Oxidative potential and cellular toxicity of carbonaceous aerosols undergoing aging in an atmospheric simulation chamber

This study investigates how chemical composition, atmospheric aging, and environmental conditions affect the oxidative potential (OP) and cellular toxicity of soot particles using an atmospheric simulation chamber (ASC). In the ASC ChAMBRe were simulated real-world summer and winter scenarios, exposing pure soot particles (generated by using the mini-inverted soot generator) and various secondary aerosol precursors (i.e., toluene, 2,5-dimethylfuran and α-pinene) alternatively to light or dark conditions and different oxidants. OP was assessed using multiple assays (namely, 2′,7′-dichlorofluorescein – DCFH, Dithiothreitol - DTT and Ascorbic Acid – AA), revealing that soot particles exposed to light, especially in presence of toluene, exhibited higher OP. The presence of toluene also increased cellular reactive oxygen species (ROS) production, leading to elevated cytotoxicity, DNA damage, and release of the proinflammatory cytokine interleukin-8 (IL-8) in BEAS-2B cells. Ammonium sulfate addition reduced OP and do not enhance toxicological responses, suggesting that non-toxic components in aged particulate matter (PM) may mitigate some harmful effects. Toxicological assessment showed increased cytotoxicity, genotoxicity, oxidative stress, and inflammatory responses in soot generated under high irradiance conditions typical of summer and traffic environments, compared to low irradiance winter scenarios. Strong correlations were observed between OP and toxicological endpoints, such as ROS formation, LDH release, micronuclei formation, and IL-8 secretion underscoring the role of chemical composition and environmental aging in determining PM toxicity. The study highlights OP assays as a reliable tool for predicting PM-induced oxidative stress and potential health effects, emphasizing the importance of considering soot chemical composition and aging processes in urban air pollution assessments.