Reactive oxygen species in pulmonary inflammation by ambient particulates

Summertime oxidative potential of atmospheric PM2.5 over New Delhi: Effect of aerosol ageing

Exposure to elevated particulate matter (PM) concentrations in ambient air has become a major health concern over urban areas worldwide. Reactive oxygen species (ROS) generation due to ambient PM (termed as their oxidative potential, OP) is shown to play a major role in PM-induced health effects. In the present study, the OP of the ambient PM2.5 samples, collected during summer 2019 from New Delhi, were measured using the dithiothreitol (DTT) assay. Average volume-normalized OP (OPV) was 2.9 ± 1.1 nmol DTT min-1 m-3, and mass-normalized OP (OPm) was 61 ± 29 pmol DTT min-1 μg-1. The regression statistics of OPv vs chemical species show the maximum slope of OPV with the elemental carbon (EC, r2 = 0.72) followed by water-soluble organic carbon (WSOC, r2 = 0.72), and organic carbon (OC, r2 = 0.64). A strong positive correlation between OPm and secondary inorganic aerosols (SIA, such as NH4+ and NO3- mass fractions) was also observed, indicating that the sources emitting NO2 and NH3, precursors of NO3- and NH4+, also emit DTT-active species. Interestingly, the slope value of OPv vs OC for aged aerosols (OM/OC > 1.7, f44 > 0.12 and f43 < 0.04) was 1.7 times higher than relatively fresh organic aerosols (OA, OM/OC < 1.7, f44 < 0.12, f43 > 0.04). An increase in OPv and OPoc with f44 indicates the formation of more DTT active species with the ageing of OA. A linear increase in OPoc with increasing Nitrogen/Carbon (N/C) ratio suggests that nitrogenous OA have higher OP.

Subacute Exposure to Gaseous Pollutants from Diesel Engine Exhaust Attenuates Capsaicin-Induced Cardio-Pulmonary Reflex Responses Involving Oxidant Stress Mechanisms in Adult Wistar Rats

Intravenous injection of capsaicin produces vagal-mediated protective cardio-pulmonary (CP) reflexes manifesting as tachypnea, bradycardia, and triphasic blood pressure (BP) response in anesthetized rats. Particulate matter from diesel engine exhaust has been reported to attenuate these reflexes. However, the effects of gaseous constituents of diesel exhaust are not known. Therefore, the present study was designed to investigate the effects of gaseous pollutants in diesel exhaust, on capsaicin-induced CP reflexes in rat model. Adult male rats were randomly assigned to three groups: Non-exposed (NE) group, filtered diesel exhaust-exposed (FDE) group and N-acetyl cysteine (NAC)-treated FDE group. FDE group of rats (n = 6) were exposed to filtered diesel exhaust for 5 h a day for 5 days (D1-D5), and were taken for dissection on day 6 (D6), while NE group of rats (n = 6) remained unexposed. On D6, rats were anesthetized, following which jugular vein was cannulated for injection of chemicals, and femoral artery was cannulated to record the BP. Lead II electrocardiogram and respiratory movements were also recorded. Results show that intravenous injection of capsaicin (0.1 ml; 10 µg/kg) produced immediate tachypneic, hyperventilatory, hypotensive, and bradycardiac responses in both NE and FDE groups of rats. However, these capsaicin-induced CP responses were significantly attenuated in FDE group as compared to the NE group of rats. Further, FDE-induced attenuation of capsaicin-evoked CP responses were diminished in the N-acetyl cysteine-treated FDE rats. These findings demonstrate that oxidant stress mechanisms could possibly be involved in inhibition of CP reflexes by gaseous pollutants in diesel engine exhaust.

The efficient applications of native flora for phytorestoration of mine tailings: a pan-global survey

Mine tailings are the discarded materials resulting from mining processes after minerals have been extracted. They consist of leftover mineral fragments, excavated land masses, and disrupted ecosystems. The uncontrolled handling or discharge of tailings from abandoned mine lands (AMLs) poses a threat to the surrounding environment. Numerous untreated mine tailings have been abandoned globally, necessitating immediate reclamation and restoration efforts. The limited feasibility of conventional reclamation methods, such as cost and acceptability, presents challenges in reclaiming tailings around AMLs. This study focuses on phytorestoration as a sustainable method for treating mine tailings. Phytorestoration utilizes existing native plants on the mine sites while applying advanced principles of environmental biotechnology. These approaches can remediate toxic elements and simultaneously improve soil quality. The current study provides a global overview of phytorestoration methods, emphasizing the specifics of mine tailings and the research on native plant species to enhance restoration ecosystem services.

The role of lysosomes in airborne particulate matter-induced pulmonary toxicity

An investigation of the potential role of lysosomes in airborne particulate matter (APM) induced health risks is essential to fully comprehend the pathogenic mechanisms of respiratory diseases. It is commonly accepted that APM-induced lung injury is caused by oxidative stress, inflammatory responses, and DNA damage. In addition, there exists abundant evidence that changes in lysosomal function are essential for cellular adaptation to a variety of particulate stimuli. This review emphasizes that disruption of the lysosomal structure/function is a key step in the cellular metabolic imbalance induced by APMs. After being ingested by cells, most particles are localized within lysosomes. Thus, lysosomes become the primary locus where APMs accumulate, and here they undergo degradation and release toxic components. Recent studies have provided incontrovertible evidence that a wide variety of APMs interfere with the normal function of lysosomes. After being stimulated by APMs, lysosome rupture leads to a loss of lysosomal acidic conditions and the inactivation of proteolytic enzymes, promoting an inflammatory response by activating the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Moreover, APMs interfere with autophagosome production or block autophagic flux, resulting in autophagy dysfunction. Additionally, APMs disrupt the normal function of lysosomes in iron metabolism, leading to disruption on iron homeostasis. Therefore, understanding the impacts of APM exposure from the perspective of lysosomes will provide new insights into the detrimental consequences of air pollution.

Occupational exposure to particulate matter and staff sickness absence on the London underground

The London Underground (LU) employs over 19,000 staff, some of whom are exposed to elevated concentrations of particulate matter (PM) within the network. This study quantified the occupational exposure of LU staff to subway PM and investigated the possible association with sickness absence (SA). A job exposure matrix to quantify subway PM2.5 staff exposure was developed by undertaking measurement campaigns across the LU network. The association between exposure and SA was evaluated using zero-inflated mixed-effects negative binomial models. Staff PM2.5 exposure varied by job grade and tasks undertaken. Drivers had the highest exposure over a work shift (mean: 261 µg/m3), but concentrations varied significantly by LU line and time the train spent subway. Office staff work in office buildings separate to the LU network and are unexposed to occupational subway PM2.5. They were found to have lower rates of all-cause and respiratory infection SA compared to non-office staff, those who work across the LU network and are occupational exposed to subway PM2.5. Train drivers on five out of eight lines showed higher rates of all-cause SA, but no dose-response relationship was seen. Only drivers from one line showed higher rates of SAs from respiratory infections (incidence rate ratio: 1.24, 95% confidence interval 1.10-1.39). Lower-grade customer service (CS) staff showed higher rates of all-cause and respiratory infection SA compared to higher grade CS staff. Doctor-certified chronic respiratory and cardiovascular SAs were associated with occupational PM2.5 exposure in CS staff and drivers. While some groups with higher occupational exposure to subway PM reported higher rates of SA, no evidence suggests that subway PM is the main contributing factor to SA. This is the largest subway study on health effects of occupational PM2.5 exposure and may have wider implications for subway workers, contributing to safer working environments.

A review on factors related to patient comfort experience in hospitals

The creation of a welcoming hospital atmosphere is necessary to improve patient wellbeing and encourage healing. The goal of this study was to examine the variables affecting hospitalised patients' comfort. The study procedure included a thorough search of the Web of Science and Scopus databases, as well as the use of software analytic tools to graphically map enormous literature data, providing a deeper understanding of the linkages within the literature and its changing patterns. Insights from a range of disciplines, including engineering, psychology, immunology, microbiology, and environmental science, were included into our study using content analysis and clustering approaches. The physical environment and the social environment are two crucial factors that are related to patient comfort. The study stress the need of giving patient comfort a top priority as they heal, especially by tackling indoor air pollution. Our research also emphasises how important hospital care and food guidelines are for improving patient comfort. Prioritising patients who need specialised care and attention, especially those who have suffered trauma, should be the focus of future study. Future research in important fields including trauma, communication, hospital architecture, and nursing will be built on the findings of this study. To enhance research in these crucial areas, worldwide collaboration between experts from other nations is also advised. Although many studies stress the significance of patient comfort, few have drawn conclusions from a variety of disciplines, including medicine, engineering, immunology, microbiology, and environmental science, the most crucial issue of thoroughly researching the improvement of patient comfort has not been addressed. Healthcare workers, engineers, and other professions will benefit greatly from this study's investigation of the connection between hospital indoor environments and patient comfort.

