Delhi’s AQI improves; remains in ‘moderate’ category for 3rd consecutive day

Strong winds in the region have led to an unusually clean spell of air over the last three days, pushing Delhi’s AQI in ‘moderate’ category for the first time in December since 2020

Delhi’s air quality index (AQI) remained in the ‘moderate’ category for the third consecutive day, rising to a reading of 197 at 7am on Thursday in comparison to an AQI of 163 which was recorded at 4pm on Wednesday.

Forecasts show, while the AQI is expected to remain in the moderate range on Thursday. (File image)

Strong winds in the region have led to an unusually clean spell of air over the last three days, pushing Delhi’s AQI in ‘moderate’ category for the first time in December since 2020, when Delhi recorded one moderate air day on December 14 (160).

Forecasts show, while the AQI is expected to remain in the moderate range today, it will deteriorate to the ‘poor’ category by Friday and ‘very poor’ by Saturday.

“These improved ventilation conditions are likely to prevail from December 14 to 15. The air quality is likely to deteriorate marginally on December 15, but it will remain in the ‘moderate’ category, but will touch the ‘poor’ category on December 16. The air quality is likely to deteriorate further on December 17 and will touch the ‘very poor’ category,” said the Early Warning System (EWS) for Delhi, a forecasting model being used by the Commission for Air Quality Management (CAQM) in NCR.

It adds that the AQI in the subsequent six days is also likely to be ‘very poor’, with meteorological conditions to be highly unfavourable for dispersion of pollutants from December 17 onwards. This includes a dip in wind speed, particularly at night.

The CPCB classifies an AQI between 0-50 as ‘good’, between 51 and 100 as ‘satisfactory’, between 101 and 200 as ‘moderate’, between 201 and 300 as ‘poor’, between 301 and 400 as ‘very poor’ and over 400 as ‘severe’.

RK Jenamani, scientist at India Meteorological Department (IMD) said following the departure of a western disturbance which was influencing north India till December 11, wind speeds had picked up, leading to improved ventilation and dispersal of pollutants from December 12.

Delhi’s AQI was 218 (poor) on December 12, which improved to a reading of 177 (moderate) on December 13. The AQI on December 14 was even lower, at 163.

“Wind speed was 15 km/hr during the day on Wednesday with it touching 30 km/hr in parts. These strong winds have kept the AQI under check, but a drop in wind speed is once again expected now as the atmospheric conditions will become more stable. Winds during this spell can become calm at night,” Jenamani said.

This is also the cleanest air spell for Delhi since early October, when rains led to pollutants settling down.

The last time Delhi had cleaner air was on October 14, when a reading of 154 was recorded.

On the weather front, Delhi recorded a maximum of 24.6°C on Wednesday – one degree above normal for this time of the year.

The minimum was meanwhile recorded at 10°C, a degree above normal as well. Forecast for today shows that the minimum is likely to return closer to 8°C while the maximum will hover around the 25°C mark.