In vitro toxicity of particulate matter (PM) collected at different sites in the Netherlands is associated with PM composition, size fraction and oxidative potential--the RAPTES project

The oxidative potential of fine ambient particulate matter in Xinxiang, North China: Pollution characteristics, source identification and regional transport

Atmospheric fine particulate matter (PM2.5) can trigger the production of cytotoxic reactive oxygen species (ROS), which can trigger or exacerbate oxidative stress and pulmonary inflammation. We collected 111 daily (∼24 h) ambient PM2.5 samples within an urban region of North China during four seasons of 2019-2020. PM2.5 samples were examined for carbonaceous components, water-soluble ions, and elements, together with their oxidative potential (represent ROS-producing ability) by DTT assay. The seasonal peak DTTv was recorded in winter (2.86 ± 1.26 nmol min-1 m-3), whereas the DTTm was the highest in summer (40.6 ± 8.7 pmol min-1 μg-1). WSOC displayed the highest correlation with DTT activity (r = 0.84, p < 0.0001), but the influence of WSOC on the elevation of DTTv was extremely negligible. Combustion source exhibited the most significant and robust correlation with the elevation of DTTv according to the linear mixed-effects model result. Source identification investigation using positive matrix factorization displayed that combustion source (36.2%), traffic source (30.7%), secondary aerosol (15.7%), and dust (14.1%) were driving the DTTv, which were similar to the results from the multiple linear regression (MLR) analysis. Backward trajectory analysis revealed that the major air masses originate from local and regional transportation, but PM2.5 OP was more susceptible to the influence of short-distance transport clusters. Discerning the influence of chemicals on health-pertinent attributes of PM2.5, such as OP, could facilitate a deep understanding of the cause-and-effect relationship between PM2.5 and impacts.

Air Pollution and Osteoporosis

PURPOSE OF REVIEW

The purpose of this review is to provide a background of osteoporosis and air pollution, discussing increasing incidence of the disease with exposure to pollutants and the role that inflammation may play in this process.

RECENT FINDINGS

Osteoporosis-related fractures are one of the most pressing challenges for the ageing global population, with significant increases in mortality known to occur after major osteoporotic fractures in the elderly population. Recent studies have established a firm correlative link between areas of high air pollution and increased risk of osteoporosis, particularly alarming given the increasingly urban global population. While the culprit pollutants and molecular mechanisms underlying this phenomenon have not yet been elucidated, initial studies suggest a role for inflammatory cascades in this phenomenon. While much more research is required to identify the most damaging air pollutants and to delineate the specific inflammatory molecular mechanisms, it is clear from the literature that shedding light on these pathways would unveil potential therapeutic targets to treat bone diseases, including osteoporosis. Major deficiencies of current animal models highlight the need for complex human in vitro models such as organ-on-a-chip technology to better understand the impact of air pollution.

Review of in vitro studies evaluating respiratory toxicity of aerosols: impact of cell types, chemical composition, and atmospheric processing

In recent decades, several cell-based and acellular methods have been developed to evaluate ambient particulate matter (PM) toxicity. Although cell-based methods provide a more comprehensive assessment of PM toxicity, their results are difficult to comprehend due to the diversity in cellular endpoints, cell types, and assays and the interference of PM chemical components with some of the assays' techniques. In this review, we attempt to clarify some of these issues. We first discuss the morphological and immunological differences among various macrophage and epithelial cells, belonging to the respiratory systems of human and murine species, used in the in vitro studies evaluating PM toxicity. Then, we review the current state of knowledge on the role of different PM chemical components and the relevance of atmospheric processing and aging of aerosols in the respiratory toxicity of PM. Our review demonstrates the need to adopt more physiologically relevant cellular models such as epithelial (or endothelial) cells instead of macrophages for oxidative stress measurement. We suggest limiting macrophages for investigating other cellular responses (e.g., phagocytosis, inflammation, and DNA damage). Unlike monocultures (of macrophages and epithelial cells), which are generally used to study the direct effects of PM on a given cell type, the use of co-culture systems should be encouraged to investigate a more comprehensive effect of PM in the presence of other cells. Our review has identified two major groups of toxic PM chemical species from the existing literature, i.e., metals (Fe, Cu, Mn, Cr, Ni, and Zn) and organic compounds (PAHs, ketones, aliphatic and chlorinated hydrocarbons, and quinones). However, the relative toxicities of these species are still a matter of debate. Finally, the results of the existing studies investigating the effect of aging on PM toxicity are ambiguous, with varying results due to different cell types, different aging conditions, and the presence/absence of specific oxidants. More systematic studies are necessary to understand the role of different SOA precursors, interactions between different PM components, and aging conditions in the overall toxicity of PM. We anticipate that our review will guide future investigations by helping researchers choose appropriate cell models, resulting in a more meaningful interpretation of cell-based assays and thus ultimately leading to a better understanding of the health effects of PM exposure.

Indoor air quality in subway microenvironments: Pollutant characteristics, adverse health impacts, and population inequity

Rapidly increasing urbanization in recent decades has elevated the subway as the primary public transportation mode in metropolitan areas. Indoor air quality (IAQ) inside subways is an important factor that influences the health of commuters and subway workers. This review discusses the subway IAQ in different cities worldwide by comparing the sources and abundance of particulate matter (PM2.5 and PM10) in these environments. Factors that affect PM concentration and chemical composition were found to be associated with the subway internal structure, train frequency, passenger volume, and geographical location. Special attention was paid to air pollutants, such as transition metals, volatile/semi-volatile organic compounds (VOCs and SVOCs), and bioaerosols, due to their potential roles in indoor chemistry and causing adverse health impacts. In addition, given that the IAQ of subway systems is a public health issue worldwide, we calculated the Gini coefficient of urban subway exposure via meta-analysis. A value of 0.56 showed a significant inequity among different cities. Developed regions with higher per capita income tend to have higher exposure. By reviewing the current advances and challenges in subway IAQ with a focus on indoor chemistry and health impacts, future research is proposed toward a sustainable urban transportation systems.

Characterization of airborne endotoxin in personal exposure to fine particulate matter (PM2.5) and bioreactivity for elderly residents in Hong Kong

The heavy metals and bioreactivity properties of endotoxin in personal exposure to fine particulate matter (PM2.5) were characterized in the analysis. The average personal exposure concentrations to PM2.5 were ranged from 6.8 to 96.6 μg/m3. The mean personal PM2.5 concentrations in spring, summer, autumn, and winter were 32.1±15.8, 22.4±11.8, 35.3±11.9, and 50.2±19.9 μg/m3, respectively. There were 85 % of study targets exceeded the World Health Organization (WHO) PM2.5 threshold (24 hours). The mean endotoxin concentrations ranged from 1.086 ± 0.384-1.912 ± 0.419 EU/m3, with a geometric mean (GM) varied from 1.034 to 1.869. The concentration of iron (Fe) (0.008-1.16 μg/m3) was one of the most abundant transition metals in the samples that could affect endotoxin toxicity under Toll-Like Receptor 4 (TLR4) stimulation. In summer, the interleukin 6 (IL-6) levels showed statistically significant differences compared to other seasons. Spearman correlation analysis showed endotoxin concentrations were positively correlated with chromium (Cr) and nickel (Ni), implying possible roles as nutrients and further transport via adhering to the surface of fine inorganic particles. Mixed-effects model analysis demonstrated that Tumor necrosis factor-α (TNF-α) production was positively associated with endotoxin concentration and Cr as a combined exposure factor. The Cr contained the highest combined effect (0.205-0.262), suggesting that Cr can potentially exacerbate the effect of endotoxin on inflammation and oxidative stress. The findings will be useful for practical policies for mitigating air pollution to protect the public health of the citizens.

Assessing the Impact of Non-Exhaust Emissions on the Asthmatic Airway (IONA) Protocol for a Randomised Three-Exposure Crossover Study

BACKGROUND

People living with asthma are disproportionately affected by air pollution, with increased symptoms, medication usage, hospital admissions, and the risk of death. To date, there has been a focus on exhaust emissions, but traffic-related air pollution (TRAP) can also arise from the mechanical abrasion of tyres, brakes, and road surfaces. We therefore created a study with the aim of investigating the acute impacts of non-exhaust emissions (NEEs) on the lung function and airway immune status of asthmatic adults.

METHODS

A randomised three-condition crossover panel design will expose adults with asthma using a 2.5 h intermittent cycling protocol in a random order at three locations in London, selected to provide the greatest contrast in the NEE components within TRAP. Lung function will be monitored using oscillometry, fractional exhaled nitric oxide, and spirometry (the primary outcome is the forced expiratory volume in one second). Biomarkers of inflammation and airborne metal exposure will be measured in the upper airway using nasal lavage. Symptom responses will be monitored using questionnaires. Sources of exhaust and non-exhaust concentrations will be established using source apportionment via the positive matrix factorisation of high-time resolution chemical measures conducted at the exposure sites.

DISCUSSION

Collectively, this study will provide us with valuable information on the health effects of NEE components within ambient PM2.5 and PM10, whilst establishing a biological mechanism to help contextualise current epidemiological observations.

Inter-continental variability in the relationship of oxidative potential and cytotoxicity with PM2.5 mass

Most fine ambient particulate matter (PM2.5)-based epidemiological models use globalized concentration-response (CR) functions assuming that the toxicity of PM2.5 is solely mass-dependent without considering its chemical composition. Although oxidative potential (OP) has emerged as an alternate metric of PM2.5 toxicity, the association between PM2.5 mass and OP on a large spatial extent has not been investigated. In this study, we evaluate this relationship using 385 PM2.5 samples collected from 14 different sites across 4 different continents and using 5 different OP (and cytotoxicity) endpoints. Our results show that the relationship between PM2.5 mass vs. OP (and cytotoxicity) is largely non-linear due to significant differences in the intrinsic toxicity, resulting from a spatially heterogeneous chemical composition of PM2.5. These results emphasize the need to develop localized CR functions incorporating other measures of PM2.5 properties (e.g., OP) to better predict the PM2.5-attributed health burdens.

