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Fine particulate matter (PM2.5) has been shown to cause oxidative stress, which has negative health consequences. The oxidative potential (OP) of PM2.5, a promising health exposure metric, was assessed in five Colombian cities using the synthetic respiratory tract lining fluid assay that tracks the depletions of glutathione and ascorbate. For this, a set of 91 integrated 2-week ambient PM2.5 samples were collected using Ultrasonic Personal Aerosol Samplers (UPAS) at background (5), traffic (37), industrial (12) and residential (37) sites. Across all site types, mean PM2.5 mass concentration was 20.20 ± 9.36 µg m− 3. The oxidative potential (OPAA for ascorbate and OPGSH for glutathione) varied widely across cities with an average of 2.67 ± 1.27 for AA and 2.93 ± 1.22 % depletion m− 3 for GSH. OP metrics among cities were not correlated with PM2.5 mass concentrations. Overall, industrial sites showed higher PM2.5 mass concentrations and OPAA. In contrast, OPGSH was not found to differ among industrial, traffic, or residential sites, but was lower for background sites. Our findings provide substantial evidence of variations in PM2.5 OP between cities and within the cities. Further research is needed to assess the association between OP and adverse health effects, as well as to attribute the sources that cause such variations. [ABSTRACT FROM AUTHOR]

Successful implementation of Safe and Sustainable by Design (SSbD) and grouping approaches requires simple, reliable, and cost-effective assays to facilitate hazard screening at early stages of product development. Especially for nanomaterials (NMs), which exist in many different forms, efficient hazard screening is of utmost importance. Oxidative potential (OP), which is the ability of a substance to induce reactive oxygen species (ROS), is an important indicator of the potential to induce oxidative damage and oxidative stress. A frequently used assay to measure OP of NMs is the ferric reducing ability of serum (FRAS) assay. Although the widely used cuvette-based FRAS protocol is considered a robust assay, its low throughput makes the screening of multiple materials challenging. Here, we adapt the original cuvette-based FRAS assay protocol, into a 96-well format and thereby improve its user-friendliness, simplicity, and screening capacity. The adapted protocol allows for the screening of multiple NMs per plate, and multiple plates per day, where the original protocol allows for the screening of one NM dose-range per day. When comparing the two protocols, the adapted protocol showed slightly decreased assay precision as compared to the original protocol. The results obtained with the adapted protocol were compared using eight reference NMs in an interlaboratory study and showed acceptably low intra- and interlaboratory variation. We conclude that the adapted FRAS assay protocol is suitable to be used for hazard screening to facilitate SSbD and grouping approaches. [ABSTRACT FROM AUTHOR]

• Water-soluble metal ions were the dominant contributors to the DTT activity in PM 2.5. • Organics contributed more to DTT activity in 2022 than in 2017/2018. • PM 2.5 showed a lower exposure risk and higher intrinsic oxidative toxicity in 2022. • The relative contributions of vehicle emissions, coal/biomass burning, and ship emissions to DTT activity decreased dramatically in 2022. The toxicity of PM 2.5 does not necessarily change synchronously with its mass concentration. In this study, the chemical composition (carbonaceous species, water-soluble ions, and metals) and oxidative potential (dithiothreitol assay, DTT) of PM 2.5 were investigated in 2017/2018 and 2022 in Xiamen, China. The decrease rate of volume-normalized DTT (DTT v) (38%) was lower than that of PM 2.5 (55%) between the two sampling periods. However, the mass-normalized DTT (DTT m) increased by 44%. Clear seasonal patterns with higher levels in winter were found for PM 2.5 , most chemical constituents and DTT v but not for DTT m. The large decrease in DTT activity (84%−92%) after the addition of EDTA suggested that water-soluble metals were the main contributors to DTT in Xiamen. The increased gap between the reconstructed and measured DTT v and the stronger correlations between the reconstructed/measured DTT ratio and carbonaceous species in 2022 were observed. The decrease rates of the hazard index (32.5%) and lifetime cancer risk (9.1%) differed from those of PM 2.5 and DTT v due to their different main contributors. The PMF-MLR model showed that the contributions (nmol/(min·m3)) of vehicle emission, coal + biomass burning, ship emission and secondary aerosol to DTT v in 2022 decreased by 63.0%, 65.2%, 66.5%, and 22.2%, respectively, compared to those in 2017/2018, which was consistent with the emission reduction of vehicle exhaust and coal consumption, the adoption of low-sulfur fuel oil used on board ships and the reduced production of WSOC. However, the contributions of dust + sea salt and industrial emission increased. The change trends of PM 2.5 , DTT activity, non-cancer and cancer risks due to the selected elements (V, Cr(VI), Mn, Ni, As, Se, Cd, Ba, Pb, Mo, Sb, and Co) [Display omitted] [ABSTRACT FROM AUTHOR]

