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... Study design and methods for toxicological analyses are described in more detail elsewhere. 17,31 Mouse macrophage cells (RAW264.7, ATCC, USA) were grown in RPMI 1640 medium supplemented with 10% heat inactivated fetal bovine serum, 2 mM L-glutamine, and 100 U mL −1 penicillin−streptomycin in a humid atmosphere of 5% CO 2 (37°C). ...
... The cells were suspended into 1 mL of PBS (Gibco, UK), and half of them were used in a propidium iodide exclusion assay, and the other half was fixed with ethanol (70% v/v, Altia, Finland) and stored at +4°C for DNA content analysis with flow cytometry (CyAn ADP, Beckman Coulter Inc., USA). For ROS analysis, another PM exposure experiment was done as described by Uski et al. 17 Flow Cytometry Analysis. Particle induced effects on cell cycle, total amount of propidium iodide (PI) positive cells (PI-exclusion assay), and the intracellular accumulation of reactive oxygen and nitrogen species were analyzed using a CyAn ADP (Beckman Coulter Inc., USA) cytometer with Summit software (version 4.3; Beckman Coulter Inc., USA). ...
... In the following toxicological analysis report, the particles are denoted as ZnO (Figure 2c), K 2 SO 4 (Figure 2b), K 2 SO 4 + Zn ( Figure 2d), K 2 CO 3 (Figure 2a), and wood combustion PM ( Figure 2e), according to the main chemical species analyzed for the samples. Wood combustion PM physicochemical data and toxicity are adopted from an earlier report by Uski et al. 17 All toxicological analyses were done with the mouse macrophage cell line, which provides a model to study the mechanisms activated in the cells of the first line immune defense against particles in lungs. ...
Article
Multiple studies show that particulate mass (PM) generated from incomplete wood combustion may induce adverse health issues in humans. Previous findings have shown that also the PM from efficient wood combustion may induce enhanced production on reactive oxygen species, inflammation and cytotoxicity in vitro and in vivo. Underlying factors of these effects may be traced back to volatile inorganic transition metals, especially zinc, which can be enriched in the ultrafine fraction of biomass combustion particulate emission. In this study nanoparticles composed of potassium, sulfur, and zinc, which are the major components forming inorganic fine PM, were synthesized and tested in vitro. In addition, in vitro toxicity of PM from efficient combustion of wood chips was compared with that of the synthesized particles. Cytotoxicity, cell cycle arrest, ROS generation and tumor necrosis factor alpha release were related to zinc concentration in PM. Potassium sulfate and potassium carbonate did not induce toxic responses. In the light of the provided data, it can be concluded that the zinc, enriched in wood combustion emissions, caused the toxicity in all the measured endpoints.
... There is a very limited amount of information available on the involvement of Zn in the toxicity of wood combustion emissions. Recently we have published in vivo and in vitro data pointing to a putative toxic role of Zn in emission PM 1 (particles b1 μm in aerodynamic diameter, PM 1 ) from residential wood combustion (Uski et al., 2012Uski et al., , 2014 Happo et al., 2013; Torvela et al., 2014b). This study now demonstrates that Zn is the factor in emission PM 1 from pellet combustion responsible for much of the toxicity detected in in vitro and in vivo tests. ...
... Moreover, severe cytotoxicity has been detected after treatment of several human and murine cell lines with ZnO NPs (Zhang et al., 2014 ). The present findings conform also our recent in vitro study showing cytotoxicity after exposure of RAW 264.7 macrophages with emission PM 1 from efficient wood chip combustion containing high amounts of transition metals, especially Zn (Uski et al., 2014). Moreover, a significant increase in lactate dehydrogenase (LDH) and total protein has been reported in mice intratracheally exposed to ZnCl 2 (Adamson et al., 2000). ...
... However, in our previous study we detected significant apoptosis with efficient combustion derived PM containing transition metals (e.g. Zn, Cr, Cd and Cu) (Uski et al., 2014). It may be that transition metals other than Zn may be able to promote more extensive apoptotic cell death. ...
... Some PAHs are human carcinogens with well-documented mechanisms of action (Baird et al. 2005). Uski et al. found that particles collected during intermediate and smouldering combustion contain more PAHs than particles from efficient combustion which correlated with genotoxicity but not cytotoxicity or oxidative stress in murine macrophages (Uski et al. 2014). Kocbach et al. investigated the effects of collected WSPs from different combustion conditions on a co-culture model. ...
