Ultrafine particle libraries for exploring mechanisms of PM2.5-induced toxicity in human cells

Toxicity source apportionment of fugitive dust PM2.5-bound polycyclic aromatic hydrocarbons using multilayer perceptron neural network analysis in Guanzhong Plain urban agglomeration, China

Polycyclic aromatic hydrocarbons (PAHs) in urban fugitive dust, known for their toxicity and ability to generate reactive oxygen species (ROS), are a major public health concern. This study assessed the spatial distribution and health risks of 15 PAHs in construction dust (CD) and road dust (RD) samples collected from June to November 2021 over the cities of Tongchuan (TC), Baoji (BJ), Xianyang (XY), and Xi'an (XA) in the Guanzhong Plain, China. The average concentration of ΣPAHs in RD was 39.5 ± 20.0 μg g-1, approximately twice as much as in CD. Four-ring PAHs from fossil fuels combustion accounted for the highest proportion of ΣPAHs in fugitive dust over all four cities. Health-related indicators including benzo(a)pyrene toxic equivalency factors (BAPTEQ), oxidative potential (OP), and incremental lifetime cancer risk (ILCR) all presented higher risk in RD than those in CD. The multilayer perceptron neural network algorithm quantified that vehicular and industrial emissions contributed 86 % and 61 % to RD and CD BAPTEQ, respectively. For OP, the sources of biomass and coal combustion were the key generator which accounted for 31-54 %. These findings provide scientific evidence for the direct efforts toward decreasing the health risks of fugitive dust in Guanzhong Plain urban agglomeration, China.

Exercise-Mediated Protection against Air Pollution-Induced Immune Damage: Mechanisms, Challenges, and Future Directions

Air pollution, a serious risk factor for human health, can lead to immune damage and various diseases. Long-term exposure to air pollutants can trigger oxidative stress and inflammatory responses (the main sources of immune impairment) in the body. Exercise has been shown to modulate anti-inflammatory and antioxidant statuses, enhance immune cell activity, as well as protect against immune damage caused by air pollution. However, the underlying mechanisms involved in the protective effects of exercise on pollutant-induced damage and the safe threshold for exercise in polluted environments remain elusive. In contrast to the extensive research on the pathogenesis of air pollution and the preventive role of exercise in enhancing fitness, investigations into exercise resistance to injury caused by air pollution are still in their infancy. In this review, we analyze evidence from humans, animals, and cell experiments on the combined effects of exercise and air pollution on immune health outcomes, with an emphasis on oxidative stress, inflammatory responses, and immune cells. We also propose possible mechanisms and directions for future research on exercise resistance to pollutant-induced damage in the body. Furthermore, we suggest strengthening epidemiological studies at different population levels and investigations on immune cells to guide how to determine the safety thresholds for exercise in polluted environments.

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.

Metal toxin threat in wildland fires determined by geology and fire severity

Accentuated by climate change, catastrophic wildfires are a growing, distributed global public health risk from inhalation of smoke and dust. Underrecognized, however, are the health threats arising from fire-altered toxic metals natural to soils and plants. Here, we demonstrate that high temperatures during California wildfires catalyzed widespread transformation of chromium to its carcinogenic form in soil and ash, as hexavalent chromium, particularly in areas with metal-rich geologies (e.g., serpentinite). In wildfire ash, we observed dangerous levels (327-13,100 µg kg-1) of reactive hexavalent chromium in wind-dispersible particulates. Relatively dry post-fire weather contributed to the persistence of elevated hexavalent chromium in surficial soil layers for up to ten months post-fire. The geographic distribution of metal-rich soils and fire incidents illustrate the broad global threat of wildfire smoke- and dust-born metals to populations. Our findings provide new insights into why wildfire smoke exposure appears to be more hazardous to humans than pollution from other sources.