Life cycle assessment (LCA) along with a survey on epidemiologic and oxidative potential studies was used for analysing the current evidence of the impact of airborne emissions from municipal solid waste incineration (MSWI) on human health. The correspondence among investigated health outcomes and pollutants was discussed based on the Chemical Abstract Service (CAS) and the International Agency for Research on Cancer (IARC). LCA indicated the ability of MSWI in avoiding human health impact, about − 2 × 10−4 DALY/tonne together with avoided emissions of particulate matter (PM) and resource depletion, about − 2.5 × 10−3 kg Sbeq/tonne and about − 0.11 kg PM2.5 eq/tonne, respectively. Positive emissions were detected for greenhouses (about 900 kg CO2eq/tonne) and ecotoxicity (about 15,000 CTUe/tonne). Epidemiologic studies performed on population exposed to MSWI reported quite contrasting results. In some of these, hazard ratio (HR) ranging from about 0.7 to 2.2 was reported concerning the incidence of stomach, liver, breast and bladder cancer. Larger agreement was detected concerning the incidence of larynx and lung cancer with HR ranging from about 1 to about 2.6. Direct causal nexuses were not definitively identified. Oxidative potential of PM was characterized by a high Pearson correlation > 0.8 to the presence of CrVI, Cu and Zn. These heavy metals were also identified by both CAS and IARC as toxic (i.e. Cu and Zn) and cancerous (i.e. CrVI) substances affecting the organs of both respiratory and digestive apparatus. In general, even if more research is necessary, LCA, oxidative potential and the epidemiologic survey results showed a high level of accordance. This suggests their integrated exploitation for supporting the investigation of both direct and indirect consequences on environment and health related to waste incineration for both retrospective and predictive studies. [ABSTRACT FROM AUTHOR]

This study targets to determine the oxidative potential (OP) of fine aerosols in an urban-industrial area of the Lisbon Metropolitan Area (Portugal) and, in addition, to identify which pollution sources may have an impact on the OP levels of fine aerosols. For this purpose, thirty samples were selected from a set of 128 samples collected over one year (Dec 2019-Nov 2020), based on the highest load for each source (both mass and %) previously assessed by source apportionment studies (using Positive Matrix Factorisation, a total of 7 different sources were identified: soil, secondary sulphate, fuel-oil combustion, sea, vehicle non-exhaust, vehicle exhaust and industry). The OP associated with the water-soluble components of PM2.5 was assessed using the dithiothreitol (DTT) method. The samples had a mean DTT activity (normalised to the mass) of 12.9 ± 6.6 pmol min− 1 µg− 1, ranging from 3.5 to 31.8 pmol min− 1 µg− 1. The DTT activity (normalised to the volume, ) showed to have a significant positive association with PM2.5 levels (R2 = 0.714). Considering that the mass contributions of the different sources to the PM2.5 levels were known, Spearman correlations were assessed and significant correlations were found between and three different sources: vehicle exhaust (ρ = 0.647, p-value = 0.001), fuel-oil combustion (ρ = 0.523, p-value = 0.012) and industry (ρ = 0.463, p-value = 0.018). Using a multiple linear regression analysis, these three sources were found to explain 82% of the variability in , with vehicle exhaust being the most influential source. [ABSTRACT FROM AUTHOR]

The oxidative potential (OP) of particulate matter has been widely suggested as a key metric for describing atmospheric particle toxicity. Secondary organic aerosol (SOA) and redox-active transition metals, such as iron and copper, are key drivers of particle OP. However, their relative contributions to OP, as well as the influence of metal-organic interactions and particulate chemistry on OP, remains uncertain. In this work, we simultaneously deploy two novel online instruments for the first time, providing robust quantification of particle OP. We utilize online AA (OPAA) and 2,7-dichlorofluoroscein (ROSDCFH) methods to investigate the influence of Fe(II) and Cu(II) on the OP of secondary organic aerosol (SOA). In addition, we quantify the OH production (OPOH) from these particle mixtures. We observe a range of synergistic and antagonistic interactions when Fe(II) and Cu(II) are mixed with representative biogenic (β-pinene) and anthropogenic (naphthalene) SOA. A newly developed kinetic model revealed key reactions among SOA components, transition metals, and ascorbate, influencing OPAA. Model predictions agree well with OPAA measurements, highlighting metal-ascorbate and -naphthoquinone-ascorbate reactions as important drivers of OPAA. The simultaneous application of multiple OP assays and a kinetic model provides new insights into the influence of metal and SOA interactions on particle OP.

The oxidative potential (OP) of airborne particulate matter (PM) is gaining increasing attention as a health-relevant metric to describe the capacity of PM to promote oxidative stress and cause adverse health effects. To date, most OP studies use filter-based approaches to sample PM and quantify OP, which have relatively poor time resolution (∼24 h) and underestimate the contribution of reactive components to OP due to the time delay between sample collection and analysis. To address this important limitation, we have developed a novel instrument which uses a direct-to-reagent sampling approach, providing robust, continuous, high time resolution (5 min) OP quantification, hence overcoming analytical limitations of filter-based techniques. In this study, we deployed this instrument in the Marylebone Road Air Quality Monitoring Station in London, UK, alongside a broad suite of high time resolution PM2.5 composition measurements for three months continuous measurement during Summer 2023. High time resolution OP quantification reveals dynamic changes in volume-normalised (OPv) and mass normalised (OPm) OP evolving over ∼hourly timescales, observed at an average PM2.5 mass concentration of 7.1 ± 4.2 µg m−3, below the WHO interim 4 target of 10 µg m−3. In addition, high time resolution data facilitates directional analysis, allowing us to determine the influence of wind speed and wind direction on OP, and the identification of PM2.5 chemical components and sources which drive dynamic changes in OP; this includes traffic emissions, as well as emissions from the London Underground into the ambient airshed. These results demonstrate the capacity of high time resolution measurements to provide new insights into the temporal evolution of OP, as well as the composition and emission sources which drive OP, developing our understanding of the characteristics of PM2.5 which may promote adverse health impacts.

