Delhi’s air quality back to ‘very poor’ as winds stall, no relief likely this week

Air quality forecasts indicate no immediate relief, with the AQI expected to remain ‘very poor’. Delhi’s air quality is likely to be in the ‘very poor’ category from December 11 till December 13.

After just a two-day breather, Delhi’s air quality slid back into the ‘very poor’ zone on Thursday as stagnant winds once again slowed the dispersion of pollutants, pushing the 24-hour air quality index (AQI) to 305 — up from 259 (‘poor’) a day earlier, according to the Central Pollution Control Board (CPCB). The India Meteorological Department (IMD) said two back-to-back feeble western disturbances are also set to affect the region, likely raising minimum temperatures in the coming days.

The AQI was recorded at 305 (Hindustan Times)

Air quality forecasts indicate no immediate relief, with the AQI expected to remain ‘very poor’. “Delhi’s air quality is likely to be in the ‘very poor’ category from December 11 till December 13. Outlook for the subsequent six days, from December 14, shows the AQI is likely to stay ‘very poor’,” said the Centre’s Early Warning System (EWS) for Delhi on Thursday.

The CPCB classifies air quality as “moderate” when the AQI is between 101 and 200, “poor” between 201 and 300, and “very poor” between 301 and 400. Beyond 400, air quality is termed “severe”.

CPCB data showed deterioration setting in early Thursday as winds slowed, weakening pollutant dispersion. The rolling AQI average stood at 287 at 8 am; 295 at noon; and crossed the 300 threshold before the CPCB’s 4pm bulletin was issued.

Experts attributed the slide to a sharp fall in wind speed, with fluctuations expected through the week. “Winds up to 20 km/hour blew in the city during the daytime on Wednesday. However, it dipped to around 5 to 8 km/hour on Thursday, and winds briefly rose to 12 km/hour,” said Mahesh Palawat, vice-president at Skymet. He added that two feeble western disturbances will influence the region from Saturday.“The first will be from December 13-15 and the second from 17-19,” he said, adding that no significant improvement in AQI is likely ahead.

The IMD said shallow fog will persist in the early hours till December 17, with isolated pockets likely to record moderate fog between December 13 and 15. On Thursday, the minimum temperature settled at 8.6°C, one degree below normal, while the maximum rose to 25.6°C, a degree above normal.

Friday’s minimum temperature is expected to hover between 7°C and 9°C, but officials said it may rise from Saturday as the western disturbance approaches. “The minimum temperature rises when a western disturbance impacts the region, and it dips when the influence of a western disturbance is over,” said a Met official.

The IMD has forecast a further rise in night temperatures, with the minimum likely to touch 8-10°C on December 13 and 10-12°C on December 14. Daytime temperatures are expected to remain steady in the 23-25°C range over the next few days.