Fine and ultrafine atmospheric particulate matter at a multi-influenced urban site: Physicochemical characterization, mutagenicity and cytotoxicity

Assessment of wood smoke induced pulmonary toxicity in normal- and chronic bronchitis-like bronchial and alveolar lung mucosa models at air-liquid interface

BACKGROUND

Chronic obstructive pulmonary disease (COPD) has the highest increased risk due to household air pollution arising from biomass fuel burning. However, knowledge on COPD patho-mechanisms is mainly limited to tobacco smoke exposure. In this study, a repeated direct wood smoke (WS) exposure was performed using normal- (bro-ALI) and chronic bronchitis-like bronchial (bro-ALI-CB), and alveolar (alv-ALI) lung mucosa models at air-liquid interface (ALI) to assess broad toxicological end points.

METHODS

The bro-ALI and bro-ALI-CB models were developed using human primary bronchial epithelial cells and the alv-ALI model was developed using a representative type-II pneumocyte cell line. The lung models were exposed to WS (10 min/exposure; 5-exposures over 3-days; n = 6-7 independent experiments). Sham exposed samples served as control. WS composition was analyzed following passive sampling. Cytotoxicity, total cellular reactive oxygen species (ROS) and stress responsive NFkB were assessed by flow cytometry. WS exposure induced changes in gene expression were evaluated by RNA-seq (p ≤ 0.01) followed by pathway enrichment analysis. Secreted levels of proinflammatory cytokines were assessed in the basal media. Non-parametric statistical analysis was performed.

RESULTS

147 unique compounds were annotated in WS of which 42 compounds have inhalation toxicity (9 very high). WS exposure resulted in significantly increased ROS in bro-ALI (11.2%) and bro-ALI-CB (25.7%) along with correspondingly increased NFkB levels (bro-ALI: 35.6%; bro-ALI-CB: 18.1%). A total of 1262 (817-up and 445-down), 329 (141-up and 188-down), and 102 (33-up and 69-down) genes were differentially regulated in the WS-exposed bro-ALI, bro-ALI-CB, and alv-ALI models respectively. The enriched pathways included the terms acute phase response, mitochondrial dysfunction, inflammation, oxidative stress, NFkB, ROS, xenobiotic metabolism of AHR, and chronic respiratory disorder. The enrichment of the 'cilium' related genes was predominant in the WS-exposed bro-ALI (180-up and 7-down). The pathways primary ciliary dyskinesia, ciliopathy, and ciliary movement were enriched in both WS-exposed bro-ALI and bro-ALI-CB. Interleukin-6 and tumor necrosis factor-α were reduced (p < 0.05) in WS-exposed bro-ALI and bro-ALI-CB.

CONCLUSION

Findings of this study indicate differential response to WS-exposure in different lung regions and in chronic bronchitis, a condition commonly associated with COPD. Further, the data suggests ciliopathy as a candidate pathway in relation to WS-exposure.

The Cytotoxic Effects of Fine Particulate Matter (PM2.5) from Different Sources at the Air-Liquid Interface Exposure on A549 Cells

The health of humans has been negatively impacted by PM2.5 exposure, but the chemical composition and toxicity of PM2.5 might vary depending on its source. To investigate the toxic effects of particulate matter from different sources on lung epithelial cells (A549), PM2.5 samples were collected from residential, industrial, and transportation areas in Nanjing, China. The chemical composition of PM2.5 was analyzed, and toxicological experiments were conducted. The A549 cells were exposed using an air-liquid interface (ALI) exposure system, and the cytotoxic indicators of the cells were detected. The research results indicated that acute exposure to different sources of particulate matter at the air-liquid interface caused damage to the cells, induced the production of ROS, caused apoptosis, inflammatory damage, and DNA damage, with a dose-effect relationship. The content of heavy metals and PAHs in PM2.5 from the traffic source was relatively high, and the toxic effect of the traffic-source samples on the cells was higher than that of the industrial- and residential-source samples. The cytotoxicity of particulate matter was mostly associated with water-soluble ions, carbon components, heavy metals, PAHs, and endotoxin, based on the analysis of the Pearson correlation. Oxidative stress played an important role in PM2.5-induced biological toxicity.

Ambient atmospheric PM worsens mouse lung injury induced by influenza A virus through lysosomal dysfunction

BACKGROUND

Particulate matter (PM) air pollution poses a significant risk to respiratory health and is especially linked with various infectious respiratory diseases such as influenza. Our previous studies have shown that H5N1 virus infection could induce alveolar epithelial A549 cell death by enhancing lysosomal dysfunction. This study aims to investigate the mechanisms underlying the effects of PM on influenza virus infections, with a particular focus on lysosomal dysfunction.

RESULTS

Here, we showed that PM nanoparticles such as silica and alumina could induce A549 cell death and lysosomal dysfunction, and degradation of lysosomal-associated membrane proteins (LAMPs), which are the most abundant lysosomal membrane proteins. The knockdown of LAMPs with siRNA facilitated cellular entry of both H1N1 and H5N1 influenza viruses. Furthermore, we demonstrated that silica and alumina synergistically increased alveolar epithelial cell death induced by H1N1 and H5N1 influenza viruses by enhancing lysosomal dysfunction via LAMP degradation and promoting viral entry. In vivo, lung injury in the H5N1 virus infection-induced model was exacerbated by pre-exposure to silica, resulting in an increase in the wet/dry ratio and histopathological score.

CONCLUSIONS

Our findings reveal the mechanism underlying the synergistic effect of nanoparticles in the early stage of the influenza virus life cycle and may explain the increased number of respiratory patients during periods of air pollution.

Investigating industrial PAH air pollution in relation to population exposure in major countries: A scoring approach

Polycyclic aromatic hydrocarbons (PAHs) are common air pollutants worldwide, associated with industrial processes. In the general population, both modeling and field studies revealed a positive correlation between air PAH concentrations and urinary PAH metabolite levels. Many countries lack population urinary data that correspond to local PAH air concentrations. Thus, we proposed a scoring-based approximate approach to investigating that correlation in selected countries, hypothesizing that PAH air concentrations in selected regions could represent the national air quality influenced by industrial emission and further correlate to PAH internal exposure in the general population. This research compiled 85 peer-reviewed journal articles and 9 official monitoring datasets/reports covering 34 countries, 16 of which with both atmospheric PAH data and human biomonitoring data. For the air pollution score (AirS), Egypt had the highest AirS at 0.94 and Pakistan was at the bottom of the score ranking at -1.95, as well as the median in the UK (AirS: 0.50). For the population exposure score (ExpS), China gained the top ExpS at 0.44 and Spain was with the lowest ExpS of -1.52, with the median value in Italy (ExpS: 0.43). Through the correlation analysis, atmospheric PAHs and their corresponding urinary metabolites provided a positive relationship to a diverse extent, indicating that the related urinary metabolites could reflect the population's exposure to specific atmospheric PAHs. The findings also revealed that in the 16 selected countries, AirS indexes were positively correlated with ExpS indexes, implying that higher PAH levels in the air may lead to elevated metabolite urinary levels in general populations. Furthermore, lowering PAH air concentrations could reduce population internal PAH exposure, implying that strict PAH air regulation or emission would reduce health risks for general populations. Notably, this study was an ideal theoretical research based on proposed assumptions to some extent. Further research should focus on understanding exposure pathways, protecting vulnerable populations, and improving the PAH database to optimize PAH pollution control.

Chemical Composition and Transgenerational Effects on Caenorhabditis elegans of Seasonal Fine Particulate Matter

While numerous studies have demonstrated the adverse effects of fine particulate matter (PM) on human health, little attention has been paid to its impact on offspring health. The multigenerational toxic effects on Caenorhabditis elegans (C. elegans) were investigated by acute exposure. PM_2.5 and PM₁ samples were collected and analysed for their chemical composition (inorganic ions, metals, OM, PAHs) in different seasons from April 2019 to January 2020 in Lin'an, China. A higher proportion of organic carbon components (34.3%, 35.9%) and PAHs (0.0144%, 0.0200%) occupied the PM_2.5 and PM₁ samples in winter, respectively. PM₁ in summer was enriched with some metal elements (2.7%). Exposure to fine PM caused developmental slowing and increased germ cell apoptosis, as well as inducing intestinal autofluorescence and reactive oxygen species (ROS) production. PM₁ caused stronger toxic effects than PM_2.5. The correlation between PM component and F0 generation toxicity index was analysed. Body length, germ cell apoptosis and intestinal autofluorescence were all highly correlated with Cu, As, Pb, OC and PAHs, most strongly with PAHs. The highest correlation coefficients between ROS and each component are SO₄^2- (R = 0.743), Cd (R = 0.816) and OC (R = 0.716). The results imply that OC, PAHs and some transition metals play an important role in the toxicity of fine PM to C. elegans, where the organic fraction may be the key toxicogenic component. The multigenerational studies show that PM toxicity can be passed from parent to offspring, and gradually returns to control levels in the F3-F4 generation with germ cell apoptosis being restored in the F4 generation. Therefore, the adverse effects of PM on reproductive damage are more profound.

