Post-Diwali, Kol among 20 cleanest cities on Indo-Gangetic Plain
Times of India | 4 November 2024
Kolkata: Kolkata was among the relatively cleaner 20 cities that are known for their high pollution, based on PM2.5 levels on Nov 1, immediately following Diwali.
Despite widespread fireworks across Kolkata during Diwali, the city managed to fare better in air quality rankings compared to other polluted cities in the Indo-Gangetic Plain (IGP), a region extending from Punjab to Bengal that is notorious for high pollution levels. According to data from the Central Pollution Control Board (CPCB), Kolkata ranked 58th out of 77 IGP cities (with 1 indicating the worst polluted and 77 the cleanest city) on Nov 1. Pre-Diwali, the city's air quality was even better, ranking Kolkata 70th on Oct 30 and 73rd on Diwali night (October 31), as reported by the Centre for Research on Energy and Clean Air (CREA).
Pollution surged across IGP post-Diwali, with cities like Ghaziabad in Uttar Pradesh, Bikaner in Rajasthan and Delhi recording PM2.5 levels well into the hazardous range: 261, 237, and 219 micrograms per cubic metre, respectively. Many cities saw a significant PM2.5 increase after Diwali, with Meerut's levels rising from 71 micrograms per cubic metre pre-Diwali to 204 micrograms per cubic metre, and Gwalior from 57 to 202 micrograms per cubic metre.
In comparison, Bengal cities experienced relatively lower pollution levels, though there was a noticeable post-Diwali increase. "Bengal cities did see pollution rise during Diwali, but the levels remained lower than many other IGP cities," said Manoj Kumar from CREA, who led the data analysis.
The air quality data reflect a concerning trend. Pre-Diwali, only one out of six Bengal cities exceeded the National Ambient Air Quality Standard (NAAQS) of 60 micrograms per cubic metre for PM2.5. By Diwali, that number rose to two, and post-Diwali, five cities reported PM2.5 levels above NAAQS, driven largely by festival-related firework activity.
Bengal cities, including Barrackpore, Kolkata, Haldia, Howrah and Siliguri recorded a moderate increase in PM2.5 levels on Diwali night, with pollution worsening further the following day. Notably, Durgapur saw one of the largest spikes, reaching 156 micrograms per cubic metre post-Diwali, placing it in the "very poor" category, potentially exacerbated by local industrial emissions. Meanwhile, Asansol's levels rose from 55 micrograms per cubic metre to 99 micrograms per cubic metre, and Barrackpore from 55 micrograms per cubic metre to 81 micrograms per cubic metre.
Analysis of the AQI categories indicates a deterioration in air quality across Bengal during the Diwali period. On Oct 30, two Bengal cities had "good" air quality and four were "satisfactory". By Nov 1, no cities remained in the "good" category, only two were "satisfactory" and one city moved to the "very poor" category.
The post-Diwali air quality situation across IGP, including in Bengal, also underscored the urgent need for stringent pollution controls and public awareness campaigns during festival seasons to mitigate the health risks of high PM2.5 levels, experts have said.