Poor AQI at Ballygunge and Salt Lake, others moderate
Times of India | 13 December 2024
123 Kolkata: The air quality index of two zones in the city turned poor, while the rest of the five zones covered by continuous ambient air quality monitoring stations (CAAQMS) showed moderate air quality on Thursday.
Two stations – Ballygunge and Salt Lake - turned ‘poor' (AQI: 201-300). The other five zones – Fort William, Rabindra Bharati University (BT Road), Jadavpur, Rabindra Sarobar, and Victoria Memorial Hall stations showed a pale yellow colour band, representing moderate air quality.
Thanks to meteorological factors and some measures adopted by Kolkata Municipal Corporation (KMC) and West Bengal Pollution Control Board (WBPCB), like sprinkling water to prevent road dust resuspension and preventing the burning of firewood and garbage, the pollution was stopped from blowing out of proportion in the city.
The city already started implementing the graded response action plan (GRAP) in the city and other five non-attainment cities in Bengal. The GRAP gets activated the moment the AQI rises over 200 (poor). Right now, GRAP is activated across Ballygunge and Salt Lake.
"The earth's surface has become cooler than the upper atmosphere. This phenomenon, known as thermal inversion, leaves pollutants hanging close to the ground at a breathable height, putting residents at greater risk. In other seasons, we might emit a similar amount of pollutants, but they escape high in the atmosphere because of the warmer earth surface," said a PCB scientist.
Stations like Jadavpur and Victoria are fast closing the gap between ‘moderate' and ‘poor'. Because of the thermal inversion in winter, the vertical wind speed lowers significantly, and the wind's ability to disperse pollutants reduces drastically, causing a spike in pollution.
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