The findings indicate that Delhi continues to face the most severe air pollution challenge nationally.
Delhi Tops List of Most Polluted Cities in 2024-25; Patna Ranks Second: Report
Delhi recorded the highest levels of fine particulate pollution (PM2.5) among major Indian cities during 2024-25, making it the most polluted city in the country for the period, according to a study released by climate research group Climate Trends.
The analysis, based on air quality monitoring data from the Central Pollution Control Board (CPCB), examined how meteorological conditions influence PM2.5 pollution across six major cities — Delhi, Patna, Kolkata, Mumbai, Chennai and Bengaluru.
The findings indicate that Delhi continues to face the most severe air pollution challenge nationally. High local emissions combined with regional factors pushed the city’s annual average PM2.5 levels to the highest among the cities studied. During winter, Delhi also recorded the longest duration of days when the Air Quality Index (AQI) remained in the “severe” category.
Patna ranked as the second most polluted city during the period under review. The study noted that atmospheric conditions kept PM2.5 levels consistently high, reflecting a growing pollution crisis in the eastern Indus-Ganga plains.
The report also flagged rising pollution levels in some coastal metropolitan areas. Both Mumbai and Chennai recorded an increase in their annual average pollution levels in 2025, suggesting that air quality concerns in these cities may persist throughout the year rather than being limited to specific seasons.
Climate Trends is a research-based consulting and capacity-building initiative focusing on climate change, environment and sustainable development issues.
