Delhi woke up on Monday to a grey, toxic morning, recording its most polluted Diwali in five years, as people burst firecrackers beyond permitted hours and pushed air quality to alarmingly high levels. IQAir, a Swiss forecaster specialising in protection against airborne pollutants, recorded Air Quality Index (AQI) of 1,603 and 1,175 at 10 pm in Shahdara and south Delhi’s Defence Colony, respectively. However, real-time readings show Delhi’s AQI climbed to 2,283 after Diwali. Six other Indian cities also recorded AQI levels above 1,000 at 9 pm on Sunday, according to the platform.
PM2.5 readings at many of Delhi’s air monitoring stations climbed towards 1,000 micrograms per cubic metre on Diwali night, and then 36 of 59 monitoring stations went blank. PM2.5, fine particulate matter that can penetrate deep into the lungs and enter the bloodstream, is among the major pollutants of concern because of its adverse health effects.
Later on Monday evening, the Delhi Pollution Control Committee (DPCC) released the hourly air-quality readings for Diwali night at 8 pm. They show PM2.5, the fine particles that firecracker smoke fills the air with, at up to 3,744 micrograms per cubic metre (µg/m³), more than 60 times the national 24-hour standard of 60. Mundka saw the highest reading of 3,744 µg/m³ at 2 am; JNU saw 3,023 µg/m³ just two hours later, while NSUT’s West Campus reached 3,008 µg/m³ at 5 am. Mandir Marg reached 2,908 at 3 am, Nehru Nagar 2,808 at 3 am, and Wazirpur 2,721 at 1 am. Mandir Marg, Nehru Nagar, and Wazirpur were among 11 other DPCC stations where AQI levels spiked dangerously past 2,000.
In fact, not a single station’s PM2.5 level for those missing hours dropped below 1,000, reflecting the severity of the crisis. Every one of the 125 station-hours missing from the Central Pollution Control Board’s (CPCB) records is above 1,000 µg/m³ on DPCC’s website. Where both sources have a reading, the figures match. The highest reading anywhere in CPCB’s records for the night is 1,000. Counting the released readings, CPCB’s own method of calculation puts Delhi’s Air Quality Index (AQI) for the 24 hours to 9 am on November 9 at about 384, against the 370 CPCB published, and its 4 pm bulletin figure at about 360, against 344.
The average PM2.5 concentration across 39 monitoring stations that also reported data last Diwali rose from 190 µg/m³ in the 15 minutes beginning at 7.45 pm to 259 µg/m³ for the 8 pm cycle.
The 8 pm average was more than four times India’s 24-hour PM2.5 standard of 60 µg/m³. PM2.5 is fine dust, particles 2.5 micrometres across or smaller, and micrograms per cubic metre (µg/m³) measures how much of it is in the air.
As citizens gasped and no one in authority stepped up to mitigate the scourge, a ferocious blame game, instead, ensued between the Government and the Opposition. Delhi already had pollution from traffic, construction dust and crop-residue fires in the region. Calm winds, shallow fog, and disregard for restrictions on bursting firecrackers were mainly responsible for the hazardous AQI in the megalopolis.
When winds are weak and a layer of warmer air traps cooler air near the ground, those pollutants accumulate. Fireworks can add to the pollution already there. Smoggy conditions will persist for the next few days.
The average AQI in Delhi was recorded at 376 on Sunday. The next morning, the AQI was 483, dropping to 344 at 4 pm, according to the CPCB. Delhi recorded its most polluted Diwali in five years. Still, the severity was likely worse than official figures showed, as several monitoring stations went offline on Sunday night during the peak period of firecracker use in the Capital, raising questions about the reliability of the AQI tracking exercise itself. AQI readings from private agencies did, in fact, paint a much more unpleasant picture than the official figures, with most parts of Delhi-NCR reporting extremely hazardous air pollution levels and leading experts to question the Government data.
According to the Sameer app, RK Puram and Nehru Nagar, near south Delhi’s Lajpat Nagar, were among the worst-affected locations until 9 pm. Several parts across the capital recorded ‘severe’ air quality on Monday. Sonia Vihar reported the highest AQI at 449, followed by Burari Crossing at 445 and Vivek Vihar at 441; Jahangirpuri recorded 439, while Delhi University’s North Campus stood at 437 and Rohini at 435. Other areas in the ‘severe’ category included DTU (431), Bawana (424), Chandni Chowk and Patparganj (418 each), Mundka (413), NIH Narela and Punjabi Bagh (408 each), Commonwealth Sports Complex (404) and ITO (404). The AQI at ITO had earlier touched 406 at 4:20 am on Monday, according to the CPCB data.
Experts tracking the numbers in real time said the website, which is managed by the DPCC, which comes under the Environment Department of the Delhi Government, often stopped providing data on previous Diwali evenings as well.
From midnight to 2 am, more than 20 stations were not reporting data during peak smog hours, according to an analysis by the Centre for Research on Energy and Clean Air (CREA). Data from Delhi’s 59 air quality monitoring stations showed that the number of stations with missing readings increased sharply as Diwali night progressed, peaking in the early hours of Monday. While only one station had missing data at 7 pm on Sunday, the number rose to seven by 10 pm and 23 by 11 pm.
By midnight, 29 stations were not reporting data, with the number rising further to 36 at 1 am on Monday. This meant that only 23 of the city’s 59 monitoring stations were reporting readings at that time. The gap remained high at 2 am, when 35 stations had missing data, before gradually declining. At 3 am, 30 stations were not reporting, while the number dropped to 20 by 4 am, 19 by 5 am and 16 by 6 am. The situation gradually improved through the morning, with 13 stations having missing data at 7 am and seven at 8 am. By 9 am, only two stations were not reporting data, while one station continued to have missing readings until 11 am.
IQAir’s dashboard also showed a prominent air quality alert for Delhi, with data from 32 monitoring stations provided by 12 contributors. Meanwhile, real-time readings on AQI.in showed that Delhi’s AQI had climbed to 2,283 after Diwali. Six other Indian cities also recorded AQI levels above 1,000 at 9 pm on Sunday, according to the platform. On Monday morning, AQI recorded Delhi’s air quality at 637, classifying it as ‘hazardous’. According to IQAir, the concentration of PM2.5 stood at 170 micrograms per cubic metre, around 34 times the World Health Organisation’s annual guideline value.
After Diwali last year, the AAP had accused the BJP-led Delhi Government of deliberately switching off air quality monitoring stations to conceal the rise in pollution levels. The party claimed that several stations operated by the Central Pollution Control Board (CPCB), Delhi Pollution Control Committee (DPCC), India Meteorological Department (IMD) and Indian Institute of Tropical Meteorology (IITM) had stopped reporting data as pollution levels rose on Diwali night. It is alleged that the stations started functioning again the following morning. Experts monitoring the readings in real time had also reported similar gaps.
According to CPCB data, the Diwali-day AQI of 376 was the highest recorded on the day of the festival since 2021, when it was recorded at 382. Diwali falls on different days in October or November every year. It fell on November 8 this year, October 20 in 2025, October 31 in 2024, November 12 in 2023, October 24 in 2022, and November 4 in 2021. The average AQI on Diwali stood at 345 in 2025, 328 in 2024, 218 in 2023 and 312 in 2022, compared with 382 in 2021 and 376 this year.
The pollution levels remained high on the day after the festival as well. The full-day average AQI on the day after Diwali was 351 in 2025, 338 in 2024, 360 in 2023, 302 in 2022 and 462 in 2021.