Significance of Singlet Oxygen Molecule in Pathologies

Reactive oxygen species, including singlet oxygen, play an important role in the onset and progression of disease, as well as in aging. Singlet oxygen can be formed non-enzymatically by chemical, photochemical, and electron transfer reactions, or as a byproduct of endogenous enzymatic reactions in phagocytosis during inflammation. The imbalance of antioxidant enzymes and antioxidant networks with the generation of singlet oxygen increases oxidative stress, resulting in the undesirable oxidation and modification of biomolecules, such as proteins, DNA, and lipids. This review describes the molecular mechanisms of singlet oxygen production in vivo and methods for the evaluation of damage induced by singlet oxygen. The involvement of singlet oxygen in the pathogenesis of skin and eye diseases is also discussed from the biomolecular perspective. We also present our findings on lipid oxidation products derived from singlet oxygen-mediated oxidation in glaucoma, early diabetes patients, and a mouse model of bronchial asthma. Even in these diseases, oxidation products due to singlet oxygen have not been measured clinically. This review discusses their potential as biomarkers for diagnosis. Recent developments in singlet oxygen scavengers such as carotenoids, which can be utilized to prevent the onset and progression of disease, are also described.

Organic Peroxides in Aerosol: Key Reactive Intermediates for Multiphase Processes in the Atmosphere

Organic peroxides (POs) are organic molecules with one or more peroxide (-O-O-) functional groups. POs are commonly regarded as chemically labile termination products from gas-phase radical chemistry and therefore serve as temporary reservoirs for oxidative radicals (HOx and ROx) in the atmosphere. Owing to their ubiquity, active gas-particle partitioning behavior, and reactivity, POs are key reactive intermediates in atmospheric multiphase processes determining the life cycle (formation, growth, and aging), climate, and health impacts of aerosol. However, there remain substantial gaps in the origin, molecular diversity, and fate of POs due to their complex nature and dynamic behavior. Here, we summarize the current understanding on atmospheric POs, with a focus on their identification and quantification, state-of-the-art analytical developments, molecular-level formation mechanisms, multiphase chemical transformation pathways, as well as environmental and health impacts. We find that interactions with SO2 and transition metal ions are generally the fast PO transformation pathways in atmospheric liquid water, with lifetimes estimated to be minutes to hours, while hydrolysis is particularly important for α-substituted hydroperoxides. Meanwhile, photolysis and thermolysis are likely minor sinks for POs. These multiphase PO transformation pathways are distinctly different from their gas-phase fates, such as photolysis and reaction with OH radicals, which highlights the need to understand the multiphase partitioning of POs. By summarizing the current advances and remaining challenges for the investigation of POs, we propose future research priorities regarding their origin, fate, and impacts in the atmosphere.

Co-exposure to urban particulate matter and aircraft noise adversely impacts the cerebro-pulmonary-cardiovascular axis in mice

Worldwide, up to 8.8 million excess deaths/year have been attributed to air pollution, mainly due to the exposure to fine particulate matter (PM). Traffic-related noise is an additional contributor to global mortality and morbidity. Both health risk factors substantially contribute to cardiovascular, metabolic and neuropsychiatric sequelae. Studies on the combined exposure are rare and urgently needed because of frequent co-occurrence of both risk factors in urban and industrial settings. To study the synergistic effects of PM and noise, we used an exposure system equipped with aerosol generator and loud-speakers, where C57BL/6 mice were acutely exposed for 3d to either ambient PM (NIST particles) and/or noise (aircraft landing and take-off events). The combination of both stressors caused endothelial dysfunction, increased blood pressure, oxidative stress and inflammation. An additive impairment of endothelial function was observed in isolated aortic rings and even more pronounced in cerebral and retinal arterioles. The increase in oxidative stress and inflammation markers together with RNA sequencing data indicate that noise particularly affects the brain and PM the lungs. The combination of both stressors has additive adverse effects on the cardiovascular system that are based on PM-induced systemic inflammation and noise-triggered stress hormone signaling. We demonstrate an additive upregulation of ACE-2 in the lung, suggesting that there may be an increased vulnerability to COVID-19 infection. The data warrant further mechanistic studies to characterize the propagation of primary target tissue damage (lung, brain) to remote organs such as aorta and heart by combined noise and PM exposure.

Water-soluble iron in PM2.5 in winter over six Chinese megacities: Distributions, sources, and environmental implications

Water-soluble iron (ws-Fe) in PM_2.5 plays a crucial role in biogeochemical cycles and atmospheric chemical processes. The anthropogenic sources of ws-Fe have attracted considerable attention owing to its high solubility. However, few studies have investigated the content of PM_2.5 ws-Fe in the urban environment. In the present study, we characterized the spatial distributions of ws-Fe in six Chinese megacities in the winter of 2019. Furthermore, we investigated the speciation of PM_2.5 ws-Fe (ws-Fe(II) and ws-Fe(III)), potential sources of ws-Fe, and association between ws-Fe and particle-bound reactive oxygen species (ROS). Higher ws-Fe concentrations were observed in northern cities (Harbin, Beijing, and Xi'an) than in southern cities (Chengdu, Wuhan, and Guangzhou). Moreover, atmospheric ws-Fe concentrations in urban China were several folds higher than those in urban areas of the United States and several orders of magnitude higher than those in remote oceans, indicating that China is a key contributor to global atmospheric ws-Fe. The dominant form of ws-Fe was ws-Fe(III) in Beijing, whereas ws-Fe(II) was more abundant in the other five cities. The concentrations of ws-Fe and ws-Fe(II) concentrations increased with increasing PM_2.5 levels in all the six cities, however, we did not observe any consistent pattern of ws-Fe(III) concentration. Biomass burning was a dominant source of ws-Fe in all cities except Beijing. A strong positive correlation was observed between particle-bound ROS content and ws-Fe; this finding is consistent with those of previous studies indicating that ws-Fe in PM_2.5 notably influences atmospheric chemical processes and human health.

The association of chemical composition particularly the heavy metals with the oxidative potential of ambient PM2.5 in a megacity (Guangzhou) of southern China

Atmospheric fine particulate matters (PM_2.5) can cause adverse health effects through the generation of reactive oxygen species (ROS), which is normally characterized by the oxidative potential (OP). However, the particulate components that are mainly responsible for the ROS-induced OP remain controversial and warrant further investigation, especially in megacities where high exposure exists and particulate composition is complex. In this study, we measured the OP of PM_2.5 using the dithiothreitol (DTT) assay with and without chelation of metals in a megacity in southern China, Guangzhou, in January and April. We explored the correlations between OP and various chemical components in PM_2.5, including water-soluble ions, organic carbon (OC), elemental carbon (EC), and metal elements. There are strong correlations between OP^DTTv (volume-normalized) and concentrations of PM_2.5, OC, and EC, while the correlations between OP^DTTm (mass-normalized) and mass-normalized water-soluble ions, OC, EC or metal elements are weak. The OP values with chelation were reduced by ∼90%, indicating that water-soluble heavy metals were the major contributors to OP of PM_2.5 in Guangzhou. On the other hand, correlations between OP^DTTm and OC improved significantly after the chelation of heavy metals, implying that OC explains the variance of OP^DTTm although its contribution to OP is much smaller than that of heavy metals. We postulate that there might be synergetic effects between water-soluble heavy metals (which contribute most to OP) and OC (which explains the variance of OP) in ROS generation by PM_2.5. The findings of the current study provide a better understanding on the critical components in PM_2.5 and potential synergism that might be responsible for health effects in urban areas.

The oxidative potential of particulate matter (PM) in different regions around the world and its relation to air pollution sources

In this study, we investigated the impact of urban emission sources on the chemical composition of ambient particulate matter (PM) as well as the associated oxidative potential. We collected six sets of PM samples in five urban location sites around the world over long time periods varying from weeks to months, intentionally selected for their PM to be dominated by unique emission sources: (1) PM_2.5 produced mainly by traffic emissions in central Los Angeles, United States (US); (2) PM_2.5 dominated by biomass burning in Milan, Italy; (3) PM_2.5 formed by secondary photochemical reactions thus dominated by secondary aerosols in Athens, Greece; (4) PM₁₀ emitted by refinery and dust resuspension in Riyadh, Saudi Arabia (SA); (5) PM₁₀ generated by dust storms in Riyadh, SA, and (6) PM_2.5 produced mainly by industrial and traffic emissions in Beirut, Lebanon. The PM samples were chemically analyzed and their oxidative potential were quantified by employing the dithiothreitol (DTT) assay. Our results revealed that the Milan samples were rich in water soluble organic carbon (WSOC) and PAHs, even exceeding the levels measured on Los Angeles (LA) freeways. The PM in Athens was characterized by high concentrations of inorganic ions, specifically sulfate which was the highest of all PM samples. The ambient PM in LA was impacted by the traffic-emitted primary organic and elemental carbon. Furthermore, the contribution of metals and elements per mass of PM in Riyadh and Beirut samples were more pronounced relative to other sampling areas. The highest intrinsic PM redox activity was observed for PM with the highest WSOC fraction, including Milan (biomass burning) and Athens (secondary organic aerosols, SOA). PM in areas characterized by high metal emissions including dust events, refinery and industry, such as Riyadh and Beirut, had the lowest oxidative potential as assessed by the DTT assay. The results of this study illustrate the impact of major emission sources in urban areas on the redox activity and oxidative potential of ambient PM, providing useful information for developing efficient air pollution control and mitigation policies in polluted areas around the globe.

