(MENAFN- Live Mint) Delhi, Ghaziabad and Noida emerged as most polluted cities in the month of October, while Dharuhera in Haryana topped the chart, according to a study by the Centre for Research on Energy and Clean Air (CREA) released on Tuesday.

The air quality in the national capital remained in the 'very poor' category over the last few days.

The national capital was ranked the sixth most polluted city in the country in October, with an average concentration of 107 μg/m3, three times higher than its September average of 36 μg/m3.

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The report by CREA says that the sharp rise in pollution levels, despite stubble burning contributing less than 6 per cent of Delhi's PM2.5 levels in October, highlights the impact of year-round emission sources.

It also noted that there is a need for long-term mitigation plans beyond short seasonal measures like the Graded Response Action Plan.

Dharuhera breaches NAAQS limit

On 77% of days, Dharuhera, which recorded two 'Severe' and nine 'Very Poor' days in October, breached the National Ambient Air Quality Standard (NAAQS) limit.

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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.

Cleanest city in October

Shillong in Meghalaya, was India's cleanest city in October with an average PM2.5 concentration of 10 μg/m3.

The report stated that four cities from Karnataka, three from Tamil Nadu, and one each from Meghalaya, Sikkim and Chhattisgarh were among the top 10 cleanest cities.

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, said the report.

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On Tuesday, Delhi recorded a marginally better Air Quality Index (AQI) than Monday. However, pollution levels across several parts of the city remained alarming. Since Diwali, the AQI in the National Capital Region (NCR) has been reeling under the 'poor' and 'very poor' categories in several areas.

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An AQI between 0 and 50 is considered 'good', 51-100 'satisfactory', 101-200 'moderate', 201-300 'poor', 301-400 'very poor', and 401-500 'severe'.

'Monitor AQI, wear N95 mask'

Earlier this week, Dr Randeep Guleria, the former director of AIIMS Delhi, said that those who have underlying respiratory conditions need to be extra careful.

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