Delhi records most polluted Diwali in 5 years; AQI remains ‘very poor’ a day later

Delhi recorded its most polluted Diwali in five years, with the average Air Quality Index (AQI) touching 376 on Sunday. Pollution levels remained high on Monday, with the overall AQI standing at 371 at 10 am, as a blanket of smog and fog enveloped the city.

The post-Diwali AQI was the highest recorded on the day after the festival since 2021, according to Central Pollution Control Board (CPCB) data.

Of the 51 monitoring stations that recorded data on Monday morning, 14 were in the severe category, four in the poor category and the remaining 33 in the very poor category. Delhi Technological University recorded the worst reading at 439. The overall AQI had stood at 370 at 8 am.

The average AQI on Diwali was the highest since 2021, when it was recorded at 382. The corresponding figures were 345 in 2025, 328 in 2024, 218 in 2023 and 312 in 2022.

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.

The city woke up to thick smog and fog on Monday, with visibility dropping sharply at both major weather stations.

At Safdarjung, visibility fell to 50 metres at 6.30 am, compared with 700 metres a day earlier. At Palam, it stood at 400 metres against 800 metres on Sunday.

Visibility subsequently improved. At 9 am, it was 500 metres at Safdarjung and 900 metres at Palam, with both stations reporting shallow fog, according to India Meteorological Department (IMD) data.

Safdarjung recorded dense fog from 2.30 am to 9 am, following shallow fog between 10.30 pm and 2.30 am. At Palam, moderate fog was reported from 5 am to 8.30 am after shallow fog earlier in the night.

“It is smog along with fog,” IMD officials said.

They attributed the hazy conditions and changes in AQI to dry weather and calm winds. Winds remained calm over Safdarjung and Palam during the previous evening.

Swiss air quality monitoring platform IQAir classified Delhi's air quality as very unhealthy on Monday morning, recording an AQI of 245 at 8.30 am. PM2.5 concentration stood at 170 micrograms per cubic metre, around 34 times the World Health Organisation's annual guideline value.

Meanwhile, AQI.in recorded Delhi's AQI at 2,283 at 9 pm on Sunday, with six other Indian cities also reporting readings above 1,000. On Monday morning, the platform recorded Delhi's AQI at 637 and classified it as hazardous.

Several areas, including Bawana, Burari, Jahangirpuri, Sonia Vihar, Punjabi Bagh, Okhla and Rohini, continued to record severe air quality on Monday.

Despite restrictions on firecrackers, fireworks were reported in several parts of the capital on Sunday evening, including Pitampura, Burari, Mayur Vihar and parts of Lutyens' Delhi.

An order issued by the district magistrate (East) had permitted the bursting of green firecrackers only on 7 and 8 November, between 6 am and 7 am and 8 pm and 10 pm. Residents reported that fireworks continued beyond the permitted evening window, with particularly high activity in Pitampura, Burari and Mayur Vihar.

The order also prohibited firecrackers within 300 metres of hospitals, nursing homes, health centres, old-age homes, educational institutions and other notified silence zones.

Only CSIR-NEERI-certified green firecrackers were permitted for sale at locations designated by the Delhi Police in coordination with the district administration. Joint patrolling and enforcement teams had also been announced to check unauthorised sales and the use of prohibited firecrackers.

According to the Air Quality Early Warning System (EWS), Delhi's air quality is likely to remain in the severe category over the next few days.

The EWS said a ventilation index below 6,000 square metres per second, coupled with average wind speeds of less than 10 kilometres per hour, was unfavourable for the effective dispersal of pollutants.

Unfavourable weather conditions, vehicular emissions, Diwali celebrations and the ongoing peak stubble-burning season in neighbouring states are among the factors expected to contribute to the deterioration.

The CPCB classifies AQI readings of 0–50 as good, 51–100 as satisfactory, 101–200 as moderate, 201–300 as poor, 301–400 as very poor and 401–500 as severe.