Source apportionment of atmospheric PM 10 Oxidative Potential: synthesis of 15 year-round urban datasets in France

Abstract. Reactive oxygen species (ROS) carried or induced by particulate matter (PM) are suspected to induce oxidative stress in vivo, leading to adverse health impacts, such as respiratory or cardiovascular diseases. The oxidative potential (OP) of PM, displaying the ability of PM to oxidize the lung environment, is gaining a strong interest to examine health risks associated to PM exposure. In this study, OP was measured by two different acellular assays (dithiothreitol, DTT and ascorbic acid, AA) on PM10 filter samples from 15 yearly time series of filters collected at 14 different locations in France between 2013 and 2018, including urban, traffic and Alpine valley site typologies. A detailed chemical speciation was also performed on the same samples allowing the source-apportionment of PM using positive matrix factorization (PMF) for each series, for a total number of more than 1700 samples. This study provides then a large-scale synthesis on the source-apportionment of OP using coupled PMF and multiple linear regression (MLR) models. The primary road traffic, biomass burning, dust, MSA-rich, and primary biogenic sources had distinct positive redox-activity towards the OPDTT assay, whereas biomass burning and road traffic sources only display significant activity for the OPAA assay. The daily median source contribution to the total OPDTT highlighted the dominant influence of the primary road traffic source. Both the biomass burning and the road traffic sources contributed evenly to the observed OPAA. Therefore, it appears clearly that residential wood burning and road traffic are the two main target sources to prioritized in order to decrease significantly the OP in Western Europe and, would the OP being a good proxy of human health impact, to lower the health risks from PM exposure.