Delhi's air quality reached the severe category at 20 of its 59 monitoring stations on Diwali night, November 8, 2026, despite restrictions on firecracker use imposed by the Supreme Court.
An analysis of air quality data from 2017 to 2025 also shows that pollution levels worsened across Delhi-NCR on the day after Diwali in eight of the nine years examined, raising questions about the effectiveness of existing pollution control measures.
According to real-time data from the Central Pollution Control Board (CPCB), Delhi's overall Air Quality Index (AQI) stood at 370 at 9 pm on November 8 and rose to 373 by 11 pm, remaining in the 'very poor' category. PM2.5, fine particulate matter that can penetrate deep into the lungs, was the dominant pollutant.
At around 10 pm, 20 monitoring stations recorded AQI readings above 400, classified as 'severe'. Sonia Vihar recorded 463 and Jahangirpuri 450, while 33 stations reported 'very poor' air quality and six were in the 'poor' category.
The pollution persisted overnight, with Delhi's AQI recorded at 367 at 3 am on November 9.
Several neighbouring cities also recorded deteriorating air quality between 9 pm and 11 pm on Diwali.
Ghaziabad's AQI increased from 353 to 360, Noida's from 312 to 319 and Gurugram's from 276 to 280. Greater Noida's AQI rose from 299 to 301, crossing into the 'very poor' category.
However, pollution levels declined slightly in Ballabhgarh and Bulandshahr.
Among 285 cities monitored nationally, Delhi ranked fourth for pollution at 11 pm, behind Mandi Gobindgarh (389), Khora (384) and Ballabhgarh (383).
The CPCB's 24-hour average AQI for Delhi was 376 on November 8, compared with 369 the previous day. These daily averages differ from real-time hourly readings and should not be directly compared.
An analysis of AQI data for Delhi, Ghaziabad, Noida, Greater Noida, Gurugram and Faridabad between 2017 and 2025 shows a consistent pattern of worsening pollution immediately after Diwali.
In eight of the nine years, the average AQI across the cities increased the following day. The exception was 2022.
Of 52 available city-level comparisons, AQI increased on 44 occasions, declined seven times and remained unchanged once. This means pollution worsened in approximately 85 per cent of the observations.
The sharpest increases were recorded in some years when Diwali fell in November.
In 2018, the average AQI across the six cities rose from around 269 on Diwali to 416 the following day. In 2021, it increased from 387 to approximately 469, with all six cities recording readings around 460 or higher.
In 2023, the average AQI increased by approximately 88 per cent, from 187 to 352. Delhi's AQI rose from 218 to 358, while Noida's increased from 189 to 363.
However, 2022 bucked the trend, with the six-city average declining from approximately 295 to 287.
The pattern was also evident in years when Diwali fell in October. Average AQI rose from 340 to 378 in 2019, from 276 to 281 in 2024 and from 291 to 319 in 2025.
A complete comparable dataset for 2026 was not yet available at the time of the analysis.
The Supreme Court has repeatedly intervened to regulate firecracker sales and use in Delhi-NCR since 2016, moving between bans, restrictions and limited permissions.
In November 2016, the court suspended wholesale and retail firecracker sale licences in Delhi-NCR. It subsequently introduced phased restrictions, including permission for certified green firecrackers and limits on bursting times.
In October 2018, the court restricted Diwali firecracker use to between 8 pm and 10 pm, while prohibiting certain chemicals and unlicensed sales.
Further orders in 2021 and 2023 reinforced restrictions on prohibited firecrackers, including those containing barium.
In 2024 and early 2025, the court moved towards year-round bans across Delhi-NCR, directing neighbouring states to introduce similar restrictions.
However, in October 2025, it permitted certified green firecrackers for limited periods on a trial basis.
On October 29, 2026, the court again allowed their use between 6 am and 7 am and between 8 pm and 10 pm on November 7 and 8.
Firecrackers were prohibited within 300 metres of hospitals, healthcare centres, old-age homes and notified silence zones. A complete ban was to resume from November 9.
Despite these measures, several Delhi monitoring stations recorded severe pollution on Diwali night.
Firecrackers are not the only factor contributing to Delhi's post-Diwali pollution.
The city's air quality early warning system forecast severe pollution from November 9, citing unfavourable weather conditions, vehicle emissions, firecrackers and agricultural residue burning in neighbouring states.
Low wind speeds and poor atmospheric ventilation can trap pollutants close to the ground, allowing concentrations to build up.
According to the forecast, transport was expected to contribute around 19 per cent of Delhi's pollution on November 8, while stubble burning accounted for an estimated 3.5 per cent. Its projected contribution for November 9 was approximately 2.99 per cent.