Current assessment of air quality or control effectiveness is solely based on particulate matter (PM) mass levels, without considering their toxicity differences in terms of health benefits. Here, we collected a total of 465 automobile air conditioning filters from 31 major Chinese cities to study the composition and toxicity of PM at a national scale. Dithiothreitol assay showed that normalized PM toxicity (NIOG) in different Chinese cities varied greatly from the highest 4.99 × 10−3 for Changsha to the lowest 7.72 × 10−4 for Yinchuan. NIOG values were observed to have significant correlations with annual PM10 concentration (r = -0.416, p = 0.020) and some PM components (total fungi, SO42− and calcium element). The concentrations of different elements and water-soluble ions in PM also varied by several orders of magnitude for 31 cities in China. Endotoxin concentrations in PM analyzed using limulus amebocyte lysate assay ranged from 2.88 EU/mg PM (Hangzhou) to 62.82 EU/mg PM (Shijiazhuang) among 31 Chinese cities. Besides, real-time qPCR revealed 10∼100-fold differences in total bacterial and fungal levels among 31 Chinese cities. The concentrations of chemical (water soluble ions and trace elements) and biological (fungi, bacteria and endotoxin) components in PM were found to be significantly correlated with some meteorological factors and gaseous pollutants such as SO2. Our results have demonstrated that PM toxicity from 31 major cities varied greatly up to 6.5 times difference; and components such as fungi and SO42− in PM could play important roles in the observed PM toxicity. The city-specific air pollution control strategy that integrates toxicity factors should be enacted in order to maximize health and economic co-benefits. This work also provides a comprehensive view on the overall PM pollution situation in China.

Recent studies indicate that mass concentration alone is not the best parameter to assess the toxicity and the health effects of particulate matter (PM). Indeed, the chemical composition of the particles plays an important role, and oxidative potential (OP) measurements are being proposed as an alternative way to assess toxicity. The European Union (EU) is currently proposing a draft of the new air quality directive which includes OP measurements but does not specify the methods and/or protocols of analysis. In this light, the purpose of this study was to evaluate the feasibility of two literature assays, namely ascorbic acid (AA) and dithiothreitol (DTT), for routine PM analysis by testing urban PM filters from a one-year sampling campaign conducted by ARPA Lombardia. Indoor PM samples were also tested to emphasize the importance of monitoring closed spaces in which people spend most of their time. Following the optimization of the DTT assay, both methods proved to be suitable for large-scale PM analysis. The results show that the oxidative strength of urban PM is constant throughout the year for the outdoor samples (OPAA: 0.067–0.39 nmol min−1 m−3; OPDTT: 0.033–0.109 nmol min−1 m−3), indicating the need for routine OP monitoring. Instead, indoor areas were characterized by particles with a lower oxidative capacity (OPAA: 5.40–24 pmol min−1 m−3; OPDTT: 9.7–32 pmol min−1 m−3), driven both by lower concentrations and a different chemical composition. All the data collected highlight the need to add this parameter as part of the chemical characterization of PM, moving in the same direction as the new EU air quality directive. [ABSTRACT FROM AUTHOR]

Located between Mexico and the US, the San Ysidro/El Chaparral Land Port of Entry (SYPOE) is one of the busiest border crossings in the world. People with activities at the SYPOE are exposed to vehicular pollutants, especially particles with aerodynamic diameters < 2.5 µm (PM2.5) and black carbon (BC), both associated with adverse health effects. This study presents the first PM2.5 and BC concentration measurements collected on the Mexican side of the SYPOE. The oxidative potential (OP) for PM2.5 and the inhalation dose of BC for people at the border were also evaluated. Autumn and winter showed the highest PM2.5 concentrations (at 28.7 μg m−3 and 28.2 μg m−3, respectively). BC concentration peaked in the winter of 2017 (at 5.7 ± 6 μgm−3), demonstrating an increase during periods with low wind speeds. The highest OPDTT of PM2.5 was reached in winter, with a value of 18.5 pmol min−1 µg−1 (0.6 nmol min−1m−3). The highest average daily inhalation dose for pedestrians was registered in the autumn of 2018 (5.9 μg for a 60-min waiting time), whereas, for workers, it was in the winter of 2017 (19 μg for a 10-h shift on average). Decreasing waiting times for pedestrians and adjusting work schedules for border workers on high concentration days could ameliorate environmental justice. [ABSTRACT FROM AUTHOR]

This study is a comprehensive analysis of the oxidative potential (OP) of particulate matter (PM) and its environmental and health impacts. The researchers conducted a bibliometric analysis and scoping review, screening 569 articles and selecting 368 for further analysis. The study found that OP is an emerging field of study, with a notable increase in the number of publications in the 2010s compared to the early 2000s. The research is primarily published in eight journals and is concentrated in a few academic and university-based institutions. The study identified key research hotspots for OP-PM, emphasizing the importance of capacity building, interdisciplinary collaboration, understanding emission sources and atmospheric processes, and the impacts of PM and its OP. The study highlighted the need to consider the effects of climate change on OP-PM and the regulatory framework for PM research. The findings of this study will contribute to a better understanding of PM and its consequences, including human exposure and its effects. It will also inform strategies for managing air quality and protecting public health. Overall, this study provides valuable insights into the field of OP-PM research and highlights the need for continued research and collaboration to address the environmental and health impacts of PM. [ABSTRACT FROM AUTHOR]

