Diwali fireworks spike city AQI from ‘satisfactory’ to ‘moderate’
Times of India | 2 November 2024
Kolkata: The air quality in Kolkata on Friday slipped after Diwali and Kali Puja revelry the previous evening, but for the second time since Covid, the dip was not sharp, staying within the ‘moderate' AQI level on the whole. In 2022, the air quality had been better — in the ‘satisfactory' range — because of Diwali's proximity to Cyclone Sitrang.
An AQI reading between 101 and 200 is considered ‘moderate'. Between 51 and 100 is ‘satisfactory'.
Scientists at the state pollution control board (PCB), which monitors the city's AQI, said the sharp decline from ‘satisfactory' till the intervening midnight of Thursday and Friday to ‘moderate' on Friday was due to rampant fireworks revelry. One station — at the BT Road campus of Rabindra Bharati University (RBU) — even recorded ‘very poor' AQI level: 330 at 6pm on Friday.
"The vibrant, low-decibel fireworks, though designed to produce less noise, emit significantly more pollutants than cheaper, traditional firecrackers due to their complex manufacturing processes and higher metal content," said PCB chairman Kalyan Rudra. "It's imperative that we exercise restraint and rethink the impact of these displays, with a focused effort to raise awareness."
Scientists said the AQI could easily have been much worse, had the weather been colder. "The heat helped disperse particulate matter. Had it been any less warm, the pollution count would have been higher and the AQI poorer," a scientist said.
The AQI data from Thursday evening and Friday reveal a deterioration in Kolkata's air quality, particularly after the onset of Diwali celebrations. On Thursday afternoon, all recorded stations showed ‘satisfactory' AQI levels, with monitoring stations at Ballygunge, Bidhannagar, Fort William, Jadavpur, RBU (BT Road), and Victoria Memorial hovering between 50 and 68. However, by 9pm on Thursday, as firecracker activity peaked, some stations reported a moderate increase in AQI, indicating a shift towards the ‘moderate' range. Ballygunge, for example, saw a rise from 59 at 6pm to 196 at 6pm the next day, suggesting it was fireworks pollution. Other stations displayed relatively stable readings by the evening, likely reflecting an initial tolerance in the atmosphere before the full impact of pollutants was observed.
The AQI levels on Friday depict a stark contrast, indicating the significant impact of firework-related pollution overnight. By 3pm, the levels escalated drastically, with Ballygunge reaching 190 and RBU (BT Road) jumping to 202, both nearing the ‘poor' category. The RBU (BT Road) station experienced the most significant AQI rise, climbing to a ‘very poor' level of 330 by 6pm on Friday. Jadavpur and Bidhannagar also recorded noticeable AQI spikes, reaching 119 and 135, respectively, suggesting that the AQI was persistently affected across various areas of Kolkata throughout the day. This steady increase across all locations, except Fort William, reflects the accumulation of air pollutants from the previous night's fireworks.