Source-Specific Radioactivity and Oxidative Potential of Urban PM2.5

Radioactive constituents of fine particulate matter (PM2.5) are an under-recognized dimension of urban air pollution, posing emerging challenges for sustainable public health management. In this study, we experimentally demonstrate a mechanistic link between particle radioactivity (PR) and oxidative potential in the urban atmosphere by integrating alpha and beta activity measurements of long-lived radon progeny (210Pb, 210Bi, 210Po) with dithiothreitol (DTT) assays. Using source apportionment, we present the first integrated evidence that biomass burning and industrial activity jointly drive both radiological activity and oxidative potential, highlighting a shared source-specific toxicity profile for PM2.5. Our results establish PR as an emerging, particle-bound radiological indicator of PM2.5 oxidative potential, offering source-specific insights with potential applications in air quality and health-relevant regulations. Recognizing the intrinsic coupling of radiological and chemical reactivities provides a new framework for evaluating synergistic health risks beyond conventional mass-based air quality metrics.