Assessment of Oxidative Potential in Ambient Air: Comparison of Gas-Phase DTTv with Combined PM + Gas DTTv

Abstract The OP of the gas phase is a significant yet often overlooked aspect of environmental toxicity. While long-term exposure to reactive oxygen species (ROS) associated with particulate matter (PM) is known to have adverse health effects, the potential for gas phase compounds to cause similar effects has yet to be fully understood. The sources and atmospheric chemistry of ambient air in the gas phase remain poorly understood, possibly due to limitations in current measurement techniques. This study utilized the Dithiothreitol (DTT) assay, a widely used method for quantifying OP in epidemiological research because it is less time and resource-intensive compared to other techniques. We measured the volumetric OP values (OPDTTv) in the gas phase and ambient air (PM + gas) during sampling in spring, summer, and autumn. The results indicate that the OP in the ambient air PM + gas is nearly twice that of the gas phase. Specifically, the value of OP in gas phase during autumn (6.98 ± 1.8) was higher than in spring (4.6 ± 1.6) and summer (4.4 ± 2.2), with minimal difference observed between spring and summer. Furthermore, the results revealed an indirect correlation between ozone (O 3 ) and OP in the gas phase (DTTv.gas) as well as between O 3 and ambient air (DTTv.PM + gas). However, other variable correlations were found to be positive and direct. Graphical abstract