Secular Trends of Mortality and Years of Life Lost Due to Chronic Obstructive Pulmonary Disease in Wuhan, China from 2010 to 2019: Age-Period-Cohort Analysis

BACKGROUND

Chronic obstructive pulmonary disease (COPD) has been an important public health issue in China. This study aimed to analyze the temporal trends in mortality and years of life lost (YLL) from COPD, and explore the effects of age, period, and cohort in Wuhan, China from 2010 to 2019.

METHODS

Data were collected from the cause of death surveillance system in Wuhan. Age-standardized mortality rate (ASMR), age-standardized YLL rate (ASYR) and the estimated annual percent changes (EAPC) were calculated to evaluate the temporal trends. The age-period-cohort (APC) model was adopted to estimate the age, period, and cohort effects.

RESULTS

From 2010 to 2019, COPD accounted for 26,051.15 deaths and 394,659.58 person years YLL in Wuhan. Recently, the death burden of COPD in Wuhan has somewhat improved, especially after 2015, with declining trends in ASMR and ASYR. Additionally, the ASMR and ASYR of COPD was higher in males. And these of males showed the overall upward trends, with EAPCs of 1.06 (0.13, 2.00) and 1.21 (0.12, 2.31), respectively, while females showed downward trends since 2010. According to APC model, the age effect of COPD increased with age, and the cohort risk ratios (RRs) followed the overall downward trends. Period RRs for the Wuhan population generally tended to rise and then fall, with females showing a clear downward trend after 2015, while period RRs for males maintained an upward trend throughout the study period.

CONCLUSIONS

Recently, the death burden from COPD in Wuhan has improved, especially after 2015, with improvements in ASMR, ASYR and period RRs. Sex differences still exist. COPD posed a greater threat to the elderly, especially males. Public health managers should continue to execute more targeted programs to lessen the death burden of COPD in Wuhan.

Oxidative potential associated with water-soluble components of PM2.5 in Beijing: The important role of anthropogenic organic aerosols

Oxidative stress is the mainstream toxicological mechanism for the adverse health outcomes of ambient aerosols. However, our understanding of the crucial redox-active species affecting the oxidative potential of water-soluble aerosols (OP_WS) remains limited. In this study, the OP_WS of PM_2.5 in Beijing was measured using dithiothreitol (DTT) assay, including DTT consumption rate and ·OH formation rate. OP_WS was more closely related to water-soluble organic compounds (WSOC) rather than transition metals. Laboratory simulations were conducted to investigate the effects of individual target species in the context of complex metal-organic interactions. The results showed that reducing WSOC can effectively decrease OP_WS, while reducing Cu²⁺ increased OP_WS. Parallel factor analysis demonstrated that OP_WS was the most significantly correlated with the highly oxidized humic-like or quinone-like substances. Multiple linear regression showed that aromatic secondary organic carbon (SOC) (34.4%), other primary combustion sources of WSOC (20.0%), primary biomass burning WSOC (19.8%), transition metal ions (12.9%) and biomass burning SOC (12.8%) made significant contributions to DTT_V. In addition to the anthropogenic sources of WSOC, the aged biogenic SOC also contributed to OH_V, particularly in summer. Reducing anthropogenic WSOC was the key to the effective control of OP_WS of PM_2.5 in Beijing.

Assessment of the association of exposure to polycyclic aromatic hydrocarbons, oxidative stress, and inflammation: A cross-sectional study in Augsburg, Germany

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been linked to acute and chronic health effects through the suggested pathways of oxidative stress and inflammation. However, evidence is still limited. We aimed to investigate jointly the relationship of PAHs, oxidative stress, and inflammation.

METHODS

We measured 13 biomarkers of PAH exposure (n = 6: hydroxylated polycyclic aromatic hydrocarbons, [OH-PAHs]), oxidative stress (n = 6: malondialdehyde (MDA); 8-hydroxy-2'-deoxyguanosine (8-OHdG); and 4 representatives of the compound class of F_2α-isoprostanes) in urine, and inflammation (n = 1: high-sensitivity C-reactive protein, [hs-CRP]) in serum from 400 participants at the second follow-up (2013/2014) of the German KORA survey S4. Multiple linear regression models were applied to investigate the interplay between biomarkers.

RESULTS

Concentrations of biomarkers varied according to sex, age, smoking status, season, and a history of obesity, diabetes, or chronic kidney disease. All OH-PAHs were significantly and positively associated with oxidative stress biomarkers. An interquartile range (IQR) increase in sum OH-PAHs was associated with a 13.3% (95% CI: 9.9%, 16.9%) increase in MDA, a 6.5% (95% CI: 3.5%, 9.6%) increase in 8-OHdG, and an 8.4% (95% CI: 6.6%, 11.3%) increase in sum F_2α-isoprostanes. Associations were more pronounced between OH-PAHs and F_2α-isoprostanes but also between OH-PAHs and 8-OHdG for participants with potential underlying systemic inflammation (hs-CRP ≥ 3 mg/L). We observed no association between OH-PAHs and hs-CRP levels. While 8-OHdG was significantly positively associated with hs-CRP (13.7% [95% CI: 2.2%, 26.5%] per IQR increase in 8-OHdG), F_2α-isoprostanes and MDA indicated only a positive or null association, respectively.

CONCLUSION

The results of this cross-sectional study suggest, at a population level, that exposure to PAHs is associated with oxidative stress even in a low exposure setting. Oxidative stress markers, but not PAHs, were associated with inflammation. Individual risk factors were important contributors to these processes and should be considered in future studies. Further longitudinal studies are necessary to investigate the causal chain of the associations.

The Oxidative Potential of Fine Particulate Matter and Biological Perturbations in Human Plasma and Saliva Metabolome

Particulate oxidative potential may comprise a key health-relevant parameter of particulate matter (PM) toxicity. To identify biological perturbations associated with particulate oxidative potential and examine the underlying molecular mechanisms, we recruited 54 participants from two dormitories near and far from a congested highway in Atlanta, GA. Fine particulate matter oxidative potential ("FPMOP") levels at the dormitories were measured using dithiothreitol assay. Plasma and saliva samples were collected from participants four times for longitudinal high-resolution metabolic profiling. We conducted metabolome-wide association studies to identify metabolic signals with FPMOP. Leukotriene metabolism and galactose metabolism were top pathways associated with ≥5 FPMOP-related indicators in plasma, while vitamin E metabolism and leukotriene metabolism were found associated with most FPMOP indicators in saliva. We observed different patterns of perturbed pathways significantly associated with water-soluble and -insoluble FPMOPs, respectively. We confirmed five metabolites directly associated with FPMOP, including hypoxanthine, histidine, pyruvate, lactate/glyceraldehyde, and azelaic acid, which were implications of perturbations in acute inflammation, nucleic acid damage and repair, and energy perturbation. The unique metabolic signals were specific to FPMOP, but not PM mass, providing initial indication that FPMOP might constitute a more sensitive, health-relevant measure for elucidating etiologies related to PM_2.5 exposures.

Iron Speciation in Respirable Particulate Matter and Implications for Human Health

Particulate matter (PM) air pollution poses a major global health risk, but the role of iron (Fe) is not clearly defined because chemistry at the particle-cell interface is often not considered. Detailed spectromicroscopy characterizations of PM_2.5 samples from the San Joaquin Valley, CA identified major Fe-bearing components and estimated their relative proportions. Iron in ambient PM_2.5 was present in spatially and temporally variable mixtures, mostly as Fe(III) oxides and phyllosilicates, but with significant fractions of metallic iron (Fe(0)), Fe(II,III) oxide, and Fe(III) bonded to organic carbon. Fe(0) was present as aggregated, nm-sized particles that comprised up to ∼30% of the Fe spectral fraction. Mixtures reflect anthropogenic and geogenic particles subjected to environmental weathering, but reduced Fe in PM originates from anthropogenic sources, likely as abrasion products. Possible mechanistic pathways involving Fe(0) particles and mixtures of Fe(II) and Fe(III) surface species may generate hydrogen peroxide and oxygen-centered radical species (hydroxyl, hydroperoxyl, or superoxide) in Fenton-type reactions. From a health perspective, PM mixtures with reduced and oxidized Fe will have a disproportionate effect in cellular response after inhalation because of their tendency to shuttle electrons and produce oxidants and electrophiles that induce inflammation and oxidative stress.

Precipitation of aqueous transition metals in particulate matter during the dithiothreitol (DTT) oxidative potential assay

Transition metals in particulate matter (PM) are hypothesized to have enhanced toxicity based on their oxidative potential (OP). The acellular dithiothreitol (DTT) assay is widely used to measure the OP of PM and its chemical components. In our prior study, we showed that the DTT assay (pH 7.4, 0.1 M phosphate buffer, 37 °C) provides favorable thermodynamic conditions for precipitation of multiple metals present in PM. This study utilizes multiple techniques to characterize the precipitation of aqueous metals present at low concentrations in the DTT assay. Metal precipitation was identified using laser particle light scattering analysis, direct chemical measurement of aqueous metal removal, and microscopic imaging. Experiments were run with aqueous metals from individual metal salts and a well-characterized urban PM standard (NIST SRM-1648a, Urban Particulate Matter). Our results demonstrated rapid precipitation of metals in the DTT assay. Metal precipitation was independent of DTT but dependent on metal concentration. Metal removal in the chemically complex urban PM samples exceeded the thermodynamic predictions and removal seen in single metal salt experiments, suggesting co-precipitation and/or adsorption may have occurred. These results have broad implications for other acellular assays that study PM metals using phosphate buffer, and subsequently, the PM toxicity inferred from these assays.

