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The air quality in Delhi reached alarming levels on Diwali this year, with PM2.5 concentrations peaking at 603 micrograms per cubic meter (µg/m³) on the midnight of October 31st. This marked a significant increase of nearly 13% compared to Diwali peaks observed in both 2022 and 2023, as revealed by an analysis conducted by the Centre for Science & Environment (CSE). The analysis also revealed that PM2.5 concentrations surged by almost 46% from October 28th to October 31st, coinciding with the peak of firecracker usage during the festivities.
The analysis, led by Anumita Roychowdhury and Sharanjeet Kaur, highlighted that PM2.5 levels during Diwali were more than twice as high as the average night-time pollution recorded over the preceding seven nights. The Air Quality Forecasting system, run by IITM Pune, had issued a warning about severe pollution levels on October 31st and November 1st due to emissions from firecrackers and stubble/waste fires. Furthermore, the daytime PM2.5 levels on Diwali were nearly 92% higher than last year's average, pointing towards a significant contribution from local and regional sources, particularly from farm fires, which saw a sharp increase.
The analysis identified nine air quality monitoring stations where PM2.5 concentrations exceeded the critical threshold of 900 µg/m³ on Diwali night. The highest levels were recorded at Nehru Nagar (994 µg/m³), Anand Vihar (992 µg/m³), Pusa IMD (985 µg/m³), Wazirpur (980 µg/m³), and JLN Stadium (963 µg/m³). The Diwali night also saw higher levels of NO2 compared to last year, indicating increased traffic congestion and road activity during the festival. Researchers have noted that NO2 levels have been consistently higher on Diwali night and the preceding nights for the past three years.
While the relatively warm weather in October, the warmest since 1901, provided some relief, with adequate winds facilitating quicker dissipation of pollutants, the air quality in Delhi is expected to worsen in the coming days as temperatures drop. Despite a gradual decline to moderate levels by the afternoon of November 1st, preventing a smog episode, the increase in farm fires, particularly on October 31st, has contributed to a 27% increase in Delhi's air pollution. Data from the Indian Agricultural Research Institute (IARI) shows a sharp rise in fire count, going from 380 on October 30th to 605 on October 31st and 983 on November 1st, with Punjab accounting for the majority (80%) of the fires.
Experts emphasize the significant impact of local air pollution sources, even with a relatively low share of smoke from farm fires this season, highlighting the need for swift and large-scale mitigation measures. The alarming pollution levels on Diwali serve as a stark reminder of the ongoing air quality challenges in Delhi and the urgent need for collaborative efforts to address them.