Understanding Delhi's Diwali pollution in 5 graphs

The AQI for Anand Vihar was 386 at 11 pm on the night of October 31 — much higher than last year's 302 on Diwali night.

Despite a blanket ban on firecrackers in Delhi-NCR, Diwali night in the region saw no dearth of fireworks. The revelry took the air quality index above 350 at most stations.

The AQI for Anand Vihar was 386 at 11 pm on the night of October 31 — much higher than last year's 302 on Diwali night. The AQI on 2022’s Diwali night was 374 and 440 in 2021. This shows a clear upsurge after a decline over the past couple of years.

The day after Diwali usually sees a surge in AQI levels. At 5 am on November 1, the AQI was 394 compared to 289 in 2023 at the Anand Vihar monitoring station. Data from the Central Pollution Control Board’s National Air Quality Index also reveals how air pollution is higher this year around Diwali days compared to the previous two years. At Anand Vihar, a “severe” AQI of 412 and 427 was recorded at 5 pm and 11 pm the day before Diwali, i.e. on October 30 this year, and was lower on Diwali day. However, in 2022 and 2023, AQI levels were lower on the day before Diwali and worsened only on the day of the festival.

This year, the festivities have taken a higher toll on almost all regions in Delhi. Of the 56 AQI monitoring stations in the national capital, only one recorded "moderate" levels of pollution, as of 7 am on November 1. Meanwhile, nine stations reported "poor" conditions and 46 rung alarm bells with "very poor" air quality.

An analysis of hourly pollution data for some areas of Delhi shows a similar trend: a sudden and massive spike after 10 pm on October 31 till about 3 am on November 1. The below graphic highlights this trend for Anand Vihar, Wazirpur and Okhla Phase-2, but similar spikes can also be seen for Nehru Nagar, Patparganj and Vivek Vihar.

A study on pollution from firecrackers conducted by Chest Research Foundation in Pune and similar research on air pollution and cigarette equivalence by Berkeley Earth suggest that "snake tablets", a very popular firecracker in India, emit the maximum amount of PM2.5 pollutants, equivalent to smoking 2,932 cigarettes. "Chakris" and "anars", on the other hand, produce 9,490 and 4,860 micrograms per cubic metre of PM2.5 pollutants, equal to smoking 431 and 221 cigarettes respectively.