Are reactive oxygen species (ROS) a suitable metric to predict toxicity of carbonaceous aerosol particles?

Abstract

Abstract. It is being suggested that particle-bound or particle-induced reactive oxygen species (ROS), which significantly contribute to the oxidative potential (OP) of aerosol particles, are a promising metric linking aerosol compositions to toxicity and adverse health effects. However, accurate ROS quantification remains challenging due to the reactive and short-lived nature of many ROS components and the lack of appropriate analytical methods for a reliable quantification. Consequently, it remains difficult to gauge their impact on human health, especially to identify how aerosol particle sources and atmospheric processes drive particle-bound ROS formation in a real-world urban environment. In this study, using a novel online particle-bound ROS instrument (OPROSI), we comprehensively characterized and compared the formation of ROS in secondary organic aerosols (SOA) generated from organic compounds that represent anthropogenic (naphthalene, SOANAP) and biogenic (β-pinene, SOAβPIN) precursors. The SOA mass was condensed onto soot particles (SP) under varied atmospherically relevant conditions (photochemical aging and humidity). We systematically analysed the ability of the aqueous extracts of the two aerosol types (SOANAP-SP and SOAβPIN-SP) to induce ROS production and OP. We further investigated cytotoxicity and cellular ROS production after exposing human lung epithelial cell cultures (A549) to extracts of the two aerosols. A significant finding of this study is that more than 90 % of all ROS components in both SOA types have a short lifetime, highlighting the need to develop online instruments for a meaningful quantification of ROS. Our results also show that photochemical aging promotes particle-bound ROS production and enhances the OP of the aerosols. Compared to SOAβPIN-SP, SOANAP-SP elicited a higher acellular and cellular ROS production, a higher OP and a lower cell viability. These consistent results between chemical-based and biological-based analyses indicate that particle-bound ROS quantification could be a feasible metric to predict aerosol particle toxicity and adverse human effects. Moreover, the cellular ROS production caused by SOA exposure not only depends on aerosol type, but is also affected by exposure dose, highlighting a need to mimic the process of particle deposition onto lung cells and their interactions as realistically as possible to avoid unknown biases.

Oxidative Potential of Atmospheric Aerosols over Different Regions of India and Surrounding Oceans

“…One of the possibilities could be the mixing (internal and external) of EC with DTT-active N-containing OA, which might result in a positive relationship between EC and OP M . Owing to being intrinsically more redox-active, the aged species from combustion-related sources might be a threat to inhabitants as it can cause acute inflammation through oxidative stress …”

“…Owing to being intrinsically more redox-active, the aged species from combustion-related sources might be a threat to inhabitants as it can cause acute inflammation through oxidative stress. 65 3.1.1. Atmospheric Processing of Mineral Dust and Oxidative Potential.…”

On the Complementarity and Informative Value of Different Electron Ionization Mass Spectrometric Techniques for the Chemical Analysis of Secondary Organic Aerosols

“…Furthermore, the applied techniques cover online to offline approaches and therefore, vary essentially in time resolution, which may be particularly important for specific analytes. In the case of, for example, highly reactive oxygen species (ROS), which are produced during the photochemical aging of NAP, their concentration may greatly be underestimated by offline methods due to their fast degradation . In addition, sampling artifacts, as well as the storage and handling of QF filters, could affect the partitioning of the gas and particle phases compared to online methods.…”

“…Experimental Setup for Aerosol Generation, Online Characterization, and Filter Sampling. The experimental setup has been previously described in detail by Offer et al 32 and Zhang et al 33 and is only briefly presented here. Elemental carbon (EC)-rich SPs with a geometric mean diameter of about 100 nm were produced by means of a miniature CAST soot generator (model 5201C, Jing Ltd., Switzerland).…”

The oxidative potential of fresh and aged elemental carbon-containing airborne particles: a review

“…This agrees well with the studies where PAHs are well correlated with OP (r ¼ 0.93, p < 0.05); 151 n-alkanes are moderately correlated with OP in warm and cold seasons (r ¼ 0.67 and 0.83), 152 and organic acids are poorly correlated with OP (r coefficient and p not shown). 153 However, despite the high correlation coefficient for PAHs, the roles of fuel type and the vehicular operational and environmental conditions introduce great uncertainties of PAH components and hence their roles in the OP remain poorly understood. The concentrations of PAHs in the exhaust of vehicle engines are much lower in low-load runs than in high-load runs because PAHs with three-and four rings are present in the gas phase in low-load runs but in the particle phase in high load runs.…”