Heterogeneous aggregation of carbon and silicon nanoparticles with benzo[a]pyrene modulates their impacts on the pulmonary surfactant film

Inhaled nanoparticles (NPs) can deposit in alveoli where they interact with the pulmonary surfactant (PS) and potentially induce toxicity. Although nano-bio interactions are influenced by the physicochemical properties of NPs, isolated NPs used in previous studies cannot accurately represent those found in atmosphere. Here we used molecular dynamics simulations to investigate the interplay between two types of NPs associated with benzo[a]pyrene (BaP) at the PS film. Silicon NPs (SiNPs), regardless of aggregation and adsorption, directly penetrated through the PS film with minimal disturbance. Meanwhile, BaPs adsorbed on SiNPs were rapidly solubilized by PS, increasing the BaP's bioaccessibility in alveoli. Carbon NPs (CNPs) showed aggregation and adsorption-dependent effects on the PS film. Compared to isolated CNPs, which extracted PS to form biomolecular coronas, aggregated CNPs caused more pronounced PS disruption, especially around irregularly shaped edges. SiNPs in mixture exacerbated the PS perturbation by piercing PS film around the site of CNP interactions. BaPs adsorbed on CNPs were less solubilized and suppressed PS extraction, but aggravated biophysical inhibition by prompting film collapse under compression. These results suggest that for proper assessment of inhalation toxicity of airborne NPs, it is imperative to consider their heterogeneous aggregation and adsorption of pollutants under atmospheric conditions.

Lung protective effects of dietary malate esters derivatives from Bletilla striata against SiO2 nanoparticles through activation of Nrf2 pathway

Objective

To study the protective activities of the dietary malate esters derivatives of Bletilla striata against SiO₂ nanoparticles-induced A549 cell lines and its mechanism action.

Methods

The components were isolated and elucidated by spectroscopic methods such as 1D NMR and 2D NMR. And MTT assays was used to tested these components on the A549 cell survival rates and ROS or proteins levels were detected by Western blotting.

Results

A new glucosyloxybenzyl 2-isobutylmalate (a malate ester derivative), along with 31 known compounds were isolated and identified from n-BuOH extract of EtOH extract of B. striata. Among them, compounds 3, 4, 11, 12 and 13 possessed noteworthy proliferative effects for damaged cells, with ED₅₀ of 14.0, 13.1, 3.7, 11.6 and 11.5 µmol/L, respectively, compared to positive control resveratrol (ED₅₀, 14.7 µmol/L). Militarine (8) prominently inhibited the intracellular ROS level, and increased the expression of Nrf2 and its downstream genes (HO-1 and γ-GCSc). Furthermore, Nrf2 activation mediates the interventional effects of compound 8 against SiO₂ nanoparticles (nm SiO₂)-induced lung injury. Moreover, treatment with compound 8 significantly reduced lung inflammation and oxidative stress in nm SiO₂-instilled mice. Molecular docking experiment suggested that 8 bound stably to the HO-1 protein by hydrogen bond interactions.

Conclusion

The dietary malate esters derivatives of B. striata could significantly increase the viability of nm SiO₂-induced A549 cells and decrease the finer particles-induced cell damages. Militarine is especially promising compound for chemoprevention of lung cancer induced by nm SiO₂ through activation of Nrf2 pathway.

The Effects and Pathogenesis of PM2.5 and Its Components on Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), a heterogeneous disease, is the leading cause of death worldwide. In recent years, air pollution, especially particulate matter (PM), has been widely studied as a contributing factor to COPD. As an essential component of PM, PM2.5 is associated with COPD prevalence, morbidity, and acute exacerbations. However, the specific pathogenic mechanisms were still unclear and deserve further research. The diversity and complexity of PM2.5 components make it challenging to get its accurate effects and mechanisms for COPD. It has been determined that the most toxic PM2.5 components are metals, polycyclic aromatic hydrocarbons (PAHs), carbonaceous particles (CPs), and other organic compounds. PM2.5-induced cytokine release and oxidative stress are the main mechanisms reported leading to COPD. Nonnegligibly, the microorganism in PM 2.5 may directly cause mononuclear inflammation or break the microorganism balance contributing to the development and exacerbation of COPD. This review focuses on the pathophysiology and consequences of PM2.5 and its components on COPD.