Atmospheric particulate matter (PM) has been related to numerous adverse health effects in humans. Nowadays, it is believed that one of the possible mechanisms of toxicity could be the oxidative stress, which involves the development of reactive oxygen species (ROS). Different assays have been proposed to characterize oxidative stress, such as dithiothreitol (DTT) and ascorbic acid (AA) acellular assays (OPDTT and OPAA), as a metric more relevant than PM mass measurement for PM toxicity. This study evaluates the OP of the bioaccessible fraction of 65 PM10 samples collected at an Atlantic Coastal European urban site using DTT and AA assays. A physiologically based extraction (PBET) using Gamble's solution (GS) as a simulated lung fluid (SLF) was used for the assessment of the bioaccessible fraction of PM10. The use of the bioaccessible fraction, instead of the fraction assessed using conventional phosphate buffer and ultrasounds assisted extraction (UAE), was compared for OP assessment. Correlations between OPDTT and OPAA, as well as total and bioaccessible concentrations of polycyclic aromatic hydrocarbons (PAHs) and metal(oid)s, were investigated to explore the association between those compounds and OP. A correlation was found between both OP (OPDTT and OPAA) and total and bioaccessible concentrations of PAHs and several metal(oid)s such as As, Bi, Cd, Cu, Ni, and V. Additionally, OPDTT was found to be related to the level of K+. [ABSTRACT FROM AUTHOR]

Numerous studies have shown negative health effects related to exposure to ambient particulate matter (PM), likely due to induced oxidative stress. In this study, we have examined ambient PM samples from Birr, a small (~5000 inhabitants) town in central Ireland, for their water-soluble DTT-based oxidative potential (OP_DTT) with a resolution of 6 h, together with online chemical characterization measurements, to assess the OP of organic aerosols, in particular from residential solid fuel burning. The OP_DTT normalized by the volume of sampled air shows a high variability, ranging from <0.1 to 3.8 nmol min−1 m−3, and a high correlation with PM mass. A lower variability was associated with the mass-normalized OP. Nevertheless, both tended to present higher values during night-time pollution episodes. Simple and multivariate linear regression approaches linked OP_DTT to residential solid fuel burning, and in particular to wood (~87%) and peat (~13%) combustion. The results of the present study show how residential solid fuel burning can have a severe impact on air quality, even in small towns, with potential negative health effects on the exposed population. [ABSTRACT FROM AUTHOR]

Exposure to air pollutants especially fine particulate matter (PM2.5) poses serious risks to human health including cytotoxic and genotoxic effects. However, depending on the meteorological conditions and emission sources, chemical composition of PM2.5 and consequently related adverse health effects may vary in different locations. In this study, cytotoxic and genotoxic effects of water-soluble and organic fraction of ambient air PM2.5 of Isfahan city, Iran, were evaluated using the MTT and comet assay, respectively. Concentrations of polycyclic aromatic hydrocarbons (PAHs) as important toxic agents of organic fraction of particles were also determined. The results showed that both fraction of PM2.5 especially organic fraction induce cytotoxic and genotoxic effects at tested concentrations. Analysis of PAHs showed a concentration of 1.5–18.6 ng/m3 of total PAHs and 0.99–11.2 ng/m3 for carcinogenic PAHs, respectively, with an important role on the toxic effect of PM2.5 organic fraction. Overall, our results showed a considerable cytotoxic effect (0–64%) of organic fraction of fine particles at all times of the year which may be related to the vehicular emission. In addition, the results showed more cytotoxicity of water-soluble fraction of PM2.5 in dust events. The results of study highlight the need to reduce PM2.5 pollution especially through controlling of PAH emission sources such as vehicles. However, further research is needed to improve our knowledge about the PM chemical composition and related emission sources to manage air pollution-associated health effects. [ABSTRACT FROM AUTHOR]

The capacity of particulate matter (PM) to generate reactive oxygen species (ROS) in vivo leading to oxidative stress, is thought to be a main pathway for the health effect of PM inhalation. Exogenous ROS from PM can be assessed by acellular oxidative potential (OP) measurements as a proxy of the induction of oxidative stress in the lungs. Here, we investigate the importance of OP apportionment methods on OP repartition by PM sources in different types of environments. PM sources derived from receptor models (e.g. EPA PMF) are coupled with regression models expressing the associations between PM sources and OP measured by ascorbic acid (OPAA) and dithiothreitol assay (OPDTT). These relationships are compared for eight regression techniques: Ordinary Least Squares, Weighted Least Squares, Positive Least Squares, Ridge, Lasso, Generalized Linear Model, Random Forest, and Multilayer Perceptron. The models are evaluated on one year of PM10 samples and chemical analyses at each of six sites of different typologies in France to assess the possible impact of PM source variability on OP apportionment. Source-specific OPDTT and OPAA and out-of-sample apportionment accuracy vary substantially by model, highlighting the importance of model selection depending on the datasets. Recommendations for the selection of the most accurate model are provided, encompassing considerations such as multicollinearity and homoscedasticity. [ABSTRACT FROM AUTHOR]

