Source apportionment of particulate matter and its oxidative potential in an urban-industrial hot spot of Central Italy

One-year PM10 monitoring was conducted in a hot spot of Central Italy in 2022. The study area is an open-air laboratory for in-depth investigation into PM emissions and their health effects due to the presence of intense residential and industrial sources. PM10 was collected daily on quartz filters using a high-volume sampling system to obtain a comprehensive chemical characterization, including OC, EC, levoglucosan, ions, macro-, micro-, and trace elements, as well as the measurement of OP of PM10 by employing OPDTT, OPAA, and OPDCFH assays. Source apportionment of PM10 mass concentration and its OP was performed by PMF and MLR, respectively. PMF analysis identified 7 main emission sources of PM10: biomass burning for home heating, vehicular traffic including exhaust and non-exhaust emissions, two steel plant sources, soil dust, sea spray, and secondary inorganics. PM10 mass concentration was dominated by biomass burning (29%), vehicular traffic (20%), and soil dust (17%). Source apportionment of OP by MLR revealed a differential sensitivity among the three OP assays: OPDTT responded significantly (p < 0.05) to urban sources (biomass burning 36%, vehicular traffic 24%), steel plant emissions (10%), and secondary inorganic species (18%), OPAA to vehicular traffic (43%), and OPDCFH to biomass burning (42%). These distinct specificities underscore why the employment of multiple assays is useful for the assessment of OP of PM10 and highlight the need for further research to elucidate the accuracy of OP assays in reflecting oxidative stress mechanisms and health effects, calling for caution in adopting OP as a regulatory metric.