Characteristics and health risks of parent, alkylated, and oxygenated PAHs and their contributions to reactive oxygen species from PM2.5 vehicular emissions in the longest tunnel in downtown Xi'an, China

A vehicular emission study was conducted in the longest inner-city tunnel in Xi'an, northwestern China in four time periods (I: 07:30-10:30, II: 11:00-14:00, III: 16:30-19:30, and IV: 20:00-23:00 LST). A sum of 40 PAHs, including parent (p-PAHs), alkylated (a-PAHs), and oxygenated (o-PAHs) in fine particulate matter (PM_2.5) were quantified. The relationships between the PAHs and the formation of reactive oxygen species (ROS) were also studied. The average total quantified PAHs concentration was 236.3 ± 48.3 ng m^-3. The p-PAHs were found to be the most dominated group, accounting for an average of 88.1% of the total quantified PAHs, followed by a-PAHs (6.1%) and o-PAHs (5.8%). On the base of the number of aromatic rings, the groups of ≤5 rings (92.5 ± 1.2%) had higher fractions than the high ones (≥6 rings, 7.5 ± 1.2%) for pPAHs. Diurnal variations of PAHs subgroups exhibited the highest levels in Period III, consistent with the largest traffic counts in evening rush hours. However, less reduction of few PAHs in the night period demonstrates that the emissions of compressed natural gas (CNG) and methanol-fueled vehicles cannot be ignored while their contribution increased. High ROS activity levels were observed in the traffic-dominated samples, implying the potential oxidative damages to humans. Additionally, diurnal variation of the ROS activity was consistent with the total quantified PAHs and toxic equivalency of benzo[a]pyrene. Good correlations (R > 0.6, p < 0.05) were seen between individual groups of PAHs (especially for 3-5 rings p-PAHs, 4 rings a-PAHs, and 2-3 rings o-PAHs) and ROS activity, supporting that the vehicular emitted PAHs possibly initiate oxidative stress. The multiple linear regression analysis further illustrated that chrysene contributed the highest (25.0%) to ROS activity. In addition to highlighting the potential hazards to the PAHs from the vehicular emission, their roles to mitigate the health effects by formations of ROS were firstly reported in northwestern China.

Real-time chemical composition of ambient fine aerosols and related cytotoxic effects in human lung epithelial cells in an urban area

Particulate matter with aerodynamic diameters ≤1 μm (PM₁) in the atmosphere, especially that which is emitted from anthropogenic sources, can induce considerable negative effects on the cardiopulmonary system. To investigate the chemical emission characteristics and organic sources in Yuen Long (Hong Kong), both offline and online approaches for PM₁ samples were applied by filter-based samplers and a Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM), respectively. The toxicological effects on human A549 lung alveolar epithelial cells were investigated, and associations between cytotoxicity and organic sources and compositions were evaluated. The organics from the Q-ACSM measurement were the largest contributor to submicron aerosols in both seasons of our study, and the mass fraction was higher in winter (60%) than it was in autumn (46%). Regarding organic sources, the mass fraction of hydrocarbon-like organics (HOA) increased from 7% in autumn to 38% in winter, whereas cooking organics (COA) decreased from 30% in autumn to 18% in winter, and oxygenated organics (OOA) decreased from 63% to 45%. Organic compounds contributed more during pollution episodes, and more secondary ions were formed by means of the oxidation process. Oxidative and inflammatory responses in A549 cells were found with PM₁ exposures; the differences in chemical compositions resulted in the higher cytotoxicity in winter than autumn. The cooking organic aerosol in residential area was significantly correlated with cell inflammation. Both elemental carbon and specific inorganic ions (SO₄^2- and Mg²⁺) contributed to the intracellular cytotoxicity. This study demonstrated that specific atmospheric particulate matter chemical properties and sources can trigger distinct cell reactions; the inorganic ions from cooking emissions cannot be disregarded in terms of their pulmonary health risks in residential areas.