The impact of reductive pulmonary inhalants on ultrafine particles (UFPs)-induced pulmonary oxidative stress remains a crucial consideration, yet the concentration-dependent effects of these inhalants have remained unexplored. Here we synthesized composite UFPs simulating atmospheric UFPs, primarily composed of metals and quinones. We subjected these UFPs to varying concentrations (0–7000 μM) of two reductive pulmonary inhalants, N-acetylcysteine and salbutamol, to assess their influence on oxidative potential, measured through the dithiothreitol assay (OPDTT). Simultaneously, we analysed the soluble metal content of UFPs to uncover potential relationships between oxidative potential and metal solubility. Our results unveil a dual role played by these inhalants in shaping the OPDTT of composite UFPs. Specifically, OPDTT generally increased as inhalant concentrations rose from 0 to 300 μM. However, an intriguing reversal occurred when concentrations exceeded 500 μM, resulting in a decline in OPDTT. Relative to untreated UFPs, these inhalants induced promotion and inhibition effects within concentration ranges of 100–500 and >1000 μM, respectively. While no significant correlation emerged between OPDTT and soluble metal content as inhalant concentrations ranged from 0 to 7000 μM, noteworthy positive correlations emerged at lower inhalant concentrations (e.g., N-acetylcysteine at 0–300 μM). These findings provide insights into the potential influence of reductive pulmonary inhalants on health risks associated with UFP exposure, further underscoring the need for continued research in this critical area.

The mass concentration of atmospheric particulate matter (PM) has been continuously decreasing in the Beijing-Tianjin-Hebei region. However, health endpoints do not exhibit a linear correlation with PM mass concentrations. Thus, it is urgent to clarify the prior toxicological components of PM to further improve air quality. In this study, we analyzed the long-term oxidative potential (OP) of water-soluble PM2.5, which is generally considered more effective in assessing hazardous exposure to PM in Beijing from 2018 to 2022 based on the dithiothreitol assay and identified the crucial drivers of the OP of PM2.5 based on online monitoring of air pollutants, receptor model, and random forest (RF) model. Our results indicate that dust, traffic, and biomass combustion are the main sources of the OP of PM2.5 in Beijing. The complex interactions of dust particles, black carbon, and gaseous pollutants (nitrogen dioxide and sulfur dioxide) are the main factors driving the OP evolution, in particular, leading to the abnormal rise of OP in Beijing in 2022. Our data shows that a higher OP is observed in winter and spring compared to summer and autumn. The diurnal variation of the OP is characterized by a declining trend from 0:00 to 14:00 and an increasing trend from 14:00 to 23:00. The spatial variation in OP of PM2.5 was observed as the OP in Beijing is lower than that in Shijiazhuang, while it is higher than that in Zhenjiang and Haikou, which is primarily influenced by the distribution of black carbon. Our results are of significance in identifying the key drivers influencing the OP of PM2.5 and provide new insights for advancing air quality improvement efforts with a focus on safeguarding human health in Beijing.

There is a need for monitoring air pollution associated with black carbon (BC) using a passive monitor is required in remote areas where the measurements are absent. In this pilot study, we developed a quantitative method to determine dry deposition submicron BC using dual-wavelength ultraviolet–visible spectroscopy. Furthermore, we measured the levels of dry deposition BC on plant leaves from 30 plant species located in urban Nanjing using the established method. The oxidative potential of BC on plant leaves as passive bio-monitoring samplers was assessed. The concentrations of black carbon (BC) on tree leaves varied from 0.01 to 1.6 mg m−2. Significant differences in levels of BC across leaves from different tree types were observed. The values of oxidative potential in deposited particles of leaf samples were observed to be in the range of 33–46 nmol min−1 mg−1 using the dithiothreitol (DTT) assay and 18–32 nmol min−1 mg−1 using the ascorbic acid (AA) assay, respectively. In comparison, the oxidative potential of BC-dominated mass in water extracts of leaf samples was in the range of 5–35 nmol min−1 mg−1 measured using the DTT assay and 2 to 12 nmol min−1 mg−1 using the AA assay, respectively. We found variations in the levels of OP across the leaves of different tree types were not large, while the levels of OP in terms of BC-dominated mass varied greatly. These results indicate that the established method with dual-wavelength ultraviolet–visible spectroscopy could provide a simple tool to determine submicron BC in plant leaves of the passive monitor. [ABSTRACT FROM AUTHOR]

The oxidative potential (OP) is defined as the ability of inhaled PM components to catalytically/non-catalytically generate reactive oxygen species (ROS) and deplete lung antioxidants. Although several studies have measured the OP of particulate matter (PM OP) soluble components using different antioxidants under neutral pH conditions, few studies have measured PM OP with acidic lung fluids. This study provides new insights into the use of acidic rather than neutral fluids in OP assays. Thus, the first aim of this study was to clarify the effect of using an acidic lung fluid on ascorbic acid (AA) depletion. This was achieved by measuring the oxidative potential (OP-AA) of individual compounds known to catalyze the AA oxidation (CuSO4, CuCl2, and 1,4-NQ) in artificial lysosomal fluid (ALF, pH 4.5), a commonly used acidic simulated lung fluid, and in a neutral fluid (phosphate-buffered saline (PBS1x), pH 7.4). Our results from these individual compounds showed a significant decrease of OP-AA in the acidic fluid (ALF) with respect to the neutral fluid (PBS). Then, the second aim of this work was to investigate whether the OP-AA assay could be applied to PM2.5 samples extracted in acidic conditions. For this purpose, OP-AA and bioaccessible concentrations of metal(loid)s (V, Mn, Fe, Ni, Cu, Zn, As, Mo, Cd, Sb, and Pb) of PM2.5 samples collected in an urban-industrial area that were extracted in ALF were analyzed. The mean volume-normalized OP (OP-AAv) value was 0.10 ± 0.07 nmol min−1 m−3, clearly lower than the values found in the literature at neutral pH. OP-AAv values were highly correlated with the ALF-bioaccessible concentration of most of the studied metal(loid)s, mainly with Cu and Fe. [ABSTRACT FROM AUTHOR]

