E-Paper
Change in wind direction helps clean Noida’s toxic air slightly
Noida: Noida and adjoining regions got a short breather on Thursday, with the air quality improving slightly from ‘very-poor’ to ‘poor’, owing temporary change in
Noida: Noida and adjoining regions got a short breather on Thursday, with the air quality improving slightly from ‘very-poor’ to ‘poor’, owing temporary change in wind directions.
According to weather analysts, the winds were earlier north-westerly, bringing with them the smoke from stubble burning from neighbouring Punjab and Haryana. They have now shifted directions and are blowing from the east, and are likely to remain so till October 19.
However, experts warn that next week would see far more toxic air as wind directions will revert to north-westerly (the usual direction in winter), while the share of smoke coming from stubble burning on the air quality of Delhi-NCR will also increase from the current 8% to 18%.
On Thursday, the Central pollution Control Board (CPCB)’s air quality index (AQI) for Noida, on a scale of 0 to 500 with 0 being the least polluted and 500+ the most severe, was 283 in the ‘poor’ category. The AQI was 326 or ‘very poor’ on Wednesday. The AQI of Ghaziabad was 298 or ‘poor’ on Thursday, against 339 or ‘very poor’ a day before.
Loni in Ghaziabad remained the most polluted region in NCR and the second most polluted in the country (after Sirsa in Haryana) despite a slight improvement with an AQI of 315 on Thursday against 358 on Wednesday.
According to weather analysts, although the wind directions were easterly, their slow speed (3 to 10 kmph) only managed to bar entry of pollutants from Punjab and Haryana, but were not strong enough to disperse the aerosols trapped in the region.
“Due to a cyclonic circulation over the Arabian Sea, the lower wind directions in NCR have changed from north-westerly to easterly. Although the higher winds are still north-easterly, the lower or surface wind is easterly and they are acting as a shield for this region. The winds are expected to remain the same till October 19,” Mahesh Palawat, director of private weather forecasting agency, Skymet, said.
As the monsoon withdraws, the winds in the national capital and the regions around it change to the north-westerly, which is dry and cold in nature and brings along pollutants from Punjab and Haryana where stubble is burned to pave way for the sowing of winter crops.
The share of stubble burning is only 10% currently, and the locally generated pollutant (vehicle, dust, fireworks and industries, etc) still continue to be the major reason of the pollution in Delhi-NCR, where the pollutants get trapped due to weather conditions.
“Till October 19, the air quality will not deteriorate and stay in the upper end of ‘poor’ category. However, a spike is likely after that since the ventilation index and mixing height is likely to drop — both conducive for keeping particles trapped in the air. Also, the contribution of stubble burning is likely to increase from the current 8% to up to 18% from October 20 onwards,” Shambhavi Shukla, senior research associate and air pollution expert, Centre for Science and Environment.
The mixing height is the height at which pollution can disperse easily, while the ventilation index is a combination of wind-speed and mixing height. The higher the ventilation index, the better the air quality.
