Delhi experienced a significant spike in PM2.5 pollution levels on Diwali night this year, reaching a peak of 603 µg/m³ by midnight—13% higher than the previous two years' peaks, according to a report by the Centre for Science and Environment (CSE). The elevated pollution was largely attributed to a combination of firecracker usage, increased traffic congestion, and rising farm fires in neighboring states.
Key findings from the CSE report indicated that the PM2.5 levels had already been steadily increasing in the days leading up to Diwali, with a notable 46% rise from October 28 to October 31. Additionally, the 12-hour PM2.5 concentration on Diwali night this year was 34% higher than in 2022. However, unlike previous years, there was a unique trend this Diwali: a sudden surge in pollution levels at night followed by a quicker dissipation by noon the next day. This prevented the pollution from forming a prolonged smog episode, as seen in prior years. By midday on November 1, PM2.5 levels had dropped to a moderate level of 97 µg/m³.
Warm atmospheric conditions, adequate wind, and efficient ventilation in the city contributed to this faster dissipation. This October was reported as one of the warmest, which may have aided the natural clearing of pollutants.
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The report also highlighted the role of increased farm fires in worsening Delhi's air quality. On Diwali day, the number of stubble-burning incidents rose sharply from 60 on October 30 to 605 on October 31. Punjab accounted for 80% of these incidents, followed by Uttar Pradesh (13%) and Haryana (7%), collectively increasing Delhi’s pollution share by 27%.
Nitrogen dioxide (NO2) levels, an indicator of traffic congestion, were also higher this year on Diwali night. ITO recorded the highest NO2 levels at 182 µg/m³, followed by JLN Stadium (104 µg/m³) and Patparganj (101 µg/m³), reflecting the impact of traffic buildup. Lodhi Road, with an NO2 level of just 2 µg/m³, remained the least affected area in the city.
The report sheds light on the ongoing challenge of managing air quality in Delhi, particularly during the festive season when pollution sources like firecrackers, vehicle emissions, and agricultural burning converge to intensify the city's air pollution problem.