The air quality level ranged from moderate to poor in the city for the past one week, he said.
However on Saturday, the air quality index at Rabindra Bharati University air monitoring station in North Kolkata read 312 (PM 2.5) at 1 pm which is in "very poor" category in environmental parlance, the official said.
Such air quality conditions have the potential to cause serious breathing problem for COPD patients living in the neighborhood of BT Road, Cossipore, Sinthi, North Dumdum, Paikpara areas particularly those afflicted by Covid-19 virus, green crusader and environmentalist S M Ghosh said.
The air quality index (AQI) had ranged between 270 to 320 at Rabindra Bharati air monitoring station this November, he said.
In rest of the city AQI was poor in the southern parts as well reading 245 at Ballygunje air monitoring station and 224 at Jadavpur on Saturday at 1 pm, the WBPCB official said. Poor means breathing difficulties but not as severe as very poor.
In Rabindra Sarobar, Victoria Memorial and Bidhannagar areas, the first two pockets having large green cover and the last one a satellite township, the air quality was moderate indicating the situation may not be as grim as in other parts but neither satisfactory as well.
In Rabindra Sarobar the AQI was 147, in Victoria Memorial area it was 145 and in Bidhannagar 180, less than 21 points of poor category.
Last week AQI ranged from 150 to 250 across the city except Rabindra Bharati University, the official said.
As the subtle particulates hanging in air, caused by vehicular emission and other commercial activities, refuse to go away due to foggy conditions in this season, the air quality index takes a dip in winter. The pcb is taking steps like banning smoke belching vehicles in Kolkata and Howrah, banning coal-based oven in road stalls and spraying water in construction sites to check the menace, he said.
With PTI inputs.