China has long-term high PM2.5 levels, and its Oxidative Potential (OP) is worth studying asit may unravel the impacts of aerosol pollution on public health better than PM2.5 alone. OP and PM2.5 are influenced by meteorological factors, anthropogenic emissions sources and atmospheric aging. Although their impact on PM2.5 have been studied, OP measurements only recently became available and on a limited scale, as they require considerable technical expertise and resources. For this, the joint relationship between PM2.5 and OP for a wide range of meteorological conditions and emissions profiles remain elusive. Towards this, we estimated PM2.5 and OP over China using the Danish Eulerian Hemispheric Model (DEHM) system with meteorological input from WRF weather forecast model. It was found that higher values of PM2.5 and OP were primarily concentrated in urban agglomerations in the central and eastern regions of China, while lower values were found in the western and northeastern regions. Furthermore, the probability density function revealed that about 40% of areas in China had an annual average PM2.5 concentrations exceeding the Chinese concentrations limit; 36% of the regions have OP below 1 41% have OP between 1 and, and 23% have OP above 2. Analysis of the simulations indicate that meteorological conditions and anthropogenic emission contributed 46% (65%) and 54% (35%) to the PM2.5 concentration (OP) variability. The emission sensitivity analysis also highlighted PM2.5 and OP levels are mostly determined by secondary aerosol formation and biomass burning. [ABSTRACT FROM AUTHOR]

The impact of incense burning on ambient air quality was investigated by measuring the concentrations of fine particles (PM2.5), elemental carbon (EC), organic carbon (OC), and their oxidative potential (OP) at three temple premises in Kathmandu Valley, Nepal. These temples, namely, Bajrabarahi, Bagalamukhi, and Bhadrakali, are located in three distinct environments: forest, residential, and roadside, respectively. During the incense burning event days, the PM2.5 concentration at Bhadrakali (431.4 μgm−3) was significantly higher than that measured at the Bagalamukhi (135.2 μgm−3) and Bajrabarahi (84.7 μgm−3) temple premises. This observation is consistent with the fact that Bhadrakali Temple had the highest intensity of incense burning. Additionally, the temple premises were also influenced by vehicular emissions from transportation facilities. Carbonaceous aerosols significantly increased during incense burning events, indicating that incense burning contributes significantly to the formation of primary and secondary OC. Moreover, the OP of PM2.5 during the incense burning event days was higher compared to non-event days (p < 0.05), suggesting an elevated health risk due to the increased concentration and toxicity of fine particles. These findings highlight the substantial impact of incense burning on air quality in temple premises, emphasizing the need to implement effective strategies to mitigate the associated health risks. [ABSTRACT FROM AUTHOR]

Inhalation of atmospheric PM 2.5 can induce the generation of excessive reactive oxygen species (ROS) in human alveoli, triggering local and systemic inflammation, which can directly or indirectly result in respiratory and cardiovascular diseases. In this study, we assessed the oxidative potential (OP) of fresh and O 3 -aged PM 2.5 particles from various urban and rural emission sources using the dithiothreitol (DTT) method. Our results revealed variations in the OP of fresh PM 2.5 among different emission sources, with biomass burning sources exhibiting the highest OP, followed by industrial areas, vehicular emissions, cooking emissions, and suburban areas, respectively. Water-soluble organics and transition metals might potentially exert significant influence on particle OP. O 3 aging notably decreased the OP of PM 2.5 particles, possibly due to the oxidation of highly DTT-active components into low redox-active small molecules. Moreover, the evolution of OP in different PM 2.5 components, including methanol-soluble and insoluble fractions, exhibited distinct responses to O 3 aging for source-oriented PM 2.5. Additionally, differences in chemical composition between fresh and aged PM 2.5 were further elucidated through measurements of component-dependent hygroscopic behaviors and phase transitions. This study systematically delineates variances in the toxic potential of fresh and O 3 -aged PM 2.5 from various anthropogenic sources. The findings highlight the intrinsic compositional dependence of particle OP and provide essential insights for assessing the health effects of source-oriented PM 2.5 , as well as for formulating human health protection policies. [ABSTRACT FROM AUTHOR]

This study is a comprehensive analysis of the oxidative potential (OP) of particulate matter (PM) and its environmental and health impacts. The researchers conducted a bibliometric analysis and scoping review, screening 569 articles and selecting 368 for further analysis. The study found that OP is an emerging field of study, with a notable increase in the number of publications in the 2010s compared to the early 2000s. The research is primarily published in eight journals and is concentrated in a few academic and university-based institutions. The study identified key research hotspots for OP-PM, emphasizing the importance of capacity building, interdisciplinary collaboration, understanding emission sources and atmospheric processes, and the impacts of PM and its OP. The study highlighted the need to consider the effects of climate change on OP-PM and the regulatory framework for PM research. The findings of this study will contribute to a better understanding of PM and its consequences, including human exposure and its effects. It will also inform strategies for managing air quality and protecting public health. Overall, this study provides valuable insights into the field of OP-PM research and highlights the need for continued research and collaboration to address the environmental and health impacts of PM.