Association between combined exposure to ambient air pollutants, genetic risk, and incident gout risk: A prospective cohort study in the UK Biobank

BACKGROUND

Limited research has been conducted on the association between long-term exposure to air pollutants and the incidence of gout.

OBJECTIVES

This study aims to assess the individual and combined effects of prolonged exposure to five air pollutants (NO2, NOx, PM10, PMcoarse and PM2.52) on the incidence of gout among 458,884 initially gout-free participants enrolled in the UK Biobank.

METHODS

Employing a land use regression model, we utilized an estimation method to ascertain the annual concentrations of the five air pollutants. Subsequently, we devised a weighted air pollution score to facilitate a comprehensive evaluation of exposure. The Cox proportional hazards model was utilized to investigate the association between ambient air pollution and gout risk. Interaction and stratification analyses were conducted to evaluate age, sex, BMI, and genetic predisposition as potential effect modifiers in the air pollution-gout relationship. Furthermore, mediation analyses were conducted to explore the potential involvement of biomarkers in mediating the association between air pollution and gout.

RESULTS

Over a median follow-up time of 12.0 years, 7,927 cases of gout were diagnosed. Significant associations were observed between the risk of gout and a per IQR increase in NO2 (HR3: 1.05, 95 % CI4: 1.02-1.08, p = 0.003), NOx (HR: 1.04, 95 % CI: 1.01-1.06, p = 0.003), and PM2.5 (HR: 1.03, 95 % CI: 1.00-1.06, p = 0.030). Per IQR increase in the air pollution score was associated with an elevated risk of gout (p = 0.005). Stratified analysis revealed a significant correlation between the air pollution score and gout risk in participants ≥60 years (HR: 1.05, 95 % CI: 1.02-1.09, p = 0.005), but not in those <60 years (p = 0.793), indicating a significant interaction effect with age (p-interaction=0.009). Mediation analyses identified five serum biomarkers (SUA:15.87 %, VITD: 5.04 %, LDLD: 3.34 %, GGT: 1.90 %, AST: 1.56 %5) with potential mediation effects on this association.

CONCLUSIONS

Long-term exposure to air pollutants, particularly among the elderly population, is associated with an increased risk of gout. The underlying mechanisms of these associations may involve the participation of five serum biomarkers.

New insight into air pollution-related cardiovascular disease: an adverse outcome pathway framework of PM2.5-associated vascular calcification

Despite the air quality has been generally improved in recent years, ambient fine particulate matter (PM2.5), a major contributor to air pollution, remains one of the major threats to public health. Vascular calcification is a systematic pathology associated with an increased risk of cardiovascular disease. Although the epidemiological evidence has uncovered the association between PM2.5 exposure and vascular calcification, little is known about the underlying mechanisms. The adverse outcome pathway (AOP) concept offers a comprehensive interpretation of all of the findings obtained by toxicological and epidemiological studies. In this review, reactive oxygen species generation was identified as the molecular initiating event (MIE), which targeted subsequent key events (KEs) such as oxidative stress, inflammation, endoplasmic reticulum stress, and autophagy, from the cellular to the tissue/organ level. These KEs eventually led to the adverse outcome, namely increased incidence of vascular calcification and atherosclerosis morbidity. To the best of our knowledge, this is the first AOP framework devoted to PM2.5-associated vascular calcification, which benefits future investigations by identifying current limitations and latent biomarkers.

The Oxidative Potential of Airborne Particulate Matter Research Trends, Challenges, and Future Perspectives-Insights from a Bibliometric Analysis and Scoping Review

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.

Coarse particulate matter (PM10) induce an inflammatory response through the NLRP3 activation

INTRODUCTION

PM exposure can induce inflammatory and oxidative responses; however, differences in these adverse effects have been reported depending on the chemical composition and size. Moreover, inflammatory mechanisms such as NLRP3 activation by PM10 have yet to be explored.

OBJECTIVE

To assess the impact of PM10 on cell cytotoxicity and the inflammatory response through in vitro and in vivo models.

METHODOLOGY

Peripheral blood mononuclear cells (PBMCs) from healthy donors were exposed to PM10. Cytotoxicity was determined using the LDH assay; the expression of inflammasome components and the production of pro-inflammatory cytokines were quantified through qPCR and ELISA, respectively; and the formation of ASC complexes was examined using confocal microscopy. For in vivo analysis, male C57BL6 mice were intranasally challenged with PM10 and bronchoalveolar lavage fluid was collected to determine cell counts and quantification of pro-inflammatory cytokines by ELISA. RNA was extracted from lung tissue, and the gene expression of inflammatory mediators was quantified.

RESULTS

PM10 exposure induced significant cytotoxicity at concentrations over 100 µg/mL. Moreover, PM10 enhances the gene expression and release of pro-inflammatory cytokines in PBMCs, particularly IL-1β; and induces the formation of ASC complexes in a dose-dependent manner. In vivo, PM10 exposure led to cell recruitment to the lungs, which was characterized by a significant increase in polymorphonuclear cells compared to control animals. Furthermore, PM10 induces the expression of several inflammatory response-related genes, such as NLRP3, IL-1β and IL-18, within lung tissue.

CONCLUSION

Briefly, PM10 exposure reduced the viability of primary cells and triggered an inflammatory response, involving NLRP3 inflammasome activation and the subsequent production of IL-1β. Moreover, PM10 induces the recruitment of cells to the lung and the expression of multiple cytokines; this phenomenon could contribute to epithelial damage and, thus to the development and exacerbation of respiratory diseases such as viral infections.

Toxicological evaluation and concentration of airborne PM0.1 in high air pollution period in Guangzhou, China

The emissions and exposure limits for airborne PM0.1 are lacking, with limited scientific data for toxicity. Therefore, we continuously monitored and calculated the number and mass concentrations of airborne PM0.1 in December 2017, January 2018 and March 2018 during the high pollution period in Guangzhou. We collected PM0.1 from the same period and analyzed their chemical components. A549, THP-1 and A549/THP-1 co-cultured cells were selected for exposure to PM0.1, and evaluated for toxicological responses. Our aims are to 1) measure and analyze the number and mass concentrations, and chemical components of PM0.1; 2) evaluate and compare PM0.1 toxicity to different airway cells models at different time points. Guangzhou had the highest mass concentration of PM0.1 in December 2017, while the number concentration was the lowest. Chemical components in PM0.1 vary significantly at different time periods, and the correlation between the chemical composition or source of PM0.1 and the mass and number concentration of PM0.1 was dissimilar. Exposure to PM0.1 disrupted cell membranes, impaired mitochondrial function, promoted the expression of inflammatory mediators, and interfered with DNA replication in the cell cycle. The damage caused by exposure to PM0.1 at different times exhibited variations across different types of cells. PM0.1 in March 2018 stimulated co-cultured cells to secrete more inflammatory mediators, and CMA was significantly related to the expression of them. Our study indicates that it is essential to monitor both the mass and number concentrations of PM0.1 throughout all seasons annually, as conventional toxicological experiments and the internal components of PM0.1 may not effectively reveal the health damages caused by elevated number levels of PM0.1.

Monitoring redox stress in human airway epithelial cells exposed to woodsmoke at an air-liquid interface

Wildland fires contribute significantly to the ambient air pollution burden worldwide, causing a range of adverse health effects in exposed populations. The toxicity of woodsmoke, a complex mixture of gases, volatile organic compounds, and particulate matter, is commonly studied in vitro using isolated exposures of conventionally cultured lung cells to either resuspended particulate matter or organic solvent extracts of smoke, leading to incomplete toxicity evaluations. This study aimed to improve our understanding of the effects of woodsmoke inhalation by building an advanced in vitro exposure system that emulates human exposure of the airway epithelium. We report the development and characterization of an innovative system that permits live-cell monitoring of the intracellular redox status of differentiated primary human bronchial epithelial cells cultured at an air-liquid interface (pHBEC-ALI) as they are exposed to unfractionated woodsmoke generated in a tube furnace in real time. pHBEC-ALI exposed to freshly generated woodsmoke showed oxidative changes that were dose-dependent and reversible, and not attributable to carbon monoxide exposure. These findings show the utility of this novel system for studying the molecular initiating events underlying woodsmoke-induced toxicity in a physiologically relevant in vitro model, and its potential to provide biological plausibility for risk assessment and public health measures.

