Particulate matter (PM) is a complex mixture of suspended solid and liquid particles characterized by toxicological properties (1). Oxidative stress is considered as one of the most important mechanism of PM toxicity on living organisms. Reactive oxygen species (ROS) may in fact damage lipids in biological membranes, enzymatic proteins and DNA. ROS content in PM samples is frequently evaluated in the literature in terms of oxidative potential (OP). However, the relations between the obtained results and the chemical and physical characteristic of particles are still largely unknown.In this work we report the results obtained by three different assays for measuring oxidative potential (OP) on selected components of PM having a very different chemical composition (road dust, soil dust, brake dust, desert dust, pellet ash and coke and certified material NIST1648a – urban dust). The first two methods are based on the decrease of reducing species concentration (respectively Dithiothreitol - DTT and Ascorbic Acid - AA) due to ROS (2); the third one is based on the formation of a fluorescent compound (dichlorofluorescein - DCF) from oxidation of 2′,7′-dichlorofluorescein (DCFH ) in the presence of horseradish peroxidase (HRP) (3). The results show that the three methods respond very differently to each dust and that, accordingly to the results of a previous study of the oxidative stress on simple in vivo organism model (4), the un-soluble chemical components of dusts have an OP much higher than that of the soluble species.

1-Canepari et al. 2013, Aerosol and Air Quality Research 13, 1619-1629.

2-Fang et al. 2015, Atmospheric Chemistry and Physics 15, 30609–30644.

3-Huang et al. 2016, Water, Air, & Soil Pollution 227-164.

4-Marcoccia et al. 2017, Chemosphere 173, 124-134.