NEW DELHI: On Diwali and the day after, the capital recorded its worst PM2.5 levels of the year since Jan, analysis shows. Even on Wednesday, two days after the festival, some of its areas continued to choke on exponentially high particulate pollution. According to a study by Centre for Research on Energy and Clean Air (CREA), the city had an average PM2.5 concentration of 228 micrograms per cubic metre (µg/m³) on Diwali and 241 the next day. It was only on four days in Jan this year that PM2.5 had crossed these levels.
The analysis also showed that Delhi on Tuesday was the seventh most polluted city in the country, behind Haryana’s Jind (412), Dharuhera (298), Gurgaon (290), Narnaul (266), Bahadurgarh (247), and Rajasthan’s Bhiwadi (244). Rohtak (223), Noida (218) and Ghaziabad (207) made up the worst 10.
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On Diwali, the hourly PM2.5 concentration at some places of Delhi went off the charts, with that in Nehru Nagar surging from 679 µg/m³ at 9pm to a staggering 1,763 at 10pm — 29 times the daily national ambient air quality standard and 118 times WHO’s daily safe guideline of 15. The situation was mirrored at several other areas on Diwali night, with 14 out of 20 DPCC monitored stations surpassing the hourly PM2.5 concentration of 1,000, against only five stations on Diwali last year.“However, the AQI levels appear lower than reality because several CAAQMS stations maxed out or recorded missing values. This reminds us to interpret data cautiously and recognise that pollutant concentrations might have exceeded the instruments’ detection limits. For instance, Anand Vihar reported missing data from 11pm on 20 Oct to 3pm the next day, a window when Diwali pollution typically peaks, suggesting concentrations went beyond the measurable range,” said Manoj Kumar, analyst, CREA. Even two days after Diwali, areas like Anand Vihar showed hourly PM2.5 levels of 579 µg/m³, still high but a slight improvement over the peak particulate pollution of 656 a day earlier.According to experts, as pollutants turn finer, health risks increase. “These particles (PM2.5) are so small they can easily enter the bloodstream and impact different organs in the body, leading to toxic effects. The tinier the particle, the greater the health risk,” said Anumita Roy Chowdhury, executive director, Centre for Science and Environment (CSE).
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