Delhi pollution after Diwali: firecrackers over 80% on November 9, IITM data

Firecrackers were responsible for more than 80% of Delhi's estimated pollution load on Monday, 9 November 2026, the morning after Diwali, according to source-analysis data from the Indian Institute of Tropical Meteorology (IITM) reported on 10 November. A separate analysis of the same IITM data put firecrackers' share of fine particulate matter (PM2.5) at 71.1% between 1 am and 9 am that day. By the next day the picture had changed: IITM estimated that firecrackers accounted for 29.9% of the pollution between 1 am and 9 am on Tuesday, 10 November. The data suggest stubble burning was not a significant contributor on 9 November. Delhi's Air Quality Index (AQI) stood at 366, in the "very poor" category, at 6.15 am on 9 November.

Every winter, Delhi argues over what causes its worst air: vehicles, industry, construction dust, crop-stubble fires in Punjab and Haryana, or Diwali fireworks. Source-apportionment tools, such as the decision support system run with IITM, estimate how much each source contributes on a given day. They are models, not direct measurements, but they give policymakers a way to see which source is driving a spike.

This year's figures point clearly at the festival night. When more than four-fifths of the estimated pollution load on the morning after Diwali comes from firecrackers, and stubble burning is not a major factor that day, the spike was largely self-made in the city. The sharp fall to under 30% a day later shows how quickly the firecracker effect fades once bursting stops, while the city's other sources remain.

The finding matters for policy. The Supreme Court allowed green crackers, which are meant to emit less, in Delhi-NCR on 7 and 8 November. The data do not show how much of the smoke came from green crackers and how much from conventional ones, but they will feed into the debate on whether permitted crackers, bursting hours and enforcement worked. For citizens, the lesson is that the worst hours were overnight and early morning after Diwali, when outdoor exercise and school travel carry the most exposure.

Peepals timeline: The Supreme Court permitted green crackers in Delhi-NCR on 7 and 8 November 2026. Diwali celebrations followed, and at 6.15 am on Monday, 9 November, Delhi's AQI was 366. IITM's source analysis put firecrackers at more than 80% of the pollution load that day, and at 71.1% of PM2.5 between 1 am and 9 am. By Tuesday, 10 November, their share between 1 am and 9 am was down to 29.9%, according to the reported data.

Short-term: Delhi's air stayed in the "very poor" range after Diwali, though the firecracker share dropped sharply by 10 November.

Long-term: The data will inform decisions on cracker permissions and enforcement for future festivals, and the wider debate on Delhi's winter pollution sources.

Who is affected: Delhi residents, especially children, older people and those with breathing problems; pollution-control authorities; and courts deciding on cracker rules.

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