Effects of reactive oxygen species generation induced by Wonju City particulate matter on mitochondrial dysfunction in human middle ear cell

Atmospheric particulate matter (PM) contains different components that can elicit varying adverse health effects in humans and animals. Studies on PM toxicity and its underlying mechanisms in the middle ear are limited, and they generally use a PM standard. However, as PM composition varies temporally and geographically, it is crucial to identify the toxic PM constituents according to season and region and investigate their associated health effects. Thus, we sought to determine whether PM induces cytotoxicity and inflammatory factor and reactive oxygen species (ROS) generation in human middle ear epithelial cells obtained from patients with otitis media. The cells were treated with both standard urban PM and PM directly captured from the atmosphere in Wonju City. The association between mitochondrial dysfunction and PM was investigated. PM exposure significantly increased COX-2 and TNF-α mRNA expression, increased ROS generation, induced inflammatory responses, and caused abnormalities in mitochondrial motility and function. Furthermore, PM induced cell apoptosis, which consequently reduced cell survival, particularly at the concentration of 100 μg/mL. Overall, our study provides new insights into the toxic effects of standard and atmospheric PM on middle ear cell line.

The leading role of adsorbed lead in PM2.5-induced hippocampal neuronal apoptosis and synaptic damage

Neurodegenerative diseases may be caused by air pollution, such as PM_2.5. However, particles still need to be elucidated the mechanism of synergistic neurotoxicity induced by pollutant-loading PM_2.5. In this study, we used a reductionist approach to study leading role of lead (Pb) in PM_2.5-induced hippocampal neuronal apoptosis and synaptic damage both in vivo and in vitro. Pb in PM_2.5 caused neurotoxicity: 1) by increasing ROS levels and thus causing apoptosis in neuronal cells and 2) by decreasing the expression of PSD95 via interfering with the calcium signaling pathway through cAMP/CREB/pCREB/BDNF/PSD95 pathway and reducing the synapse length by 50%. This study clarifies a key factor in PM_2.5-induced neurotoxicity and provides the experimental basis for reducing PM_2.5-induced neurotoxicity.

Elucidation of the Critical Role of Core Materials in PM2.5-Induced Cytotoxicity by Interrogating Silica- and Carbon-Based Model PM2.5 Particle Libraries

An insoluble core with adsorbed pollutants constitutes the most toxic part of PM_2.5 particles. However, the toxicological difference between carbon and silica cores remains unknown. Here, we employed 32-membered carbon- and silica-based model PM_2.5 libraries that each was loaded with four toxic airborne pollutants including Cr(VI), As(III), Pb²⁺, and BaP in all possible combinations to explore their contributions to cytotoxicity in normal human bronchial cells. The following three crucial findings were revealed: (1) more adsorption of polar pollutants in a silica core (such as Cr(VI), As(III), and Pb²⁺) and nonpolar ones in a carbon core (such as BaP); (2) about 41% more cell uptake of carbon- than silica-based particles; and (3) about 59% less toxicity in silica- than carbon-based particles when pollutants other than Cr(VI) were loaded. This was reversed after Cr(VI) loading (silica particles were 56% more toxic). The difference maker is that compared to stable silica, carbon particles reduce Cr(VI) to less toxic Cr(III). Our findings highlight the different roles of carbon and silica cores in inducing health risks of PM_2.5 particles.

Role of air pollution by particulate matter in the pathogenesis of cardiovascular diseases. Prevention measures

The review highlights contemporary concepts about the role of atmospheric air pollution by particulate matter (PM) in pathogenesis of cardiovascular diseases (CVD). We used publications from the PubMed and Russian Science Citation Index databases. The influence of PM on the development and progression of CVD is considered depending on size, origin, chemical composition, concentration in air. PM with an aerodynamic diameter of ≤2,5 μm (PM2,5) are recognized as the most dangerous. Epidemiological studies have established a dose-dependent effect PM. Oxidative stress, damage of genome of cell and epigenetic changes associated with PM effect are the important component of CVD pathogenesis. Systematization of scientific data through a formalized description helps to understand the pathogenesis of CVD and facilitates its practical use for assessing the risk of occurrence, early diagnosing, prognostication, increasing the effectiveness of treatment, and developing preventive measures.

