policymakers and citizens take timely action.
