Kolkata, Nov 10 (IANS): At a time when rain in several parts of Delhi-NCR has resulted in marginal improvement in the air quality index (AQI), the same in certain pockets in and around Kolkata has started showing sharp deterioration from Friday.

Environmental activists fear that if the situation is such on Friday, how bad it can turn from Sunday onwards when there will be prolonged burning of firecrackers on the occasion of Kali Puja and Diwali.

At least at four points in and around Kolkata, the PM 2.5 level has crossed the 300-mark, which is considered hazardous. The worst has been reported from Ballygunge in South Kolkata where PM 2.5 level touched 356 on Friday.

The second among the four worst-hit areas is Bidhannagar on the outskirts of Kolkata where the PM 2.5 level has been recorded at 338. In the Rabindra Bharati University area, also on the outskirts of Kolkata, the level touched 320.

The fourth in the category is the Rabindra Sadan area in Kolkata, where the PM 2.5 level has been recorded at 312 on Friday.

Environment activists are especially worried about the deteriorating PM 2.5 levels at Rabindra Sadan, as the Victoria Memorial and the Maidan -- known as the 'Lungs of Kolkata' -- is located nearby.

According to experts, on an average the AQI recorded at Victoria Memorial is 202, which is considered as 'poor' and this is because of the heavy vehicular pressure on the roads adjacent to it and the resulting auto-emission.