Science & Tech · Science & Environment · 5 hrs ago
PM2.5 data missing at Delhi stations during Deepavali pollution peak
After Deepavali night, PM2.5 readings went missing for hours at several Delhi monitoring stations as pollution peaked.
The gaps affected stations including Anand Vihar, Patparganj and Bawana, according to the Delhi pollution-control authorities’ websites.
From midnight to 5 a.m.
on November 9, 227 hourly readings were missing across 59 central monitoring stations, and only 14 stations had complete data.
PM2.5 consists of fine particles that can enter the lungs and bloodstream, and an air-quality analyst said missing readings can make the AQI appear better than conditions really are.
Before readings disappeared, Patparganj’s PM2.5 level reached 2,597 micrograms per cubic metre, while Delhi’s AQI later reached the severe category at 4 a.m.
Delhi Labour Minister Kapil Mishra said the government would look into the missing data and inform the media.
Stage III pollution-control measures are in force in Delhi and adjoining districts in Haryana, Uttar Pradesh and Rajasthan.
PM2.5 readings went missing for hours at several government monitoring stations in Delhi during the pollution peak after Deepavali night.
Between midnight on November 8 and 5 a.m. on November 9, 227 hourly PM2.5 observations were missing across 59 CPCB monitoring stations.
Only 14 of those stations reported complete data, while 45 had at least one missing hourly observation.
A CREA analyst said missing hourly data could make the AQI appear lower than it would be if actual pollution levels were reflected.
Delhi’s AQI reached 404 in the severe category at 4 a.m. on November 9, according to the CPCB live dashboard.
- Who
- Delhi government and central government monitoring stations, and Manoj Kumar of CREA.
- What
- PM2.5 readings were missing for several hours at multiple stations during the pollution peak after Deepavali.
- When
- Overnight from November 8 to November 9, 2026.
- Where
- Delhi, including stations at Anand Vihar, Patparganj and Bawana.
- Why
- Not stated.
This story does not have two clearly opposing sides.
227 hourly PM2.5 observations were missing across 59 CPCB monitoring stations in Delhi.
Patparganj recorded PM2.5 at 2,597 micrograms per cubic metre before data went missing for two hours.
Anand Vihar recorded PM2.5 at 1,396 micrograms per cubic metre after data had been missing for three hours.
Delhi’s AQI reached 404 in the severe category, according to the CPCB live dashboard.
Delhi’s 24-hour average AQI was 370 in the very poor category.
- Missing observations
- 227 hourly PM2.5 readings across 59 CPCB monitoring stations
- Complete data
- 14 stations reported complete data; 45 had at least one missing observation
- Patparganj PM2.5
- 2,597 micrograms per cubic metre at 1 a.m. on November 9
- Anand Vihar PM2.5
- 1,396 micrograms per cubic metre at 3 a.m. on November 9
- Delhi AQI
- 404 at 4 a.m.; 370 24-hour average at 9 a.m. on November 9
What people are saying
When the hourly PM2.5 data is missing, it will artificially lower the Air Quality Index (AQI), showing better air quality, when the actual air quality is worse
the government will look into the issue within an hour and inform the media about it