Identifying urban emission sources and their contribution to the oxidative potential of fine particulate matter (PM2.5) in Kuwait

In this study, we investigated the seasonal variations, chemical composition, sources, and oxidative potential of ambient PM2.5 (particles with a diameter of less than 2.5 μm) in Kuwait City. The sampling campaign was conducted within the premises of Kuwait Institute for Scientific Research from June 2022 to May 2023, covering different seasons throughout the year. The personal cascade impactor sampler (PCIS) operated at flow rate of 9 L/min was employed to collect weekly PM2.5 samples on PTFE and quarts filters. These collected samples were analyzed for carbonaceous species (i.e., elemental and organic carbon), metals and transition elements, inorganic ions, and DTT (dithiothreitol) redox activity. Furthermore, principal component analysis (PCA) and multi-linear regression (MLR) were used to identify the predominant emission sources and their percentage contribution to the redox activity of PM2.5 in Kuwait. The results of this study highlighted that the annual-averaged ambient PM2.5 mass concentrations in Kuwait (59.9 μg/m3) substantially exceeded the World Health Organization (WHO) guideline of 10 μg/m3. Additionally, the summer season displayed the highest PM2.5 mass concentration (75.2 μg/m3) compared to other seasons, primarily due to frequent dust events exacerbated by high-speed winds. The PCA identified four primary PM2.5 sources: mineral dust, fossil fuel combustion, road traffic, and secondary aerosols. The mineral dust was found to be the predominant source, contributing 36.1% to the PM2.5 mass, followed by fossil fuel combustion and traffic emissions with contributions of 23.7% and 20.3%, respectively. The findings of MLR revealed that road traffic was the most significant contributor to PM2.5 oxidative potential, accounting for 47% of the total DTT activity. In conclusion, this comprehensive investigation provides essential insights into the sources and health implications of PM2.5 in Kuwait, underscoring the critical need for effective air quality management strategies to mitigate the impacts of particulate pollution in the region.

New health index derived from oxidative potential and cell toxicity of fine particulate matter to assess its potential health effect

Toxicological data and exposure levels of fine particulate matters (PM2.5) are necessary to better understand their health effects. Simultaneous measurements of PM2.5 oxidative potential (OP) and cell toxicity in urban areas (Beijing, China and Gwangju, Korea) reveal their dependence on chemical composition. Notably, acids (Polar), benzocarboxylic acids, and Pb were the chemical components that affected both OP and cell toxicity. OP varied more significantly among different locations and seasons (winter and summer) than cell toxicity. Using the measured OP, cell toxicity, and PM2.5 concentration, a health index was developed to better assess the potential health effects of PM2.5. The health index was related to the sources of PM2.5 derived from the measured chemical components. The contributions of secondary organic aerosols and dust to the proposed health index were more significant than their contributions to PM2.5 mass. The developed regression equation was used to predict the health effect of PM2.5 without further toxicity measurements. This new index could be a valuable health metric that provides information beyond just the PM2.5 concentration level.

Effect of industrialization on the differences in sources and composition of ambient PM2.5 in two Southern Ontario locations

PM2.5 was sampled over a seven-year period (2013-2019) at two locations ∼50 km apart in Southern Ontario (concurrently for five years: 2015-2019). One is a heavily industrialized site (Hamilton), while the other was a rural site (Simcoe). To assess the impact of industrialization on the composition and sources of PM affecting air quality in these two locations, positive matrix factorization coupled with dispersion normalization (DN-PMF) was used to identify six and eight factors at Simcoe and Hamilton, respectively. The Simcoe factors in order of diminishing PM mass contribution were: particulate sulphate (pSO4), secondary organic aerosol (SOA), crustal matter, particulate nitrate (pNO3), biomass burning, and vehicular emissions. At Hamilton, the effects of industrialization were observed by the ∼36% higher average ambient PM2.5 concentration for the study period as well as the presence of factors unique to metallurgy, i.e., coking and steelmaking, compared to Simcoe. The coking and steelmaking factors contributed ∼15% to the PM mass at Hamilton. Seasonal variants of appropriate nonparametric trend tests with the associated slopes (Sen's) were used to assess statistically significant changes in the factor contributions to PM2.5 over time. Specifically at Hamilton, a significant decline in PM contributions was noted for coking (-0.03 μg/m³/yr or -4.1%/yr) while steelmaking showed no statistically significant decline over the study period. Other factors at Hamilton that showed statistically significant declines over the study period were: pSO4 (-0.27 μg/m³/yr or -12.6%/yr), biomass burning (-0.05 μg/m³/yr or -9.02%/yr), crustal matter (-0.03 μg/m³/yr or -5.28%/yr). These factors mainly accounted for the significant decline in PM2.5 over the study period (-0.35 μg/m³/yr or -4.24%/yr). This work shows the importance of long-term monitoring in assessing the unique contributions and temporal changes of industrialization on air quality in Ontario and similarly affected locations.

Acute and repeated exposures of normal human bronchial epithelial (NHBE) cells culture to particles from a coloured pyrotechnic smoke

Coloured pyrotechnic smokes are frequently used in the military field and occasionally by civilians, but their health hazards have been little studied. The main concern could rise from inhalation of smoke particles. Our previous study showed that acute exposure to particles from a red signalling smoke (RSS) induced an antioxidant and inflammatory responses in small airway epithelial cells. The aim of this study was to further explore the toxicity of RSS particles at a more proximal level of the respiratory tract, using normal human bronchial epithelial cells grown at the Air-Liquid Interface. Acute exposure (24 h) induced an oxidative stress that persisted 24 h post-exposure, associated with particle internalization and epithelium morphological changes (cuboidal appearance and loss of cilia). Repeated exposures (4×16h) to RSS particles did not trigger oxidative stress but cell morphological changes occurred. Overall, this study provides a better overview of the toxic effects of coloured smoke particles.

Climate Change and New Challenges for Rural Communities: Particulate Matter Matters

Climate change presents multiple challenges to rural communities. Here, we investigated the toxicological potential of the six types of particulate matter most common to rural Arkansas: soil, road, and agricultural dusts, pollen, traffic exhaust, and particles from biomass burning in human small airway epithelial cells (SAECs). Biomass burning and agricultural dust demonstrated the most potent toxicological responses, exhibited as significant (p < 0.05) up-regulation of HMOX1 (oxidative stress) and TNFα (inflammatory response) genes as well as epigenetic alterations (altered expression of DNA methyltransferases DNMT1, DNMT3A, and DNMT3B, enzymatic activity, and DNA methylation of alpha satellite elements) that were evident at both 24 h and 72 h of exposure. We further demonstrate evidence of aridification in the state of Arkansas and the presence of winds capable of transporting agricultural dust- and biomass burning-associated particles far beyond their origination. Partnerships in the form of citizen science projects may provide important solutions to prevent and mitigate the negative effects of the rapidly evolving climate and improve the well-being of rural communities. Furthermore, the identification of the most toxic types of particulate matter could inform local policies related to agriculture, biomass burning, and dust control.

Toxicity and health effects of ultrafine particles: Towards an understanding of the relative impacts of different transport modes

Exposure to particulate matter (PM) has been associated with a wide range of adverse health effects, but it is still unclear how particles from various transport modes differ in terms of toxicity and associations with different human health outcomes. This literature review aims to summarize toxicological and epidemiological studies of the effect of ultrafine particles (UFPs), also called nanoparticles (NPs, <100 nm), from different transport modes with a focus on vehicle exhaust (particularly comparing diesel and biodiesel) and non-exhaust as well as particles from shipping (harbor), aviation (airport) and rail (mainly subway/underground). The review includes both particles collected in laboratory tests and the field (intense traffic environments or collected close to harbor, airport, and in subway). In addition, epidemiological studies on UFPs are reviewed with special attention to studies aimed at distinguishing the effects of different transport modes. Results from toxicological studies indicate that both fossil and biodiesel NPs show toxic effects. Several in vivo studies show that inhalation of NPs collected in traffic environments not only impacts the lung, but also triggers cardiovascular effects as well as negative impacts on the brain, although few studies compared NPs from different sources. Few studies were found on aviation (airport) NPs, but the available results suggest similar toxic effects as traffic-related particles. There is still little data related to the toxic effects linked to several sources (shipping, road and tire wear, subway NPs), but in vitro results highlighted the role of metals in the toxicity of subway and brake wear particles. Finally, the epidemiological studies emphasized the current limited knowledge of the health impacts of source-specific UFPs related to different transport modes. This review discusses the necessity of future research for a better understanding of the relative potencies of NPs from different transport modes and their use in health risk assessment.

Emerging roles of air pollution and meteorological factors in autoimmune eye diseases

Autoimmune eye diseases (AEDs), a collection of autoimmune inflammatory ocular conditions resulting from the dysregulation of immune system at the ocular level, can target both intraocular and periorbital structures leading to severe visual deficit and blindness globally. The roles of air pollution and meteorological factors in the initiation and progression of AEDs have been increasingly attractive, among which the systemic and local mechanisms are both involved in. Exposure to excessive air pollution and extreme meteorological conditions including PM2.5/PM0.1, environmental tobacco smoke, insufficient sunshine, and high temperature, etc., can disturb Th17/Treg balance, regulate macrophage polarization, activate neutrophils, induce systemic inflammation and oxidative stress, decrease retinal blood flow, promote tissue fibrosis, activate sympathetic nervous system, adversely affect nutrients synthetization, as well as induce heat stress, therefore may together deteriorate AEDs. The crosstalk among inflammation, oxidative stress and dysregulated immune system appeared to be prominent. In the present review, we will concern and summarize the potential mechanisms underlying linkages of air pollution and meteorological factors to ocular autoimmune and inflammatory responses. Moreover, we concentrate on the specific roles of air pollutants and meteorological factors in several major AEDs including uveitis, Graves' ophthalmopathy (GO), ocular allergic disease (OAD), glaucoma, diabetic retinopathy (DR), etc.

