Kolkata, Nov 24 (PTI) Even 10 days after Diwali and Kali Puja festivals, Kolkata's air quality remained 'poor' causing serious health concerns to citizens.

While Ballygunge area in the southern part of the city recorded an air quality index (AQI) of 296 at 6 pm on Thursday, Bidhannagar (284) in the east and Jadavpur (252) in the south were not far behind at the same time of the day, a West Bengal Pollution Control Board (WBPCB) official said.

Among other air monitoring stations, Rabindra Sarobar registered 254 AQI at 6 pm, he said, adding all the readings were classified as 'poor' in environmental terms.

Even an eco-sensitive zone such as Rabindra Sarobar crossed the 300 mark during the day, the official added.

During the Kali Puja and Diwali festivals, the AQI ranged between 189 and 255 across the city.

The official said as the wintry conditions set in and the temperature dipped below 20 degree celsius, cases of respiratory problems have started to spiral.

'An AQI between 201 and 300 causes health alert, over 300 triggers health warnings of emergency conditions,' he said.

'The entire population is likely to be affected by serious health effects if there is no rain caused by depression or other weather disturbances,' environmentalist Somendra Mohan Ghosh said.

Till a week ago, the AQI hovered between 100 - 200 (moderate) while on Tuesday, the average air quality ranged between 160-220 in the city.

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