NCR dominates list of India’s 10 most polluted cities in October, Delhi ranks sixth: Study

Delhi ranked sixth with an average concentration of 107 µg/m³, three times higher than its September average of 36 µg/m³.

Despite stubble burning contributing less than 6 per cent of Delhi’s PM2.5 levels in October, the sharp rise highlights the impact of year-round emission sources and the need for long-term mitigation plans beyond short seasonal measures like the Graded Response Action Plan, it noted.

Dharuhera was ranked as the most polluted city in October, with a monthly average PM2.5 concentration of 123 µg/m³, breaching the National Ambient Air Quality Standard (NAAQS) limit on 77 per cent of the days.

It recorded two ‘Severe’ and nine ‘Very Poor’ days during the month. Following Dharuhera, the next most polluted cities were Rohtak, Ghaziabad, Noida, Ballabgarh, Delhi, Bhiwadi, Greater Noida, Hapur, and Gurgaon.

Overall, four cities each from Uttar Pradesh and Haryana dominated the top 10 list, all located within the NCR.

Shillong, Meghalaya, was India’s cleanest city in October with an average PM2.5 concentration of 10 µg/m³. The top 10 cleanest cities included four from Karnataka, three from Tamil Nadu, and one each from Meghalaya, Sikkim and Chhattisgarh.

Out of 249 cities, 212 recorded PM2.5 levels below India’s NAAQS of 60 µg/m³. However, only six cities met the World Health Organization’s (WHO) daily safe guideline of 15 µg/m³.

In October, cities with ‘Good’ air quality (0–30 µg/m³) dropped from 179 in September to 68, while those in the ‘Satisfactory’ range (31–60 µg/m³) increased from 52 to 144.

Cities in the ‘Moderate’ range (61–90 µg/m³) rose from 4 to 27, while nine cities fell into the ‘Poor’ (91–120 µg/m³) category and one city reached the ‘Very Poor’ (121–250 µg/m³).