Pomegranate peel powder (PPP) is a rich source of many bioactive components particularly polyphenols that are interlinked to various technological and functional properties. In the present study, chicken tender pops were developed with incorporation of PPP, and its effect on quality attributes and storage stability of the product were evaluated. The treatments were formulated using 0%, 3%, 6%, and 9% PPP in replacement of chicken. The physicochemical properties, texture profile, instrumental color, sensory attributes, and storage stability were assessed for 21 days at refrigeration temperature, at a regular interval of 7 days. The results indicated that the inclusion of PPP significantly (p <.05) increased the dietary fiber from 0.25% in T0 to 1.45% in T3 at Day 0 and WHC 43.60% ± 0.02 in T0 to 49.36% ± 0.02 in T3 at Day 0, whereas the moisture content significantly reduced from 60.05% ± 0.03 in T0 to 55.08% ± 0.01 in T3 at the start of the study. In addition, the values of TBARS were significantly (p <.05) reduced for treated samples 0.72 mg MDA/Kg in T3 as compared to control 1.17 mg MDA/Kg on the 21st day of storage, whereas a significant increase (p <.05) in TPC from 0.90 mg GAE/g to 3.87 mg GAE/g in T0 to T3 was observed at the start of the study. For TPA, a significant (p <.05) increase was noticed in hardness, chewiness, and gumminess, whereas cohesiveness and springiness showed a non‐significant (p >.05) change in treated samples in relation to control, and the instrumental color (L* and a*) decreased significantly. However, pH, crude fiber, fat, ash, and protein content showed non‐significant (p >.05) variations over time. The sensory evaluation suggested that chicken tender pops supplemented with 6% PPP (T2) presented high overall acceptability and balanced organoleptic properties. Hence, it can be concluded that PPP can be effectively utilized as a natural fiber source, antioxidant, and antimicrobial agent in novel functional foods. [ABSTRACT FROM AUTHOR]

Many studies have examined the associations between exposure to indoor and outdoor atmospheric particulate matter and health outcomes in humans. There is increasing evidence that the oxidative characteristics of such particulate matter have a role in determining the adverse health effects of fine particulates. Moreover, since people spend more time in indoors (office and home), indoor air quality and its impact on human health have increased in importance. However, to date, studies examining the oxidative characteristics of indoor particulates are few, and there has been a limited examination of the impact on physiological conditions of indoor fine particulates exposure on microorganisms. Therefore, this study aimed to investigate the oxidative characteristics of fine particulates in an indoor environment on the -3rd floor. The chemical characteristics of indoor PM2.5 samples were determined through their elemental composition, particle oxidation state, and organic and inorganic functional groups using EDX and FTIR spectrometry. Oxidative characteristics were also examined in terms of the cellular response of opportunistic bacteria (Staphylococcus aureus and Escherichia coli) by oxidative stress indicators (e.g., antioxidant, catalase, superoxide dismutase, glutathione (reduced), lipid peroxidation, and hydrogen peroxide), applied to artificial lung fluid and TRIS soluble fractions of aerosol that was extracted from the fine mode (PM2.5) of 120-h filter samples. Bacterial activity and protein content of S. aureus and E. coli were also studied in order to understand the main biochemical response of opportunistic bacteria. The chemical analysis results showed that elements in the indoor PM2.5 filters were both crustal origin (e.g., Al, Si, K, and Ca) and anthropogenic (e.g., Ba, Zn, and Ce). The identified functional groups were S = O, N–H, N = O, C = O, C-H, and O–H, which can cause oxidative stress. Bacteria-based oxidative indicators showed that both PM2.5 and physicological fluids induced the oxidative stress. However, oxidative responses were changed by the type of bacteria and physicological fluid, and PM2.5 was disturbed by the natural protection of physicological fluids. [ABSTRACT FROM AUTHOR]

Epidemiological studies suggest that measuring the oxidation potential of particles is more appropriate than measuring PM mass concentration. For the quantification of oxidation potential (OP) associated with ambient particulate matter (PM), two cell-based and cell-free methods are commonly used. One of the most widely used cell-free methods for particle oxidation potential is the dithiothreitol (DTT, HSCH2 (CH (OH))2 CH2SH)), which requires less controlled environments and offers faster readout of PM oxidative potential. In the present study, to observe the seasonal variations of the OP of the particulate matter of different sizes (PM1, PM2.5), using a DTT assay water-based, the OP was measured during spring, summer, and autumn in the ambient air of Tehran city, the capital of Iran from 2021/4/17 to 2021/12/6. PM1 samples were collected with Sioutas cascade impactor using low-volume air samplers operating at a flow rate of 9 L/min, with high-volume air samplers (operating at a flow rate of 1.415 m3/min) used for PM2.5. PM1 and PM2.5 mass concentrations in ambient air were within (13.8–111.2) and (18.4–148.2) μg/m3 respectively. The results of the present study revealed that generally, OP of PM1 was higher than OP of PM2.5, and this value was larger in autumn than in spring and in spring higher than in summer. The correlation between the mass concentration of PM2.5 and oxidative potential mass normalized (OPDTTm) for total and spring was significant with R2 equal to 0.64 and 0.81, respectively, while a significant correlation was observed between oxidative potential volume normalized (OPDTTv) and PM2.5 mass concentration in summer with R2 of 0.63. It is expected that the existence of these studies can lead to measuring oxidative potential with the direct reading approach in the future. Highlights: • The ability of particles to generate reactive oxygen species (ROS) was measured for the first time in Iran. • Acellular assay dithiothreitol was used for oxidative potential (OP) in ambient air PM1 and PM2.5 of Tehran, Iran. • OP of PM1 was higher than the OP of PM2.5 • The value OP of PM1 and PM2.5 was higher in autumn > spring > summer. [ABSTRACT FROM AUTHOR]

