Delhi pollution on Diwali rockets to worst in 5 years

Delhi experienced its most polluted Diwali day in five years on November 8, with the Air Quality Index (AQI) reaching 376 at 4pm. The city narrowly avoided its worst post-Diwali pollution day in five years, with the AQI dipping from 370 at 11am to 344 by 4pm, better than the 2025 post-Diwali air quality. The AQI for Diwali in 2025, 2024, 2023, 2022, and 2021 was 345, 328, 218, 312, and 382 respectively. Post-Diwali, the AQI in 2025 was 351, 339, 358, 303, and 462 respectively.

Several monitoring stations failed to report crucial AQI data on Diwali day. Hourly data went missing for 35 air quality monitoring stations. Only 47 stations contributed to the average AQI on the day, out of the 60 monitoring stations managed by the Delhi Pollution Control Committee, Central Pollution Control Board, Indian Institute of Tropical Meteorology, and Indian Meteorological Department. Firecrackers emerged as the biggest contributor to pollution a day before Diwali, accounting for 41.1% of the total load.

Traces of lead, potassium, and sulphur in the air were confirmed, although officials could only confirm the presence of mercury in a long-term study. At midnight on Diwali night, the Indian Institute of Tropical Meteorology recorded its highest average PM2.5 concentration, at 671.1 micrograms per cubic metre. Among individual stations, Jahangirpuri in northwest Delhi recorded a peak of 4,985 µg/m³ on Sunday night and Monday morning.

The post-Diwali reprieve was attributed more to meteorological conditions than pollution-control measures. An unusual shift in winds from northwesterly to strong easterly aided in the rapid dispersion of pollutants, preventing a sharper spike in pollution levels, especially when Punjab saw the highest farm fire incidents of the season. Experts warned that winter conditions could bring back familiar pollution levels, with deteriorating air quality posing a significant health risk.