Oxidative stress indices induced by industrial and urban PM2.5-bound metals in A549 cells

The detrimental effects of atmospheric fine particulate matter (PM_2.5) on human health are of major global concern. PM_2.5-bound metals are toxic compounds that contribute to cellular damage. To investigate the toxic effects of water-soluble metals on human lung epithelial cells and their bioaccessibility to lung fluid, PM_2.5 samples were collected from both urban and industrial areas in the metropolitan city of Tabriz, Iran. Oxidative stress indices, including proline content, total antioxidant capacity (TAC), cytotoxicity, and DNA damage levels of water-soluble components of PM_2.5, were evaluated. Furthermore, an in vitro test was conducted to assess the bioaccessibility of various PM_2.5-bound metals to the respiratory system using simulated lung fluid. PM_2.5 average concentrations in urban and industrial areas were 83.11 and 97.71 μg/m³, respectively. The cytotoxicity effects of PM_2.5 water-soluble constituents from urban areas were significantly higher than in industrial areas and the IC₅₀ was found to be 96.76 ± 3.34 and 201.31 ± 5.96 μg/mL for urban and industrial PM_2.5 samples, respectively. In addition, higher PM_2.5 concentrations increased the proline content in a concentration-dependent manner in A549 cells, which plays a protective role against oxidative stress and prevents PM_2.5-induced DNA damage. Also, the partial least squares regression revealed that Be, Cd, Co, Ni, and Cr, were significantly correlated with DNA damage and proline accumulation, which caused cell damage through oxidative stress. The results of this study showed that PM_2.5-bound metals in highly polluted metropolitan city caused substantial changes in the cellular proline content, DNA damage levels and cytotoxicity in human lung A549 cells.

Assessment of coarse, fine, and ultrafine particulate matter at different microenvironments of fire stations

The concentrations of respirable particulate matter (PM) and the impact on indoor air quality in occupational settings remains poorly characterized. This study assesses, for the first time, the cumulative and non-cumulative concentrations of 14 fractions of coarse (3.65-9.88 μm), fine (0.156-2.47 μm), and ultrafine (0.015-0.095 μm) PM inside the garage of heavy vehicles, firefighting personal protective equipment' storage room, bar, and a common area of seven Portuguese fire stations. Sampling campaigns were performed during a regular work week at the fire stations. Levels of daily total cumulative PM ranged from 277.4 to 413.2 μg/m³ (maximum values of 811.4 μg/m³), with the bar (370.1 μg/m³) and the PPE' storage room (361.3 μg/m³) presenting slightly increased levels (p > 0.05) than the common area (324.8 μg/m³) and the garage (339.4 μg/m³). The location of the sampling site, the proximity to local industries and commercial activities, the layout of the building, the heating system used, and indoor sources influenced the PM concentrations. Fine (193.8-301.0 μg/m³) and ultrafine (41.3-78.2 μg/m³) particles were predominant in the microenvironments of all fire stations and accounted for 71.5% and 17.8% of daily total cumulative levels, respectively; coarse particles (23.3-47.1 μg/m³) represented 10.7% of total PM. The permissible exposure limit (5.0 mg/m³) defined by the Occupational Safety and Health Organization for respirable dust was not overcome in the evaluated fire stations. Results suggest firefighters' regular exposure to fine and ultrafine PM inside fire stations which will contribute to cardiorespiratory health burden. Further studies are needed to characterize firefighters' exposure to fine and ultrafine PM inside fire stations, identify main emission sources, and evaluate the contribution of exposures at fire stations to firefighters' occupational health risks.

Short-term effects of fine particulate matter constituents on mortality considering the mortality displacement in Zhejiang province, China

BACKGROUND

Evidence linking mortality and short-term exposure to particulate matter (PM_2.5) constituents was sparse. The mortality displacement was often unconsidered and may induce incorrect risk estimation.

OBJECTIVES

To assess the short-term effects of PM_2.5 constituents on all-cause mortality considering the mortality displacement.

METHODS

Daily data on all-cause mortality and PM_2.5 constituents, including sulfate (SO₄^2-), nitrate (NO₃^-), ammonium (NH₄⁺), organic matters (OM), and black carbon (BC), were collected from 2009 to 2020. The mortality effect of PM_2.5 and its constituents was estimated using a distributed lag non-linear model. Stratified analyses were performed by age, sex, and season.

RESULTS

Per interquartile range increases in SO₄^2-, NO₃^-, NH₄⁺, OM, and BC were associated with the 1.42% (95%CI: 0.98, 1.87), 3.76% (3.34, 4.16), 2.26% (1.70, 2.83), 2.36% (2.02, 2.70), and 1.26% (0.91, 1.61) increases in all-cause mortality, respectively. Mortality displacements were observed for PM_2.5, SO₄^2-, NH₄⁺, OM, and BC, with their overall effects lasting for 7-15 days. Stratified analyses revealed a higher risk for old adults (>65 years) and females, with stronger effects in the cold season.

CONCLUSIONS

Short-term exposures to PM_2.5 constituents were positively associated with increased risks of mortality. The mortality displacement should be considered in future epidemiological studies on PM constituents.

DATA AVAILABILITY

Data will be made available on request.

The skin is no barrier to mixtures: Air pollutant mixtures and reported psoriasis or eczema in the Personalized Environment and Genes Study (PEGS)

BACKGROUND

Autoimmune (AI) diseases appear to be a product of genetic predisposition and environmental triggers. Disruption of the skin barrier causes exacerbation of psoriasis/eczema. Oxidative stress is a mechanistic pathway for pathogenesis of the disease and is also a primary mechanism for the detrimental effects of air pollution.

METHODS

We evaluated the association between autoimmune skin diseases (psoriasis or eczema) and air pollutant mixtures in 9060 subjects from the Personalized Environment and Genes Study (PEGS) cohort. Pollutant exposure data on six criteria air pollutants are publicly available from the Center for Air, Climate, and Energy Solutions and the Atmospheric Composition Analysis Group. For increased spatial resolution, we included spatially cumulative exposure to volatile organic compounds from sites in the United States Environmental Protection Agency Toxic Release Inventory and the density of major roads within a 5 km radius of a participant's address from the United States Geological Survey. We applied logistic regression with quantile g-computation, adjusting for age, sex, diagnosis with an autoimmune disease in family or self, and smoking history to evaluate the relationship between self-reported diagnosis of an AI skin condition and air pollution mixtures.

RESULTS

Only one air pollution variable, sulfate, was significant individually (OR = 1.06, p = 3.99E-2); however, the conditional odds ratio for the combined mixture components of PM2.5 (black carbon, sulfate, sea salt, and soil), CO, SO2, benzene, toluene, and ethylbenzene is 1.10 (p-value = 5.4E-3).

SIGNIFICANCE

While the etiology of autoimmune skin disorders is not clear, this study provides evidence that air pollutants are associated with an increased prevalence of these disorders. The results provide further evidence of potential health impacts of air pollution exposures on life-altering diseases.

SIGNIFICANCE AND IMPACT STATEMENT

The impact of air pollution on non-pulmonary and cardiovascular diseases is understudied and under-reported. We find that air pollution significantly increased the odds of psoriasis or eczema in our cohort and the magnitude is comparable to the risk associated with smoking exposure. Autoimmune diseases like psoriasis and eczema are likely impacted by air pollution, particularly complex mixtures and our study underscores the importance of quantifying air pollution-associated risks in autoimmune disease.

Assessing oxidative stress induction ability and oxidative potential of PM2.5 in cities in eastern and western Japan

Oxidative stress is an important cause of respiratory diseases associated with exposure to PM_2.5. Accordingly, acellular methods for assessing the oxidative potential (OP) of PM_2.5 have been evaluated extensively for use as indicators of oxidative stress in living organisms. However, OP-based assessments only reflect the physicochemical properties of particles and do not consider particle-cell interactions. Therefore, to determine the potency of OP under various PM_2.5 scenarios, oxidative stress induction ability (OSIA) assessments were performed using a cell-based method, the heme oxygenase-1 (HO-1) assay, and the findings were compared with OP measurements obtained using an acellular method, the dithiothreitol assay. For these assays, PM_2.5 filter samples were collected in two cities in Japan. To quantitatively determine the relative contribution of the quantity of metals and subtypes of organic aerosols (OA) in PM_2.5 to the OSIA and the OP, online measurements and offline chemical analysis were also performed. The findings showed a positive relationship between the OSIA and OP for water-extracted samples, confirming that the OP is generally well suited for use as an indicator of the OSIA. However, the correspondence between the two assays differed for samples with a high water-soluble (WS)-Pb content, which had a higher OSIA than would be expected from the OP of other samples. The results of reagent-solution experiments showed that the WS-Pb induced the OSIA, but not the OP, in 15-min reactions, suggesting a reason for the inconsistent relationship between the two assays across samples. Multiple linear regression analyses and reagent-solution experiments showed that WS transition metals and biomass burning OA accounted for approximately 30-40% and 50% of the total OSIA or the total OP of water-extracted PM_2.5 samples, respectively. This is the first study to evaluate the association between cellular oxidative stress assessed by the HO-1 assay and the different subtypes of OA.

Induction of toxicity in human colon cells and organoids by size- and composition-dependent road dust

Environmental pollution, including the annual resurgence of particulate matter derived from road dust, is a serious issue worldwide. Typically, the size of road dust is less than 10 μm; thus, road dust can penetrate into human organs, including the brain, through inhalation and intake by mouth. Therefore, the toxicity of road dust has been intensively studied in vitro and in vivo. However, in vitro systems, including 2D cell cultures, cannot mimic complex human organs, and there are several discrepancies between in vivo and human systems. Here, we used human colon cells and organoids to evaluate the cytotoxicity of particulate matter derived from road dust. The toxicity of road dust collected in industrialized and high traffic areas and NIST urban particulate matter reference samples were evaluated in 2D and 3D human colon cells as well as colon organoids and their characteristics were carefully examined. Data suggest that the size and elemental compositions of road dust can correlate with colon organoid toxicity, and thus, a more careful assessment of the size and elemental compositions of road dust should be conducted to predict its effect on human health.