The potential reach of point-of-care (POC) diagnostics into daily routines for exposure to reactive oxygen species (ROS) and Cu in aerosolized particulate matter (PM) demands that microfluidic paper-based analytical devices (μPADs) take into consideration the simple detection of these toxic PM components. Here, we propose μPADs with a dual-detection system for simultaneous ROS and Cu(II) detection. For colorimetric ROS detection, the glutathione (GSH) assay with a folding design to delay the reaction yielded complete ROS and GSH oxidation, and improved homogeneity of color development relative to using the lateral flow pattern. For electrochemical Cu(II) determination, 1,10-phenanthroline/Nafion modified graphene screen-printed electrodes showed ability to detect Cu(II) down to pg level being low enough to be applied to PM analysis. No intra- and inter-interference affecting both systems were found. The proposed μPADs obtained LODs for 1,4-naphthoquinone (1,4-NQ), used as the ROS representative, and Cu(II) of 8.3 ng and 3.6 pg, respectively and linear working ranges of 20 to 500 ng for ROS and 1 × 10−2 to 2 × 102 ng for Cu(II). Recovery of the method was between 81.4 and 108.3% for ROS and 80.5–105.3% for Cu(II). Finally, the sensors were utilized for simultaneous ROS and Cu(II) determination in PM samples and the results statistically agreed with those using the conventional methods at 95% confidence. [ABSTRACT FROM AUTHOR]

Oxidative stress (OS) associated with metals in urban dust has become a public health concern. Chronic diseases linked to general inflammation are particularly affected by OS. This research analyzes the spatial distribution of metals associated with OS, the urban dust´s oxidative potential (OP), and the occurrence of diseases whose treatments are affected by OS. We collected 70 urban dust samples during pre- and post-monsoon seasons to achieve this. We analyzed particle size distribution and morphology by scanning electron microscopy, as well as metal(loid)s by portable X-ray fluorescence, and OP of dust in artificial lysosomal fluid by using an ascorbic acid depletion assay. Our results show that the mean concentration of Fe, Pb, As, Cr, Cu, and V in pre-monsoon was 83,984.6, 98.4, 23.5, 165.8, 301.3, and 141.9 mg kg−1, while during post-monsoon was 50,638.8, 73.9, 16.7, 124.3, 178.9, and 133.5 mg kg−1, respectively. Impoverished areas with the highest presence of cardiovascular, cancer, diabetes, and respiratory diseases coincide with contaminated areas where young adults live. We identified significant differences in the OP between seasons. OP increases during the pre-monsoon (from 7.8 to 237.5 nmol AA min−1) compared to the post-monsoon season (from 1.6 to 163.2 nmol AA min−1). OP values are much higher than measured standards corresponding to contaminated soil and urban particulate matter, which means that additional sources beside metals cause the elevated OP. The results show no risk from chronic exposure to metals; however, our results highlight the importance of studying dust as an environmental factor that may potentially increase oxidative stress. [ABSTRACT FROM AUTHOR]

Air pollution poses a serious threat to human health. The implementation of air pollution prevention and control policies has gradually reduced the level of atmospheric fine particles in Beijing. Exploring the latest characteristics of PM2.5 has become the key to further improving pollution reduction measures. In the current study, outdoor PM2.5 samples were collected in the spring and summer of Beijing, and the chemical species, oxidative potential (OP), and sources of PM2.5 were characterized. The mean PM2.5 concentration during the entire study period was 41.6 ± 30.9 μg m−3. Although the PM2.5 level in summer was lower, its OP level was significantly higher than that in spring. SO42–, NH4+, EC, NO3–, and OC correlated well with volume-normalized OP (OPv). Strong positive correlations were found between OPv and the following elements: Cu, Pb, Zn, Ni, As, Cr, Sn, Cd, Al, and Mn. Seven sources of PM2.5 were identified, including traffic, soil dust, secondary sulfate, coal and biomass burning, oil combustion, secondary nitrate, and industry. Multiple regression analysis indicated that coal and biomass combustion, industry, and traffic were the main contributors to the OPv in spring, while secondary sulfate, oil combustion, and industry played a leading role in summer. The source region analysis revealed that different pollution sources were related to specific geographic distributions. In addition to local emission reduction policies, multi-provincial cooperation is necessary to further improve Beijing's air quality and reduce the adverse health effects of PM2.5. [ABSTRACT FROM AUTHOR]

In numerous epidemiological studies, exposure to particulate matter (PM) has been associated with negative health outcomes. It has been established so far that the detrimental health effects of particles cannot be explained by a single parameter, such as particle mass, as the complexity of chemical composition and reactivity of particles are not always represented by the mass loadings. The oxidative potential (OP) of aerosol particles represents a promising indicator of their potential toxicity. To develop strategies and regulations at improving the air quality, an increasing number of studies are focused on the application of source apportionment (SA) of PM., while a limited number of SA investigations have been applied to OP. In this review previous research of SA of atmospheric PM OP and proposed guidelines for future studies are summarized. Most of the research studies were carried out in an urban area and focused on PM2.5, while few studies examined other PM fractions. It was noted that the three dominant contributors to OP were biomass burning (9-97%), secondary aerosols (6-67%), and traffic/ vehicles (16-88%). The presence of other factors that contributed to the increase of OP to a lesser extent depended on the location and season. Further, a considerable discrepancy in the contribution of various OP vs. PM sources was discovered using SA models. Because of this, the use of SA is not equivalent when considering the mass of PM and its toxicity. [ABSTRACT FROM AUTHOR]