A toxic haze engulfed the national capital as the air quality stayed in the ‘very poor’ category for the fourth straight day on Thursday. The 24-hour rolling average air quality index (AQI) stood at 328 (very poor) around 8am, marginally down from Wednesday. The AQI was at a season-high of 353 (very poor) at 4pm on Wednesday, Central Pollution Control Board (CPCB) data showed.
The impact of stubble burning remains negligible at present, with local pollutants combining with cross-boundary pollution from neighbouring states. The contribution of stubble burning to Delhi’s PM 2.5 stood at 1.6% on Wednesday, data from the Centre’s Decision Support System (DSS) showed.
Experts said while winds are picking up during the day, they are not consistently strong to allow pollutants to disperse significantly. “Winds of 5-7 km/hr are being recorded with spells when the wind speed drops too. Similar weather is expected to persist till the weekend. A western disturbance will then impact Delhi from October 27 but it will be too feeble to again cause any rain and settle pollutants,” an IMD official said.
Monday, on the occasion of Diwali, was this season’s first ‘very poor’ air day. However, winds of up to 10 km/hr the next day allowed emissions to disperse – preventing the AQI from touching ‘severe’.
CPCB data at 8 am on Thursday showed out of Delhi’s 38 active air quality stations, one – Anand Vihar (429) – was in the ‘severe’ range, while 30 others were in ‘very poor’ category.
Forecasts by the Centre’s Early Warning System (EWS) for Delhi shows the AQI is likely to remain in the ‘very poor’ range till at least Saturday. In the subsequent six days, it should oscillate between ‘poor’ and ‘very poor’ as variable to easterly winds continue to keep stubble emissions away.
Delhi’s minimum on Thursday stood at 18.1 °C – three degrees below normal. This was a sharp dip from a minimum of 21.8°C on Wednesday. The maximum was meanwhile recorded at 32.1°C on Wednesday, which was a degree below normal. Both the maximum and minimum are now expected to stay in this range till the weekend.