Delhi Air Pollution: The Delhi Pollution Control Committee (DPCC) released the missing hourly air-quality data for Diwali night around 8 PM on Monday. The delayed figures reveal that PM2.5, the hazardous fine particulate matter in firecracker emissions, surged up to 3,744 micrograms per cubic metre (µg/m³). This is over 60 times the national 24-hour standard of 60 µg/m³, Hindustan Times reported. 

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The most severe spikes were recorded across multiple monitoring stations during the early hours of November 9:

  • Mundka: Recorded 3,744 µg/m³ at 2:00 AM.
  • Jawaharlal Nehru University (JNU): Recorded 3,023 µg/m³ at 4:00 AM.
  • NSUT West Campus: Recorded 3,008 µg/m³ at 5:00 AM.
  • Mandir Marg & Nehru Nagar: Recorded 2,908 µg/m³ and 2,808 µg/m³, respectively, at 3:00 AM.
  • Wazirpur: Recorded 2,721 µg/m³ at 1:00 AM.

Overall, 11 DPCC monitoring locations surpassed 2,000 µg/m³, the report added. 

Every single hour out of the 125 station-hours missing from Central Pollution Control Board (CPCB) records was above 1,000 µg/m³ on DPCC's website. While values match where both data sources are present, CPCB's central framework capped maximum readings for the night at 1,000 µg/m³.

What Happened On Diwali Night?

As air quality deteriorated on November 8, 36 out of Delhi’s 59 monitoring stations went blank in CPCB's database by 1:00 AM.

Speaking to Hindustan Times, an official stated that technical glitches caused the temporary blackout, confirming that all 43 DPCC stations were operational and recording hourly numbers.

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Because India's Air Quality Index (AQI) formula caps hourly sub-indices at 500 once PM2.5 crosses roughly 420 µg/m³, readings in the thousands have a limited impact on the upper scale limit.

However, factoring the newly released numbers into CPCB's standard formula pushes Delhi's overall AQI for the 24 hours ending at 9:00 AM on November 9 to approximately 384, up from the published 370, while the 4:00 PM bulletin figure rises from 344 to around 360, the report added. These figures are provisional, and as of 7:58 PM on Monday, the newly released values had not yet been integrated into CPCB's records.