Liquid-Gas Interface of Iron Aqueous Solutions and Fenton Reagents

Fenton chemistry, involving the reaction between Fe²⁺ and hydrogen peroxide, is well-known due to its applications in the mineralization of extremely stable molecules. Different mechanisms, influenced by the reaction conditions and the solvation sphere of iron ions, influence the fate of such reactions. Despite the huge amount of effort spent investigating such processes, a complete understanding is still lacking. This work combines photoelectron spectroscopy and theoretical calculations to investigate the solvation and reactivity of Fe²⁺ and Fe³⁺ ions in aqueous solutions. The reaction with hydrogen peroxide, both in homogeneous Fenton reagents and at the liquid-vapor interface, illustrates that both ions are homogeneously distributed in solutions and exhibit an asymmetric octahedral coordination to water in the case of Fe²⁺. No indications of differences in the reaction mechanism between the liquid-vapor interface and the bulk of the solutions have been found, suggesting that Fe³⁺ and hydroxyl radicals are the only intermediates.

Effects of antioxidant on oxidative stress and autophagy in bronchial epithelial cells exposed to particulate matter and cigarette smoke extract

Background

We evaluated the effect of particulate matter (PM) and cigarette smoke extract (CSE) on bronchial epithelial cell survival, as well as oxidative stress and autophagy levels. Moreover, we aimed to assess the effect of the antioxidant N-acetylcysteine (NAC) on the adverse effects of PM and CSE exposure.

Methods

Normal human bronchial epithelial cells (BEAS-2B cells) were exposed to urban PM with or without CSE, after which cytotoxic effects, including oxidative stress and autophagy levels, were measured. After identifying the toxic effects of urban PM and CSE exposure, the effects of NAC treatment on cell damage were evaluated.

Results

Urban PM significantly decreased cell viability in a concentration-dependent manner, which was further aggravated by simultaneous treatment with CSE. Notably, pretreatment with NAC at 10 mM for 1 hour reversed the cytotoxic effects of PM and CSE co-exposure. Treatment with 1, 5, and 10 mM NAC was shown to decrease reactive oxygen species levels induced by exposure to both PM and CSE. Additionally, the autophagy response assessed via LC3B expression was increased by PM and CSE exposure, and this also attenuated by NAC treatment.

Conclusion

The toxic effects of PM and CSE co-exposure on human bronchial epithelial cells, including decreased cell viability and increased oxidative stress and autophagy levels, could be partly prevented by NAC treatment.

Isopanepoxydone inhibits oxidative damage in murine alveolar macrophages via NRF2 and NLRP3 inflammasome

BACKGROUND

Respiratory diseases due to particulate matter are a serious health issue. We sought to investigate the efficacy of isopanepoxydone (ISO) isolated from the Panus rudis as a therapeutic against particulate matter-induced respiratory complications.

MATERIALS AND METHODS

ISO was isolated from a culture broth of Panus rudis using solvent partition, silica gel, and column chromatography, and high-performance liquid chromatography. Its chemical structure was determined spectroscopically. Murine alveolar macrophages (MH-S) were treated with ISO to investigate the inhibition of nitric oxide (NO) while cytotoxicity was investigated via a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The expression of pro-inflammatory mediators, cytokines, and protein expression levels in the oxidative protective and inflammasome pathway were also investigated. Reactive oxygen species in MH-S cells were investigated using 2',7'-dichlorofluorescein diacetate while immunofluorescence was performed to investigate the expression of activated apoptosis-associated speck-like proteins (ASC) containing a caspase recruitment domain in MH-S cells.

RESULTS

ISO effectively inhibited CFA-induced NO production with no cytotoxicity on MH-S cells and pro-inflammatory mediators and cytokines were also inhibited (except tumor necrosis factor α and interleukin-6). ISO enhanced the protein expression of nuclear factor erythroid 2-related factor 2, while suppressing proteins in the inflammasome pathway, but did not suppress the expression of nuclear factor-kappa B. ISO also reduced detectable ROS other than preventing the activation of ASC.

CONCLUSION

Pathways of action of ISO in MH-S cells that prevent oxidative damage and suppress the expression of proteins in the inflammasome pathway were investigated. ISO may be developed as a treatment for respiratory inflammation.

Association between exposure to air pollutants and the risk of hospitalization for pulmonary embolism in Beijing, China: A case-crossover design using a distributed lag nonlinear model

BACKGROUND

Pulmonary embolism (PE) is a life-threatening condition. Few studies have evaluated the relationship between air pollution and PE, and these results have been inconsistent. Therefore, our study aimed to investigate the association between air pollutant exposure and the risk of hospitalization due to PE.

MATERIALS AND METHODS

Daily PE admissions, meteorological data, and ambient pollution data from January 1, 2015, to December 31, 2018, were collected in Beijing. A quasi-Poisson regression model combined with time-stratified case-crossover design and a distributed lag nonlinear model was used to determine the effect of air pollutant exposure on PE admission. To examine the stability of air pollutants' effects, multi-pollutant analyses were performed. Stratified analyses by age and sex were further conducted.

RESULTS

There were 5060 PE admissions during the study period, with an estimated incidence of 6.5 per 100,000. PM_2.5, PM₁₀, SO₂, O₃ and CO exposures were significantly associated with elevated risk of PE hospitalization. The highest cumulative risks were observed at a lag of 0-28 days for PM_2.5 (relative risk [RR] = 1.056, 95% confidence intervals [CI]: 1.015-1.098), PM₁₀ (RR = 1.042, 95%CI: 1.010-1.075), and CO (RR = 1.466, 95%CI: 1.127-1.906), at a lag of 0-27 days for SO₂ (RR = 1.674, 95%CI: 1.200-2.335), and at a lag of 0-4 days for O₃ (RR = 1.019, 95%CI: 1.001-1.038). All associations mentioned above except O₃ remained significant in multi-pollutant models. Stratified analyses showed that women and those aged ≥65 years people were more sensitive to PM₁₀ and CO exposure than men and those aged <65 years. The effect of PM_2.5 exposure was statistically significant in all subgroups.

CONCLUSIONS

Exposure to PM_2.5, PM₁₀, SO₂, and CO showed a positive association with PE hospitalization. High-risk PE groups should take special precautions on days with poor air quality.

Arum italicum mediated silver nanoparticles: Synthesis and investigation of some biochemical parameters

The science world advancing day by day contributes to living systems in many areas with the development of nanotechnology. Besides being easily obtained from plants, the advantages it brings increase the importance of nanotechnology. Environmentally friendly, economical, and compatible with plants are just a few of the advantages it brings. Silver metal is one of the most preferred active ingredients in nanoparticle synthesis. Arum italicum is used in the treatment of various diseases in the health sector due to the structures it contains. In our study, nanoparticle synthesis was made by using Ag metal with Arum italicum plant. Then, the antimicrobial, DNA damage prevention and DPPH radical quenching activity of Ag NPs/Ai nanoparticles were investigated. The interaction of the plant with Ag, analysis by X-ray diffraction (XRD), UV visible spectrophotometer (UV-vis), scanning electron microscope and energy dispersive X-ray (SEM-EDX), Fourier-converted infrared spectroscopy (FT-IR) methods has been done. It has been observed that Ag NPs/Ai clusters formed by Arum italicum with Ag have an antibacterial effect against Bacillus subtilis, Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli pathogens. However, an antifungal effect hasn't been observed against Candida albicans fungus. Pseudomonas aeruginosa bacteria exerted a stronger effect than an antibiotic. It is seen that Ag NPs/Ai has a protective and anti-damage effect against DNA damage. The antioxidant effect of Ag NPs/Ai is remarkable when DPPH radical quenching activity is compared to positive control BHA and BHT.

Lipid peroxidation index of particulate matter: Novel metric for quantifying intrinsic oxidative potential and predicting toxic responses

Using particulate matter (PM) mass as exposure metric does not reveal the intrinsic PM chemical characteristics or toxic potential, which is crucial for monitoring the sources of emission causing adverse health effects and developing risk mitigating strategies. Oxidative stress and ensuing lipid peroxidation (LPO) in the lung are crucial underlying mechanisms of action by which PM drives cardiorespiratory disease. In the current study, we have postulated and demonstrated that the intrinsic potential of PM to elicit LPO, defined as "LPO index" as a novel approach for characterizing oxidative potential of PM (PMOP) and predicting biological toxicity. First, we exposed unsaturated phosphatidylcholine (PC), an abundant phospholipid in the cell membrane, pulmonary surfactant, and lipoproteins to PM and analyzed the total burden of LPO byproducts generated as a measure of LPO index using a LPO reporter dye, BODIPY-C11. PM exposure resulted in a concentration-dependent increase in LPO. Second, we developed a novel method to expose the captured serum apoB100 lipoprotein particles to PM or its constituents and assessed the levels of specific oxidized-phospholipid on apoB100 particles by immunoassay using E06 monoclonal antibody (mab) that recognizes only PC containing oxidized-phospholipids (Ox-PCs). The immunoassay was highly sensitive to evaluate the PM LPO index and was modifiable by metal quenchers and exogenous antioxidant and radical quenchers. Third, to prove the pathophysiological relevance of Ox-PCs, we found that PM exposure generates Ox-PCs in mice lungs, pulmonary surfactant and lung cells. Fourth, we observed that treatment of macrophages with BAL fluid from PM exposed mice or PM-exposed pulmonary surfactant stimulated IL-6 production, which was abrogated by neutralization of Ox-PCs by mab E06 suggesting that Ox-PCs in lungs are proinflammatory. Overall, our study suggests that Ox-PCs as a probe of PM LPO index is a biologically relevant pathogenic biomarker and has a high value for evaluating PMOP.