Oxidative stress response in pulmonary cells exposed to different fractions of PM2.5-0.3 from urban, traffic and industrial sites

The aim of this work was to study the relationship between oxidative stress damages and particulate matter (PM) chemical composition, sources, and PM fractions. PM_2.5-0.3 (PM with equivalent aerodynamic diameter between 2.5 and 0.3 μm) were collected at urban, road traffic and industrial sites in the North of France, and were characterized for major and minor chemical species. Four different fractions (whole PM_2.5-0.3, organic, water-soluble and non-extractable matter) were considered for each of the PM_2.5-0.3 samples from the three sites. After exposure of BEAS-2B cells to the four different fractions, oxidative stress was studied in cells by quantifying reactive oxygen species (ROS) accumulation, oxidative damage to proteins (carbonylated proteins), membrane alteration (8-isoprostane) and DNA damages (8-OHdG). Whole PM_2.5-0.3 was capable of inducing ROS overproduction and caused damage to proteins at higher levels than other fractions. Stronger cell membrane and DNA damages were found associated with PM and organic fractions from the urban site. ROS overproduction was correlated with level of expression of carbonylated proteins, DNA damages and membrane alteration markers. The PM_2.5-0.3 collected under industrial influence appears to be the less linked to cell damages and ROS production in comparison with the other influences.

Reproductive toxicity and underlying mechanisms of fine particulate matter (PM2.5) on Caenorhabditis elegans in different seasons

Although numerous studies have investigated that atmospheric fine particulate matter (PM_2.5) can be toxic to environmental organisms, the research on the reproductive toxicity of PM_2.5 is limited, and the key toxic components and underlying mechanisms remain unknown. In this work, PM_2.5 samples of four seasons in Nanjing from March 1, 2021, to February 28, 2022 were collected and the chemical components were analyzed. Caenorhabditis elegans (C. elegans) was employed to conduct the toxicological testing. The reproductive toxicity of PM_2.5 to C. elegans in different seasons was evaluated by multiple reproductive endpoints. Exposure to high concentrations of PM_2.5 significantly decreased the brood size and the number of fertilized eggs in utero. PM_2.5 exposure also increased the number of germ cell corpses and caused abnormal expression of apoptosis-related genes (ced-9, ced-4, and ced-3), which confirmed that PM_2.5 induced germline apoptosis. In addition, PM_2.5 exposure significantly increased the production of reactive oxygen species (ROS) in C. elegans and the fluorescence intensity of HUS-1 protein in of transgenic strain WS1433. Meanwhile, the expression of genes related to DNA damage (cep-1, clk-2, egl-1, and hus-1) and oxidative stress (mev-1, isp-1, and gas-1) also significantly altered in C. elegans, suggesting induction of DNA damage and oxidative stress. According to Pearson correlation analyses, DNA damage and oxidative stress were significantly correlated with multiple reproductive endpoints in C. elegans. Thus, it was speculated that PM_2.5 caused reproductive dysfunction and germ cell apoptosis in C. elegans may be by inducing ROS and DNA damage. In addition, heavy metals in PM_2.5 were significantly correlated with multiple endpoints at physiological and biochemical, suggesting that the heavy metals might be an important contributor to the reproductive toxicity induced by PM_2.5.

Sub-micron particle number emission from residential heating systems: A comparison between conventional and condensing boilers fueled by natural gas and liquid petroleum gas, and pellet stoves

Pollutant emissions from residential heating systems represent a main concern in terms of outdoor air quality. Differently from other pollutants, sub-micron particle emission from heating systems has not yet been exhaustively characterized by the scientific literature, with limited data available, in particular, for gas-fueled boilers. In the present paper, an experimental campaign to measure the sub-micron particle number concentrations and distributions at the stack of different automatically-fed small-scale heating systems (conventional and condensing boilers fueled by natural gas and liquid petroleum gas, and pellet stoves) was performed. Based on the measured concentrations, corresponding emission rates and emission factors were also estimated. The results of the experimental campaign revealed that the highest concentrations were measured for pellet stoves (median value >10⁷ part. m^-3), whereas conventional (about 1 × 10⁶ part. m^-3) and condensing boilers (<10⁶ part. m^-3) presented much lower concentrations. No effect of the fuel (natural gas, liquid petroleum gas) on the total concentration measured at the stack of boilers was recognized, whereas a smaller distribution mode (at 10 nm) was measured for gas-fired boilers. Because of the particle concentration values, the highest particle emission rates and factors were the pellet stove ones (median values of 2.1 × 10¹⁵ part. h^-1 and 8.4 × 10¹³ part. kWh^-1, respectively), whereas emission rates for conventional and condensing boilers were about 5 × 10¹³ part. h^-1 and 2 × 10¹³ part. h^-1, respectively. The estimated emission factors were also adopted to perform a simplified evaluation of the relative contributions of the investigated automatically-fed small-scale heating systems in terms of particle number on a national scale (Italy): we obtained that the pellet stove contribution is the main one as it accounts for 87% of total emissions of particle number for heating purpose.

Exposure to particulate matter: a brief review with a focus on cardiovascular effects, children, and research conducted in Turkey

Exposure to environmental particulate matter (PM), outdoor air pollution in particular, has long been associated with adverse health effects. Today, PM has widely been accepted as a systemic toxicant showing adverse effects beyond the lungs. There are numerous studies, from those in vitro to epidemiological ones, suggesting various direct and indirect PM toxicity mechanisms associated with cardiovascular risks, including inflammatory responses, oxidative stress, changes in blood pressure, autonomic regulation of heart rate, suppression of endothelium-dependent vasodilation, thrombogenesis, myocardial infarction, and fibrinolysis. In addition to these and other health risks, considerations about air quality standards should include individual differences, lifestyle, and vulnerable populations such as children. Urban air pollution has been a major environmental issue for Turkey, and this review will also address current situation, research, and measures taken in our country.

Particulate Matter-Induced Acute Coronary Syndrome: MicroRNAs as Microregulators for Inflammatory Factors

The most prevalent cause of mortality and morbidity worldwide is acute coronary syndrome (ACS) and its consequences. Exposure to particulate matter (PM) from air pollution has been shown to impair both. Various plausible pathogenic mechanisms have been identified, including microRNAs (miRNAs), an epigenetic regulator for gene expression. Endogenous miRNAs, average 22-nucleotide RNAs (ribonucleic acid), regulate gene expression through mRNA cleavage or translation repression and can influence proinflammatory gene expression posttranscriptionally. However, little is known about miRNA responses to fine PM (PM_2.5, PM₁₀, ultrafine particles, black carbon, and polycyclic aromatic hydrocarbon) from air pollution and their potential contribution to cardiovascular consequences, including systemic inflammation regulation. For the past decades, microRNAs (miRNAs) have emerged as novel, prospective diagnostic and prognostic biomarkers in various illnesses, including ACS. We wanted to outline some of the most important studies in the field and address the possible utility of miRNAs in regulating particulate matter-induced ACS (PMIA) on inflammatory factors in this review.

Ecotoxicity testing of airborne particulate matter-comparison of sample preparation techniques for the Vibrio fischeri assay

The bioassay based on the bioluminescence inhibition of the marine bacterium Vibrio fischeri has been the most widely used test for the assessment of airborne particulate matter ecotoxicity. Most studies available use an extract of the solid sample, either made with water or organic solvents. As an alternative, a whole-aerosol test is also available where test bacteria are in actual contact with contaminated particles. In our study, different extraction procedures were compared to this direct contact test based on the V. fischeri assay and analytical measurements. The lowest PAH content and the highest EC₅₀ were determined in water extract, while the highest PAH amount and lowest EC₅₀ were measured in dichloromethane, hexane, and dimethyl-sulphoxide extracts. EC₅₀ of the direct contact test was comparable to that of the methanol extract. Our results suggest that the sensitivity of the direct contact test equals to that of extraction procedures using organic solvents, moreover, it is mimicking an environmentally realistic exposure route.