Autophagy changes in lung tissues of mice at 30 days after carbon black-metal ion co-exposure

OBJECTIVES

Accumulating studies have investigated the PM2.5-induced pulmonary toxicity, while gaps still remain in understanding its toxic mechanism. Due to its high specific surface area and adsorption capacity similar to nanoparticles, PM2.5 acts as a significant carrier of metals in air and then leads to altered toxic effects. In this study, we aimed to use CBs and Ni as model materials to investigate the autophagy changes and pulmonary toxic effects at 30 days following intratracheal instillation of CBs-Ni mixture.

MATERIALS AND METHODS

Groups of mice were instilled with 100 µL normal saline (NS), 20 µg CBs, and 4 µg Ni or CBs-Ni mixture, respectively. At 7 and 30 days post-instillation, all the mice were weighed and then sacrificed. The evaluation system was composed of the following: (a) autophagy and lysosomal function assessment, (b) trace element biodistribution observation in lungs, (c) pulmonary lavage biomedical analysis, (d) lung histopathological evaluation, (e) coefficient analysis of major organs and (f) CBs-Ni interaction and cell proliferation assessment.

RESULTS

We found that after CBs-Ni co-exposure, no obvious autophagy and lysosomal dysfunction or pulmonary toxicity was detected, along with complete clearance of Ni from lung tissues as well as recovery of biochemical indexes to normal range.

CONCLUSIONS

We conclude that the damaged autophagy and lysosomal function, as well as physiological function, was repaired at 30 days after exposure of CBs-Ni. Our findings provide a new idea for scientific assessment of the impact of fine particles on environment and human health, and useful information for the comprehensive treatment of air pollution.

Air quality warning system based on a localized PM2.5 soft sensor using a novel approach of Bayesian regularized neural network via forward feature selection

It is highly significant to develop efficient soft sensors to estimate the concentration of hazardous pollutants in a region to maintain environmental safety. In this paper, an air quality warning system based on a robust PM_2.5 soft sensor and support vector machine (SVM) classifier is reported. The soft sensor for the estimation of PM_2.5 concentration is proposed using a novel approach of Bayesian regularized neural network (BRNN) via forward feature selection (FFS). Zuoying district of Taiwan is selected as the region of study for implementation of the estimation system because of the high pollution in the region. Descriptive statistics of various pollutants in Zuoying district is computed as part of the study. Moreover, seasonal variation of particulate matter (PM) concentration is analyzed to evaluate the impact of various seasons on the increased levels of PM in the region. To investigate the linear dependence of concentration of different pollutants to the concentration of PM_2.5, Pearson correlation coefficient, Kendall's tau coefficient, and Spearman coefficient are computed. To achieve high performance for the PM_2.5 estimation, selection of appropriate forward features from the input variables is carried out using FFS technique and Bayesian regularization is incorporated to the neural network system to avoid the overfitting problem. The comparative evaluation of performance of BRNN/FFS estimation system with various other methods shows that our proposed estimation system has the lowest mean square error (MSE), root mean square error (RMSE), and mean absolute error (MAE). Moreover, the coefficient of determination (R-squared) is around 0.95 for the proposed estimation method, which denotes a good fit. Evaluation of the SVM classifier showed good performance indicating that the proposed air quality warning system is efficient.

