Development of new health metric for fine particles based on differential toxicity

Abstract

Many sources of ambient fine particulate matter (PM2.5) include biomass burning, biological emissions, industrial combustion (coal, heating), sea aerosols, and traffic (diesel and gasoline engine exhaust) (Shiraiwa et al., 2017, Debnath et al., 2022). Different of sources of PM2.5 are expected to have different chemical components and give different toxic effect to environment and human body. Adverse health effect of PM2.5 include respiratory diseases, cardiovascular diseases, and central nerve damage. (Kyung & Jeong, 2020, Kim et al., 2020, J. Li et al., 2022) To assess adverse health effect of PM2.5 mass concentration was widely used in many countries. However, PM2.5 mass concentration cannot fully explain the toxicity of PM2.5 because PM2.5 mass concentration does not consider the different chemical component and toxic effect of different sources of PM2.5. The previously suggested new metric (Park et al., 2018) consider the physicochemical factors and toxic effect of PM2.5 by considering source-specific experimental results. New metric established the source toxicity database by collecting source sample experimental data and external source databases. The source specific toxicity score was calculated by collecting database and this metric will explain toxic effect of PM2.5 and other previous metrics. In this study, to explain the validity of the new metric, this metric was applied to 3 different sites, (urban Beijing (China), Gwangju (Korea) sites (2018, 2019, 2020 Winter and 2019 Summer) and rural Gimje (Korea) sites (2020, 2021 Summer and 2021 Winter). To see the validity of the metric result, PM2.5 mass concentrations, for chemical comparison, oxidative potential (OP) (cell-free dithiothreitol (DTT) assay, and neutral red uptake (NRU) assay was measured for cytotoxicity result. The average health metric results were 10.4, 7.2 and 8.6 at at Beijing, Gwangju, Gimje sites respectively. The average PM2.5 mass concentrations were 39.7, 27.1 and 25.2 (μg/m3). The volume normalized oxidative potential (OP-DTTv) of 3 sites was 2.204, 1.287 and 0.547 nmol/min/m3. The cytotoxic assay, NRU assay result was volume normalized (NRUv). The value of NRUv was 17.11, 12.94 and 25.24. Although the PM2.5 mass concentrations low in Gimje site, the health metric showed higher score. The seasonal difference in metric results was observed, Beijing and Gwangju showed lower health metric result in summer (winter > summer), but the Gimje site showed the opposite (2021 summer > 2021 winter). For OP-DTT assay result, Beijing showed the highest value, while Gimje site was lowest (Beijing > Gwangju > Gimje). The seasonal variance of OP-DTT assay showed same result as metric, in 2 sites Beijing and Gwangju (winter > summer). The result of Gimje 2021 summer when the biomass burning event was conducted near sampling sites as OP-DTT assay were known as reactive to organic carbon and transition metals, (Bates et al., 2019; Charrier-Klobas et al., 2016; Gao et al., 2017) these sites showed higher fraction in the transition metals component. The cytotoxic assay NRUv showed same as OP-DTTv result, (Beijing > Gwangju > Gimje) and the seasonal variance in the NRUv was same as metric result, winter NRU result showed higher value in 3 sites, (winter > summer). New health metric result showed validity with previous assay results, comparing with the human death rate with the metric result in Gwangju and Gimje site using generalized additive model (GAM).