Kolkata Emerges as Third Most Polluted State Capital in India During Winter 2025-26
Kolkata has been identified as the third most-polluted state capital in India based on average PM2.5 concentration during the winter season of 2025–26, according to a comprehensive analysis conducted by the Centre for Research on Energy and Clean Air (CREA). The study reveals that the city recorded an average PM2.5 concentration of 78 µg/m³ over the October to February period, placing it significantly above the national ambient air quality standard (NAAQS) of 40 µg/m³.
National Air Pollution Rankings and Key Findings
Delhi topped the list as the most polluted megacity with a winter PM2.5 concentration of 163 µg/m³, followed by Bhubaneswar at 81 µg/m³. Kolkata's position highlights a concerning trend of elevated pollution levels in urban centers across the country. The analysis, which utilized data from continuous ambient air quality monitoring stations (CAAQMS) operated by the Central Pollution Control Board from October 1, 2025, to February 28, 2026, indicates a widespread deterioration in air quality.
Over the past five years, winter PM2.5 levels in Kolkata have fluctuated but consistently remained well above the national standard. After a temporary dip in the previous winter, pollution levels rebounded this season, underscoring persistent challenges in managing air quality. Across India, the situation is alarming, with 204 out of 238 cities with sufficient monitoring data recording winter average PM2.5 concentrations above the national standard, up from 173 in the winter of 2024–25.
Performance of Major Cities and Clean Air Initiatives
Other major cities also struggled with air pollution. Mumbai and Chennai exceeded the national standard with winter averages of 48 µg/m³ and 44 µg/m³, respectively. In contrast, Bengaluru was the only state capital to stay within the national limit, recording an average PM2.5 concentration of 39 µg/m³. Notably, none of the analysed cities met the World Health Organization's stringent guideline of 5 µg/m³, highlighting the global scale of the issue.
The study further examined India's National Clean Air Programme (NCAP) cities, finding that 84 out of 96 with adequate data exceeded the national PM2.5 standard. In the Indo-Gangetic Plain, one of the world's most polluted regions, 75 of 79 monitored cities recorded PM2.5 levels above the national standard during winter 2025–26.
Expert Insights and Recommendations
CREA analyst Manoj Kumar emphasized the findings indicate persistent and widespread non-compliance with air quality standards. He stated, "While the commission for air quality management set PM2.5 reduction targets for NCAP cities, similar nationwide targets are needed, with stronger controls on gaseous pollutants like sulphur dioxide, nitrogen dioxide, and volatile organic compounds that contribute to secondary PM2.5 formation." This call for action underscores the need for comprehensive strategies to address pollution sources beyond particulate matter.
Top Polluted and Cleanest Cities in India
The analysis also provided rankings for individual cities. Ghaziabad emerged as the most polluted city with an average PM2.5 concentration of 172 µg/m³, followed closely by Noida at 166 µg/m³. On a positive note, Karnataka's Chamarajanagar was identified as the cleanest city, with an average PM2.5 concentration of 19 µg/m³ during the winter period, offering a benchmark for improvement in other regions.
This report serves as a critical reminder of the ongoing air quality crisis in India, with Kolkata's ranking highlighting specific challenges in eastern urban centers. As pollution levels continue to exceed safe limits, urgent policy interventions and public awareness are essential to safeguard public health and environmental sustainability.
