Tuesday - 5 March 2024 - 5:04 AM

Diwali air quality analysis in 11 capital cities

Dr. seema javed

Unseasonal rain ahead of Diwali made the high pollution levels of several capital cities such as Delhi, Mumbai and Chennai dip just ahead of the festival. But the Supreme Court’s firecracker ban was flouted in many places, and air pollution started to spike on the night of November 12th and touched hazardous levels in quite a few places.

NCAP Tracker analysed PM 2.5 (fine particulate matter) data for 11 capital cities, viz. Bengaluru,
Bhopal, Chandigarh, Chennai, Delhi, Gandhinagar, Hyderabad, Mumbai and Patna, for the
day before Diwali, the day of Diwali and the day after Diwali (till 12 pm) for the years 2022 and 2023.

The data was sourced from the Continuous Ambient Air Quality Monitoring Stations (CAAQMS) of the Central Pollution Control Board (CPCB).

Key Highlights:

1. On November 11, 2023 – a day before Diwali this year – eight of the 10 capital cities
analysed, viz. Bengaluru, Bhopal, Chandigarh, Chennai, Delhi, Hyderabad and
Mumbai, had lower PM 2.5 levels as compared to October 23, 2022, the day before Diwali
last year. For the same days, Gandhinagar, Kolkata and Patna had levels that were higher in
2023 than in 2022.

2. On November 12, 2023, that is, Diwali day, only three cities – Bengaluru, Delhi and
Gandhinagar – had PM 2.5 levels lower than those on Diwali in 2022, that is, on October 24.

3. PM 2.5 levels on this Diwali and for the 12 hours after (till noon on November 13) were
above the Central Pollution Control Board’s (CPCB) daily average ‘good’ limit of 30 ug/m3
in all the cities that were analysed.

4. Among the 11 cities, the highest average PM 2.5 level on the day of Diwali 2023 was
observed in Patna. At 206.1 ug/m3, the level as over 13 times more than the WHO’s daily
safe limit of 15 ug/m3.

5. On November 13 (from midnight to 12 pm), Delhi recorded the highest PM 2.5 average of
395.9 ug/m3 among all the cities analysed.

6. Bengaluru recorded lower PM 2.5 averages in 2023 as compared to 2022 for the day before
Diwali, Diwali day and the day after Diwali. Additionally, on the day after Diwali 2023, it
recorded the lowest PM 2.5 average among the 11 cities analysed in this report.

7. Among the 11 cities, the highest spike (recorded at 15-minute intervals) was seen in Delhi. It
was at 999.5 ug/m3 at Pusa on November 13 at 1:30 am. Several other capital cities also saw
extremely high PM 2.5 levels on this year’s Diwali and the following day (November 13), from
midnight to 12 pm.

8. All cities saw PM 2.5 levels peak between midnight and 1:30 am on November 13, 2023.

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