Delhi records 3rd worst Diwali pollution since 2021, data gaps cloud full picture

Delhi recorded its third worst Diwali air pollution in the past seven years, according to available data. Many air quality stations went dark during the peak hours, making it difficult to assess the full extent of the pollution. Despite relatively favorable weather, the air quality remained in the "severe" category, which is considered the most harmful level.

Over 80% of the functioning stations reported "severe" air quality from 10 pm on Diwali night until 6 am the next morning, with 61% of the reporting stations having an Air Quality Index (AQI) of 400 or higher at 9 pm on Diwali. This analysis used six stations that consistently reported data during Diwali nights from 2021 to the present, revealing that Delhi's air pollution was third worst for most hours after the Diwali night.

The peak PM2.5 sub-index averaged 655, which was the third highest peak pollution in recent years, surpassed only by 2021 and 2025. The pollution levels were notably lower in 2022-2024, averaging 483, 583, and 489, respectively. Favorable weather conditions likely contributed to the reduced pollution levels this year, as meteorological data from Palam shows it was among the warmest three to four Diwalis since 2021.