Potential cytotoxicity of trace elements and polycyclic aromatic hydrocarbons bounded to particulate matter: a review on in vitro studies on human lung epithelial cells

A large number of studies have been conducted for clarifying toxicological mechanisms of particulate matter (PM) aimed to investigate the physicochemical properties of PM and providing biological endpoints such as inflammation, perturbation of cell cycle, oxidative stress, or DNA damage. However, although several studies have presented some effects, there is still no consensus on the determinants of biological responses. This review attempts to summarize all past research conducted in recent years on the physicochemical properties of environmental PM in different places and the relationship between different PM components and PM potential cytotoxicity on the human lung epithelial cells. Among 447 papers with our initial principles, a total of 50 articles were selected from 1986 to April 2020 based on the chosen criteria for review. According to the results of selected studies, it is obvious that cytotoxicity in human lung epithelial cells is created both directly or indirectly by transition metals (such as Cu, Cr, Fe, Zn), polycyclic aromatic hydrocarbons (PAH), and ions that formed on the surface of particles. In the selected studies, the findings of the correlation analysis indicate that there is a significant relationship between cell viability reduction and secretion of inflammatory mediators. As a result, it seems that the observed biological responses are related to the composition and the physicochemical properties of the PMs. Therefore, the physicochemical properties of PM should be considered when explaining PM cytotoxicity, and long-term research data will lead to improved strategies to reduce air pollution.

Occurrence and toxicity of polycyclic aromatic hydrocarbons derivatives in environmental matrices

In the last years, there is great attention paid to the determination of polycyclic aromatic hydrocarbons (PAHs) in different environmental matrices. Extensive reviews on PAHs presence and toxicity were published recently. However, PAHs formation and transformation in the environment lead to the production of PAHs derivatives containing oxygen (O-PAHs), nitrogen (N-PAHs and aazarenes AZA) or sulfur (PASHs) in the aromatic ring. The development of new analytical methods enabled the determination of these novel contaminants. The presence of oxygen, nitrogen, or sulfur in PAHs aromatic rings increased their toxicity. The most common primary sources of PAHs derivatives are biological processes such as microbial activity (in soil, water, and wastewater treatment plants (O-PAHs)) and all processes involving combustion of fuel, coal, and biomass (O-PAHs, N-PAHs, AZA, PASHs). The secondary resources involved i) photochemical (UV light), ii) radical-mediated (OH, NO₃), and iii) reactions with oxidants (O₃, NO_x) (O-PAHs, N-PAHs, AZA). Furthermore, N-PAHs were able to transform to their corresponding O-PAHs, while other derivatives were not. It indicated that N-PAHs are more vulnerable to photooxidation in the environment. 85% of O- and N-PAHs were detected with particle matter below 2.5 μm suggesting their easier bioaccessibility. More than 90% of compounds with four and more aromatic cycles were present in the particle phase in the air. Although the concentrations of N-PAHs or O-PAHs may be similar to PAHs concentration or even 1000 times lower than parent PAHs, PAHs derivatives accounted for a significant portion of the total mutagenicity. The present review is describing the results of the studies on the determination of PAHs derivatives in different environmental matrices including airborne particles, sediments, soil, and organisms. The mechanisms of their formation and toxicity were assessed.

In vitro toxicity of indoor and outdoor PM10 from residential wood combustion

Particulate matter with aerodynamic diameter < 10 μm (PM₁₀) was collected, indoors and outdoors, when wood burning appliances (open fireplace and woodstove) were in operation. The PM₁₀ ecotoxicity was assessed with the Vibrio fischeri bioluminescence inhibition assay, while the cytotoxicity was evaluated by the WST-8 and lactate dehydrogenase (LDH) release assays using A549 cells. Extracts of PM₁₀-bound polycyclic aromatic hydrocarbons (PAH) were tested for their mutagenicity through the TA98 and TA100 Ames test. The bioluminescent inhibition assay revealed that indoor particles released from the fireplace were the most toxic. Indoors, the reduction in A549 cell metabolic activity was over two times higher for the fireplace in comparison with the woodstove (32 ± 3.2% and 72 ± 7.6% at the highest dose, respectively). Indoor particles from the fireplace were found to induce greater cytotoxicity than the corresponding outdoor samples. Combined WST-8 and LDH results suggest that PM₁₀ exposure induce apoptotic cell death pathway in which the cell membrane integrity is maintained. Indoor and outdoor samples lacked direct and indirect mutagenic activity in any of the tester strains. For indoor-generated PM₁₀, organic carbon and PAH were significantly correlated with cell viability and bioluminescence reduction, suggesting a role of organic compounds in toxicity.

Exposure levels and health risk of PAHs associated with fine and ultrafine aerosols in an urban site in northern Algeria

Size distribution of toxicants in airborne particulates remains insufficiently investigated in Algeria. A 1-year campaign was performed at Bab Ezzouar, Algiers (Algeria), aimed at characterizing particulates for their physical and chemical features. For this purpose, scanning electronic microscopy (SEM), Raman spectroscopy (RaS), and GC-MS methodologies were applied. The samples were collected on daily basis by means of a high-volume sampling (HVS) system equipped with cascade impactor separating three size fractions, i.e., particles with aerodynamic diameters d < 1.0 μm (PM₁), 1.0 μm <d<2.5 μm (PM_2.5), and 2.5 μm <d<10 μm (PM₁₀), respectively. The organic fraction was recovered from substrate through solvent extraction in an ultrasonic bath, separated and purified by column chromatography, then analyzed by gas chromatography coupled with mass spectrometry (GC-MS). Investigation was focused on polycyclic aromatic hydrocarbons (PAHs) and the concentration ratios suitable to investigate the source nature. Further information was drawn from SEM and Raman analyses. Total PAH concentrations ranged broadly throughout the study period (namely, from 4.1 to 59.7 ng m^-3 for PM₁, from 2.72 to 32.3 ng m^-3 for PM_2.5 and from 3.30 to 32.7 ng m^-3 for PM₁₀). Both approaches and principal component analysis (PCA) of data revealed that emission from vehicles was the most important PAH source, while tobacco smoke provided an additional contribution.

The North-western Italy air quality monitoring network: Improving experience of PM2.5 assessment with mutagenicity assay

The finest fraction of Particulate Matter (PM2.5) carries a large number of pollutants, some of which are assessed as genotoxic, such as some Polycyclic Aromatic Hydrocarbons (PAHs). In many countries, PM2.5 in combination with some PAHs are monitored to assess the concentrations of pollutants, while the air quality is rarely assessed by means of biological assays. Epidemiological studies have demonstrated a significant correlation between these two pollutants and human adverse effects, in particular on the respiratory system. Nevertheless, other air pollutants can induce a biological effect and the cumulative effect of the PM2.5 complex mixture may not be easily deduced by PM2.5 and PAH levels. This study aimed to combine the legislative monitoring of PM2.5 with the study of its mutagenicity. During a full year, daily air samples were collected in nine sites of the North-western Italy air quality monitoring network (Piedmont Region) and PM2.5 and PAH concentrations were assessed. Monthly pooled organic extracts were tested with the Salmonella assay using TA98 and TA100 strains, with and without metabolic activation (±S9), and using TA98NR and YG1021 strains. In all sites, a positive response was observed for TA98 and TA100 especially without S9. A significant mutagenic seasonal variation was detected, with higher mutagenicity in winter and lower responses in summer (average total mutagenicity ratio 27:1). The response of TA98NR and YG1021 compared with TA98 suggested a significant contribution of nitro-compounds to the mutagenicity. No significant differences were found between urban background and rural sites denoting the spread of pollution. A mutagenicity increase, 1.28 Total Mutagenicity Factor/20 m³, was observed for each PM2.5 μg increment. PAH levels and corresponding Toxic Equivalent Factors were highly correlated to mutagenicity results. This work confirms that complex environmental mixtures can be appropriately assessed through the implementation of physical-chemical analyzes with bioassays able to evaluate synergistic and antagonistic effects, especially for highest and lowest pollution settings.

Evaluation of soils under the influence of coal mining and a thermoelectric plant in the city of Candiota and vicinity, Brazil

Coal burning generates gases, particles, and condensation by-products that are harmful to soil, water, and to the atmosphere. The aim of this study was to characterize and identify the cytotoxic and mutagenic potential of soil samples from the cities of Aceguá, Bagé, Candiota and Pinheiro Machado, near a large coal-fired power plant. Our study describes soil characteristics and contributes to the evaluation of the genotoxic activity of coal mining and burning, using the Comet Assay and Micronucleus test in V79 cells, as well as mutagenicity assays with Salmonella typhimurium strains. Comet Assay results show that the winter soil samples of Candiota and Pinheiro Machado induced a significant increase of the Damage Index for cells, as well as for the Aceguá summer sample. The micronucleus test did not detect differences between cities and seasons. A component analysis indicates associations between results obtained in Comet Assay and Ti and phenanthene concentrations for Pinheiro Machado during the winter, and Al for Aceguá during the summer and Zn during the winter. Results of Salmonella/microsome assays were negative, only Candiota and Pinheiro Machado samples showed a statistical increase of his + colonies in TA102. Our work describes biological data on these cells exposed to coal-contaminated soil, confirming the sensitivity of the Comet Assay in V79 cells and Salmonella/microsome assay for the evaluation of the effects of complex mixtures. These findings help to understand the spatial distribution of contaminants in the local soil related to a power plant, which is important for planning public safety actions.

