Firecrackers accounted for 71% of Delhi’s PM2.5 pollution on day after Diwali: Study

Millat Times Desk

11 November 2026 (Publish: 10:30 AM IST)

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Firecrackers were the biggest contributor to Delhi’s fine particulate matter pollution on November 9, accounting for 71% of the city’s PM2.5 levels, according to data from the Indian Institute of Tropical Meteorology (IITM).

The data, published by IITM’s Air Quality Warning and Integrated Decision Support System for Delhi, showed a sharp rise in pollution from firecrackers around Diwali, which was celebrated on November 8 in most parts of north India.

Firecrackers accounted for 43.4% of Delhi’s PM2.5 pollution on Diwali, compared with 5.6% on November 5, 9.3% on November 6 and 5.6% on November 7.

Their contribution remained the highest among identified pollution sources on November 9, while vehicle emissions accounted for 6.9% of PM2.5 levels.

The share of firecrackers declined to 29.8% on November 10, the data showed.

The figures are part of IITM’s source apportionment exercise, a scientific method used to identify and estimate the contribution of different sources to air pollution.

Sachin Ghude, an IITM scientist who heads the institute’s decision support system, told The Wire that this was the first time firecrackers had been assessed separately in the source apportionment analysis.

The IITM data were based on 24-hour averages for all dates except November 10, when measurements covered only 1 am to 9 am, Ghude told The Wire.

The exercise was intended to distinguish pollution from firecrackers from that caused by stubble burning, which typically intensifies during the same period, he said.

Ghude warned that the high concentration of pollutants released by firecrackers posed a health risk. He also pointed to elevated levels of toxic metals, including lead and aluminium.

Lead concentrations peaked at 20.788 micrograms per cubic metre during the night, he said.

The Central Pollution Control Board’s National Ambient Air Quality Standards prescribe a 24-hour permissible limit of 1 microgram per cubic metre for lead in ambient air.

PM2.5 refers to fine particles with a diameter of 2.5 micrometres or less. These particles can penetrate deep into the lungs and enter the bloodstream, increasing the risk of respiratory and cardiovascular illnesses.

Firecrackers release particulate matter through the burning of chemical compounds, including potassium nitrate, sulphur and charcoal, as well as metals used to produce different colours and effects.

The impact can be particularly severe during winter in northern India, when weak winds and stagnant atmospheric conditions restrict the dispersal of pollutants.

A study published in the journal Scientific Reports said pollution spikes across the Indo-Gangetic Basin were often intensified by stagnant post-monsoon weather, allowing pollutants to remain trapped in the atmosphere for several days.

Prolonged exposure to such pollution can increase the risk of respiratory emergencies, including asthma and chronic obstructive pulmonary disease (COPD), cardiovascular events and premature deaths, particularly among children, older people and those with existing health conditions.