Ecological and human health risk assessment

The literature review presented in this paper covers the risk assessment process that is important to human health as well as the health of ecology in the form of receptors. One of the important objectives of present review is to provide summary of the scientific studies published in the year 2018. The review starts with literature published on the assessment of health risks, which are valuable to human and ecology. Most of the literature in the entire article focuses on techniques used for the analysis of scientific data and methods. In addition, review also highlights data interpretation, uncertainty, policy, and regulatory guidance associated with the management of human and ecological risks. Particularly, the review on the risk assessment related to human health and ecology is divided into two main sections. These sections provide broad state of knowledge on the risk assessment process used to health of human and ecological systems focused on investigation of polluted sites, techniques of remediation, and tools required for natural resource management.

PM2.5-Associated Health Impacts of Beehive Coke Oven Ban in China

Historically, beehive coke ovens (BCOs) were extensively operated in China and emitted large quantities of pollutants, including primary PM_2.5 and secondary PM_2.5 precursors, and other climate forcers. Although these ovens were legally banned in 1996 by the Coal Law, the process of phasing them out took over a decade to accomplish. Based on historical operation data derived from remote sensing images, temporal trends and the spatial distribution of the emissions of various pollutants from BCOs were compiled and used to model the resulting perturbation in ambient PM_2.5, population exposure, and PM_2.5-associated adverse health impacts. Historically, PM_2.5 originating from BCOs affected a vast region across China, which peaked in approximately 1996 and decreased afterward until the ovens' final elimination in 2011. According to the results of a supply-demand model, emissions from the BCOs would have continued to increase after 1996 if they had not been banned. As a result, national average PM_2.5 attributable to BCOs in 2014 would have been more than three times as high as that in 1996. It was estimated that the cumulative number of premature deaths associated with BCO-originating PM_2.5 from 1982 to 2014 was as high as 365 000 (95% confidence interval 259 000-402 000). The number would have nearly tripled if BCOs had not been banned and halved if the ban had been implemented immediately after the regulation was in force, suggesting the importance of legislation implementation.

Nrf2 protects against diverse PM2.5 components-induced mitochondrial oxidative damage in lung cells

Nrf2 is an important transcription factor implicated in the oxidative stress response, which has been reported to play an important role in the way by which air pollution particulate matter (PM_2.5) induces adverse health effects. This study investigates the mechanism by which Nrf2 exerts its protective effect in PM_2.5 induced toxicity in lung cells. Lung cells silenced for Nrf2 (shNrf2) demonstrated diverse susceptibility to various PM extracts; water extracts containing high levels of dissolved metals exhibited higher capacity to generate mitochondrial reactive oxygen species (ROS) and hence increased oxidative stress levels. Organic extracts containing high levels of polycyclic aromatic hydrocarbons (PAHs) increased mortality and reduced ROS production in the silenced cells. shNrf2 cells exhibited a higher basal mitochondrial respiration rate compared to the control cells. Following exposure to water extracts, the mitochondrial respiration increased, which was not observed with the organic extracts. shNrf2 cells exposed to the organic extracts showed lower mitochondrial membrane potential and lower mtDNA copy number. Nrf2 may act as a signaling mediator for the mitochondria function following PM_2.5 exposure.

Cr(VI)/Pb2+ are responsible for PM2.5-induced cytotoxicity in A549 cells while pulmonary surfactant alleviates such toxicity

The composition of PM_2.5 is extremely complicated, making the causes of PM_2.5-induced toxicity hard to understand. To identify the major toxic components of PM_2.5 particles, we used reductionism approach, synthesized and investigated a model PM_2.5 library containing 24 carbon nanoparticles with adsorbed pollutants including Cr(VI), Pb²⁺, As(III) and BaP either individually or in combinations. Our data showed that major physicochemical characteristics of model PM_2.5 library members were similar to PM_2.5 particles from Guangzhou city (PM_2.5-GZ). Cytotoxicity of lung cells (A549) was increasing as the member of adsorbed pollutants at environment relevant concentrations. Using these model particles, we identified that co-existence of Cr(VI) and Pb²⁺ components contributed to the PM_2.5-induced cytotoxicity in A549 cells. Besides, pulmonary surfactant reduced the PM_2.5-induced cytotoxicity in A549 cells probably via enhancing cell autophagy. The findings from this study suggest that systematic investigation using model PM_2.5 particle library helps identify key toxic pollutants in otherwise very complex PM_2.5 particles and facilitate our understanding of the underlying biological mechanisms.