PM2.5 characterization of primary and secondary organic aerosols in two urban-industrial areas in the East Mediterranean

Primary and secondary organic aerosols in PM_2.5 were investigated over a one-year campaign at Zouk Mikael and Fiaa, Lebanon. The n-alkanes concentrations were quite similar at both sites (26-29 ng/m³) and mainly explained by anthropogenic emissions rather than natural ones. The concentrations of total Polycyclic Aromatic Hydrocarbons (PAHs) were nearly three times higher at Zouk Mikael (2.56 ng/m³) compared to Fiaa (0.95 ng/m³), especially for indeno[1,2,3-c,d]pyrene linked to the presence of the power plant. A characteristic indeno[1,2,3-c,d]pyrene/(indeno[1,2,3-c,d]pyrene + benzo[g,h,i]perylene) ratio in the range 0.8-1.0 was determined for heavy fuel oil combustion from the power plant. Fatty acids and hopanes were also investigated and were assigned to cooking activities and vehicular emissions respectively. Phthalates were identified for the first time in Lebanon with high concentrations at Zouk and Fiaa (106.88 and 97.68 ng/m³ respectively). Moreover, the biogenic secondary aerosols revealed higher concentrations in summer. The total terpene concentration varied between 131 ng/m³ at Zouk Mikael in winter to 469 ng/m³ at Fiaa in summer. Additionnally, the concentrations of the dicarboxylic acids especially for adipic and phthalic acids were more influenced by anthropogenic sources.The analysis of molecular markers and diagnostic ratios indicated that the sites were strongly affected by anthropogenic sources such as waste open burning, diesel private generators, cooking activities, road transport, power plant, and industrial emissions. Moreover, results showed different pattern during winter and summer seasons. Whereas, higher concentrations of biogenic markers were clearly encountered during the summer period.

3D nanointerface enhanced optical microfiber for real-time detection and sizing of single nanoparticles

Portable devices, which can detect and characterize the individual nanoparticles in real time, are of insignificant interest for early diagnosis, homeland security, semiconductor manufacturing and environmental monitoring. Optical microfibers present a good potential in this field, however, are restricted by the sensitivity limit. This study reports the development of a 3D plasmonic nanointerface, which is made of a Cu-BTC framework supporting Cu_3-xP nanocrystals, enhancing the optical microfiber for real-time detection and sizing of single nanoparticles. The Cu_3-xP nanocrystals are successfully embedded in the 3D Cu-BTC framework. The localized-surface plasmon resonance is tuned to coincide with the evanescent field of the optical microfiber. The 3D Cu-BTC framework, as the scaffold of nanocrystals, confines the local resonance field on the microfiber with three dimensions, at which the binding of target nanoparticles occurs. Based on the evanescent field confinement and surface enhancement by the nanointerface, the optical microfiber sensor overcomes its sensitivity limit, and enables the detection and sizing of the individual nanoparticles. The compact size and low optical power supply of the sensor confirm its suitability as a portable device for the real-time single-nanoparticle characterization, especially for the convenient evaluation of the ultrafine particles in the environment. This work opens up an approach to overcome the sensitivity limit of the optical microfibers, as long with stimulating the portable real-time single-nanoparticle detection and sizing.

Atmospheric particle-bound polycyclic aromatic hydrocarbons, n-alkanes, hopanes, steranes and trace metals: PM2.5 source identification, individual and cumulative multi-pathway lifetime cancer risk assessment in the urban environment

The occurrence of atmospheric fine particles (PM_2.5)-associated polycyclic aromatic hydrocarbons (PAHs), trace metals and organic molecular markers was investigated by conducting an intensive sampling campaign at the Eastern Mediterranean urban area of Nicosia (Cyprus). Sixty-two 24-hr PM_2.5 samples were collected and analyzed for fifty parent and alkylated PAHs, twenty-five long chain n-alkanes, seventeen hopanes and twelve steranes used for source apportionment. The same number and kind of samples were analyzed to determine twenty-eight trace metals. Emphasis was given to investigate the air levels of the scarcely monitored although highly carcinogenic PAHs such as dibenzopyrenes, dibenzoanthracenes, 7H-benzo[c]fluorene and 5-methyl-chrysene, not included in the USEPA's sixteen PAH priority list (USEPA-16). UNMIX receptor model was applied to apportion the sources of atmospheric emissions of the determined organic compounds and trace metals and evaluate their daily contributions to the corresponding PM_2.5 associated concentrations. For comparison purposes, principal component analysis with multiple linear regression (PCA/MLR) was also applied and its results are reported. The UNMIX receptor model, compared to PCA/MLR, offered a more precise source profile and more reliable daily mass source distributions by eliminating negative contributions. The individual and cumulative multi-pathway lifetime cancer risk (posed via inhalation, ingestion and dermal contact) by exposure to PM_2.5-associated USEPA-16 listed and non-listed PAHs and selected airborne trace metals (As, Cd, Co, Ni, and Pb) were assessed. To estimate the contribution of each emission source to the total cancer risk, multiple linear regression analysis was performed, using as independent variables the daily source mass contributions and as dependent variables the respective cancer risk units. The estimated total cumulative cancer risk comprising all toxic PAHs, besides those included in the priority list, and metals was higher than the USEPA's threshold by a factor of eight, denoting a potential risk for long-term exposure of a population in the urban environment.

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

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

Investigation by mass spectrometry and 32P post-labelling of DNA adducts formation from 1,2-naphthoquinone, an oxydated metabolite of naphthalene

Naphthalene is the simplest representative of polycyclic aromatic hydrocarbons (PAHs). It is detected as major pollutant in the different compartments of the environment. This compound is considered by the international agency for research on cancer (IARC), the specialized cancer agency of the World Health Organisation (WHO), as a possible carcinogenic (group 2B) since 2002, mainly based on studies on chronic inhalation in rodent by the national toxicology program of the U.S. department of health and human services. In humans, its main metabolites correspond to derivatives substituted in position and 1 and 2 as 1,2-naphthoquinone (1,2-NphQ). Based on previous studies, 1,2-NphQ is supposed to react with DNA to form mostly depurinating adducts, a possible initiating step of carcinogenicity. To confirm this potentiality, adducts were synthetized by the reaction of 1,2-NphQ with 2'-deoxyguanosine (2'-dG) in N,N-dimethylformamide (DMF), water and calf thymus DNA. 2'-dG adducts were analyzed by ³²P post-labelling, HPLC with ultra-violet detection and ultra-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). We found stable DNA adducts detected in DNA. We proposed a formation mechanism by a 1,4-Michael addition with 2'-dG. Adducts with 2'-deoxyxanthosine are formed after a spontaneous deamination of 2'-dG. These adducts are good candidates as biomarkers allowing evaluation of exposure to naphthalene and its derivatives in the development of pathologies such as cancer.

Inflammatory responses of urban air PM modulated by chemical composition and different air quality situations in Nanjing, China

The health risks of air pollutants and ambient particulate matter (PM) are widely known. PM composition and toxicity have shown substantial spatiotemporal variability. Yet, the connections between PM composition and toxicological and health effects are vaguely understood. This is a crucial gap in knowledge that needs to be addressed in order to establish air quality guidelines and limit values that consider the chemical composition of PM instead of the current assumption of equal toxicity per inhaled dose. Here, we demonstrate further evidence for varying toxicological effects of urban PM at equal mass concentrations, and estimate how PM composition and emission source characteristics influenced this variation. We exposed a co-culture model mimicking alveolar epithelial cells and macrophages with size-segregated urban ambient PM collected before, during, and after the Nanjing Youth Olympic Games 2014. We measured the release of a set of cytokines, cell cycle alterations, and genotoxicity, and assessed the spatiotemporal variations in these responses by factorial multiple regression analysis. Additionally, we investigated how a previously identified set of emission sources and chemical components affected these variations by mixed model analysis. PM-exposure induced cytokine signaling, most notably by inducing dose-dependent increases of macrophage-regulating GM-CSF and proinflammatory TNFα, IL-6, and IL-1β concentrations, modest dose-dependent increase for cytoprotective VEGF-A, but very low to no responses for anti-inflammatory IL-10 and immunoregulatory IFNγ, respectively. We observed substantial differences in proinflammatory cytokine production depending on PM sampling period, location, and time of day. The proinflammatory response correlated positively with cell cycle arrest in G1/G0 phase and loss of cellular metabolic activity. Furthermore, PM_0.2 caused dose-dependent increases in sub-G1/G0 cells, suggesting increased DNA degradation and apoptosis. Variations in traffic and oil/fuel combustion emissions contributed substantially to the observed spatiotemporal variations of toxicological responses.

