Daijiworld Media Network - Kolkata
Kolkata, Apr 11: A groundbreaking study by researchers at the Bose Institute has revealed that the toxicity of PM2.5 ultrafine air pollutants harmful to human health shows a sudden and dangerous spike once it crosses the threshold of 70 micrograms per cubic metre.
The research, led by Prof Abhijit Chatterjee and published in Science of The Total Environment, underscores that pollution control policies should aim to cap PM2.5 levels below this critical mark. "Once the PM2.5 load exceeds this value, the toxicity starts to increase rapidly and goes beyond control," said the team from the autonomous institute under the Department of Science and Technology.
PM2.5, or particulate matter with a diameter of 2.5 micrometres or smaller, is a major air pollutant linked to respiratory and cardiovascular diseases. The Kolkata-based study examined how its oxidative potential (OP) its ability to generate harmful reactive oxygen species (ROS) in human lungs changes with pollution levels.
The team found a non-linear relationship: the toxicity remains stable up to 70 µg/m³, then surges sharply till around 130 µg/m³, after which further increases in PM2.5 show little change in toxicity. This sudden jump in OP, the study suggests, poses severe risks to public health as the body's natural antioxidants become overwhelmed by the ROS introduced through inhaled particles.
Biomass and solid waste burning were identified as key culprits driving this spike in toxicity. "While the National Clean Air Programme (NCAP) has helped reduce road dust, vehicular and industrial emissions, the lack of control over biomass and waste burning continues to exacerbate PM2.5 toxicity," researchers observed.
Launched in 2019, NCAP aims to reduce air pollution by 40 per cent by 2026 (compared to 2017 levels), targeting 131 non-attainment cities, including Kolkata. However, experts now say targeted interventions are needed to specifically address the overlooked sources that intensify PM2.5’s health impact.
The findings urge policymakers to reevaluate existing strategies and double down on measures to keep pollution levels below the critical 70 µg/m³ threshold to prevent a steep rise in toxicity and related health hazards.