Aizawl Cleanest, Delhi Most Polluted in Winter 2024-25 Air Report
Delhi ranked as India’s most polluted city in Winter 2024-25, with 173 cities failing national air quality standards, as per CREA’s latest report.
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The Centre for Research on Energy and Clean Air (CREA) has released its Winter Ambient Air Quality Snapshot for India, highlighting severe air pollution across multiple cities. According to the report, 173 out of 238 analyzed cities recorded winter-average PM2.5 levels exceeding India’s National Ambient Air Quality Standards (NAAQS) of 40 µg/m³. None of the cities met the World Health Organization’s (WHO) guideline of 5 µg/m³, underscoring the persistent air quality crisis. The analysis covers the period from October 1, 2024, to February 28, 2025.
Delhi recorded the highest winter-average PM2.5 level at 159 µg/m³, retaining its position as India's most polluted city. Byrnihat followed with 157 µg/m³. Other cities in the top 10 most polluted list included Hajipur, Ghaziabad, Gurgaon, Noida, Patna, Asansol, Durgapur, and Charkhi Dadri. Cities in Bihar, Uttar Pradesh, Haryana, West Bengal, and Assam recorded severe pollution levels alongside Delhi.
A total of 100 cities featured in the top 10 most polluted cities list at least once over the 151-day period. Among them, 44 cities appeared more than 10 times. Byrnihat had the most frequent occurrences (111 days), followed by Delhi (105), Hajipur (80), Ghaziabad (52), and Bahadurgarh (47).
Aizawl in Mizoram recorded the lowest winter-average PM2.5 level at 7 µg/m³, making it the cleanest city during the analyzed period. Among the top 10 cleanest cities, six were from Karnataka, three from Tamil Nadu, and one from Mizoram.
Among the 98 cities under the National Clean Air Programme (NCAP) with available data, 78 recorded PM2.5 levels above NAAQS. In non-NCAP cities, 95 out of 140 exceeded the national standards, highlighting that pollution is not restricted to designated areas but is a widespread issue across urban centers.
Significant data gaps hindered a comprehensive assessment of air pollution trends. No air quality data was recorded for any day from monitoring stations in Darbhanga, Ernakulam, Hosur, Kochi, Kozhikode, Pathardih, and Thoothukudi. Additionally, 44 cities, including 21 from Haryana, had less than 80% data coverage. Initially, all 24 cities in Haryana had available data, but by December, several stations had stopped reporting. By the end of the season, only Charkhi Dadri, Faridabad, and Gurgaon maintained the 80% data coverage threshold.
Manoj Kumar, Analyst at CREA, highlighted the need for stronger policies to mitigate winter air pollution. He noted that both NCAP and non-NCAP cities face high pollution levels, requiring an expansion of air quality control measures beyond NCR.