Characterization of ambient PM1 at a suburban site of Agra: chemical composition, sources, health risk and potential cytotoxicity

The present study was conducted at a University campus of Agra to determine concentrations of crustal and trace elements in submicron mode (PM₁) particles to reveal sources and detrimental effects of PM₁-bound metals (Cr, Cd, Mn, Zn, As, Co, Pb, Cu and Ni) in samples collected in the foggy (1 December 2016-17 January 2017) and non-foggy periods (1 April 2016-30 June 2016). Samples were collected twice a week on preweighed quartz fibre filters (QM-A 47 mm) for 24 h using Envirotech APM 577 (flow rate 10 l min^-1). Mass concentration of PM₁ was 135.0 ± 28.2 and 54.0 ± 18.5 µg/m³ during foggy and non-foggy period, respectively; crustal and trace elements were 13 and 4% during foggy and 11 and 3% in the non-foggy period. Source identification by PCA (principal component analysis) suggested that biomass burning and coal combustion was the prominent sources in foggy period followed by resuspended soil dust, industrial and vehicular emission, whereas in non-foggy period resuspended soil dust was dominant followed by biomass burning and coal combustion, industrial and vehicular emissions. In both episodes, Mn has the highest Hq (hazard quotient) value and Cr has the highest IlcR (Incremental Lifetime Cancer Risk) value for both adults and children. In vitro cytotoxicity impact on macrophage (J774) cells was also tested using MTT assay which revealed decreasing cell viability with increasing particle mass.

Seasonal variability of chemical composition and mutagenic effect of organic PM2.5 pollutants collected in the urban area of Wrocław (Poland)

The objective of the study was the assessment of the mutagenicity of chemical pollutants adsorbed on suspended particulate matter with aerodynamic diameter < 2.5 μm (PM2.5) in the four seasons. Samples were collected from the urban agglomeration of Wroclaw, Poland and evaluated for mutagenicity using two Salmonella typhimurium strains TA98 and TA100 with and without metabolic activation with microsomal fraction S9. The work covered sampling of suspended dusts in four seasons: summer, spring, autumn and winter. The dust samples were collected on glass filters using air aspirator and the organic matter of PM2.5 was extracted using Soxhlet extractor. The levels of polycyclic aromatic hydrocarbon compounds (PAH), nitro-PAH and dinitro-PAH were determined in the extract. Variable degree of air pollution with mutagenic substances was determined at the selected study site. A greater, negative effect of chemical compounds on DNA was determined in dust samples collected in the autumn-winter season in comparison to samples collected in the spring-summer season. In the majority of tests, higher mutagenicity was obtained in analyses conducted on total extracts in comparison to tests conducted in the presence of PAH pollutant fractions. The obtained mutagenic ratio values pointed to the presence of chemical compounds with a character of both promutagens and direct mutagens. Samples collected in the autumn-winter season were observed to have a higher diversity of organic substances absorbed on PM2.5 dusts. Particular samples differed in the total content and percent contribution of particular PAHs, nitro-PAHs, and other organic compounds. In addition, the identified substances included compounds belonging to different chemical classes: aliphatic compounds, cycloalkanes, mono- and bicycling arenes, polycyclic arenes, compounds containing oxygen, nitrogen, and sulphur.

Circular RNA 406961 interacts with ILF2 to regulate PM2.5-induced inflammatory responses in human bronchial epithelial cells via activation of STAT3/JNK pathways

Fine particulate matter (PM_2.5) has been verified to augmented the incidence of pneumonia, asthma, pulmonary fibrosis, and other pulmonary diseases. Airway inflammation is the pathological basis of the respiratory system, and understanding the molecular mechanisms responsible for airway inflammation may thus support the diagnosis and treatment of respiratory diseases. In our study, human bronchial epithelial cells (BEAS-2B) were exposed to various concentrations of PM_2.5 for 48 h. PM_2.5 entered the cells, resulting in increased production of interleukin 6 (IL-6) and interleukin 8 (IL-8) and decreased the expression of circular RNA 406961 (circ_406961). Further, PM_2.5 with a concentration of 75 μg/mL was applied to mechanism study. Functional experiments further confirmed that circ_406961 inhibited PM_2.5-induced BEAS-2B cell inflammation. RNA pull-down and mass spectrometry showed that circ_406961 interacted with interleukin enhancer-binding factor 2 (ILF2), which could regulate phosphorylation of signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase 8 (MAPK8, JNK). Our studies showed that circ_406961 inhibited activation of STAT3/JNK pathways via interacting with ILF2 protein, thereby inhibiting the PM_2.5-induced inflammatory reaction.

Characteristics of Carbonaceous Matter in Aerosol from Selected Urban and Rural Areas of Southern Poland

The purpose of this study is to obtain a detailed picture of the spatial and seasonal variability of carbonaceous matter in southern Poland. Particulate matter (PM) samples from eight selected urban and rural background sites were analyzed for organic carbon (OC) and elemental carbon (EC) (thermal-optical method, “eusaar_2” protocol), and the content of secondary (SOC) and primary organic carbon (POC) was estimated. The OC and EC dynamics were further studied using each of the thermally-derived carbon fractions (OC1–4, PC, and EC1–4). Clear spatiotemporal variability of carbonaceous compounds concentrations was observed, with higher levels recorded during the heating season. The considered measurement sites differed particularly in the shares of SOC and POC, with higher values of POC contents especially in rural areas. In terms of the content of carbon fractions, the analyzed sites showed roughly the same characteristics, with PC, OC4, and OC2 as dominant fractions of OC and with clear dominance of EC3 and EC2 over other EC fractions. The results obtained as part of this work may be a valuable source of information about the actual status of the carbonaceous matter, which remains one of the least known components of atmospheric PM.

Influence of wood species on toxicity of log-wood stove combustion aerosols: a parallel animal and air-liquid interface cell exposure study on spruce and pine smoke

Background

Wood combustion emissions have been studied previously either by in vitro or in vivo models using collected particles, yet most studies have neglected gaseous compounds. Furthermore, a more accurate and holistic view of the toxicity of aerosols can be gained with parallel in vitro and in vivo studies using direct exposure methods. Moreover, modern exposure techniques such as air-liquid interface (ALI) exposures enable better assessment of the toxicity of the applied aerosols than, for example, the previous state-of-the-art submerged cell exposure techniques.

Methods

We used three different ALI exposure systems in parallel to study the toxicological effects of spruce and pine combustion emissions in human alveolar epithelial (A549) and murine macrophage (RAW264.7) cell lines. A whole-body mouse inhalation system was also used to expose C57BL/6 J mice to aerosol emissions. Moreover, gaseous and particulate fractions were studied separately in one of the cell exposure systems. After exposure, the cells and animals were measured for various parameters of cytotoxicity, inflammation, genotoxicity, transcriptome and proteome.

Results

We found that diluted (1:15) exposure pine combustion emissions (PM₁ mass 7.7 ± 6.5 mg m^− 3, 41 mg MJ^− 1) contained, on average, more PM and polycyclic aromatic hydrocarbons (PAHs) than spruce (PM₁ mass 4.3 ± 5.1 mg m^− 3, 26 mg MJ^− 1) emissions, which instead showed a higher concentration of inorganic metals in the emission aerosol. Both A549 cells and mice exposed to these emissions showed low levels of inflammation but significantly increased genotoxicity. Gaseous emission compounds produced similar genotoxicity and a higher inflammatory response than the corresponding complete combustion emission in A549 cells. Systems biology approaches supported the findings, but we detected differing responses between in vivo and in vitro experiments.

Conclusions

Comprehensive in vitro and in vivo exposure studies with emission characterization and systems biology approaches revealed further information on the effects of combustion aerosol toxicity than could be achieved with either method alone. Interestingly, in vitro and in vivo exposures showed the opposite order of the highest DNA damage. In vitro measurements also indicated that the gaseous fraction of emission aerosols may be more important in causing adverse toxicological effects. Combustion aerosols of different wood species result in mild but aerosol specific in vitro and in vivo effects.

