Oxidative Potential by PM_2.5 in the North China Plain: Generation of Hydroxyl Radical

Abstract

Adverse health effects of ambient PM 2.5 (d p < 2.5 μm) can be associated with the production of reactive oxygen species (ROS), among which hydroxyl radical (•OH) is the most reactive. However, •OH generated by PM 2.5 has not been quantified and studied in the North China Plain (NCP), which has suffered from heavy air pollution in recent years. In this study, PM 2.5 samples were collected at an urban site (Beijing) and a suburban site (Wangdu), extracted in a cell-free surrogate lung fluid (SLF), and •OH generated in the extracts were quantified. The results show that more •OH is produced on heavily polluted days than that on clean days (2.0 and 1.6 times higher in Beijing and Wangdu, respectively). The production of •OH per unit mass (ng/μg• PM 2.5 ) decreases with the increase of ambient PM 2.5 concentration because SO 4 2− , NO 3 − , and NH 4 + dominate the increased PM 2.5 , while these secondary inorganic components do not contribute to the generation of •OH. Trace metals (e.g., Fe, Cu, Se) and carbonaceous species (organic carbon and elemental carbon) correlate well with the •OH production, indicating that particles from combustion sources including coal combustion, vehicle exhaust, and industry contribute more to •OH generation.

Oxidative potential of solvent-extractable organic matter of ambient total suspended particulate in Bangkok, Thailand

“…1(b)), indicating that less ROS may be produced as the OC concentration increases. This is consistent with the observed relationship between typical health endpoints (e.g., ischemic heart disease, stroke, and chronic obstructive pulmonary disease) and PM exposure in epidemiological studies, 42 suggesting that OP v is an ideal indicator of adverse health effect.…”

“…Similar trends were observed in Seoul 43 and Beijing. 42 Studies on the contribution of chemical species to the OP of PM have identified quinones and transition metals as the main contributors. 44 The contribution of metal ions to OP could be neglected in this study, since the extraction solvents were HPLC grade (purity > 99.9%), which could mostly eliminate interference from metal ions prior to DTT assay.…”

“…9,45 Thus, we speculate that the nonlinear relationship between OP m and OC (well fit by a power function), is likely contributed by the non-DTT-active components. 42,46…”

“…9,45 Thus, we speculate that the nonlinear relationship between OP m and OC (well t by a power function), is likely contributed by the non-DTT-active components. 42,46 EOM, as a main component of PM, has a strong association with mortality and hospitalization due to cardiovascular and respiratory diseases. 17,47,48 Our results indicate that the EOM of TSP in Bangkok has ROS-generating potential, demonstrating a degree of risk to local inhabitants.…”

Influence of COVID-19 lockdown on the variation of organic aerosols: Insight into its molecular composition and oxidative potential

“…Many previous studies also found high correlations between the organic species of PM 2.5 , especially water-soluble organic carbon (WSOC), with its oxidative potential. Nevertheless, few of them have clarified the specific chemical species that were dominant in the ROS production ( Chen et al, 2019 ; Li et al, 2019c ). Ma et al (2018) have identified the individual species of water-soluble HULIS associated with the oxidative potential of PM 2.5 and found a series of aromatic acids (CHO) and nitrophenol analogs (CHON).…”