Hydroxyl Radical Production by Air Pollutants in Epithelial Lining Fluid Governed by Interconversion and Scavenging of Reactive Oxygen Species

Air pollution is a major risk factor for human health. Chemical reactions in the epithelial lining fluid (ELF) of the human respiratory tract result in the formation of reactive oxygen species (ROS), which can lead to oxidative stress and adverse health effects. We use kinetic modeling to quantify the effects of fine particulate matter (PM2.5), ozone (O₃), and nitrogen dioxide (NO₂) on ROS formation, interconversion, and reactivity, and discuss different chemical metrics for oxidative stress, such as cumulative production of ROS and hydrogen peroxide (H₂O₂) to hydroxyl radical (OH) conversion. All three air pollutants produce ROS that accumulate in the ELF as H₂O₂, which serves as reservoir for radical species. At low PM2.5 concentrations (<10 μg m^-3), we find that less than 4% of all produced H₂O₂ is converted into highly reactive OH, while the rest is intercepted by antioxidants and enzymes that serve as ROS buffering agents. At elevated PM2.5 concentrations (>10 μg m^-3), however, Fenton chemistry overwhelms the ROS buffering effect and leads to a tipping point in H₂O₂ fate, causing a strong nonlinear increase in OH production. This shift in ROS chemistry and the enhanced OH production provide a tentative mechanistic explanation for how the inhalation of PM2.5 induces oxidative stress and adverse health effects.

Continuous measurement of reactive oxygen species inside and outside of a residential house during summer

Reactive oxygen species (ROS) are an important contributor to adverse health effects associated with ambient air pollution. Despite infiltration of ROS from outdoors, and possible indoor sources (eg, combustion), there are limited data available on indoor ROS. In this study, part of the second phase of Air Composition and Reactivity from Outdoor aNd Indoor Mixing campaign (ACRONIM-2), we constructed and deployed an online, continuous, system to measure extracellular gas- and particle-phase ROS during summer in an unoccupied residence in St. Louis, MO, USA. Over a period of one week, we observed that the non-denuded outdoor ROS (representing particle-phase ROS and some gas-phase ROS) concentration ranged from 1 to 4 nmol/m³ (as H₂ O₂ ). Outdoor concentrations were highest in the afternoon, coincident with peak photochemistry periods. The indoor concentrations of particle-phase ROS were nearly equal to outdoor concentrations, regardless of window-opening status or air exchange rates. The indoor/outdoor ratio of non-denuded ROS (I/O_ROS ) was significantly less than 1 with windows open and even lower with windows closed. Combined, these observations suggest that gas-phase ROS are efficiently removed by interior building surfaces and that there may be an indoor source of particle-phase ROS.

Elucidating long-term trends, seasonal variability, and local impacts from thirteen years of near-road particle size data (2006-2019)

Significant attention, especially in the last decade, has been focussed on elevated concentrations of ultrafine particulate matter (UFP) in urban areas and the adverse health effects associated with exposure to UFP. Despite this, there is a relative scarcity of long-term ambient UFP measurements. This study examined trends in UFP measurements made continuously near a busy roadway in downtown Toronto, Canada, between the years 2006 and 2019 using a fast mobility particle sizer (FMPS). These long-term trends were associated with other air pollutant concentrations-namely: nitric oxide (NO), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and fine particulate matter mass concentrations (PM_2.5)-and persistent declining trends were observed for each during the study period. From 2006 to 2019, reductions of 45%, 68%, 39%, 83%, and 41%, for UFP, NO, NO₂, SO₂, and PM_2.5, respectively, were observed. These reductions are in part associated with a total phase-out of coal-fired electricity generation in Ontario, Canada, between 2004 and 2015, and continuous improvements in vehicle emissions control technologies. Additionally, deconvolution of the time-series yielded seasonal fluctuations which were analysed as a function of particle diameter and ambient temperature, the results from which may aid in the comparison of UFP measurements made in climates with different ambient temperature ranges in a meaningful way. Finally, the UFP data were background-subtracted and it was found that local sources (such as vehicle traffic) contributed ~45% to total concentrations and this fraction remained relatively constant throughout the study. A multilinear function regressed on these local and background concentrations better elucidated the sources contributing to UFP variability-background concentrations were largely covariate with SO₂ emissions whereas local concentrations were more affected by NO emissions. The data in this study shows clear co-benefits to reducing UFP concentrations by targeting NO_x and SO_x emissions.

Atmospheric conditions and composition that influence PM2.5 oxidative potential in Beijing, China

Epidemiological studies have consistently linked exposure to PM_2.5 with adverse health effects. The oxidative potential (OP) of aerosol particles has been widely suggested as a measure of their potential toxicity. Several acellular chemical assays are now readily employed to measure OP; however, uncertainty remains regarding the atmospheric conditions and specific chemical components of PM_2.5 that drive OP. A limited number of studies have simultaneously utilised multiple OP assays with a wide range of concurrent measurements and investigated the seasonality of PM_2.5 OP. In this work, filter samples were collected in winter 2016 and summer 2017 during the atmospheric pollution and human health in a Chinese megacity campaign (APHH-Beijing), and PM_2.5 OP was analysed using four acellular methods: ascorbic acid (AA), dithiothreitol (DTT), 2,7-dichlorofluorescin/hydrogen peroxidase (DCFH) and electron paramagnetic resonance spectroscopy (EPR). Each assay reflects different oxidising properties of PM_2.5, including particle-bound reactive oxygen species (DCFH), superoxide radical production (EPR) and catalytic redox chemistry (DTT/AA), and a combination of these four assays provided a detailed overall picture of the oxidising properties of PM_2.5 at a central site in Beijing. Positive correlations of OP (normalised per volume of air) of all four assays with overall PM_2.5 mass were observed, with stronger correlations in winter compared to summer. In contrast, when OP assay values were normalised for particle mass, days with higher PM_2.5 mass concentrations (μgm^-3) were found to have lower mass-normalised OP values as measured by AA and DTT. This finding supports that total PM_2.5 mass concentrations alone may not always be the best indicator for particle toxicity. Univariate analysis of OP values and an extensive range of additional measurements, 107 in total, including PM_2.5 composition, gas-phase composition and meteorological data, provided detailed insight into the chemical components and atmospheric processes that determine PM_2.5 OP variability. Multivariate statistical analyses highlighted associations of OP assay responses with varying chemical components in PM_2.5 for both mass- and volume-normalised data. AA and DTT assays were well predicted by a small set of measurements in multiple linear regression (MLR) models and indicated fossil fuel combustion, vehicle emissions and biogenic secondary organic aerosol (SOA) as influential particle sources in the assay response. Mass MLR models of OP associated with compositional source profiles predicted OP almost as well as volume MLR models, illustrating the influence of mass composition on both particle-level OP and total volume OP. Univariate and multivariate analysis showed that different assays cover different chemical spaces, and through comparison of mass- and volume-normalised data we demonstrate that mass-normalised OP provides a more nuanced picture of compositional drivers and sources of OP compared to volume-normalised analysis. This study constitutes one of the most extensive and comprehensive composition datasets currently available and provides a unique opportunity to explore chemical variations in PM_2.5 and how they affect both PM_2.5 OP and the concentrations of particle-bound reactive oxygen species.

Association between ambient air pollution and mortality from chronic obstructive pulmonary disease in Wuhan, China: a population-based time-series study

Evidence on the short-term effects of ambient air pollution on chronic obstructive pulmonary disease (COPD) mortality is still not conclusive. The aim of this study was to investigate the relationships between them in Wuhan China. Daily death numbers, concentrations of air pollutants (PM2.5, PM10, SO2, NO2, and O3), and meteorological characteristics in Wuhan from January 1, 2014, to December 31, 2019, were collected. Time-series analysis using generalized additive model was applied. The results showed that a total of 16,150 deaths (7.37 deaths per day) from COPD were observed. The daily average concentrations of PM2.5, PM10, SO2, NO2, and O3 were 59.03, 90.48, 12.91, 48.84, and 91.77 μg/m3, respectively. In single pollutant model, for every increase of 10 μg/m3 in PM10, SO2, and NO2 levels, COPD mortality increased by 0.583% (95% CI: 0.055-1.113%), 4.299% (95% CI: 0.978-7.729%), and 1.816% (95% CI: 0.515-3.313%) at lag03, respectively. No significant associations were found for PM2.5 and O3. Subgroup analysis demonstrated that females were more susceptible to PM2.5, PM10, SO2, and NO2. The concentrations of PM10, SO2, and NO2 were significantly associated with COPD mortality for older adults. The effects of PM2.5 and O3 on COPD mortality were higher in warm period. In two-pollutant models, the significantly positive associations between SO2 and NO2 and COPD mortality remained after adjusting for PM2.5 or O3. In conclusions, short-term exposure to PM10, SO2, and NO2 are significantly associated with a higher risk of COPD mortality. Female or elderly are more susceptible to air pollution. It is urgent to implement the environmental protection policy.

