Kolkata AQI plunges to ‘poor’, GRAP starts issuing alerts
Times of India | 6 December 2024
123 Kolkata: The air quality of Kolkata on Thursday plunged to the ‘poor' level, with wind speed dipping below 2 metres per second. This absolute calm in the air movement robs the wind of its biggest healing ability — the dispersal of pollutants.
With the air quality index spiking to 201 and above, the Graded Response Action Plan (GRAP) started issuing alerts on Thursday. With the GRAP-I alert being sent, the transport department, an important stakeholder in the GRAP system, swung into action against polluting vehicles along with the city police, one of the biggest stakeholders. Police already started action against Vano, a van retrofitted with stolen parts of motorcycles that run on adulterated fuel.
Moreover, the sprinkling activities have been intensified across the city, said a PCB official.
Kolkata during the winter suffers poor and very poor days for a specific few days when, thanks to thermal inversion, the vertical wind movement lowers. This happens due to lower radiative temperature on the ground. This phenomenon occurs in Dec and early Jan when the soil is cool and there is no or less transfer of heat from the soil. This phenomenon causes calm wind conditions in the lower atmosphere. In this period, wind speed goes down below 2 metres per second, said a WBPCB scientist.
Kolkata on Thursday woke up to a grey, calm morning, with Rabindra Bharati University's continuous ambient air quality monitoring station (CAAQMS) in north Kolkata emerging as the most polluted station, closely followed by Ballygunge. Rabindra Sarobar CAAQMS emerged as the cleanest among the stations, with its air swinging to moderate in the evening.
According to the source apportionment study, the city's pollution is marked by trans-boundary pollution coming along the Indo-Gangetic Plain right from Punjab. Coal combustion is the biggest contributor to PM2.5 pollution, be it thermal power plants or roadside food vendors' coal-fired ovens. After coal, the biggest contributor is vehicular tailpipe emission. If coal's contribution is 30%, vehicular emission is as high as 26%.
"Apart from pushing for electric vehicles, we are trying hard to have a shift from the conventional chullahs to smokeless green chullahs," said a senior WBPCB official.
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