Abstract

This work is an overview of the oxidative potential (OP) values up to date measured in Italy, with the aim to provide a picture of the spatial and seasonal variability of OP in the various geographical areas across Italy. The summarized works used the common acellular assays-based dithiothreitol (OPDTT), ascorbic acid (OPAA), glutathione (OPGSH), and 2',7'-dichlorodfluorescein (OPDCFH) assays. The paper describes the association of OP responses with PM chemical composition, the sensitivity of various acellular OP assays to PM components and emission sources, and PM size distribution of the measured OP values. Our synthesis indicates that crustal and transition metals (e.g., Fe, Ni, Cu, Cr, Mn, Zn, and V), secondary ions and carbonaceous components (elemental carbon, EC, organic carbon, OC and water soluble carbon, WSOC) show significant correlations with OP across different urban and rural areas and size ranges. These chemical species are mainly associated with various PM sources, including residual/fuel oil combustion, traffic emissions, and secondary organic aerosol formation. Although the OP assays are sensitive to the same redox-active species, they differ in the association with PM chemical components. The DDT assay is mainly sensitive to the organic compounds that are mostly accumulated in the fine PM fraction, i.e., tracers of burning sources, and redox active organics associated with other markers of photochemical aging. In contrast, OPAA and OPGSH were mostly responsive to metals, mainly those related to non-exhaust traffic emissions (Cu, Zn, Cr, Fe, Ni, Mn, Sn, Cd, Pb), that are mainly accumulated in the coarse PM. Among the investigated sites, our synthesis shows larger OP values in Trentino region and the Po Valley, that may be explained by the high density of anthropogenic sources, and the orographic and meteorological characteristics, that favor the pollutants accumulation and aerosol photo-oxidative aging.

Highlights

  • In recent years, the oxidative potential (OP) of particulate matter (PM) has been proposed as a biologically relevant metric to be associated with a number of health endpoints and biomarkers of toxic effects in humans [1,2,3,4,5,6,7]

  • The relevant studies concerning Italian sites published up to May 2019 were searched in the Web of Science database, using as inclusion criteria that they report OP data of PM samples collected in Italian sites measured using cell-free systems

  • Future work should be needed to optimize and standardize the operative conditions of each OP acellular assay in order to provide consistent data for comparison between data of different locations and times

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Summary

Introduction

The oxidative potential (OP) of particulate matter (PM) has been proposed as a biologically relevant metric to be associated with a number of health endpoints and biomarkers of toxic effects in humans [1,2,3,4,5,6,7]. It is based on the increasing consensus that the oxidative stress is an important mechanism of human toxicity related to exposure to atmospheric aerosols. The acellular version of the 20 ,70 -dichlorodfluorescein (DCFH) assay uses the enzymatic production of the fluorescent probe largely used for the evaluation of oxidative stress in living cells

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