During the last winter, 204 out of 238 Indian cities recorded average PM2.5 (a chief pollutant) levels above the Indian standard of 40 g/m³, as per the Central Pollution Control Board (CPCB) data analysed by the Centre for Research on Energy and Clean Air (CREA).

Ghaziabad was the most polluted city, recording an average PM2.5 concentration of 172 g/m³, followed by Noida (166 g/m³), and Delhi (163 g/m³), as per CREA, a Finland-based independent research group.

As per the analysis, Greater Noida was the fourth most polluted, followed by Bahadurgarh, Dharuhera, Gurugram, Bhiwadi, Charkhi Dadri, and Baghpat. Uttar Pradesh and Haryana accounted for four cities each in the top ten most polluted cities, along with Delhi and one city from Rajasthan.

PM2.5 (particulate matter 2.5) are fine inhalable particles that can get into the lungs and bloodstream and lead to various respiratory and other diseases.

The analysis was based on Continuous Ambient Air Quality Monitoring Stations (CAAQMS) data from the CPCB between October 1, 2025 and February 28, 2026.

Also, none of the cities analysed met the World Health Organization’s (WHO) PM2.5 standard of 5 g/m³, as per the analysis.

“Among India’s megacities, Delhi (163 g/m³), Kolkata (78 g/m³), Mumbai (48 g/m³), and Chennai (44 g/m³) recorded winter 2025-26 average PM2.5 concentrations above the national standard. Bengaluru recorded an average PM2.5 concentration of 39 g/m³, slightly below the NAAQS limit,” CREA said in a statement.

Cleanest city

Chamarajanagar in Karnataka was the cleanest city in India during the last winter, with an average PM2.5 concentration of 19 g/m³. The ten cleanest cities included eight cities from Karnataka and one each from Madhya Pradesh and Meghalaya, as per the analysis.