In a surprising turn of events, Bangalore has emerged as the most polluted city in India for October 2025, according to a recent study by the Centre for Research on Energy and Clean Air (CREA). This study reveals that Delhi, often perceived as the country's pollution capital, ranked sixth, trailing behind its neighbouring cities Ghaziabad and Noida.

The CREA report highlights a significant decline in air quality across India, particularly in the Indo-Gangetic Plain and the National Capital Region (NCR). Dharuhera in Haryana was identified as the most polluted city, with an alarming average PM2.5 concentration of 123 µg/m³, exceeding the National Ambient Air Quality Standard (NAAQS) on 77% of the days. The city recorded two days classified as 'Severe' and nine as 'Very Poor' in terms of air quality.

Delhi's average PM2.5 level for October was 107 µg/m³, nearly three times higher than its September average of 36 µg/m³. Despite stubble burning contributing less than 6% to Delhi's pollution levels, the sharp increase in air quality deterioration underscores the impact of year-round emissions from vehicles, industries, and construction activities. This situation indicates that short-term measures like the Graded Response Action Plan (GRAP) may not be sufficient to address the ongoing pollution crisis.

The top ten most polluted cities also included Rohtak, Ghaziabad, Noida, Ballabgarh, Bhiwadi, Greater Noida, Hapur, and Gurgaon, all located within the NCR and neighbouring states. In contrast, Shillong in Meghalaya was noted as the cleanest city, with a PM2.5 concentration of just 10 µg/m³. Other clean cities included several from Karnataka and Tamil Nadu.

Out of 249 cities assessed, 212 recorded PM2.5 levels below the NAAQS limit of 60 µg/m³, but only six cities met the World Health Organization’s daily safe guideline of 15 µg/m³. The number of cities with 'Good' air quality plummeted from 179 in September to just 68 in October, highlighting the urgent need for effective long-term strategies to combat air pollution and protect public health.