‘Air pollution in city reduces by 28% from previous years’

SOUMITRA NANDI, MP, 31 Oct 2024, Kolkata: A study by Bose Institute examining the relationship between particulate matter PM 2.5 concentrations and its potential oxidative stress (OS) on living human cells in Kolkata, a non-attainment city under the Centre’s National Clean Air Programme (NCAP), revealed that the programme has been efficacious in lessening the PM 2.5 load in city by 28 per cent from previous years. 

The study assumes significance as air pollution levels in the Indo Gangetic Plain see spikes with the winter season setting in. It is for the first time the variability of oxidative potential (OP) based toxicity of PM 2.5 was analysed. Higher the value of OP, higher is the toxicity of PM 2.5 in damaging the living cell, enhancing oxidative stress which is generated due to formation of a huge number of reactive oxygenated species. A

Findings revealed that the number of high pollution days (PM 2.5>200µg m-3) during the post-NCAP era reduced significantly compared to the pre-NCAP era. The number of days with less concentration of the particulate matter saw an increase and was within the daily standard as prescribed by the Central Pollution Control Board. 

PM 2.5 can damage human lung cells by posing an oxidant/antioxidant imbalance by forming reactive oxygenated species within the cell. Scientists claimed that OP of PM 2.5 over Kolkata during winter didn’t reduce despite implementation of NCAP policies. Source apportionment studies identified that while NCAP was effective in controlling emissions from vehicles, industries and secondary sources, biomass/solid fuel/trash burning along with road dust remains a problem for the megacity. 

The toxic metals and associated organic contaminants from these enhance toxicity of OP of PM 2.5 even when the cumulative load of PM 2.5 gets reduced significantly. Also Read - At least one killed, 2 injured with over 80% burns in fire at factory 

The researchers mentioned 70µg m-3 as the benchmark concentration of PM 2.5 for Kolkata in terms of OP-based toxicity. They called for all possible policy implementation on days when PM 2.5 daily concentration breaches the benchmark. 

“It is a need of the hour that a dataset should be generated for the PM 2.5 toxicity associated with individual sources, e.g. people exposed to vehicular emissions, domestic emissions, biomass/waste burning, road-dust etc. 

Earlier, vehicular emission was the major concern in Kolkata. Presently, the contribution of solid waste/biomass burning and the dust emissions together are exceeding the vehicular emissions,” said Prof. Abhijit Chatterjee, professor, department of Chemical Sciences Bose Institute (Dept. of Science and Technology, Govt. of India) 

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