AQI stays moderate, blue skies in Delhi for second day in a row

Delhi enjoyed clear skies and moderate air quality for the second day, with AQI at 165, but pollution is expected to rise again this weekend.

For the second consecutive day, Delhi residents enjoyed clear blue skies and improved air quality, as the city remained in the “moderate” zone on Thursday. Strong winds and bright sunshine continued to disperse pollutants, bringing relief from the recent spate of heavy pollution.

Commuters in the early morning chill at Kartavya Path in New Delhi on Thursday. (Vipin Kumar/HT Photo)

The 24-hour average Air Quality Index (AQI) was recorded at 165 (“moderate”) at 4pm on Thursday, a slight improvement from Wednesday’s reading of 178 (“moderate”), Central Pollution Control Board (CPCB) said.

The last time Delhi experienced cleaner air was 54 days ago, on October 12, when the AQI stood at 155. For December, this marked the lowest AQI in two years, with the previous best being 163 on December 14, 2022.

However, forecasts suggest the reprieve may be short-lived. A drop in minimum temperatures over the weekend is expected to bring a rise in pollution levels.

The AQI is likely to slip back into the “poor” category from Friday, with predictions indicating that conditions may range from “poor” to “very poor” through the next week, according to the Centre’s Early Warning System (EWS) for Delhi.

Mahesh Palawat, vice president at Skymet Weather, attributed the improvement to consistently strong winds in the region, reaching speeds of up to 20km/h since Tuesday.

“There is not enough moisture, so fog is not forming. We are seeing strong winds and bright sunshine, which help in improving the AQI. Winds should remain consistent till Saturday but drop from Sunday onwards as a western disturbance starts to influence the region, so there could be a deterioration in AQI by then,” he said.

The CPCB classifies AQI between 0 and 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”

The day’s average AQI of 165 was calculated at 4pm on the basis of 38 ambient air quality stations. Out of these, 34 were in moderate, with the highest AQI recorded at Shadipur (263).

It was also in December 2022, when Delhi last recorded five consecutive days where the AQI was between poor and moderate. This happened between December 12 and 16, data showed.

Historically, an improvement in Delhi’s air quality has been a rarity this time of the year.

Data from last December showed the average AQI was 348, with three “severe” air days recorded. The lowest AQI recorded last year’s December was 286, while the highest was 450 on December 23.

Typically, the second half of December witnesses a spike in pollution levels due to plummeting temperatures, low wind speeds, and the return of dense fog.