Strong winds improve Delhi air to ‘moderate’ level again

This also marked the fifth “moderate” air day this month, making it one of the best starts to December, since CPCB started publishing daily AQI data in 2015

New Delhi

Delhi recorded an AQI of 199 on Wednesday. (Arvind Yadav/HT Photo)

Strong winds over the past two days improved Delhi’s air quality, from a “poor” air quality index (AQI) of 234 on Tuesday to a “moderate” AQI of 199 on Wednesday, according to the 24-hour average data shared by the Central Pollution Control Board (CPCB) in its daily bulletin at 4pm.

This also marked the fifth “moderate” air day this month, making it one of the best starts to December, since CPCB started publishing daily AQI data in 2015. So far, three “moderate” days each were recorded in December 2022, 2019 and 2015.

To be sure, there has never been a “good” or “satisfactory” air day recorded in any December since 2015. The lowest AQI recorded in December is 140, which was on December 26, 2015. 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”.

Meanwhile, the air quality started deteriorating again from late evening, clocking a “poor” AQI of 203 at 7pm and 210at 10pm, according to realtime data.

The Air Quality Early Warning System (AQEWS) for Delhi said the air quality is expected to stay “poor” for the next two days. “The air quality is likely to be in ‘poor’ category from Thursday to Saturday. The outlook for subsequent six days is that the air quality is likely to be in ‘poor’ category,” AQEWS said in its bulletin on Wednesday evening.

Wednesday’s average AQI was calculated based on data from 38 ambient air quality monitoring stations. By 7pm on Wednesday, of the 38 working stations, 20 were already in the “poor” category. The lowest AQI was 135, at Pusa, and the highest was 284, at Mundka.

This month, Delhi recorded moderate AQIs on December 4 (178), December 5 (165), December 6 (197) and December 9 (186).

Data from December 2023 shows the average AQI was 348, with three “severe” air days. The lowest AQI recorded last December was 286, while the highest was 450. Typically, the second half of December witnesses a spike in pollution due to plummeting temperatures, low wind speeds, and the return of dense fog.