Similar polycyclic aromatic hydrocarbon and genotoxicity profiles of atmospheric particulate matter from cities on three different continents

The extractable organic material (EOM) from atmospheric total suspended particles (TSP) contains several organic compounds including non-substituted polycyclic aromatic hydrocarbons (PAHs), alkyl-PAHs, and nitro-PAHs. These chemicals seem to be among the key drivers of TSP genotoxicity. We have shown previously that the mutagenic potencies of the EOM from Limeira, Stockholm, and Kyoto, cities with markedly different meteorological conditions and pollution sources are similar. Here we compare the profiles of non-substituted PAHs (27 congeners), alkyl-PAHs (15 congeners), and nitro-PAHs (7 congeners) from the same EOM samples from these cities. We also compared the genotoxicity profiles using comet and micronucleus assays in human bronchial epithelial cells. The profiles of PAHs, as well as the cytotoxic and genotoxic potencies when expressed in EOM, were quite similar among the studied cities. It seems that despite the differences in meteorological conditions and pollution sources of the cities, removal, mixing, and different atmospheric transformation processes may be contributing to the similarity of the PAHs composition and genotoxicity profiles. More studies are required to verify if this would be a general rule applicable to other cities. Although these profiles were similar for all three cities, the EOM concentration in the atmospheres is markedly different. Thus, the population of Limeira (∼10-fold more EOM/m³ than Stockholm and ∼6-fold more than Kyoto) is exposed to higher concentrations of genotoxic pollutants, and Kyoto's population is 1.5-fold more exposed than Stockholm's. Therefore, to reduce the risk of human exposure to TSP genotoxins, the volume of emissions needs to be reduced.

Exposure to Submicron Particles and Estimation of the Dose Received by Children in School and Non-School Environments

In the present study, the daily dose in terms of submicron particle surface area received by children attending schools located in three different areas (rural, suburban, and urban), characterized by different outdoor concentrations, was evaluated. For this purpose, the exposure to submicron particle concentration levels of the children were measured through a direct exposure assessment approach. In particular, measurements of particle number and lung-deposited surface area concentrations at “personal scale” of 60 children were performed through a handheld particle counter to obtain exposure data in the different microenvironments they resided. Such data were combined with the time–activity pattern data, characteristics of each child, and inhalation rates (related to the activity performed) to obtain the total daily dose in terms of particle surface area. The highest daily dose was estimated for children attending the schools located in the urban and suburban areas (>1000 mm2), whereas the lowest value was estimated for children attending the school located in a rural area (646 mm2). Non-school indoor environments were recognized as the most influential in terms of children’s exposure and, thus, of received dose (>70%), whereas school environments contribute not significantly to the children daily dose, with dose fractions of 15–19% for schools located in urban and suburban areas and just 6% for the rural one. Therefore, the study clearly demonstrates that, whatever the school location, the children daily dose cannot be determined on the basis of the exposures in outdoor or school environments, but a direct assessment able to investigate the exposure of children during indoor environment is essential.

Fifteen Years of Airborne Particulates in Vitro Toxicology in Milano: Lessons and Perspectives Learned

Air pollution is one of the world’s leading environmental causes of death. The epidemiological relationship between outdoor air pollution and the onset of health diseases associated with death is now well established. Relevant toxicological proofs are now dissecting the molecular processes that cause inflammation, reactive species generation, and DNA damage. In addition, new data are pointing out the role of airborne particulates in the modulation of genes and microRNAs potentially involved in the onset of human diseases. In the present review we collect the relevant findings on airborne particulates of one of the biggest hot spots of air pollution in Europe (i.e., the Po Valley), in the largest urban area of this region, Milan. The different aerodynamic fractions are discussed separately with a specific focus on fine and ultrafine particles that are now the main focus of several studies. Results are compared with more recent international findings. Possible future perspectives of research are proposed to create a new discussion among scientists working on the toxicological effects of airborne particles.

Quantification of primary and secondary sources to PM2.5 using an improved source regional apportionment method in an industrial city, China

Identifying and quantifying the major sources of atmospheric particulate matter (PM) is essential for the development of pollution mitigation strategies to protect public health. However, urban PM is affected by local primary emissions, transport, and secondary formation; therefore, advanced methods are needed to elucidate the complex sources and transport patterns. Here, an improved source apportionment method was developed by incorporating the receptor model, Lagrangian simulation, and emissions inventories to quantify PM_2.5 sources for an industrial city in China. PM_2.5 data including ions, metals, organic carbon, and elemental carbon were obtained by analyzing 1 year of sampling results at urban and rural sites. This method identified coal combustion (30.64%), fugitive dust (13.25%), and vehicles (12.51%) as major primary sources. Secondary sources, including sulfate, nitrate, and secondary organic aerosols also contributed strongly (25.28%-30.76% in total) over urban and rural areas. Hebei Province was the major regional source contributor (43.05%-57.51%) except for fugitive dust, on which Inner Mongolia had a greater impact (43.51%). The megacities of Beijing and Tianjin exerted strong regional impacts on the secondary nitrate and secondary organic aerosols factors, contributing 11.32% and 15.65%, respectively. Pollution events were driven largely by secondary inorganic aerosols, highlighting the importance of reducing precursor emissions at the regional scale, particularly in the Beijing-Tianjin-Hebei region. Overall, our results demonstrate that this novel method offers good flexibility and efficiency for quantifying PM_2.5 sources and regional contributions, and that it can be extended to other cities.

Quasi-ultrafine particles promote cell metastasis via HMGB1-mediated cancer cell adhesion

With increasingly severe air pollution, the aggravated health risks of particulate matter, especially ultrafine particles, are emerging as an urgent and sensitive topic. Considering the heterogeneity and complexity of ultrafine particles, there is insufficient evidence about their toxic effects and possible molecular mechanisms. To address this question, we analyzed the emission characteristics of quasi-ultrafine particles collected during winter in a typical coal-burning city, Taiyuan, and confirmed their contribution to lung cancer cell adhesion and metastasis. For the specific mechanism, we revealed that the endocytosis of quasi-ultrafine particles stimulated the release of HMGB1, induced NFκB-facilitated proinflammatory cytokine production through the interaction of HMGB1 with RAGE, and resulted in cancer-endothelial cell adhesion. These findings remind us of the potential effects of anthropogenic quasi-ultrafine particle pollution and provide a theoretical reference for the mitigation of tumorigenesis in a severe particulate matter contaminated environment.

Connecting the Oxidative Potential of Secondary Organic Aerosols with Reactive Oxygen Species in Exposed Lung Cells

It has been hypothesized that the cytotoxicity of secondary organic aerosols (SOA) is mediated through the formation of reactive oxygen species (ROS) in the exposed cells. Here, lung epithelial cells (A549) residing at the air-liquid interface were exposed to proxies of anthropogenic and biogenic SOA that were photochemically aged under varying nitrogen oxide (NOx) concentrations in an oxidation flow reactor. The total organic peroxides and ROS radical content in the SOA were quantified by the iodometric spectrophotometric method and by continuous-wave electron paramagnetic resonance. The effect of the exposure was evaluated by measuring cell viability and cellular ROS production following the exposure. The results demonstrate that SOA that aged in the absence of NOx contained more ROS than fresh SOA and were more toxic toward the cells, while varying NOx conditions had no significant influence on levels of the ROS content in fresh SOA and their toxicity. Analysis of ROS in the exposed cells using flow cytometry showed a similar trend with the total ROS content in the SOA. This study provides a first and direct observation of such association.

Assessment of genotoxic effects on elderly populations exposed to high traffic areas: Results for supporting public health surveillance

In urban areas with intense vehicular traffic, particulate matter in suspension, especially the fraction of particles with ultra-fine diameter, has been regarded as the main problem of chronic diseases in susceptible populations, such as the elderly. This study aimed to determine the genotoxic effects of exposure to air pollution evaluating the association between the frequencies of micronuclei (MN) and binucleated (BN) cells in exfoliated oral mucosa cells of elderly population and exposure conditions, considering the influence of traffic and concentration of PM in different aerodynamic diameters. Traffic of passenger vehicles, heavy duty trucks and environmental concentrations of Particulate Matter were measured twice a day during 28 days before biological sampling of oral mucosa from 154 participants living in areas of distinct levels of urban traffic. Data from this study showed that the group of participants living near road traffic exhibited higher MN cell frequency, when compared to the other groups of subjects. In addition, a canonical correlation analysis between environmental and genotoxicity variables analysis revealed that high concentrations of the particulate matter were correlated with intense traffic and the genotoxicity in exfoliated oral cells.

