Dataset Information

Assessing the Oxidative Potential of Outdoor PM_2.5 in Wintertime Fairbanks, Alaska.

ABSTRACT: The oxidative potential (OP) of outdoor PM_2.5 in wintertime Fairbanks, Alaska, is investigated and compared to those in wintertime Atlanta and Los Angeles. Approximately 40 filter samples collected in January-February 2022 at a Fairbanks residential site were analyzed for OP utilizing dithiothreitol-depletion (OP^DTT) and hydroxyl-generation (OP^OH) assays. The study-average PM_2.5 mass concentration was 12.8 μg/m³, with a 1 h average maximum of 89.0 μg/m³. Regression analysis, correlations with source tracers, and contrast between cold and warmer events indicated that OP^DTT was mainly sensitive to copper, elemental carbon, and organic aerosol from residential wood burning, and OP^OH to iron and organic aerosol from vehicles. Despite low photochemically-driven oxidation rates, the water-soluble fraction of OP^DTT was unusually high at 77%, mainly from wood burning emissions. In contrast to other locations, the Fairbanks average PM_2.5 mass concentration was higher than Atlanta and Los Angeles, whereas OP^DTT in Fairbanks and Atlanta were similar, and Los Angeles had the highest OP^DTT and OP^OH. Site differences were observed in OP when normalized by both the volume of air sampled and the particle mass concentration, corresponding to exposure and the intrinsic health-related properties of PM_2.5, respectively. The sensitivity of OP assays to specific aerosol components and sources can provide insights beyond the PM_2.5 mass concentration when assessing air quality.

SUBMITTER: Yang Y

PROVIDER: S-EPMC10928717 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature

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Assessing the Oxidative Potential of Outdoor PM2.5 in Wintertime Fairbanks, Alaska.

Yang Yuhan Y Battaglia Michael A MA Mohan Magesh Kumaran MK Robinson Ellis S ES DeCarlo Peter F PF Edwards Kasey C KC Fang Ting T Kapur Sukriti S Shiraiwa Manabu M Cesler-Maloney Meeta M Simpson William R WR Campbell James R JR Nenes Athanasios A Mao Jingqiu J Weber Rodney J RJ

ACS ES&T air 20240210 3

The oxidative potential (OP) of outdoor PM2.5 in wintertime Fairbanks, Alaska, is investigated and compared to those in wintertime Atlanta and Los Angeles. Approximately 40 filter samples collected in January-February 2022 at a Fairbanks residential site were analyzed for OP utilizing dithiothreitol-depletion (OPDTT) and hydroxyl-generation (OPOH) assays. The study-average PM2.5 mass concentration was 12.8 μg/m3, with a 1 h average maximum o ...[more]

PMID: 38482267

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Project description:Epidemiological studies have consistently linked exposure to PM2.5 with adverse health effects. The oxidative potential (OP) of aerosol particles has been widely suggested as a measure of their potential toxicity. Several acellular chemical assays are now readily employed to measure OP; however, uncertainty remains regarding the atmospheric conditions and specific chemical components of PM2.5 that drive OP. A limited number of studies have simultaneously utilised multiple OP assays with a wide range of concurrent measurements and investigated the seasonality of PM2.5 OP. In this work, filter samples were collected in winter 2016 and summer 2017 during the atmospheric pollution and human health in a Chinese megacity campaign (APHH-Beijing), and PM2.5 OP was analysed using four acellular methods: ascorbic acid (AA), dithiothreitol (DTT), 2,7-dichlorofluorescin/hydrogen peroxidase (DCFH) and electron paramagnetic resonance spectroscopy (EPR). Each assay reflects different oxidising properties of PM2.5, including particle-bound reactive oxygen species (DCFH), superoxide radical production (EPR) and catalytic redox chemistry (DTT/AA), and a combination of these four assays provided a detailed overall picture of the oxidising properties of PM2.5 at a central site in Beijing. Positive correlations of OP (normalised per volume of air) of all four assays with overall PM2.5 mass were observed, with stronger correlations in winter compared to summer. In contrast, when OP assay values were normalised for particle mass, days with higher PM2.5 mass concentrations (μgm-3) were found to have lower mass-normalised OP values as measured by AA and DTT. This finding supports that total PM2.5 mass concentrations alone may not always be the best indicator for particle toxicity. Univariate analysis of OP values and an extensive range of additional measurements, 107 in total, including PM2.5 composition, gas-phase composition and meteorological data, provided detailed insight into the chemical components and atmospheric processes that determine PM2.5 OP variability. Multivariate statistical analyses highlighted associations of OP assay responses with varying chemical components in PM2.5 for both mass- and volume-normalised data. AA and DTT assays were well predicted by a small set of measurements in multiple linear regression (MLR) models and indicated fossil fuel combustion, vehicle emissions and biogenic secondary organic aerosol (SOA) as influential particle sources in the assay response. Mass MLR models of OP associated with compositional source profiles predicted OP almost as well as volume MLR models, illustrating the influence of mass composition on both particle-level OP and total volume OP. Univariate and multivariate analysis showed that different assays cover different chemical spaces, and through comparison of mass- and volume-normalised data we demonstrate that mass-normalised OP provides a more nuanced picture of compositional drivers and sources of OP compared to volume-normalised analysis. This study constitutes one of the most extensive and comprehensive composition datasets currently available and provides a unique opportunity to explore chemical variations in PM2.5 and how they affect both PM2.5 OP and the concentrations of particle-bound reactive oxygen species.

Project description:The main objective of this study was chemical characterization and source apportionment of the oxidative potential of ambient PM2.5 samples collected in an urban background area in Athens, Greece. Ambient PM2.5 samples were collected during the summer (June-September) of 2017 and winter (February-March) of 2018 at a residential, urban background site in the outlying neighborhood of the Demokritos National Laboratory in Athens, Greece. The collected PM samples were analyzed for their chemical constituents including metals and trace elements, water-soluble organic carbon (WSOC), elemental and organic carbon (EC/OC), and marker of biomass burning (i.e., levoglucosan). In addition, the DCFH in vitro assay was performed to determine the oxidative potential of the PM2.5 samples. We performed a series of statistical analyses, including Spearman rank-order correlation analysis, principal component analysis (PCA), and multi linear regression (MLR) to determine the most significant species (as source tracers) contributing to the oxidative potential of PM2.5. Our findings revealed that the intrinsic (per PM mass) and extrinsic (per m3 of air volume) oxidative potentials of the collected ambient PM2.5 samples were significantly higher than those measured in many urban areas around the world. The results of the MLR analyses indicated that the major pollution sources contributing to the oxidative potential of ambient PM2.5 were vehicular emissions (characterized by EC) (44%), followed by secondary organic aerosol (SOA) formation (characterized by WSOC) (16%), and biomass burning (characterized by levoglucosan) (9%). The oxidative potential of the collected ambient PM2.5 samples was also higher in summer compared to the winter, mainly due to higher concentrations of EC and WSOC during this season. Results from this study corroborate the impact of traffic and SOA on the oxidative potential of ambient PM2.5 in greater Athens area, and can be helpful in adopting appropriate public health policies regarding detrimental outcomes of exposure to PM2.5.

Dataset Information

Assessing the Oxidative Potential of Outdoor PM_2.5 in Wintertime Fairbanks, Alaska.

Publications

Assessing the Oxidative Potential of Outdoor PM<sub>2.5</sub> in Wintertime Fairbanks, Alaska.

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