Oxidative potential of PM2.5: Source apportionment analysis across four Eastern Mediterranean sites

This study examines PM 2.5 oxidative potential (OP) measurements, assessed using the ascorbic acid (OP-AA) and dithiothreitol (OP-DTT) assays, at Eastern Mediterranean sites, in conjunction with detailed chemical characterization and source apportionment data. The dataset includes around 300 samples collected from various sites under different influences (urban, suburban, and urban-industrial). Average OP-AA v values varied between 0.41 and 0.79 nmol·min -1 ·m -3 , while average OP-DTT V varied between 0.26 and 0.49 nmol·min -1 ·m -3 . A multiple linear regression method was applied to estimate the contribution of PM sources to OP values at each site. The results showed that this approach was effective to reconstruct observed OP for both assays. Among the common sources identified, traffic non-exhaust, biomass burning, and Heavy Fuel Oil (HFO) combustion sources exhibited the highest intrinsic OP (OP m ) for both assays. Additionally, diesel generators source showed a notable contribution to OP m -AA. Conversely, sea-salts and crustal dust sources had the lowest OP m . Additionally, other sources such as secondary organic aerosols and open waste burning showed significant OP m values. In terms of OP v contribution, road traffic, biomass burning, HFO combustion and ammonium sulfate emerged as the dominant contributors at all sites, collectively accounting for more than 70% of the observed OP for both assays. • Oxidative potential was measured using AA and DTT assays at East-Mediterranean sites • Multiple linear regression was applied to link PM 2.5 sources with oxidative potential • Road traffic, biomass burning and HFO combustion showed high intrinsic OP • Diesel generators and waste burning contributed notably to intrinsic OP-AA • More than 70% of OP-AA and OP-DTT were explained by anthropogenic sources