Size-Resolved Redox Activity and Cytotoxicity of Water-Soluble Urban Atmospheric Particulate Matter: Assessing Contributions from Chemical Components

Throughout the cold and the warm periods of 2020, chemical and toxicological characterization of the water-soluble fraction of size segregated particulate matter (PM) (<0.49, 0.49−0.95, 0.95−1.5, 1.5−3.0, 3.0−7.2 and >7.2 μm) was conducted in the urban agglomeration of Thessaloniki, northern Greece. Chemical analysis of the water-soluble PM fraction included water-soluble organic carbon (WSOC), humic-like substances (HULIS), and trace elements (V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd and Pb). The bulk (sum of all size fractions) concentrations of HULIS were 2.5 ± 0.5 and 1.2 ± 0.3 μg m−3, for the cold and warm sampling periods, respectively with highest values in the <0.49 μm particle size fraction. The total HULIS-C/WSOC ratio ranged from 17 to 26% for all sampling periods, confirming that HULIS are a significant part of WSOC. The most abundant water-soluble metals were Fe, Zn, Cu, and Mn. The oxidative PM activity was measured abiotically using the dithiothreitol (DTT) assay. In vitro cytotoxic responses were investigated using mitochondrial dehydrogenase (MTT). A significant positive correlation was found between OPmDTT, WSOC, HULIS and the MTT cytotoxicity of PM. Multiple Linear Regression (MLR) showed a good relationship between OPMDTT, HULIS and Cu.

Policy-driven variations in oxidation potential and source apportionment of PM2.5 in Wuhan, central China

China has implemented several control measures to mitigate PM_2.5 pollution and improve air quality, such as the Action Plan for the Prevention and Control of Air Pollution (APPCAP). To comprehensively assess the changes in ambient PM_2.5 concentrations and the corresponding health risk with the implementation of APPCAP, this study examined PM_2.5 samples collected in Wuhan in 2012/2013 and 2018 for water-soluble ions, carbonaceous fractions, and elements, respectively. Dithiothreitol (DTT) assay was used to determine the oxidation potential (OP) of PM_2.5. The positive matrix factorization (PMF) model and the multiple linear regression (MLR) model were used to analyze PM_2.5 sources and the contribution of each source to the OP of PM_2.5. The results showed that PM_2.5 concentrations in Wuhan decreased significantly, however, there was little change in the health risk and a significant increase in intrinsic toxicity. DTT_v (the volume-normalized dithiothreitol) showed high correlations (r > 0.5, p < 0.01) with water-soluble organic carbon (WSOC), organic carbon (OC), secondary ions (NO₃^-, SO₄^2-, and NH₄⁺), and elements. Compared to 2012/2013, the contribution of vehicle emissions and secondary aerosol sources to PM_2.5 increased significantly in 2018. Biomass burning sources significantly contribute to DTT_v in the summer and autumn, and secondary aerosol sources significantly contribute to DTT_v in winter. The human health impacts from coal combustion sources remained high, while vehicle emission sources increased. In the context of decreasing PM_2.5 concentrations, the role of vehicle emissions health impacts is increasingly significant due to the large increment in vehicle ownership and high inherent OP. Therefore, targeting vehicle emissions for control is of great importance for human health and needs to be given great attention in future policymaking.

Indoor PM2.5 from occupied residences in Sweden caused higher inflammation in mice compared to outdoor PM2.5

We spend most of our time indoors; however, little is known about the effects of exposure to aerosol particles indoors. We aimed to determine differences in relative toxicity and physicochemical properties of PM_2.5 collected simultaneously indoors (PM_{2.5 INDOOR} ) and outdoors (PM_{2.5 OUTDOOR} ) in 15 occupied homes in southern Sweden. Collected particles were extracted from filters, pooled (indoor and outdoor separately), and characterized for chemical composition and endotoxins before being tested for toxicity in mice via intratracheal instillation. Various endpoints including lung inflammation, genotoxicity, and acute-phase response in lung and liver were assessed 1, 3, and 28 days post-exposure. Chemical composition of particles used in toxicological assessment was compared to particles analyzed without extraction. Time-resolved particle mass and number concentrations were monitored. PM_{2.5 INDOOR} showed higher relative concentrations (μg mg^-1 ) of metals, PAHs, and endotoxins compared to PM_{2.5 OUTDOOR} . These differences may be linked to PM_{2.5 INDOOR} causing significantly higher lung inflammation and lung acute-phase response 1 day post-exposure compared to PM_{2.5 OUTDOOR} and vehicle controls, respectively. None of the tested materials caused genotoxicity. PM_{2.5 INDOOR} displayed higher relative toxicity than PM_{2.5 OUTDOOR} under the studied conditions, that is, wintertime with reduced air exchange rates, high influence of indoor sources, and relatively low outdoor concentrations of PM. Reducing PM_{2.5 INDOOR} exposure requires reduction of both infiltration from outdoors and indoor-generated particles.

Transcriptional Response of Blood Mononuclear Cells from Patients with Inflammatory and Autoimmune Disorders Exposed to "Krakow Smog"

Despite the general awareness of the need to reduce air pollution, the efforts were undertaken in Poland to eliminate the pollutants and their harmful effect on human health seem to be insufficient. Moreover, the latest data indicate that the city of Krakow is at the forefront of the most polluted cities worldwide. Hence, in this report, we investigated the impact of particulate matter isolated from the air of Krakow (PM KRK) on the gene expression profile of peripheral blood mononuclear cells (PBMCs) in healthy donors (HD) and patients with atherosclerosis (AS), rheumatoid arthritis (RA) and multiple sclerosis (MS), after in vitro exposure. Blood samples were collected in two seasons, differing in the concentration of PM in the air (below or above a daily limit of 50 µg/m³ for PM 10). Data show that PBMCs exposed in vitro to PM KRK upregulated the expression of genes involved, among others, in pro-inflammatory response, cell motility, and regulation of cell metabolism. The transcriptional effects were observed predominantly in the group of patients with AS and MS. The observed changes seem to be dependent on the seasonal concentration of PM in the air of Krakow and may suggest their important role in the progression of AS, MS, and RA in the residents of Krakow.

Exposure to airborne particulate matter induces renal tubular cell injury in vitro: the role of vitamin D signaling and renin-angiotensin system

Background

Exposure to air pollution can interfere with the vitamin D endocrine system. This study investigated the effects of airborne particulate matter (PM) on renal tubular cell injury in vitro and explored the underlying mechanisms.

Methods

HK-2 human renal proximal tubule cells were treated with PM with or without 1,25(OH)₂D₃ analog, 19-Nor-1,25(OH)₂D₂ (paricalcitol, 10 nM) for 48 h. The dose- and time-dependent cytotoxicity of PM with or without paricalcitol was determined via cell counting kit-8 assay. Cellular oxidative stress was assessed using commercially available enzyme-linked immunosorbent assay kits. The protein expression of vitamin D receptor (VDR), cytochrome P450(CYP)27B1, CYP24A1, renin, angiotensin converting enzyme (ACE), angiotensin II type 1 receptor (AT1), nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor-kB (NF-kB), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 was determined.

Results

PM exposure decreased HK-2 cell viability in a dose- and time-dependent manner. The activities of superoxide dismutase and malondialdehyde in HK-2 cells increased significantly in the group exposed to PM. PM exposure decreased VDR and Nrf2, while increasing CYP27B1, renin, ACE, AT1, NF-kB, TNF-α, and IL-6. The expression of VDR, CYP27B1, renin, ACE, AT1, and TNF-α was reversed by paricalcitol treatment. Paricalcitol also restored the cell viability of PM-exposed HK-2 cells.

Conclusion

Our findings indicate that exposure to PM induces renal proximal tubular cell injury, concomitant with alteration of vitamin D endocrine system and renin angiotensin system. Vitamin D could attenuate renal tubular cell damage following PM exposure by suppressing the renin-angiotensin system and by partially inhibiting the inflammatory response.

Road tunnel-derived coarse, fine and ultrafine particulate matter: physical and chemical characterization and pro-inflammatory responses in human bronchial epithelial cells

BACKGROUND

Traffic particulate matter (PM) comprises a mixture of particles from fuel combustion and wear of road pavement, tires and brakes. In countries with low winter temperatures the relative contribution of mineral-rich PM from road abrasion may be especially high due to use of studded tires during winter season. The aim of the present study was to sample and characterize size-fractioned PM from two road tunnels paved with different stone materials in the asphalt, and to compare the pro-inflammatory potential of these fractions in human bronchial epithelial cells (HBEC3-KT) in relation to physicochemical characteristics.

METHODS

The road tunnel PM was collected with a vacuum pump and a high-volume cascade impactor sampler. PM was sampled during winter, both during humid and dry road surface conditions, and before and after cleaning the tunnels. Samples were analysed for hydrodynamic size distribution, content of elemental carbon (EC), organic carbon (OC) and endotoxin, and the capacity for acellular generation of reactive oxygen species. Cytotoxicity and pro-inflammatory responses were assessed in HBEC3-KT cells after exposure to coarse (2.5-10 μm), fine (0.18-2.5 μm) and ultrafine PM (≤ 0.18 μm), as well as particles from the respective stone materials used in the pavement.

RESULTS

The pro-inflammatory potency of the PM samples varied between road tunnels and size fractions, but showed more marked responses than for the stone materials used in asphalt of the respective tunnels. In particular, fine samples showed significant increases as low as 25 µg/mL (2.6 µg/cm²) and were more potent than coarse samples, while ultrafine samples showed more variable responses between tunnels, sampling conditions and endpoints. The most marked responses were observed for fine PM sampled during humid road surface conditions. Linear correlation analysis showed that particle-induced cytokine responses were correlated to OC levels, while no correlations were observed for other PM characteristics.