Cellular response and extracellular vesicles characterization of human macrophages exposed to fine atmospheric particulate matter

Exposure to fine atmospheric Particulate Matter (PM) is one of the major environmental causes involved in the development of inflammatory lung diseases, such as chronic obstructive pulmonary disease (COPD) or asthma. When PM is penetrating in the pulmonary system, alveolar macrophages represent the first line of defense, in particular by triggering a pro-inflammatory response, and also by their ability to recruit infiltrating macrophages from the bone marrow. The aim of this in vitro study was to evaluate the gene expression and cytokine production involved in the toxicological and inflammatory responses of infiltrating macrophages, as well as the Extracellular Vesicles (EVs) production, after their exposure to PM. The ability of these EVs to convey information related to PM exposure from exposed macrophages to pulmonary epithelial cells was also evaluated. Infiltrating macrophages respond to fine particles exposure in a conventional manner, as their exposure to PM induced the expression of Xenobiotic Metabolizing Enzymes (XMEs) such as CYP1A1 and CYP1B1, the enzymes involved in oxidative stress SOD2, NQO1 and HMOX as well as pro-inflammatory cytokines in a dose-dependent manner. Exposure to PM also induced a greater release of EVs in a dose-dependent manner. In addition, the produced EVs were able to induce a pro-inflammatory phenotype on pulmonary epithelial cells, with the induction of the release of IL6 and TNFα proinflammatory cytokines. These results suggest that infiltrating macrophages participate in the pro-inflammatory response induced by PM exposure and that EVs could be involved in this mechanism.

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.

Comparative mutagenic activity of atmospheric particulate matter from limeira, stockholm, and kyoto

Atmospheric particulate matter (PM) organic fractions from urban centers are frequently mutagenic for the Salmonella/microsome assay. This mutagenicity is related to both primary and secondary pollutants, and meteorological conditions have great influence on the secondary pollutant's formation. Our objective was to compare the mutagenicity of atmospheric total suspended particulates (TSP) from three cities with marked different meteorological conditions and TSP concentrations: Limeira (Brazil) with 99.0 μg/m³ , Stockholm (Sweden) with 6.2 μg/m³ , and Kyoto (Japan) with 28.0 μg/m³ . For comparison, we used the same batch of filters, sample extraction method, and Salmonella/microsome testing protocol with 11 strains of Salmonella with and without metabolic activation. Samples were collected during winter and pooled into one single extract representing each city. All samples were mutagenic for all tested strains, except for TA102. Based on the strain's selectivity, nitroarenes, polycyclic aromatic hydrocarbons, and aromatic amines play a predominant role in the mutagenicity of these samples. The mutagenic potencies expressed by mass of extracted organic material (EOM; revertants/μg EOM) were similar (~twofold difference) among the cities, despite differences in meteorological conditions and pollution sources. In contrast, the mutagenic potencies expressed by air volume (rev/m³ ) varied ~20-fold, with Limeira > Kyoto ≈ Stockholm. These results are the first systematic assessment of air mutagenicity from cities on three continents using the same protocols. The results confirm that the mutagenic potency expressed by EOM mass is similar regardless of continent of origin, whereas the mutagenic potency expressed by air volume can vary by orders of magnitude. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

Investigation on the near-field evolution of industrial plumes from metalworking activities

In a context where a significant fraction of the population lives near industrial areas, the main objectives of this study are to provide (a) new data on PM_2.5 chemical compositions, heavy-metal concentrations and trace gases released by metalworking activities and (b) new information on the near-field evolution (up to about a thousand meters) of such industrial plumes in terms of particle chemical composition and size distribution. For that purpose, a one-month field campaign was performed in an industrial area near the city of Dunkirk (Northern France), combining measurements of atmospheric dynamics and physico-chemical characterization of air masses. Comparisons between several elemental ratios (mainly Mn/Fe), particle size distributions and volatile organic compound (VOC) concentrations at the stacks and at a near-field site suggest that plumes of a ferromanganese alloy plant were quickly mixed with pollutants emitted by other sources (mainly other industries, possibly traffic and sea spray), in particular a neighboring steelworks, before reaching the sampling site. This led to the emergence of secondary particles related to condensation and/or aggregation phenomena inside the plumes. Metalworking emissions were also identified as a source of new particle formation, formed through the emission of gaseous precursors and their fast transformation and condensation, over a timescale of minutes before reaching the near-field site 800 m downwind. Ultrafine particles emitted at the stacks also quickly agglomerated to form larger particles before reaching the near-field site. These results show that, even over short distances, the chemical composition and size distribution of metalworking plumes may evolve rapidly and the characteristics of particles at the boundary of an industrial area (especially in contiguous urban areas) may differ from those emitted directly at the stacks.

Proinflammatory effects of dust storm and thermal inversion particulate matter (PM10) on human peripheral blood mononuclear cells (PBMCs) in vitro: a comparative approach and analysis

Particulate matter (PM) as the carcinogenic air pollutants can lead to aggravated health outcomes. Epidemiological studies demonstrated that PM can be engaged in different diseases such as cardiovascular, respiratory and cancer. The in vitro secretion of proinflammatory cytokines by human peripheral blood mononuclear cells (PBMCs) has been used to assess the effects of PM with an aerodynamic diameter < 10 μm (PM10). This study compared the proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and interleukin 1-beta (IL1-β) secretions of PBMCs exposed to PM10 of dust storm and inversion. We collected PM10 samples during the spring and autumn seasons in two locations. Isolated PBMCs were exposed separately to 50, 150, and 300 μg/ml of different type of PM10 for 4 and 24 h. The mean concentrations of TNF-α for the PM of dust storm and inversion were 6305.61 ± 2421 and 6651.74 ± 2820, respectively. Also the mean concentrations of IL1-β for the PM of dust storm and inversion were 556.86 ± 162 and 656.35 ± 196, respectively. Furthermore, these values for the production of IL-6 were 12,655 ± 5661 and 16,685 ± 8069, respectively. Although no significant difference was observed between the PM of dust storm and that of inversion with regard to PBMCs, the results showed a significant increase in the proinflammatory cytokine secretion of both PMs compared with the controls. Moreover, TNF-α, IL1-β, and IL-6 secreted in cells exposed to PM10 of dust storm were about 10 times more than the controls, these values for cells exposed to PM10 of inversion were around 10, 12, and 14 times more than the controls, respectively. It can be concluded that the PM10 of both dust storm and inversion can play a significant role in proinflammatory cytokine secretion due to its harmful effect on human health. Graphical abstractThis picture shows the Proinflammatory cytokine producing potential of PM10 with two sources (dust storm and urban air pollution) in exposure with human PBMCs in vitro.

Investigation and Comparison of In Vitro Genotoxic Potency of PM10 Collected in Rural and Urban Sites at Tehran in Different Metrological Conditions and Different Seasons

The particulate matter has become a serious health problem in some large cities in the world. These particles are a complex mixture of chemical compounds which change based on location and time and, consequently, can cause different health-related effects. The exact mechanism of the effect of these particles is not yet known for certain. However, it seems that numerous mechanisms through the production of ROS and, eventually, DNA destruction, which are related to a wide range of diseases, are among the causes of particles' health-related effects. The present study is aimed to evaluate and compare the genotoxicity potential of particles collected in Tehran, Iran, in urban and rural regions during spring and autumn as well as dusty and inversion conditions. These effects were examined using the comet assay on human pulmonary epithelial cells (A549). Results showed that all the particles had the potential for genotoxicity at the concentration used in this study (75,150 and 300 μg/ml). Moreover, DNA destruction changed with season, site, and even dusty and inversion atmospheric conditions. These changes mostly belonged to urban particles. In general, urban particles in autumn and, specifically, on days with inversion had higher genotoxicity (p < 0.01). Difference was observed between dusty and regular days so that regular days were more potent (p < 0.05). A strong correlation was observed between the effects of most PAH compounds and other metals such as Cr, Co, Cd, Mn, As, and also SO₄, which were mostly the result of combustion in vehicle engines in urban regions. No difference was observed for rural particles at different conditions and seasons.

Mutagenic and genotoxic effects induced by PM0.5 of different Italian towns in human cells and bacteria: The MAPEC_LIFE study

Particulate matter (PM) is considered an atmospheric pollutant that mostly affects human health. The finest fractions of PM (PM_2.5 or less) play a major role in causing chronic diseases. The aim of this study was to investigate the genotoxic effects of PM_0.5 collected in five Italian towns using different bioassays. The role of chemical composition on the genotoxicity induced was also evaluated. The present study was included in the multicentre MAPEC_LIFE project, which aimed to evaluate the associations between air pollution exposure and early biological effects in Italian children. PM₁₀ samples were collected in 2 seasons (winter and spring) using a high-volume multistage cascade impactor. The results showed that PM_0.5 represents a very high proportion of PM₁₀ (range 10-63%). PM_0.5 organic extracts were chemically analysed (PAH_s, nitro-PAH_s) and tested by the comet assay (A549 and BEAS-2B cells), MN test (A549 cells) and Ames test on Salmonella strains (TA100, TA98, TA98NR and YG1021). The highest concentrations of PAHs and nitro-PAHs in PM_0.5 were observed in the Torino, Brescia and Pisa samples in winter. The Ames test showed low mutagenic activity. The highest net revertants/m³ were observed in the Torino and Brescia samples (winter), and the mutagenic effect was associated with PM_0.5 (p < 0.01), PAH and nitro-PAH (p < 0.05) concentrations. The YG1021 strain showed the highest sensitivity to PM_0.5 samples. No genotoxic effect of PM_0.5 extracts was observed using A549 cells except for some samples in winter (comet assay), while BEAS-2B cells showed light DNA damage in the Torino, Brescia and Pisa samples in winter, highlighting the higher sensitivity of BEAS-2B cells, which was consistent with the Ames test (p < 0.01). The results obtained showed that it is important to further investigate the finest fractions of PM, which represent a relevant percentage of PM₁₀, taking into account the chemical composition and the biological effects induced.