Iron Speciation in Particulate Matter (PM2.5) from Urban Los Angeles Using Spectro-microscopy Methods

The speciation, oxidation states, and relative abundance of iron (Fe) phases in PM2.5 samples from two locations in urban Los Angeles were investigated using a combination of bulk and spatially resolved, element-specific spectroscopy and microscopy methods. Synchrotron X-ray absorption spectroscopy (XAS) of bulk samples in situ (i.e., without extraction or digestion) was used to quantify the relative fractions of major Fe phases, which were corroborated by spatially resolved spectro-microscopy measurements. Ferrihydrite (amorphous Fe(III)-hydroxide) comprised the largest Fe fraction (34-52%), with hematite (α-Fe2O3; 13-23%) and magnetite (Fe3O4; 10-24%) identified as major crystalline oxide components. An Fe-bearing phyllosilicate fraction (16-23%) was fit best with a reference spectrum of a natural illite/smectite mineral, and metallic Fe(0) was a relatively small (2-6%) but easily identified component. Sizes, morphologies, oxidation state, and trace element compositions of Fe-bearing PM from electron microscopy, electron energy loss spectroscopy (EELS), and scanning transmission X-ray microscopy (STXM) revealed variable and heterogeneous mixtures of Fe species and phases, often associated with carbonaceous material with evidence of surface oxidation. Ferrihydrite (or related Fe(III) hydroxide phases) was ubiquitous in PM samples. It forms as an oxidation or surface alteration product of crystalline Fe phases, and also occurs as coatings or nanoparticles dispersed with other phases as a result of environmental dissolution and re-precipitation reactions. The prevalence of ferrihydrite (and adsorbed Fe(III) has likely been underestimated in studies of ambient PM because it is non-crystalline, non-magnetic, more soluble than crystalline phases, and found in complex mixtures. Review of potential sources of different particle types suggests that the majority of Fe-bearing PM from these urban sites originates from anthropogenic activities, primarily abrasion products from vehicle braking systems and engine emissions from combustion and/or wear. These variable mixtures have a high probability for electron transfer reactions between Fe, redox-active metals such as copper, and reactive carbon species such as quinones. Our findings suggest the need to assess biological responses of specific Fe-bearing phases both individually and in combination to unravel mechanisms of adverse health effects of particulate Fe.

Effect of PM10 on pulmonary immune response and fetus development

Despite numerous reports that ambient particulate matter is a key determinant for human health, toxicity data produced based on physicochemical properties of particulate matters is very lack, suggesting lack of scientific evidence for regulation. In this study, we sampled inhalable particulate matters (PM10) in northern Seoul, Korea. PM10 showed atypical- and fiber-type particles with the average size and the surface charge of 1,598.1 ± 128.7 nm and -27.5 ± 2.8, respectively, and various toxic elements were detected in the water extract. On day 90 after the first pulmonary exposure, total cell number dose-dependently increased in the lungs of both sexes of mice. PM10 induced Th1-dominant immune response with pathological changes in both sexes of mice. Meanwhile, composition of total cells and expression of proteins which functions in cell-to-cell communication showed different trends between sexes. Following, male and female mice were mated to identify effects of PM10 to the next generation. PM10 remained in the lung of dams until day 21 after birth, and the levels of IgA and IgE increased in the blood of dams exposed to the maximum dose compared to control. In addition, the interval between births of fetuses, the number of offspring, the neonatal survival rate (day 4 after birth) and the sex ratio seemed to be affected at the maximum dose, and particularly, all offspring from one dam were stillborn. In addition, expression of HIF-1α protein increased in the lung tissue of dams exposed to PM10, and level of hypoxia-related proteins was notably enhanced in PM10-exposed bronchial epithelial cells compared to control. Taken together, we suggest that inhaled PM10 may induce Th1-shifting immune response in the lung, and that it may affect reproduction (fetus development) by causing lung hypoxia. Additionally, we propose that further study is needed to identify particle-size-dependent effects on development of the next generation.

Exposure to fine particulate matter induces self-recovery and susceptibility of oxidative stress and inflammation in rat lungs

PM_2.5 induces pulmonary inflammation via oxidative stress, and this role in the lungs is widely accepted, but studies on whether oxidative stress and inflammation can self-recover and be fully restored are limited. In this study, the oxidative stress and inflammation in the lungs of rats, which were first exposed to different PM_2.5 dosages (0, 0.5, 3.0, and 15.0 mg/kg body weight) and different recovery days (0, 15, and 30 days) and then were exposed to the same PM_2.5 dosages (30 mg/kg b.w.) after 30 days of recovery, were investigated. Results showed that the activity of superoxide dismutase (SOD) was significantly inhibited, and the levels of malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) significantly increased. These changes were accompanied with damage to the pathological structure of the rat lungs. After stopping PM_2.5 exposure, the difference between the PM_2.5 group and the control group gradually decreased with the extension of recovery time. However, when the rats were again exposed to the same dose of PM_2.5, the levels of IL-6, IL-1β, TNF-α, MDA, and iNOS were significantly increased, and the activities of SOD and GSH-Px were significantly inhibited in the high-dose group. And the high-dose group was accompanied by more severe lung pathological structural damage. Results showed that PM_2.5 could induce oxidative stress and inflammatory damage in the lungs of rats, and these damages gradually recovered as exposure ceased, but increased lung susceptibility in rats.

Evaluation of a high flow rate electrostatic precipitator (ESP) as a particulate matter (PM) collector for toxicity studies

In this study, we investigated the performance of an electrostatic precipitator (ESP) operating at high flow rates (i.e., 50-100 lpm) as a fine particulate matter (PM_2.5) collector for toxicological studies. The ESP optimum configuration (i.e., flow rate of 75 lpm and applied voltage of +12 kV) was determined based on maximum particle collection efficiencies and minimum ozone emissions associated with the instrument using different laboratory-generated aerosols. This configuration resulted in particle collection efficiencies above 80% for almost all particles in the size range of 0.015-2.5 μm while the ozone concentration was 17 ppb. The ESP was then deployed to our sampling site in central Los Angeles to evaluate its performance using ambient particles under the optimum configuration. Chemical composition and oxidative potential of PM_2.5 samples collected on the foils placed inside the ESP tube were compared with those collected concurrently on filters and aerosol slurries using the versatile aerosol concentration enrichment system (VACES) operating in parallel. Our results demonstrated that the ESP was more efficient in preserving labile inorganic ions and total organic carbon (TOC) compared to filters. PM samples collected on ESP substrates also showed higher intrinsic oxidative potential compared to the filters, which might be the result of better preservation of redox active semi-volatile organic compounds on the ESP substrates. However, the TOC concentrations and intrinsic oxidative potential of PM samples collected on ESP substrates were somewhat lower than the aerosol slurries collected by the VACES, probably due to deficiency of water-insoluble compounds in extracted PM samples from ESP substrates. In conclusion, while particle collection for toxicological purposes by the ESP is somewhat inferior to a direct aerosol-into-liquid collection, the ESP performs equally well, if not better, than conventional filter samplers and can be utilized as a simple and adequately efficient PM collector for toxicological studies.

Online monitoring of volatile organic compounds emitted from human bronchial epithelial cells as markers for oxidative stress

Particulate air pollution is associated with adverse respiratory effects and is a major factor for premature deaths. In-vitro assays are commonly used for investigating the direct cytotoxicity and inflammatory impacts due to particulate matter (PM) exposure. However, biological tests are often labor-intensive, destructive and limited to endpoints measured offline at single time points, making it impossible to observe the progression of cell response upon exposure. Here we explored the potential of a high-resolution proton transfer reaction mass spectrometer (PTR-MS) to detect the volatile organic compounds (VOCs) emitted by human bronchial epithelial cells (BEAS-2B) upon exposure to PM. Cells were exposed to single components (1,4-naphthoquinone and Cu(II)) known to induce oxidative stress. We also tested filter extracts of aerosols generated in a smog chamber, including fresh and aged wood burning emissions, as well as α-pinene secondary organic aerosol (SOA). We found that 1,4-naphthoquinone was rapidly internalized by the cells. Exposing cells to each of these samples induced the emission of VOCs, which we tentatively assigned to acetonitrile, benzaldehyde and dimethylbenzaldehyde, respectively. Emission rates upon exposure to fresh and aged organic aerosol from α-pinene oxidation and from biomass burning significantly exceeded those observed after exposure to similar doses of Cu(II), a proxy for transition metals with high oxidative potential. Emission rates of biomarkers from cell exposure to α-pinene SOA exhibited a statistically significant, but weak dose dependence. The emission rates of benzaldehyde scaled with cell death, estimated by measuring the apical release of cytosolic lactate dehydrogenase. Particle mass doses delivered to the BEAS-2B cells match those deposited in the human tracheobronchial tract after several hours of inhalation at elevated ambient air pollution. The results presented here show that our method has the potential to determine biomarkers of PM induced pulmonary damage in toxicological and epidemiological research on air pollution.

