Particulate matter (PM₂.₅) mass concentration remains the primary metric guiding air quality management in India, yet it does not adequately capture the health-relevant property of airborne particles. Growing evidence shows that the chemical composition and oxidative potential (OP) of PM₂.₅ are stronger predictors of adverse biological responses than mass alone.

In this talk, I will present recent advancements in measuring aerosol OP using acellular assays, real-time sampling systems, and integrated chemical–toxicological analysis. I will also combine PM₂.₅ OP datasets collected from Delhi and Illinois, USA, to compare their OP across two contrasting environments. These measurements show how traffic emissions, biomass burning, and secondary aerosol formation contribute disproportionately to toxicity despite similar mass loadings.

Linking OP with source apportionment further identifies the sources that drive the greatest health risks. By moving beyond mass-based indicators, this work highlights the value of OP as a more informative and health-relevant metric for air quality management.