Trans-boundary movement of pollutants from Jharkhand, carried forward by the northern winds since mid of October is held responsible for causing persistent air pollution in Durgapur and its suburbs. This was revealed by the IIT, Delhi, the top environment officials of Bengal government stated today.
Bengal, as a strategic plan, has set to introduce a three-layer bio-seal with planting high-rise trees in the bordering stretch to arrest the Jharkhand pollutants, the environment officials said.
IIT Delhi was assigned by the West Bengal Pollution Control Board (WBPCB) to determine the ‘culprit’ factors responsible behind the soaring air quality index (AQI) of Durgapur industrial zone that harbours cluster of polluting industries like iron & steel, cement and three thermal power generation units. IIT Delhi aimed to detect the origin of pollution and take enhanced measures to neutralise the targeted pollutants in 10 locations of the city.
The IIT experts also exercised on the chemical specification of PM10 & PM2.5 (the key polluting particulate matters), besides identifying the source of emissions and source of receptors (CM 38) and dispersion models to assess the contribution from various sources, future projection, besides the evaluation of various control measures.
The AQI of Durgapur in the past two days hit above 400 points, surpassing the hazardous Delhi level. Typically dry, cold winds blowing from the north are held responsible for this pollution.
“The IIT detected that the poor thermal immersion in the ground level caused by the slower movement of northern wind invited the current crisis,” said Subrata Ghosh, OSD, WBPCB after an assessment meeting on growing pollution levels in Durgapur and Asansol today. He said: “IIT has held northern winds from Jharkhand as the major cause for Durgapur pollution in winter.” Besides the local polluting iron & steel units, the thermal power units were cautioned heavily.
The wind vector at 10 metres and above ground that highly depends on local topography and instantaneous wind speed, direction has been termed as the villain for scaled up current Durgapur pollution. In Durgapur, the windier part of the year lasts for 4.3 months, as the Anemometer data gathered by the WBPCB’s regional authorities claimed. The calmer wind vector of the year lasts for 7.7 months from 4 September to 26 April and the October, November months are identified as the calmest months with average wind speed of 7.89 kmph and wind gushes in mostly from North for 4.4 months between October and February.
Slow wind can cause air pollution by trapping pollutants and reducing their dispersal. Cold and denser air, as explained by Dr Kalyan Adhikari, a National Institute of Technology professor working with pollution: “Moves slower than warmer air, so it traps pollutants instead of moving them away.” Lighter wind, Dr Adhikari said: “Results in poor dispersion as wind in stable meteorological conditions limits vertical air movement.” Also, fog prevents sunlight from warming up the ground and breaking inversions which promotes the formation of secondary pollutants high pressure.
The WBPCB today instructed the regional authorities to create a WhatsApp group accommodating the Asansol Durgapur Development Authority, the Durgapur Municipal Corporation and the local hazardous units to expedite vigilance.