AQI data for Delhi-NCR goes missing due to server error, says CAQM

A CPCB official said that the server issue was fixed around 4pm and the hourly data was being collected

New Delhi

The average AQI last year was 209, which was Delhi’s second best and on a par with 2021 and 2022, since collection of AQI data started in 2015. (Arvind Yadav/HT Photo)

The air quality index (AQI) data for Delhi and other NCR cities was unavailable for Wednesday due to a glitch in the National Informatics Centre’s (NIC’s) server following a power outage late Tuesday, according to an official with the Commission for Air Quality Management (CAQM) for NCR and adjoining areas.

Shortly after 4pm on Wednesday, the Central Pollution Control Board (CPCB) uploaded their hourly data, according to which Delhi’s AQI was 140 (“moderate”). However, minutes later, the data changed and showed Delhi’s AQI as 278 (“poor”).

A CPCB official said that the server issue was fixed around 4pm and the hourly data was being collected. The official, not wanting to be named, said that the 24-hour average would be uploaded by end of Wednesday. As of 10pm on Wednesday, it was still not available.

Delhi recorded a 24-hour average AQI of 283 (“poor”) at 4pm a day earlier, as wind speed dropped across the Capital on Tuesday, which led to a deterioration in air quality, with Delhi’s air back in the ‘poor’ range. The AQI was 173 (moderate) at the same time on Monday.

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”.

Forecasts by the Centre’s Early Warning System for Delhi (EWS) show that air quality is likely to be in the “poor” category on Thursday and may deteriorate further after.

“The air quality is likely to be in poor category on January 2, 2025. The air quality is likely to be in very poor category from January 3-4, 2025. The outlook for subsequent six days is that the air quality is likely to be in very poor to poor category,” EWS said in its bulletin on Wednesday evening.

Delhi air improved in ’24

Delhi recorded the highest number of “good” and “moderate” air days since 2015—barring 2020, when Covid-19 lockdown was in place—clocking 209 such days, according to data released by CAQM on Tuesday.

“Barring Covid year, which witnessed long spells of very low anthropogenic, industrial and commercial activities, 2024 recorded the highest number of ‘good to moderate’ air quality days,” CAQM said in a release.

The average AQI last year was 209, which was Delhi’s second best and on a par with 2021 and 2022, since collection of AQI data started in 2015. The lowest average AQI was recorded in 2020, at 185.

Further, 2024 clocked the fewest “poor” and “severe” air days—again, barring 2020—due to fewer farm fires, CAQM said, citing 10,909 farm fires in Punjab, 1,406 in Haryana and a total of 12,750, including NCR areas of UP, Rajasthan and NCT of Delhi.