CONCLUSIONS

The pro-inflammatory potential of fine road tunnel PM sampled during winter season was high compared to coarse PM. The differences between the PM-induced cytokine responses were not related to stone materials in the asphalt. However, the ratio of OC to total PM mass was associated with the pro-inflammatory potential.

Simulated Enzyme Activity and Efficient Antibacterial Activity of Copper-Doped Single-Atom Nanozymes

Nanozymes with good biocompatibility are novel antibacterial agents because they mimic the structure and properties of enzymes and destroy bacterial structures by generating reactive oxygen species in large quantities. Herein, we synthesized a Cu single-atom nanozyme (Cu-N-C) with intrinsic peroxidase- and oxidase-like activities. Cu-N-C can generate ·OH and O₂^·- during oxidase-catalyzed reactions, which have good antibacterial effects. Meanwhile, the antimicrobial performance can be further enhanced by light emitting diode light incubation due to photocatalysis. Lethal disruption of the membrane structure was confirmed by biofilm staining and scanning electron microscopy analysis. Notably, the antibacterial effect of Cu-N-C (MIC = 16 μg/mL) was significantly better than that of vancomycin (MIC = 1500 μg/mL), a commonly used drug for methicillin-resistant Staphylococcus aureus, and Cu-N-C outperformed the positive control cephalexin and gentamicin in terms of resistance development (27.3% less production of drug-resistant bacteria). Good biocompatibility was also verified using the MTT method, hemolysis analysis, and routine blood measurements in mice. The results of this work suggest that Cu-N-C has great potential for clinical applications as an efficient metal antimicrobial agent.

The effect of size distribution of ambient air particulate matter on oxidative potential by acellular method Dithiothreitol; a systematic review

Today air pollution caused by particulate matter (PM) is a global issue, especially in densely populated and high-traffic cities. The formation of reactive oxygen species (ROS) by various toxicological studies is considered as one of the important effects caused by airborne particles that can lead to adverse effects on human health. In this study, to answer the question of whether particle size affects oxidative potential (OP), we searched the main databases, including PubMed, Scopus, Embase, and Web of Science, and defined search strategy based on the MESH terms for the above-mentioned search engines. All articles published until 2021 were searched. An ANOVA was run using R software to show the correlation between the size distributions of particulate matter and oxidative potential (base on mass and volumetric units) in ambient air. As expected, the regression results showed that the relationship between particle size and OP values for the studies based on mass-logarithm has a significant difference in the different distribution size categories, which was related to the difference between the <2.5 and < 1 categories. However, ANOVA analysis did not show a significant difference in the volumetric OP logarithm in the different distribution size categories. In this study, it was found that sizes higher than 2.5 μm did not have much effect on human health, and it is recommended that future research focus on PM2.5.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40201-021-00768-w.

Particulate matter (PM10) induces in vitro activation of human neutrophils, and lung histopathological alterations in a mouse model

The epidemiological association between exposure to particulate matter (PM₁₀) and various respiratory and cardiovascular problems is well known, but the mechanisms driving these effects remain unclear. Neutrophils play an essential role in immune defense against foreign agents and also participate in the development of inflammatory responses. However, the role of these cells in the PM₁₀ induced inflammatory response is not yet fully established. Thus, this study aims to evaluate the effect of PM₁₀ on the neutrophil-mediated inflammatory response. For this, neutrophils from healthy adult human donors were in vitro exposed to different concentrations of PM₁₀. The cell viability and cytotoxic activity were evaluated by MTT. LDH, propidium iodide and reactive oxygen species (ROS) were quantified by flow cytometry. Interleukin 8 (IL-8) expression, peptidyl arginine deiminase 4 (PAD₄), myeloperoxidase (MPO), and neutrophil elastase (NE) expression were measured by RT-PCR. IL-8 was also quantified by ELISA. Fluorescence microscopy was used to evaluate neutrophil extracellular traps (NETs) release. The in vivo inflammatory responses were assessed in BALB/c mice exposed to PM₁₀ by histopathology and RT-PCR. The analysis shows that PM₁₀ exposure induced a cytotoxic effect on neutrophils, evidenced by necrosis and LDH release at high PM₁₀ concentrations. ROS production, IL-8, MPO, NE expression, and NETs release were increased at all PM₁₀ concentrations assessed. Neutrophil infiltration in bronchoalveolar lavage fluid (BALF), histopathological changes with inflammatory cell infiltration, and CXCL1 expression were observed in PM₁₀-treated mice. The results suggest that lung inflammation in response to PM₁₀ could be mediated by neutrophils activation. In this case, these cells migrate to the lungs and release pro-inflamatory mediators, including ROS, IL-8, and NETs. Thus, contributing to the exacerbation of respiratory pathologies, such as allergies, infectious and obstructive diseases.

Seasonal Variations in the Concentration of Particulate Matter in the Air of Cracow Affect the Magnitude of CD4+ T Cell Subsets Cytokine Production in Patients with Inflammatory and Autoimmune Disorders

Recently, the increased prevalence of chronic civilization diseases triggered by environmental pollution has been observed. In this context, the role of air pollution in the pathogenesis of autoimmune and/or inflammatory disorders is poorly elucidated. Here, we asked whether seasonal changes in the air quality of the city of Cracow affect the polarization of T cell subsets in healthy donors (HD) and patients with rheumatoid arthritis (RA), multiple sclerosis (MS), and atherosclerosis (AS). Peripheral blood mononuclear cells (PBMCs) from HD and patients were exposed in vitro to particulate matter isolated from the air of Cracow (PM CRC). Blood samples were collected in two seasons (winter and summer), with differences in air concentration of particulate matter of 10 μm (PM10) (below or above a daily limit of 50 µg/m3). The obtained data showed a significantly elevated frequency of CD4+ lymphocytes specific for IFN-γ and IL-17A after the exposure of PBMCs to PM CRC. This was observed for all patients’ groups and HD. In the case of patients, this effect was dependent on the seasonal concentration of PM in the air, paradoxically being less pronounced in the season with a higher concentration of air pollution. These observations may suggest the role of air pollution on the course of inflammatory and autoimmune disorders.

Short-term associations between barbecue fumes and respiratory health in young adults

BACKGROUND

Epidemiological studies have associated biomass combustion with (respiratory) morbidity and mortality, primarily in indoor settings. Barbecuing results in high outdoor air pollution exposures, but the health effects are unknown.

OBJECTIVE

The objective was to investigate short-term changes in respiratory health in healthy adults, associated with exposure to barbecue fumes.

METHODS

16 healthy, adult volunteers were exposed to barbecue smoke in outdoor air in rest during 1.5 h, using a repeated-measures design. Major air pollutants were monitored on-site, including particulate matter <2.5 μm (PM_2.5), particle number concentrations (PNC) and black- and brown carbon. At the same place and time-of-day, subjects participated in a control session, during which they were not exposed to barbecue smoke. Before and immediately after all sessions lung function was measured. Before, immediately after, 4- and 18 h post-sessions nasal expression levels of interleukin (IL)-8, IL6 and Tumor Necrosis Factor alpha (TNFα) were determined in nasal swabs, using quantitative polymerase chain reaction. Associations between major air pollutants, lung function and inflammatory markers were assessed using mixed linear regression models.

RESULTS

High PM_2.5 levels and PNCs were observed during barbecue sessions, with averages ranging from 553 to 1062 μg/m³ and 109,000-463,000 pt/cm³, respectively. Average black- and brown carbon levels ranged between 4.1-13.0 and 5.0-16.2 μg/m³. A 1000 μg/m³ increase in PM_2.5 was associated with 2.37 (0.97, 4.67) and 2.21 (0.98, 5.00) times higher expression of IL8, immediately- and 18 h after exposure. No associations were found between air pollutants and lung function, or the expression of IL6 or TNFα.

DISCUSSION

Short-term exposure to air pollutants emitted from barbecuing was associated with a mild respiratory response in healthy young adults, including prolonged increase in nasal IL8 without a change in lung function and other measured inflammatory markers. The results might indicate prolonged respiratory inflammation, due to short-term exposure to barbecue fumes.

Contribution of Physical and Chemical Properties to Dithiothreitol-Measured Oxidative Potentials of Atmospheric Aerosol Particles at Urban and Rural Sites in Japan

Dithiothreitol-measured oxidative potential (OPDTT) can chemically quantify the adverse health effects of atmospheric aerosols. Some chemical species are characterized with DTT activities, and the particle diameter and surface area control DTT oxidizability; however, the physical contribution to OPDTT by atmospheric aerosols is controversial. Therefore, we performed field observations and aerosol sampling at urban and rural sites in Japan to investigate the effect of both physical and chemical properties on the variation in OPDTT of atmospheric aerosols. The shifting degree of the representative diameter to the ultrafine range (i.e., the predominance degree of ultrafine particles) was retrieved from the ratio between the lung-deposited surface area and mass concentrations. The chemical components and OPDTT were also elucidated. We discerned strong positive correlations of K, Mn, Pb, NH4+, SO42−, and pyrolyzable organic carbon with OPDTT. Hence, anthropogenic combustion, the iron–steel industry, and secondary organic aerosols were the major emission sources governing OPDTT variations. The increased specific surface area did not lead to the increase in the OPDTT of atmospheric aerosols, despite the existing relevance of the surface area of water-insoluble particles to DTT oxidizability. Overall, the OPDTT of atmospheric aerosols can be estimated by the mass of chemical components related to OPDTT variation, owing to numerous factors controlling DTT oxidizability (e.g., strong contribution of water-soluble particles). Our findings can be used to estimate OPDTT via several physicochemical parameters without its direct measurement.

