CREA analysis: Ghaziabad most polluted during winter last year, Noida and Delhi follow

New Delhi: A new analysis by Centre for Research on Energy and Clean Air (CREA) found that Ghaziabad was the most polluted city in India during the last winter season (Oct 1 to Feb 28), followed by Noida and Delhi. During the period, the average PM2.5 concentration of Ghaziabad was 172 micrograms per cubic metre, against the daily national ambient air quality standard of 60 micrograms per cubic metre. Noida recorded an average concentration of 166 micrograms per cubic metre. Delhi, which ranked as the third most polluted city during winter 2025-26, recorded an average PM2.5 concentration of 163 micrograms per cubic metre. It witnessed 18 days in the severe category, 87 days in the very poor category, 24 days in the poor category, 15 days in the moderate category, six days in the satisfactory category, and only one day in the good category in terms of average PM2.5 levels. However, as per the Air Quality Index (AQI), which is calculated considering eight pollutants, Delhi did not record a ‘good' air day since 2023. Greater Noida, Bahadurgarh, Dharuhera, Gurgaon, Bhiwadi, Charkhi Dadri and Baghpat were in the top 10 cities, with Greater Noida and Baghpat in fourt and 10th place, respectively, CREA said. CREA analysed the data from the 204 cities in the country whose real-time data was available for 80% of days. Among the India megacities, Delhi was the most polluted, followed by Kolkata (78 µg/m³), Mumbai (48 µg/m³) and Chennai (44 µg/m³). However, Bengaluru recorded an average PM2.5 concentration of 39 µg/m³. "Out of 89 cities considered in the Indo-Gangetic Plains, 79 cities recorded data for more than 80% of the days during winter 2025-26. Among those, 75 cities exceeded the average national standards, and only four cities complied within the limits," said CREA.