ROS-generation potential of Humic-like substances (HULIS) in ambient PM2.5 in urban Shanghai: Association with HULIS concentration and light absorbance

Ambient fine particulate matter (PM_2.5) can cause adverse health effects through the generation of reactive oxygen species (ROS) after inhalation. Humic-like substances (HULIS) are major constituents contributing to the ROS-generation potential in organic aerosols. In this study, PM_2.5 samples in urban Shanghai during autumn and winter (2018-2019) were collected. Mass-normalized ·OH generation rate in surrogate lung fluid (SLF) was used to denote the intrinsic ROS-generation potential of PM_2.5 or of the HULIS isolated from PM_2.5. In this study, ROS-generation potential of PM_2.5 decreased with increasing ambient PM_2.5 concentration due to higher percentage of inorganic components in high PM_2.5 event. Same trend was observed for the ROS-generation potential of unit mass of HULIS, which was higher when HULIS and PM_2.5 concentrations were both relatively lower. The HULIS with high ROS-generation potential but low concentration (High-ROS/Low-Conc HULIS) were likely produced by the atmospheric aqueous-phase reactions during nighttime or under high relative humidity conditions, not from biomass burning emissions or the photochemical pollution products. The association between ROS-generation potential and light absorption properties of HULIS was studied as well. The High-ROS/Low-Conc HULIS also showed stronger light absorbance than the other HULIS. Our results implied the potentially important roles that HULIS species might play in atmospheric environment and human health even when the PM_2.5 pollution is low.

Particulate Matter Induces Tissue OxInflammation: From Mechanism to Damage

Significance: Oxidative stress and oxidative damage are central hypothetical mechanisms for the adverse effects of airborne particulate matter (PM). Activation of inflammatory cells capable of generating reactive oxygen and nitrogen species is another proposed damage pathway. Understanding the interplay between these responses can help us understand the adverse health effects attributed to breathing polluted air. Recent Advances: The consequences of PM exposure on different organs are oxidative damage, decreased function, and inflammation, which can lead to the development/exacerbation of proinflammatory disorders. Mitochondrial damage is also an important event in PM-induced cytotoxicity. Critical Issues: Reactive oxygen species (ROS) are generated during phagocytosis of the particles, leading to enhancement of oxidative stress and triggering the inflammatory response. The activation of inflammatory signaling pathways results in the release of cytokines and other mediators, which can further induce ROS production by activating endogenous enzymes, leading to a positive feedback loop, which can aggravate the effects triggered by PM exposure. Future Directions: Further research is required to elucidate the exact mechanisms by which PM exposure results in adverse health effects, in terms of the relationship between the redox responses triggered by the presence of the particles and the inflammation observed in the different organs, so the development/exacerbation of PM-associated health problems can be prevented.

Chemical Characterization of Seasonal PM2.5 Samples and Their Cytotoxicity in Human Lung Epithelial Cells (A549)

In order to study the toxicity of fine particulate matter (PM_2.5) sourced from different seasons on human health, we collected PM_2.5 samples quarterly from March 2016 to February 2017 in Nanjing, China. The component analysis results showed that high proportions of water-soluble organic carbon (WSOC), SO₄²⁻, Ca²⁺ and Mg²⁺ were found in the summer samples, while high proportions of NO₃⁻, NH₄⁺ and heavy metals were observed in the spring and winter samples. Then human lung epithelial cells (A549) were exposed to the PM_2.5 samples. The toxicological results indicated that reactive oxygen species (ROS) production in the spring and winter samples was higher than that in the summer and fall samples, which was related to the contribution of some heavy metals and inorganic ions (e.g., Pb and NO₃⁻). However, the apoptosis rates of the cells showed the opposite seasonal changes as what the ROS did, which might be caused by the higher WSOC content in the summer. In addition, regression analysis also showed the importance of the PM_2.5 components in ROS production and apoptosis. Particularly, Zn had the strongest correlation with ROS production (R = 0.863) and cell apoptosis (R = 0.675); thus, the specific toxicity of Zn in PM_2.5 deserves further investigation. Our results could be beneficial for assessing the health risks and controlling the toxic components of PM_2.5 in Nanjing.

Effects of antioxidants on oxidative stress and inflammatory responses of human bronchial epithelial cells exposed to particulate matter and cigarette smoke extract

Particulate matter (PM) is a type of air pollutant that induces adverse health effects, including acute exacerbation of chronic obstructive pulmonary disease (COPD). However, the effects of co-exposure to PM and cigarette smoke extract (CSE) on bronchial epithelial cells remain unknown. This study investigated the cytotoxic and pro-inflammatory effects of combined exposure to PM and CSE on bronchial epithelial cells, and assessed the potential of antioxidants to inhibit CSE/PM-induced oxidative stress and inflammation. Exposure of epithelial cells to PM or CSE induced cytotoxicity, inflammation, and oxidative stress, all of which were dramatically increased when cells were exposed to the combination of CSE and PM. Importantly, the adverse effects of CSE/PM exposure were suppressed when cells were treated with sulforaphane (SFN) or sulforaphane N-acetylcysteine (SFNAC). Furthermore, SFN and SFNAC suppressed the CSE/PM-induced pro-inflammatory cytokine production and expression of inflammatory genes. Combined PM and CSE exposure further activated the MAPK and Nrf2 signaling pathways. SFN and SFNAC attenuated CSE/PM-induced epithelial toxicity through the ERK/JNK signaling pathway-dependent inhibition of inflammation. Moreover, SFN and SFNAC suppressed ROS generation by activating antioxidant enzymes and Nrf2 signaling. Therefore, SFN and SFNAC could be a promising approach to prevent or mitigate the exacerbation of pulmonary diseases caused by PM and other air pollutants.

Brown Carbon Production by Aqueous-Phase Interactions of Glyoxal and SO2

Oxalic acid and sulfate salts are major components of aerosol particles. Here, we explore the potential for their respective precursor species, glyoxal and SO₂, to form atmospheric brown carbon via aqueous-phase reactions in a series of bulk aqueous and flow chamber aerosol experiments. In bulk aqueous solutions, UV- and visible-light-absorbing products are observed at pH 3-4 and 5-6, respectively, with small but detectable yields of hydroxyquinone and polyketone products formed, especially at pH 6. Hydroxymethanesulfonate (HMS), C₂, and C₃ sulfonates are major products detected by electrospray ionization mass spectrometry (ESI-MS) at pH 5. Past studies have assumed that the reaction of formaldehyde and sulfite was the only atmospheric source of HMS. In flow chamber experiments involving sulfite aerosol and gas-phase glyoxal with only 1 min residence times, significant aerosol growth is observed. Rapid brown carbon formation is seen with aqueous aerosol particles at >80% relative humidity (RH). Brown carbon formation slows at 50-60% RH and when the aerosol particles are acidified with sulfuric acid but stops entirely only under dry conditions. This chemistry may therefore contribute to brown carbon production in cloud-processed pollution plumes as oxidizing volatile organic compounds (VOCs) interact with SO₂ and water.

Pulmonary oxidative stress in wild bats exposed to coal dust: A model to evaluate the impact of coal mining on health

This study aimed to verify possible alterations involving histological and oxidative stress parameters in the lungs of wild bats in the Carboniferous Basin of Santa Catarina (CBSC) state, Southern Brazil, as a means to evaluate the impact of coal dust on the health of wildlife. Specimens of frugivorous bat species Artibeus lituratus and Sturnira lilium were collected from an area free of coal dust contamination and from coal mining areas. Chemical composition, histological parameters, synthesis of oxidants and antioxidant enzymes, and oxidative damage in the lungs of bats were analyzed. Levels of Na, Cl, Cu, and Br were higher in both species collected in the CBSC than in the controls. Levels of K and Rb were higher in A. lituratus, and levels of Si, Ca, and Fe were higher in S. lilium collected in the carboniferous basin. Both bat species inhabiting the CBSC areas exhibited an increase in the degree of pulmonary emphysema compared to their counterparts collected from control areas. Sturnira lilium showed increased reactive oxygen species (ROS) and 2',7'-dichlorofluorescein (DCF) levels, while A. lituratus showed a significant decrease in nitrite levels in the CBSC samples. Superoxide dismutase (SOD) activity did not change significantly; however, the activity of catalase (CAT) and levels of glutathione (GSH) decreased in the A. lituratus group from CBSC compared to those in the controls. There were no differences in NAD(P)H quinone dehydrogenase 1 protein (NQO1) abundance or nitrotyrosine expression among the different groups of bats. Total thiol levels showed a significant reduction in A. lituratus from CBSC, while the amount of malondialdehyde (MDA) was higher in both A. lituratus and S. lilium groups from coal mining areas. Our results suggested that bats, especially A. lituratus, living in the CBSC could be used as sentinel species for harmful effects of coal dust on the lungs.