Association of particulate matter with autoimmune rheumatic diseases among adults in South Korea

OBJECTIVE

The primary objective of this study was to investigate adverse effects of ambient particulate matter of various sizes on the incidence of the prevalent autoimmune rheumatic diseases (AIRDs): RA, AS and SLE.

METHODS

We investigated 230 034 participants in three metropolitan cities of South Korea from the National Health Insurance Service-National Sample Cohort (NHIS-NSC). Starting from January 2010, subjects were followed up until the first event of prevalent AIRDs, death, or December 2013. The 2008-2009 respective averages of particulate matter2.5 (<2.5 μm) and particulate mattercoarse (2.5 μm to 10 μm) were linked with participants' administrative district codes. Adjusted hazard ratios (aHRs) and 95% CIs were estimated using Cox regression analysis in one- and two-pollutant models.

RESULTS

Adjusted for age, sex, region, and household income, in the two-pollutant model, RA incidence was positively associated with the 10 μg/m³ increment of particulate matter2.5 (aHR = 1.74, 95% CI: 1.06, 2.86), but not with particulate mattercoarse (aHR = 1.27, 95% CI: 0.87, 1.85). In the one-pollutant model, the elevated incidence rate of RA was slightly attenuated (particulate matter2.5 aHR = 1.61, 95% CI: 0.99, 2.61; particulate mattercoarse aHR = 1.13, 95% CI: 0.80, 1.61), with marginal statistical significance for particulate matter2.5. The RA incidence was also higher in the 4th quartile group of particulate matter2.5 compared with the first quartile group (aHR = 1.83, 95% CI: 1.07, 3.11). Adverse effects from particulate matter were not found for AS or SLE in either the one- or two-pollutant models.

CONCLUSION

The important components of particulate matter10 associated with RA incidence were the fine fractions (particulate matter2.5); no positive association was found between particulate matter and AS or SLE.

Effectiveness of portable HEPA air cleaners on reducing indoor endotoxin, PM10, and coarse particulate matter in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners in the homes of children age 6-12 years with asthma in the Yakima Valley, Washington. All families received asthma education while intervention families also received two HEPA cleaners (child's bedroom, living room). We collected 14-day integrated samples of endotoxin in settled dust and PM₁₀ and PM_10-2.5 in the air of the children's bedrooms at baseline and one-year follow-up, and used linear regression to compare follow-up levels, adjusting for baseline. Seventy-one families (36 HEPA, 35 control) completed the study. Baseline geometric mean (GSD) endotoxin loadings were 1565 (6.3) EU/m² and 2110 (4.9) EU/m² , respectively, in HEPA vs. control homes while PM₁₀ and PM_10-2.5 were 22.5 (1.9) μg/m³ and 9.5 (2.9) μg/m³ , respectively, in HEPA homes, and 19.8 (1.8) μg/m³ and 7.7 (2.0) μg/m³ , respectively, in control homes. At follow-up, HEPA families had 46% lower (95% CI, 31%-57%) PM₁₀ on average than control families, consistent with prior studies. In the best-fit heterogeneous slopes model, HEPA families had 49% (95% CI, 6%-110%) and 89% lower (95% CI, 28%-177%) PM_10-2.5 at follow-up, respectively, at 50th and 75th percentile baseline concentrations. Endotoxin loadings did not differ significantly at follow-up (4% lower, HEPA homes; 95% CI, -87% to 50%).

Air pollution and cardiovascular disease: Can the Australian bushfires and global COVID-19 pandemic of 2020 convince us to change our ways?

Air pollution is a major global challenge for a multitude of reasons. As a specific concern, there is now compelling evidence demonstrating a causal relationship between exposure to airborne pollutants and the onset of cardiovascular disease (CVD). As such, reducing air pollution as a means to decrease cardiovascular morbidity and mortality should be a global health priority. This review provides an overview of the cardiovascular effects of air pollution and uses two major events of 2020-the Australian bushfires and COVID-19 pandemic lockdown-to illustrate the relationship between air pollution and CVD. The bushfires highlight the substantial human and economic costs associated with elevations in air pollution. Conversely, the COVID-19-related lockdowns demonstrated that stringent measures are effective at reducing airborne pollutants, which in turn resulted in a potential reduction in cardiovascular events. Perhaps one positive to come out of 2020 will be the recognition that tough measures are effective at reducing air pollution and that these measures have the potential to stop thousands of deaths from CVD.

Associations between air pollutant exposure and renal function: A prospective study of older adults without chronic kidney disease

We used real-world exposure scenarios to evaluate the effect of six ambient air pollutant (PM_2.5, PM₁₀, NO₂, SO₂, CO, and O₃) exposure on renal function among older adults without chronic kidney disease (CKD). We recruited 169 older adults without CKD in Beijing, China, for a longitudinal study from 2016 to 2018. The Modification of Diet in Renal Disease (MDRD) and the Chronic Kidney Disease Epidemiology Collaboration (EPI) equations were employed to derive the estimated glomerular filtration rate (eGFR). A linear mixed-effects model with random intercepts for participants was employed to determine the effects of air pollutants on renal function evaluated on the basis of eGFR and urinary albumin/creatinine ratio at different exposure windows (1-, 2-, 3-, 5-, 7-, 14-, 28-, 45-, and 60-days moving averages). An interquartile range (IQR) increase in NO₂ for was associated with significant decreases of in eGFR (MDRD equation) [percentage changes: -4.49 (95% confidence interval: -8.44, -0.37), -5.51 (-10.43, -0.33), -2.26 (-4.38, -0.08), -3.71 (-6.67, -0.65), -5.44 (-9.58, -1.11), -5.50 (-10.24, -0.51), -6.15 (-10.73, -1.33), and -6.34 (-11.17, -1.25) for 1-, 2-, 5-, 7-, 14-, 28-, 45-, and 60-days moving averages, respectively] and in eGFR (EPI equation) [percentage changes: -5.04 (-7.09, -2.94), -6.25 (-8.81, -3.62), -5.16 (-7.34, -2.92), -5.10 (-7.85, -2.28), -5.83 (-8.23, -3.36), -6.04 (-8.55, -3.47) for 1-, 2-, 14-, 28-, 45-, and 60-days moving averages, respectively]. In two-pollutant model, only the association of NO₂ exposure with eGFR remained robust after adjustment for any other pollutant. This association was stronger for individuals with hypertension for the EPI equation or BMI <25 kg/m² for the MDRD equation at lags 1 and 1-2. Our findings suggest that NO₂ exposure is associated with eGFR reduction among older adults without CKD for short (1-, 2-days) and medium (14-, 28-, 45-, 60-days) term exposure periods; thus, NO₂ exposure may contribute to renal impairment.

Oxidative potential of atmospheric PM10 at five different sites of Ahmedabad, a big city in Western India

The current study presents the oxidative potential (OP) along with a wide range of chemical speciation of particulate matter with an aerodynamic diameter less than 10 μm (PM₁₀) at five sites representing different environments in Ahmedabad, a big city in western India. On an average, PM₁₀ concentrations were 116 ± 36, 228 ± 43, 133 ± 29, 101 ± 21, and 70 ± 20 μg m^-3; volume-normalized OP (OP_V) were 2.51 ± 0.71, 5.62 ± 0.68, 2.69 ± 0.76, 2.14 ± 0.41, and 1.55 ± 0.51 nmol DTT min^-1 m^-3; and mass-normalized OP (OP_M) were 22 ± 3, 25 ± 5, 21 ± 6, 21 ± 2, and 22 ± 3 pmol DTT min^-1 μg^-1 over Bapunagar (backward residential area), Narol (industrial), Paldi (bus transport hub), Income Tax (huge running traffic) and Science City (posh residential area), respectively. Overall, OP_V showed a significant linear correlation with PM₁₀, whereas OP_M showed near uniformity with increasing PM₁₀. Although the OP_M values were similar, the site-to-site variability in PM₁₀ concentration reflects the corresponding health risks associated with PM₁₀ exposure for the people living in these areas. Further, a noticeable temporal variation in OP_M at Narol and Paldi suggests that species with diverse OP_M contributed to PM₁₀ on different days. A strong linear relationship between the ratio of OP_V to the mass concentration of organic carbon (OP_OC) and the ratio of m/z 43 signal to total water-soluble organic aerosols (WSOA) signals (f43) suggests that the fossil-fuel combustion derived WSOA have higher OP. Furthermore, the relationships of OP with water-soluble trace metals and brown carbon are also investigated and discussed in this paper. Nitrogenous organic compounds particularly emitted from the traffic-related sources in Paldi and Income Tax have higher OP_OC than those emitted from other sources over Bapunagar, Narol, and Science City.

Cellular effects of PM2.5 from Suzhou, China: relationship to chemical composition and endotoxin content

Exposure to PM_2.5 can cause adverse health outcomes. In this study, we analyzed PM_2.5 samples collected from suburban and urban sites, including a traffic tunnel in Suzhou, China, for their physicochemical properties, endotoxin contents, and effects on HepG2 and A549 cells in vitro. The greatest cellular responses, including oxidative stress, cytotoxicity, genotoxicity, inflammatory, and transcriptional activation of stress-responsive genes (i.e., HSPA1A, GADD45α), were observed in cells treated with traffic tunnel PM_2.5. Cytokine expression was also measured and closely correlated with endotoxin content, while other toxic effects were largely related to PM_2.5-bound metals and polycyclic aromatic hydrocarbons (PAHs). These findings suggested that chemical and biological composition of PM_2.5, including adsorbed trace metals, PAHs, and endotoxin, may contribute significantly to their toxicity. In addition to commonly used in vitro toxicity tests, HSPA1A and GADD45α promoter-driven luciferase reporter cells may provide a potential new tool for rapid screening and quantification of PM_2.5 toxicity.

