According to a recent study from Bose Institute scientists, close to one-fourth (or 3%) of the city’s toxic pollutant, PM2.5, comes from outside Bengals border.
The study, entitled Sources of poor air quality over Kolkata and long-term variability, was published in an Elsevier publication titled Asian Atmospheric Pollution.
The TelegraphWednesday’s report from IIT Delhi revealed that more than half of all PM 2.5 loads in Bengals’ air originates from outside the country.
Bose Institute’s findings point out that during the duration of their study, the overall load of PM 2.5 in the city increased by about 50 per cent.
PM 2.5 particulates — 0.5 to 1 micron in diameter — constitute about 80 per cent of the total load. PM 2.5 can pass into the lungs. Finer particles can get even deeper and cause greater damage.
“According to our findings, about 20 to 25 per cent of the overall PM 2.5 load in Kolkata comes from beyond its border. About half of that is from Uttar Pradesh, Bihar and Jharkhand, while major part of the rest comes from Bangladesh, Nepal and states like Assam and Meghalaya,” Abhijit Chatterjee, an associate professor of Bose Institute, said on Wednesday.
He pointed out that PM2.5 is mostly from Odisha, Andhra Pradesh, in early March. “The pollutant traverses to the city from Odisha and Andhra Pradesh through the Bay of Bengal and the Sunderbans, almost following the route of cyclones,” he said.
The study reveals that PM 2.5 from the Eastern Ghats is extremely toxic and can cause cancer.
The study also revealed that waste burning and construction have been major contributors to PM2.5 in the city over the years, replacing the pollution caused by vehicles.
“Earlier, from 2004 to 2009, pollution caused by vehicles used to contribute about 45 to 55 per cent of total PM 2.5 content in the city. Waste burning now accounts for 40-45% of the PM2.5 load. Construction is responsible for 20% to 25% of the pollutants. With a contribution of 15 to 20%, vehicles are third. The gross pollution from vehicles has not reduced,” said Chatterjee.
“The IIT Delhi and Bose Institute studies both underline the importance of looking at transboundary and regional pollution for cities like Calcutta, rather than our conventional model of looking at the city in a standalone way,” pointed out Anumita Roy Choudhury, air pollution expert from the environment think-tank, Centre for Science and Environment.