Thymoquinone treatment modulates the Nrf2/HO-1 signaling pathway and abrogates the inflammatory response in an animal model of lung fibrosis

The present study investigates the therapeutic potential of thymoquinone (TQ) in bleomycin-induced lung fibrosis (BMILF) and elucidates the target-signaling pathway for its effect. Lung fibrosis was induced in rats by a single intra-tracheal instillation of bleomycin (BM) (6.5 U/kg) followed by thymoquinone treatment (10 and 20 mg/kg p.o.) for 28 days. Control rats received saline instead of TQ. Changes in body weight, inflammatory cells count, cytokines levels, and biochemical parameters of the broncho-alveolar lavage fluid (BALF) were recorded. In addition, a histopathology examination and western blotting were performed on lung tissues. BM administration resulted in a significant weight loss, which was ameliorated by TQ treatment. BMILF was associated with a reduction in the antioxidant mechanisms and increased lipid peroxidation. Furthermore, elevated levels of inflammatory cytokines, MMP-7 expression, apoptotic markers (caspase 3, Bax, and Bcl-2), and fibrotic changes including TGF-β and hydroxyproline levels in lung tissues were evident. These abnormalities were diminished with TQ treatment. Likewise, altered total and differential cell count in BALF was significantly improved in rats treated with TQ. TQ also produced a dose-dependent reduction in the expressions of Nrf2, Ho-1 and TGF-β. These results propose that the Nrf2/Ho-1 signaling pathway is a principal target for TQ protective effect against BMILF in rats. Furthermore, TQ decreases inflammatory oxidative stress possibly through the modulation of nuclear factor Kappa-B (NF-κB) and thereby minimization of collagen deposition in the lung. Therefore, TQ can be developed as a potential therapeutic modularity in BMILF for human use.

Activatable superparamagnetic iron oxide nanoparticles scavenge reactive oxygen species in macrophages and endothelial cells

Complexed IPC-SPIOs scavenge intracellular ROS after internalization.

Correlation of Oxidative Potential with Ecotoxicological and Cytotoxicological Potential of PM10 at an Urban Background Site in Italy

Exposure to atmospheric particulate matter (PM) has detrimental effects on health, but specific mechanisms of toxicity are still not fully understood. In recent years, there has been a growing evidence that oxidative stress is an important mechanism of toxicity; however, when acellular oxidative potential (OP) data are correlated with the outcomes of in vitro (or in vivo) toxicological tests there are contrasting results. In this work, an analysis of PM10 health effect indicators was done, using the acellular Dithiotreitol (DTT) assay to retrieve OPDTT, the Microtox® test on Vibrio fischeri bacterium to assess the ecotoxicological potential, and the in vitro MTT assay on the human cell line A549 to estimate the cytotoxicological potential. The objective was to evaluate the correlation among acellular OPDTT and the results from toxicological and ecotoxicological bioassays and how these health-related indicators are correlated with atmospheric PM10 concentrations collected at an urban background site in Southern Italy. Results indicated that both bioassays showed time-dependent and dose-dependent outcomes. Some samples presented significant ecotoxic and cytotoxic response and the correlation with PM10 concentration was limited suggesting that these health endpoints depend on PM10 chemical composition and not only on exposure concentrations. OPDTT showed a statistically significant correlation with PM10 concentrations. MTT and Microtox outcomes were not correlated suggesting that the two toxicological indicators are sensitive to different physical-chemical properties of PM10. Intrinsic oxidative potential OPDTTM (DTT activity normalised with PM10 mass) was correlated with mortality observed with MTT test (normalized with PM10 mass); however, it was not correlated with Microtox outcomes.

Airborne Particulate Matter: Human Exposure and Health Effects

OBJECTIVE

Exposure to airborne particulate matter (PM) is estimated to cause millions of premature deaths annually. This work conveys known routes of exposure to PM and resultant health effects.

METHODS

A review of available literature.

RESULTS

Estimates for daily PM exposure are provided. Known mechanisms by which insoluble particles are transported and removed from the body are discussed. Biological effects of PM, including immune response, cytotoxicity, and mutagenicity, are reported. Epidemiological studies that outline the systemic health effects of PM are presented.

CONCLUSION

While the integrated, per capita, exposure of PM for a large fraction of the first-world may be less than 1 mg per day, links between several syndromes, including attention deficit hyperactivity disorder (ADHD), autism, loss of cognitive function, anxiety, asthma, chronic obstructive pulmonary disease (COPD), hypertension, stroke, and PM exposure have been suggested. This article reviews and summarizes such links reported in the literature.

Use of Dithiothreitol Assay to Evaluate the Oxidative Potential of Atmospheric Aerosols

Oxidative potential (OP) has been proposed as a useful descriptor for the ability of particulate matter (PM) to generate reactive oxygen species (ROS) and consequently induce oxidative stress in biological systems, which has been recognized as one of the most important mechanisms responsible for PM toxicity. The dithiothreitol (DTT) assay is one of the most frequently used techniques to quantify OP because it is low-cost, easy-to-operate, and has high repeatability. With two thiol groups, DTT has been used as a surrogate of biological sulfurs that can be oxidized when exposed to ROS. Within the DTT measurement matrix, OP is defined as the DTT consumption rate. Often, the DTT consumption can be attributed to the presence of transition metals and quinones in PM as they can catalyze the oxidation of DTT through catalytic redox reactions. However, the DTT consumption by non-catalytic PM components has not been fully investigated. In addition, weak correlations between DTT consumption, ROS generation, and cellular responses have been observed in several studies, which also reveal the knowledge gaps between DTT-based OP measurements and their implication on health effects. In this review, we critically assessed the current challenges and limitations of DTT measurement, highlighted the understudied DTT consumption mechanisms, elaborated the necessity to understand both PM-bound and PM-induced ROS, and concluded with research needs to bridge the existing knowledge gaps.

Preliminary review of mine air pollution in Zambia

Zambia is endowed with mineral wealth that includes copper, cobalt, gold, nickel, lead, silver, uranium, zinc, and numerous precious and semi-precious stones. Mining activities are predominantly found on the Copperbelt and North-Western Provinces, although these minerals are dotted all over the country. Copper mining in Zambia dates back to the 1900s and this period witnessed massive investment in mine development with concomitant increase in support facilities including building of new towns, roads and other commercial infrastructure. The mining sector has therefore evoked considerable national attention for its potential to contribute towards economic growth, job creation and poverty alleviation. However, mining and mineral processing by its very nature comes with environmental costs and the effects can continue long after the mining has stopped. The aim of this article was to review the relevant publications on the impacts of air pollution arising from mining operations with respect to human health, plants, animals and infrastructure and synthesize the views of researchers and suggest any additional research required to inform policy and remedial actions. This review has revealed that there is a paucity of studies on mining-related air pollution in Zambia. The main identified air pollutants were SO₂ and particulate matter (PM), both fine and ultrafine (PM₁₀, PM_5.0, PM_2.5 and PM_0.1). The main sources of these pollutants were flue gases from smelter operations and dusts within the mines and those blown from both operational and abandoned waste rock, overburden and tailings dump sites. The identified occupational diseases for miners in Zambia were silicosis and tuberculosis, which have been compounded by the prevalence of HIV/AIDS. In the hotspot townships of air-borne exposures from smelter emissions in Mufulira, ambient air SO² levels exceeded the ‘safe’ limits of international and National standards. Moreover, the top soils have turned acidic and have become laden with heavy metals (Pb, Zn, Cu, Co and Fe). These metals were also found in the dust deposited on leaves of crops. There were also visual signs of impaired vegetation cover and corroded housing infrastructure in the affected areas. In the vicinity of the abandoned Pb–Zn mine in Kabwe, the soils have been contaminated by heavy metals and pathological lead poisoning of children and wild mammals have occurred. The review article has further examined study gaps and suggested areas that need further research in order to address the challenges arising from the legacy of copper mining in Zambia. These include comprehensive PM characterization from mining environments, extent of occupation exposure to air pollutants, efficiency and efficacy of airborne control technologies, health risks and epidemiological studies in mining towns, and the influence of exposure to PM on pulmonary tuberculosis and HIV/aids among miners.

Gut dysbiosis, leaky gut, and intestinal epithelial proliferation in neurological disorders: towards the development of a new therapeutic using amino acids, prebiotics, probiotics, and postbiotics

Here we offer a review of the evidence for a hypothesis that a combination of ingestible probiotics, prebiotics, postbiotics, and amino acids will help ameliorate dysbiosis and degeneration of the gut, and therefore promote restoration of nervous system function in a number of neurological indications.

Long-term exposure to atmospheric metals assessed by mosses and mortality in France

BACKGROUND

Long-term exposure to air pollution affects health, but little is known about exposure to atmospheric metals. Estimating exposure to atmospheric metals across large spatial areas remains challenging. Metal concentrations in mosses could constitute a useful proxy. Here, we linked moss biomonitoring and epidemiological data to investigate the associations between long-term exposure to metals and mortality.

METHODS

We modelled and mapped 13 atmospheric metals from a 20-year national moss biomonitoring program to derive exposure estimates across France. In the population-based Gazel cohort, we included 11,382 participants from low to intermediate population density areas and assigned modelled metals to their residential addresses. We distinguished between airborne metals that are primarily of natural origin and those primarily of anthropogenic origin. Associations were estimated between exposure to metals and mortality (natural-cause, cardiovascular and respiratory), using Cox models, with confounder adjustment at individual level.

FINDINGS

Between 1996 and 2017, there were 1313 deaths in the cohort (including 181 cardiovascular and 33 respiratory). Exposure to the anthropogenic metals was associated with an increased risk of natural-cause mortality (hazard ratio of 1.16 [1.08-1.24] per interquartile range of exposure), while metals from natural sources were not.

INTERPRETATION

Some atmospheric anthropogenic metals may be associated with excess mortality - even in areas with relatively low levels of exposure to air pollution. Consistent with the previous literature, our findings support the use of moss biomonitoring as a tool to assess health effects of air pollution exposure at individual level.