Fireworks explode during Deepavali celebrations in Amritsar on October 31, 2024.
| Photo Credit: AFP

Ninety nine of the 265 cities for which Air Quality Index (AQI) data were available on the Central Pollution Control Board website reported “poor” air quality on Friday, November 1, 2024 (data for 24 hours prior to 4 p.m. on this day).

An AQI value of 200 or above corresponded to “poor” quality.

Thirteen cities, including Delhi, Gurugram and Ghaziabad in the National Capital Territory Region, recorded “very poor” air quality — AQI of 300 or above.

Ambala in Haryana and Amritsar in Punjab recorded the highest values of 367 and 350, respectively, while Delhi’s average AQI was 339.

These 24 hours corresponded to the period when Deepavali revellers took to burning crackers, defying a ban on it in places such as Delhi. Revellers burnt crackers on Thursday (October 31, 2024), before 4 p.m. as well.

On Thursday (October 31, 2024), the number of cities that had “very poor” and “poor” air quality was relatively fewer — six, including Delhi (second highest AQI of 328), and 43, respectively. On Wednesday (October 30, 2024), a day prior to Deepavali celebrations, only Delhi registered “very poor” air quality, with an AQI of 307. The number of cities with “poor” AQI was even fewer — 24, almost all of them in North India.

Large cities such as Mumbai, Chennai, Bengaluru, Hyderabad, and Kolkata registered a “moderate” AQI on Friday, but even among them, the AQI values had jumped from those registered on October 30.

Data from 2023 corresponding to Deepavali celebrations show that Delhi’s AQI was high at 358 on November 12, corresponding to a “very poor” air quality, jumping from 218 (“poor”) the previous day. A similar pattern was observed last year too.

Fifty-three and 85 cities had “very poor” and “poor” AQI, respectively on November 12 and 13 as compared with eight and 42 cities the previous day.

Pollution during winter

In cities such as Delhi and others in northern India, pollution levels peak during the winter season due to emissions from vehicles, industries, garbage burning and construction, besides stubble burning after the paddy season in neighbouring States with particles being trapped in the cold air.

Unfavourable winds in the early winter months that don’t flush the pollutants out, also lead to faster build-up. Firecracker burning has also contributed to exacerbating air quality during this period. On Friday, Delhi’s Anand Vihar station recorded its 10th highest concentration of PM2.5 this year (273.04 micrograms per cubic metre) if 24-hour values were considered. All nine others were in January, when winter peaks in the city.