Chemical Composition and Source-Specific Toxicity of Ambient Particulate Matter in Riyadh, Saudi Arabia

ABDULMALIK ALTUWAYJIRI, Milad Pirhadi, Constantinos Sioutas, University of Southern California

     Abstract Number: 26
     Working Group: Source Apportionment

Abstract
In this research, we analyzed the chemical composition and sources of PM10 oxidative potential in Riyadh, Saudi Arabia. We collected time-integrated PM10 filter samples during both dust and non-dust events. These samples were assessed for their content of metals, trace elements, and elemental and organic carbon (EC/OC). We also conducted DCFH and dithiothreitol (DTT) assays to evaluate the oxidative potential of the PM10 samples. Analytical methods including Pearson correlation analysis, principal component analysis (PCA), and multi-linear regression (MLR) were employed to pinpoint the primary sources influencing the toxicity of PM10. Our findings indicated that the oxidative potential of the ambient PM10 samples in this study was notably higher than those reported in many other urban areas globally. According to the MLR results, the predominant sources impacting the oxidative potential of ambient PM10 included soil and resuspended dust emissions (marked by Al, K, Fe, and Li) accounting for 31%, followed by secondary organic aerosol (SOA) formation (indicated by SO4 2- and NH 4+) at 20%, industrial activities (marked by Se and La) at 19%, and traffic emissions (characterized by EC, Zn, and Cu) at 17%. The oxidative potential was greater during dust events than non-dust events, largely due to elevated metal concentrations. This study supports the significant influence of dust emissions on the oxidative potential of ambient PM10 in Riyadh and suggests implications for public health policies to mitigate adverse health effects from PM10 exposure.