‘City AQI unlikely to reach very poor category this Diwali’

MP, 11 Nov 2023, Kolkata: A predictive analysis of Kolkata’s air quality has opined that air quality index (AQI) would remain around 200-230 (poor category) and won’t reach “very poor” condition during this Diwali. 

However, particulate matter pollution like PM 2.5 and PM 10 would significantly vary region to region and the scope of pollutants’ dispersion over those regions. It would also depend on the meteorological conditions. 

“We ran a model for the predictive analysis of particulate matter pollution in Diwali 2023. Based on our prediction, the PM2.5 would remain around 110-140 microgram per cubic meter (maximum PM2.5 level won’t cross 200 microgram per cubic meter) whereas PM10 would remain around 190-230 (maximum value won’t cross 300 microgram per cubic meter),” Prof. Abhijit Chatterjee, Scientist from Bose Institute, Kolkata said. 

Interestingly, it has been observed that during Diwali in recent years, PM10 has not increased as much as PM2.5 did. This indicates that the ultrafine pollution during Diwali enhances more than larger particulate matter. Amongst various sources of air pollutants, construction and demolition dust as well as vehicle-driven-road-dust are the major contributors to particulate matter pollution over Kolkata. 

During Diwali, vehicular movement and hence the vehicle driven road dust gets significantly reduced as well as construction/demolition activities on that day. This also helps reduce particulate matter pollution over Kolkata to a large extent. 

Therefore, fire-cracker activities although enhance the level of particulate matter, overall the hike is less for PM10.

Air quality over Kolkata during a normal day is worse than a Diwali day. During Diwali mostly fire cracker activities play a major role while on other days several mixed sources cause pollution. 

“The only concern during Diwali is the enormous hike in gaseous pollutants like Sulphur-di-oxide and Nitrogen-di-oxide,” Chatterjee added. 

The scientists have recommended that fire-cracker activities should be done as a “community activity” where an open and wider ground/place needs to be identified in every wards of the city where the residents would meet and participate and abstain from lighting crackers in a narrow road/areas where the scope of dispersion of smoke is very less.

“Water sprinkling on the road should be done during the late afternoon on Diwali day to make the surface wet. It would resist the resuspension of soil-dust/road-dust during the bursting of fire-crackers. 

The ward councillors should prepare a database of old and ailing people or babies of their respective wards who have serious objections to bursting fire crackers near their houses and try to take measures to ensure that crackers are not burst near those houses/ buildings,” Monami Dutta, PhD Scholar from Bose Institute Kolkata said. 

The scientists have also recommended bursting of firecrackers at an elevated level and not near the ground.