A recent study by Kolkata’s Bose Institute has revealed a concerning spike in the toxicity of PM2.5 particles once their concentration crosses 70 µg/m³ underscoring the urgent need for stricter pollution controls. The findings suggest that beyond this threshold, the health risks posed by PM2.5 particles increase sharply posing a greater threat to public health than previously understood.
PM2.5, or fine particulate matter with a diameter of 2.5 micrometers or less, is among the most dangerous air pollutants. These particles can penetrate deep into the lungs and bloodstream, leading to serious respiratory, cardiovascular, and neurological issues. The study focused on the oxidative potential (OP) of PM2.5, which measures its ability to generate reactive oxygen species (ROS) compounds that cause oxidative stress and damage human cells.
Led by Prof. Abhijit Chatterjee, the research team found a non-linear relationship between PM2.5 levels and toxicity. While OP remained steady up to around 70 µg/m³, it jumped sharply between 70 and 130 µg/m³, before plateauing. This key discovery marks 70 µg/m³ as a critical toxicity threshold a point at which exposure becomes especially dangerous.
The study also revealed that the most toxic fraction of PM2.5 comes from biomass and waste burning, using a source analysis model known as Positive Matrix Factorization (PMF). Unlike vehicular and industrial emissions which have seen some control under the National Clean Air Programme (NCAP) open burning remains poorly regulated, yet contributes heavily to Kolkata’s air pollution.
The Bose Institute, now acting as a nodal body under the NCAP, recommends setting 70 µg/m³ as a toxicity benchmark for Kolkata. This guidance has already influenced local policy. In winter 2024-25, tighter controls on biomass burning helped bring down both PM2.5 levels and associated toxicity.
As India continues its battle against air pollution, the study emphasizes a shift in focus from simply reducing particulate matter to tackling its toxic effects and dangerous sources. It signals a need for deeper scientific understanding and stronger enforcement, especially to curb unregulated waste burning in urban areas.