Oxidation potential (OP), reflecting the redox activities of particle matter (PM), is considered an optimal measure to explain the biological effects of PM exposure. However, the size resolution of the relationship between OP and chemical composition in PM, especially how the relationship changes after respiratory exposure, has not been well investigated. In this study, size-resolved indoor PM
10 samples were collected from a waste recycling plant from November to December 2021 using an Anderson eight-stage cascade impactor. OP, measured by a dithiothreitol (DTT) assay (defined as OP
DTT), and elements, determined by inductively coupled plasma–mass spectrometry (ICP-MS) in size-resolved PM, were determined to check their relationships and the related human exposure risk. The results indicated that compared with PM
0.4 and PM
0.4–2.1, PM
2.1–10 contributed the most to total OP
DTT and its bound elements contributed the most to potential health risks, both before and after respiratory exposure. The association between OP
DTT and the elements varied with PM size. Pearson correlation analysis showed that the PM
0.4- and PM
0.4–2.1-bound elements were moderate-to-strongly positively correlated with OP
vDTT (
r: 0.60–0.90). No significant correlation or dose–response relationship was found in PM
2.1–10. After respiratory exposure, several PM
0.4- and PM
0.4–2.1-bound elements had a moderate-to-strongly positive correlation with deposition fluxes of OP (defined as OP
Flux) (0.69–0.90). A generalized linear model analysis showed that the interquartile range (IQR) increase in the PM-bound elements (ng h
−1) was associated with a 41.7–58.1% increase in OP
Flux. Our study is a special case that enriches the knowledge of the association between OP
DTT and the chemical composition of PM of different sizes, especially after respiratory exposure, but the generalizability of the findings to other settings or types of PM may be limited. The associations among OP
DTT, other chemical compositions of PM, and human exposure risk merit further research.
Full article