Study on the multivariate prediction model and exposure level of indoor and outdoor particulate concentration in severe cold region of China

Atmospheric particulate matter( PM₁₀, PM_2.5) has been the main pollutant in most cities of China in recent years, and the exposure concentration is related to the incidence of human diseases and mortality. The time spent indoors is more than 80% for modern people. Therefore, study on the correlation and exposure level of indoor and outdoor atmospheric particles is important. To research the exposure level in the heating season and non-heating season of indoor and outdoor particulate concentration in severe cold region of China, a total of 110 samples of four types of buildings (office, classroom, urban residence and rural residence) in Daqing, a typical city of severe cold region in China, were tested by particle monitor. Based on the indoor and outdoor environmental parameters, multiple linear regression (MLR) and principal component regression (PCR), established the indoor particulate concentration prediction models. The short and long term exposure of different people in different environments in severe cold region of China was analyzed based on the people's time-activity pattern with the measured data and model. The results showed that as for the short term indoor and outdoor exposure of different people, the average combined exposure of urban people in heating season is 60.0% higher than that in non-heating season, and rural people in heating season 30.2% higher than that in non-heating season. As for the long term indoor and outdoor exposure of different people, the annual average combined exposure of urban people was 9.6% higher than that of rural people. While all for urban and rural people, differences in respiratory rates between genders resulted in an average potential dose of 21. 8% higher in male than in female.

Adverse Effects of Fine-Particle Exposure on Joints and Their Surrounding Cells and Microenvironment

Current understanding of the health risks and adverse effects upon exposure to fine particles is premised on the direct association of particles with target organs, particularly the lung; however, fine-particle exposure has also been found to have detrimental effects on sealed cavities distant to the portal-of-entry, such as joints. Moreover, the fundamental toxicological issues have been ascribed to the direct toxic mechanisms, in particular, oxidative stress and proinflammatory responses, without exploring the indirect mechanisms, such as compensated, adaptive, and secondary effects. In this Review, we recapitulate the current findings regarding the detrimental effects of fine-particle exposure on joints, the surrounding cells, and microenvironment, as well as their deteriorating impact on the progression of arthritis. We also elaborate the likely molecular mechanisms underlying the particle-induced detrimental influence on joints, not limited to direct toxicity, but also considering the other indirect mechanisms. Because of the similarities between fine air particles and engineered nanomaterials, we compare the toxicities of engineered nanomaterials to those of fine air particles. Arthritis and joint injuries are prevalent, particularly in the elderly population. Considering the severity of global exposure to fine particles and limited studies assessing the detrimental effects of fine-particle exposure on joints and arthritis, this Review aims to appeal to a broad interest and to promote more research efforts in this field.

Seasonal size distribution and mixing state of black carbon aerosols in a polluted urban environment of the Yangtze River Delta region, China

The optical properties of black carbon aerosols (BC) are determined by the particles size and the associated non-BC materials, which may be source-related or modified during secondary processing. The one-year long monitoring of BC was first conducted using a Single Particle Soot Photometer (SP2) from December 2013 to November 2014 in Nanjing, a megacity in the Yangtze River Delta region of China. The seasonal variation in the BC size distribution and mixing state were investigated. There was no apparent systematic variation in the mean BC core mass median diameter between seasons, as these values were 226 ± 12 nm, 217 ± 13 nm, 211 ± 15 nm and 221 ± 12 nm for winter, spring, summer and autumn respectively. The mixing state of BC was quantified as the bulk relative coating thickness (defined as particle size D_p over core size D_c, D_p/D_c), which ranged from 1.05 to 2.65. The BC was found to be significantly more coated in the winter (D_p/D_c = 1.50 ± 0.30) than in other seasons (D_p/D_c = 1.27 ± 0.09, 1.28 ± 0.10, 1.27 ± 0.11 in spring, summer and autumn respectively). Higher levels of coating during the winter may due to the contributions of the primary source (with the highest BC mass loadings between seasons) or secondary processes such as low temperature that facilitated the condensation. It was found that the photochemical process may enhance the coatings on BC in summer. At nighttime, the reduced and stabilized planetary boundary layer and the nighttime secondary formation may also lead to BC becoming well mixed with other components. Moreover, BC was shown to be less coated when the NO_x concentration was high. However, during all seasons, the BC coating was strongly correlated with other non-BC particulate mass, which suggests that at higher pollution levels BC was more significantly coated with other existing materials through coagulation or condensation by other secondary species.