Investigation of spatial and temporal variation of particulate matter in vitro genotoxicity and cytotoxicity in relation to the elemental composition

Even though the outdoor air pollution and its major component Particulate Matter (PM) are recently classified as human carcinogen, attempts to elucidate the underlying mechanisms of PM toxicity are still crucial and continuing with in vitro approaches in various environmental circumstances. Present study investigated the genotoxicity (Comet assay) and the cytotoxicity (lactate dehydrogenase (LDH) leakage and the water-soluble tetrazolium (WST-1) assays) of 30 daily PM_2.5 samples collected in the Kütahya province, to address their daily variability in effects with season (i.e. winter versus summer) and location (i.e. rural versus urban) using A549 human lung cancer epithelial cell line, as well as in relation to their chemical composition, specifically trace elements, organic carbon (OC) and elemental carbon (EC). The genotoxicity, measured by the percentage tail intensity (TI), of the daily PM_2.5 samples at the traffic dense urban station was higher than that of the rural site for 80% of the parallel days. The genotoxicity was significant in the winter at the urban and in the summer at the rural site. Cytotoxicity was the highest for the winter urban samples. The PM_2.5 mass, OC, and EC concentrations were not correlated to DNA damage, while there were correlations with Mn, Fe, Cu and Ba at the rural PM_2.5 samples, and Mn, Co and Ni at the urban samples, respectively. The present study is confirming that the complex composition of PM_2.5 originating from spatial and temporal changes can cause differences in the health effects.

Emissions and atmospheric processes influence the chemical composition and toxicological properties of urban air particulate matter in Nanjing, China

Ambient inhalable particulate matter (PM) is a serious health concern worldwide, but especially so in China where high PM concentrations affect huge populations. Atmospheric processes and emission sources cause spatial and temporal variations in PM concentration and chemical composition, but their influence on the toxicological characteristics of PM are still inadequately understood. In this study, we report an extensive chemical and toxicological characterization of size-segregated urban air inhalable PM collected in August and October 2013 from Nanjing, and assess the effects of atmospheric processes and likely emission sources. A549 human alveolar epithelial cells were exposed to day- and nighttime PM samples (25, 75, 150, 200, 300 μg/ml) followed by analyses of cytotoxicity, genotoxicity, cell cycle, and inflammatory response. PM_10-2.5 and PM_0.2 caused the greatest toxicological responses for different endpoints, illustrating that particles with differing size and chemical composition activate distinct toxicological pathways in A549 cells. PM_10-2.5 displayed the greatest oxidative stress and genotoxic responses; both were higher for the August samples compared with October. In contrast, PM_0.2 and PM_2.5-1.0 samples displayed high cytotoxicity and substantially disrupted cell cycle; August samples were more cytotoxic whereas October samples displayed higher cell cycle disruption. Several components associated with combustion, traffic, and industrial emissions displayed strong correlations with these toxicological responses. The lower responses for PM_1.0-0.2 compared to PM_0.2 and PM_2.5-1.0 indicate diminished toxicological effects likely due to aerosol aging and lower proportion of fresh emission particles rich in highly reactive chemical components in the PM_1.0-0.2 fraction. Different emission sources and atmospheric processes caused variations in the chemical composition and toxicological responses between PM fractions, sampling campaigns, and day and night. The results indicate different toxicological pathways for coarse-mode particles compared to the smaller particle fractions with typically higher content of combustion-derived components. The variable responses inside PM fractions demonstrate that differences in chemical composition influence the induced toxicological responses.

Indoor exposure to particles emitted by biomass-burning heating systems and evaluation of dose and lung cancer risk received by population

Homes represent a critical microenvironment in terms of air quality due to the proximity to main particle sources and the lack of proper ventilation systems. Biomass-fed heating systems are still extensively used worldwide, then likely emitting a significant amount of particles in indoor environments. Nonetheless, research on biomass emissions are limited to their effects on outdoor air quality then not properly investigating the emission in indoor environments. To this purpose, the present paper aims to evaluate the exposure to different airborne particle metrics (including both sub- and super-micron particles) and attached carcinogenic compounds in dwellings where three different heating systems were used: open fireplaces, closed fireplaces and pellet stoves. Measurements in terms of particle number, lung-deposited surface area, and PM fraction concentrations were measured during the biomass combustion activities, moreover, PM₁₀ samples were collected and chemically analyzed to obtain mass fractions of carcinogenic compounds attached onto particles. Airborne particle doses received by people exposed in such environments were evaluated as well as their excess lung cancer risk. Most probable surface area extra-doses received by people exposed to open fireplaces on hourly basis (56 mm² h^-1) resulted one order of magnitude larger than those experienced for exposure to closed fireplaces and pellet stoves. Lifetime extra risk of Italian people exposed to the heating systems under investigation were larger than the acceptable lifetime risk (10^-5): in particular, the risk due to the open fireplace (8.8 × 10^-3) was non-negligible when compared to the overall lung cancer risk of typical Italian population.

Particle-related exposure, dose and lung cancer risk of primary school children in two European countries

Schools represent a critical microenvironment in terms of air quality due to the proximity to outdoor particle sources and the frequent lack of proper ventilation and filtering systems. Moreover, the population exposed in schools (i.e. children) represents a susceptible population due to their age. Air quality-based studies involving students' exposure at schools are still scarce and often limited to mass-based particle metrics and may thus underestimate the possible effect of sub-micron particles and particle toxicity. To this purpose, the present paper aims to evaluate the exposure to different airborne particle metrics (including both sub- and super-micron particles) and attached carcinogenic compounds. Measurements in terms of particle number, lung-deposited surface area, and PM fraction concentrations were measured inside and outside schools in Barcelona (Spain) and Cassino (Italy). Simultaneously, PM samples were collected and chemically analysed to obtain mass fractions of carcinogenic compounds. School time airborne particle doses received by students in classrooms were evaluated as well as their excess lung cancer risk due to a five-year primary school period. Median surface area dose received by students during school time in Barcelona and Cassino resulted equal to 110mm² and 303mm², respectively. The risk related to the five-year primary school period was estimated as about 2.9×10^-5 and 1.4×10^-4 for students of Barcelona and Cassino, respectively. The risk in Barcelona is slightly higher with respect to the maximum tolerable value (10^-5, according to the U.S. Environmental Protection Agency), mainly due to toxic compounds on particles generated from anthropogenic emissions (mainly industry). On the other hand, the excess lung cancer risk in Cassino is cause of concern, being one order of magnitude higher than the above-mentioned threshold value due to the presence of biomass burning heating systems and winter thermal inversion that cause larger doses and great amount of toxic compounds on particles.

Current density distribution and optimization of the collection electrodes of a honeycomb wet electrostatic precipitator

Wet electrostatic precipitators (ESPs) demonstrate a robust adaptability for particulate matter control and have been confirmed to be a promising technology for removing particles and sulfuric acid aerosol from flue gas. Recent studies have shown that removing fine particles or sulfuric acid aerosol from wet ESPs requires further development. Among the components of wet ESPs, discharge electrode configurations are crucial for determining the performance of wet ESPs. This paper reports the corona discharge characteristics and removal performance of sulfuric acid aerosol using different discharge electrode configurations in a honeycomb wet ESP experimental system. Two key parameters, namely, V–I characteristics and current density distribution, with different discharge electrode geometries (e.g., electrode type, spike spacing, and spike length) and rotation angles, were investigated by using a novel electrical parameter measurement system to evaluate the effects of these parameters on corona discharge. The results showed that triple-spike and sawtooth electrodes exhibit the highest average current density. The average current density of the triple-spike electrode increased with the spike length from 10 mm to 20 mm, and the peak current density distribution on the collection electrode increased by 62.1%, but the current density decreased sharply away from the spike. Moreover, the average peak current density decreased by 30.1% when the spike spacing was 25 mm given the sharp point discharge suppression when spikes were significantly dense. The electrode configuration was optimized on the basis of the current density distribution. The highest removal efficiency of sulfuric acid aerosol was 99.2% at a specific collection area of 23.09 m² (m³ s⁻¹)⁻¹.

A novel electrical parameter measurement system was designed to measure and optimize the current density distribution of wet ESPs.