Reactive oxygen species production and inflammatory effects of ambient PM2.5 -associated metals on human lung epithelial A549 cells "one year-long study": The Delhi chapter

The fine particulate matter (PM_2.5) was collected at academic campus of Indian Institute of Technology, Delhi, India from January-December 2017. The PM_2.5 samples were analysed for carcinogenic (Cd, Cr, As, Ni, and Pb) and non-carcinogenic (V, Cu, Zn, Fe) trace metals and their elicited effects on carcinoma epithelial cell line A549. Toxicological testing was done with ELISA kit. Same analyses were repeated for standard reference material (NIST-1648a) represents urban particulate matter. The student-t test and spearman correlation were used for data analysis. The seasonality in PM_2.5 mass concentration and chemical composition showed effect on biological outcomes. The PM_2.5 in post-monsoon and winter had higher amount of trace metals compared to mass collected in pre-monsoon and monsoon. Following the trend in PM mass concentration significantly (p < 0.5) lower cell viability was observed in post-monsoon and winter compared to other two seasons. NIST UPM 1648(a) samples always had higher cytotoxicity compared to ambient PM_2.5 Delhi sample. Strong association of Chromium, Nickel, Cadmium, and Zinc was observed with cell viability and reactive oxygen species (ROS) production. In winter IL-6, IL-8 production were 2.8 and 3 times higher than values observed in post-monsoon and 53 and 9 times higher than control. In winter season trace metals As, Cu, Fe, in pre-monsoon Cr, Ni, As, Pb, V, and Fe, in post-monsoon Cd and V strongly correlated with ROS generation. ROS production in winter and pre-monsoon seasons found to be 2.6 and 1.3 times higher than extremely polluted post-monsoon season which had 2 to 3 times higher PM_2.5 concentration compared to winter and pre-monsoon. The result clearly indicated that the presence of Fe in winter and pre-monsoon seasons catalysed the ROS production, probably OH˙ radical caused high cytokines production which influenced the cell viability reduction, while in post-monsoon PM majorly composed of Pb, As, Fe and Cu and affected by photochemical smog formation showed significant association between ROS production with cell viability. Overall, in Delhi most toxic seasons for respiratory system are winter and post-monsoon and safest season is monsoon.

Size distributions of particle-generated hydroxyl radical (·OH) in surrogate lung fluid (SLF) solution and their potential sources

Although it is known that increases in ambient particulate matter (PM) levels are associated with elevated occurrence of adverse health outcomes, the understanding of the mechanisms of PM-related health effects is limited by our knowledge of how particle size and composition are altered subsequent to inhalation through respiratory-deposited processing. Here we present a particle-generated hydroxyl radical (·OH) study of the size-resolved particles as particles are inhaled in the human respiratory tract (RT), and we show that accumulation-mode particles are significant factors (71-75%) in ·OH generation of lung-deposited particles using Multiple-Path Particle Dosimetry (MPPD) model. The ability of PM to catalyze ·OH generation is mainly related to transition metals, particularly towards the upper regions of the RT (75%), and to quinones deeper in the lung (42-46%). Identification of this generation ability induced by chemical composition has shown that four potential sources (biomass burning, incomplete combustion, mobile & industry, and mineral dust) are responsible for ·OH generation. With ·OH-forming ability after PM inhalation implicated as the first step towards revealing the subsequent toxic processes, this work draws a connection between the detailed ·OH chemistry occurring on size-resolved particles and a possible toxicological mechanism based on chemical composition and sources.

Air Pollution and Central Nervous System Disease: A Review of the Impact of Fine Particulate Matter on Neurological Disorders

Background: It is widely known that the harmful effects of fine dust can cause various diseases. Research on the correlation between fine dust and health has been mainly focused on lung and cardiovascular diseases. By contrast, the effects of air pollution on the central nervous system (CNS) are not broadly recognized.

Findings: Air pollution can cause diverse neurological disorders as the result of inflammation of the nervous system, oxidative stress, activation of microglial cells, protein condensation, and cerebral vascular-barrier disorders, but uncertainty remains concerning the biological mechanisms by which air pollution produces neurological disease. Neuronal cell damage caused by fine dust, especially in fetuses and infants, can cause permanent brain damage or lead to neurological disease in adulthood.

Conclusion: It is necessary to study the air pollution–CNS disease connection with particular care and commitment. Moreover, the epidemiological and experimental study of the association between exposure to air pollution and CNS damage is critical to public health and quality of life. Here, we summarize the correlations between fine dust exposure and neurological disorders reported so far and make suggestions on the direction future research should take.

The short- and long-term associations of particulate matter with inflammation and blood coagulation markers: A meta-analysis

Inflammation and the coagulation cascade are considered to be the potential mechanisms of ambient particulate matter (PM) exposure-induced adverse cardiovascular events. Tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), and fibrinogen are arguably the four most commonly assayed markers to reflect the relationships of PM with inflammation and blood coagulation. This review summarized and quantitatively analyzed the existing studies reporting short- and long-term associations of PM2.5(PM with an aerodynamic diameter ≤2.5 μm)/PM10 (PM with an aerodynamic diameter≤10 μm) with important inflammation and blood coagulation markers (TNF-α, IL-6, IL-8, fibrinogen). We reviewed relevant studies published up to July 2020, using three English databases (PubMed, Web of Science, Embase) and two Chinese databases (Wang-Fang, China National Knowledge Infrastructure). The OHAT tool, with some modification, was applied to evaluate risk of bias. Meta-analyses were conducted with random-effects models for calculating the pooled estimate of markers. To assess the potential effect modifiers and the source of heterogeneity, we conducted subgroup analyses and meta-regression analyses where appropriate. The assessment and correction of publication bias were based on Begg's and Egger's test and "trim-and-fill" analysis. We identified 44 eligible studies. For short-term PM exposure, the percent change of a 10 μg/m3 PM2.5 increase on TNF-α and fibrinogen was 3.51% (95% confidence interval (CI): 1.21%, 5.81%) and 0.54% (95% confidence interval (CI): 0.21%, 0.86%) respectively. We also found a significant short-term association between PM10 and fibrinogen (percent change = 0.17%, 95% CI: 0.04%, 0.29%). Overall analysis showed that long-term associations of fibrinogen with PM2.5 and PM10 were not significant. Subgroup analysis showed that long-term associations of fibrinogen with PM2.5 and PM10 were significant only found in studies conducted in Asia. Our findings support significant short-term associations of PM with TNF-α and fibrinogen. Future epidemiological studies should address the role long-term PM exposure plays in inflammation and blood coagulation markers level change.

NADPH oxidase and mitochondria are relevant sources of superoxide anion in the oxinflammatory response of macrophages exposed to airborne particulate matter

Exposure to ambient air particulate matter (PM) is associated with increased cardiorespiratory morbidity and mortality. In this context, alveolar macrophages exhibit proinflammatory and oxidative responses as a result of the clearance of particles, thus contributing to lung injury. However, the mechanisms linking these pathways are not completely clarified. Therefore, the oxinflammation phenomenon was studied in RAW 264.7 macrophages exposed to Residual Oil Fly Ash (ROFA), a PM surrogate rich in transition metals. While cell viability was not compromised under the experimental conditions, a proinflammatory phenotype was observed in cells incubated with ROFA 100 μg/mL, characterized by increased levels of TNF-α and NO production, together with PM uptake. This inflammatory response seems to precede alterations in redox metabolism, characterized by augmented levels of H₂O₂, diminished GSH/GSSG ratio, and increased SOD activity. This scenario resulted in increased oxidative damage to phospholipids. Moreover, alterations in mitochondrial respiration were observed following ROFA incubation, such as diminished coupling efficiency and spare respiratory capacity, together with augmented proton leak. These findings were accompanied by a decrease in mitochondrial membrane potential. Finally, NADPH oxidase (NOX) and mitochondria were identified as the main sources of superoxide anion () in our model. These results indicate that PM exposure induces direct activation of macrophages, leading to inflammation and increased reactive oxygen species production through NOX and mitochondria, which impairs antioxidant defense and may cause mitochondrial dysfunction.

Effect of PM characterization on PM oxidative potential by acellular assays: a review

The health risks brought by particles cannot be present via a sole parameter. Instead, the particulate matter oxidative potential (PM OP), which expresses combined redox properties of particles, is used as an integrated metric to assess associated hazards and particle-induced health effects. OP definition provides the capacity of PM toward target oxidation. The latest technologies of a cellular OP measurement has been growing in relevant studies. In this review, OP measurement techniques are focused on discussing along with PM characterization because of many related studies via OP measurements investigating relationship with human health. Many OP measurement methods, such as dithiothreitol (DTT), ascorbic acid (AA), glutathione (GSH) assay and other a cellular assays, are used to study the association between PM toxicity and PM characterization that make different responses, including PM components, size and sources. Briefly, AA and DTT assays are sensitive to metals (such as copper, manganese and iron etc.) and organics (quinones, VOCs and PAH). Measured OP have significant association with certain PM-related end points, for example, lung cancer, COPD and asthma. Literature has found that exposure to measured OP has higher risk ratios than sole PM mass, which may be containing the PM health-relevant fraction. PM characterization effect on health via OP measurement display a promising method.