Changes of 8-OHdG and TrxR in the Residents Who Bathe in Radon Hot Springs

This study explored the effects of long-term bathing in radon hot springs on oxidative damage and antioxidation function in humans. In this study, blood was collected from residents in the Pingshan radon hot spring area (RHSA), Jiangzha RHSA, and control area (CA). 8-Hydroxydeoxyguanosine (8-OHdG) and thioredoxin reductase (TrxR), representing oxidation and antioxidant levels, respectively, were analyzed as indices. Compared to the CA group, the RHSA group in the Pingshan and Jiangzha areas showed significantly decreased 8-OHdG levels (Z = -3.350, -3.316, respectively, P < .05) and increased TrxR levels (Z = 2.394, 3.773, respectively, P < .05). The RHSA and CA groups in Jiangzha had lower levels of TrxR and 8-OHdG compared to those in Pingshan. This finding may be related to the different radon concentration levels, bathing time and other factors. Results suggested that long-term bathing in radon hot spring may activate antioxidant function and reduce oxidative damage in the body.

A human cell panel for evaluating safe application of nano-ZrO2/polymer composite in water remediation

Nanomaterials, such as ZrO₂ nanoparticles (ZrO₂ NPs), are very effective in water remediation. However, the safety issues related to nanoparticle release and toxicity to humans remain to be resolved. Here we evaluated the cytotoxicity of ZrO₂ NPs and their adducts with pollutants using a human cell panel containing stomach, intestine, liver and kidney cells. We found that different pollutants or ZrO₂NP/pollutant adducts targeted cells from different organs, suggesting the necessity of a cell panel to model oral exposures. The cooperation of ZrO₂ NPs and pollutants was quite complex, consisting of synergistic, antagonistic, or additive effects. For example, ZrO₂ NPs enhanced the cytotoxicity of Pb²⁺ in GES-1 cells and of Pb²⁺, Cd²⁺ in FHC cells, while alleviating the toxicity of Pb²⁺ and As (III) in HepG2 and Hek293 cells. Our results also indicated that even concentrations of pollutants that meet the national standard, the ZrO₂ NPs concentration should be kept below 17 μg/mL to avoid ZrO₂ NP/pollutant adduct synergistic toxicity.

Summer-winter differences of PM2.5 toxicity to human alveolar epithelial cells (A549) and the roles of transition metals

Atmospheric fine particulate matters (PM_2.5) induce adverse human health effects through inhalation, and the harmful effects of PM_2.5 are determined not only by its air concentrations, but also by the particle components varied temporally. To investigate seasonal differences of the aerosol toxicity effects including cell viability and membrane damage, cell oxidative stress and responses of inflammatory cytokines, the human lung epithelial cells (A549) were exposed to PM_2.5 samples collected in both summer and winter by the in vitro toxicity bioassays. Toxicological results showed that, the PM_2.5 led to the cell viability decrease, cell membrane injury, oxidative stress level increase and inflammatory responses in a dose-dependent manner. Temporally, the cytotoxicity of winter PM_2.5 was higher than summer of this studied industrial area of Nanjing, China. According to the different contents of heavy metals accumulated in PM_2.5, the transition metals such as Cu might be an important contributor to the aerosol cell toxicity.