Worst Diwali night air in Delhi in at least 3 years as firecrackers burst almost non-stop

The city’s air quality index (AQI) at 11 pm on Monday, as per Central Pollution Control Board (CPCB) data, stood at 347, in the ‘very poor’ category. It remained nearly unchanged, at 346 at 6 am Tuesday, and by 11 am, it had reached 359. It finally settled at 351 at 4 pm.

According to CPCB data, Delhi’s air quality on Diwali this year (AQI 345) was worse than last year (328 in 2024), and higher than the previous two years — 218 in 2023 and 312 in 2022. 

This is significant especially as this year the Supreme Court relaxed ban on firecrackers to allow less polluting green crackers.

While on Tuesday, the city’s average AQI rose to 351 in the very poor category, last year, Delhi had recorded an AQI of 328 on October 31 (Diwali day), which worsened to 339 (very poor) by 4 pm the next day. In 2023, the AQI on Diwali day (November 12) was 218 (poor) and climbed to 358 the following day. On November 5, 2021, the most polluted post-Diwali day was observed in recent years as the AQI reached 462 (severe). 

Hourly data also showed sharper night-time spikes despite Diwali being early this year, with several stations recording PM2.5 and PM10 concentrations above 1,500 µg/m³, unlike last year when the highest spike was around 1525µg/m³, at Nehru Nagar. 

The Nehru Nagar PM2.5 peak concentration reached 1,763 µg/m³ around 10 pm on Monday, which was almost 30 times the national 24-hour permissible limit of 60 µg/m³. 

The spikes that began around 8 pm on Monday and intensified past midnight, coinciding with the widespread bursting of firecrackers across the city. 

According to DPCC data, Anand Vihar recorded the highest PM10 concentration at 1,824 µg/m³ around 2 am, followed closely by Dwarka Sector 8 (1,602 µg/m³ at 10 pm), Patparganj (1,591 µg/m³ at 10 pm), and Jahangirpuri (1,486 µg/m³ at 1 am).

Among PM2.5 readings, the highest concentrations were logged at Nehru Nagar (1,763 µg/m³ at 10 pm), R K Puram (1,476 µg/m³ around midnight), Punjabi Bagh (1,432 µg/m³ at 1 am) and Sri Aurobindo Marg (1,431 µg/m³ at 4 am). 

Stations such as Mundka, Ashok Vihar, and Okhla Phase 2 also reported values exceeding 1,000 µg/m³ during late night.

At several locations, data was missing for multiple hours between 11 pm and 5 am, suggesting possible instrument saturation due to extremely high PM concentrations. For instance, stations at Patparganj, Nehru Nagar, JLN Stadium, and Okhla Phase 2 had gaps through the night, resuming early morning with readings still several times the safe limits.

Former DPCC additional chairperson Dr Mohan George pointed at the gaps in monitoring with several stations, including Najafgarh and Anand Vihar showing missing data. 

“Many stations have data missing from 11 pm to 6 am… If this was a ‘Green Diwali’, then the public deserves to know what exactly they breathed during the night,” Mohan George, former additional director of the DPCC, said.

“Why was CPCB’s continuous air quality tracking unavailable for several hours, and why did most monitoring stations show missing data during the peak pollution window?” he asked.

However, by 9 am on Tuesday, pollution levels, though still elevated, had reduced sharply due to wind conditions of less than 1 m/s (metre per second).

Most stations still recorded PM 2.5 between 300 and 500 µg/m³, nearly five to eight times above the 24-hour permissible limit of 60 µg/m³. For instance, Mandir Marg reported 365 µg/m³, Sonia Vihar 333 µg/m³, and Rohini around 396 µg/m³ at 9 am.

An analysis by research and advisory group Climate Trends, based on CPCB data, found that Delhi’s average PM2.5 concentration surged to 488 µg/m³ in the 24 hours following Diwali, which is over three times higher than the pre-festival average at 156.6 µg/m³. 

The study examined air quality patterns between 2021 and 2025, and found that PM2.5 levels consistently spiked during Diwali night and the early morning hours that followed. The post-Diwali average this year was the highest pollution level recorded since 2021, it added.

Punjab and Haryana together recorded only 175 stubble burning incidents between October 1 and 12 this year, down from 779 during the same period last year — a 77.5% dip in farm fires this October due to these neighbouring regions experiencing floods.