... Many metal compounds (i.e. the respective salts and oxides) are well known for their cytotoxic and carcinogenic properties (Stohs and Bagchi 1995;Beyersmann and Hartwig 2008) and have been implicated in toxicity induced by combustion-derived particles (Fritsch-Decker et al. 2011;Diabaté et al. 2011). WSPs with high metal content triggered more acute toxicity and ROS formation compared to other WSPs in rat macrophages (Uski et al. 2014). Zinc is usually the predominant trace metal in WSPs. ...
... Interestingly, efficient combustion conditions, although reducing overall emissions, lead to enrichment of Zn in the emitted particle mass. It has recently indeed been shown that Zn-rich WSPs sampled from an efficient combustion source increased ROS formation and toxicity in murine macrophages and inflammation in murine lungs, while particles derived from less efficient combustion did not (Happo et al. 2013;Uski et al. 2014). ...
Article
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Indoor air pollution is associated with increased morbidity and mortality. Specifically, the health impact of emissions from domestic burning of biomass and coal is most relevant and is estimated to contribute to over 4 million premature deaths per year worldwide. Wood is the main fuel source for biomass combustion and the shift towards renewable energy sources will further increase emissions from wood combustion even in developed countries. However, little is known about the constituents of wood smoke and biological mechanisms that are responsible for adverse health effects. We exposed A549 lung epithelial cells to collected wood smoke particles and found an increase in cellular reactive oxygen species as well as a response to bioavailable polycyclic aromatic hydrocarbons. In contrast, cell vitality and regulation of the pro-inflammatory cytokine interleukin-8 were not affected. Using a candidate approach, we could recapitulate WSP toxicity by the combined actions of its constituents soot, metals and PAHs. The soot fraction and metals were found to be the most important factors for ROS formation, whereas the PAH response can be mimicked by the model PAH benzo[a]pyrene. Strikingly, PAHs adsorbed to WSPs were even more potent in activating target gene expression than B[a]P individually applied in suspension. As PAHs initiate multiple adverse outcome pathways and are prominent carcinogens, their role as key pollutants in wood smoke and its health effects warrants further investigation. The presented results suggest that each of the investigated constituents soot, metals and PAHs are major contributors to WSP toxicity. Mitigation strategies to prevent adverse health effects of wood combustion should therefore not only aim at reducing the emitted soot and PAHs but also the metal content, through the use of more efficient combustion appliances, and particle precipitation techniques, respectively.
... [21] For example, a RAW264.7 macrophage cell line was used to investigate the toxic mechanisms of PM generated under different biomass combustion conditions. [22] It was found that PM emitted during smoldering and intermediate combustion periods had relatively small impacts on cellular metabolic activity but caused a relatively high amount of DNA damage compared to particles emitted through efficient combustion. [22] The effects of ambient PM on the secretion of tumor necrosis factor-a (TNF-a) and interleukin-1b (IL-1b) from cultured alveolar macrophages were studied, and a dose-dependent effect on the inflammatory macrophages was observed. ...
... [22] It was found that PM emitted during smoldering and intermediate combustion periods had relatively small impacts on cellular metabolic activity but caused a relatively high amount of DNA damage compared to particles emitted through efficient combustion. [22] The effects of ambient PM on the secretion of tumor necrosis factor-a (TNF-a) and interleukin-1b (IL-1b) from cultured alveolar macrophages were studied, and a dose-dependent effect on the inflammatory macrophages was observed. [23] The cell line RAW264.7 has also been adopted to investigate the cell toxicity mechanism of ambient PM in Los Angeles. ...
Article
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The pollution of particulate matter (PM) is of great concern in China and many other developing countries. It is generally recognized that the toxicity of PM is source and property dependent. However, the relationship between PM properties and toxicity is still not well understood. In this study, PM samples from direct emissions of wood, straw, coal, diesel combustion, cigarette smoking and ambient air were collected and characterized for their physicochemical properties. Their expression of intracellular reactive oxygen species (ROS) and levels of inflammatory cytokines (i.e., tumor necrosis factor-α (TNF-α)) was measured using a RAW264.7 cell model. Our results demonstrated that the properties of the samples from different origins exhibited remarkable differences. Significant increases in ROS were observed when the cells were exposed to PMs from biomass origins, including wood, straw and cigarettes, while increases in TNF-α were found for all the samples, particularly those from ambient air. The most important factor associated with ROS generation was the presence of water-soluble organic carbon, which was extremely abundant in the samples that directly resulted from biomass combustion. Metals, endotoxins and PM size were the most important properties associated with increases in TNF-α expression levels. The association of the origins of PM particles and physicochemical properties with cytotoxic properties is illustrated using a cluster analysis.
... Emissions from modern pellet boilers consist mainly of inorganic salts and only very small amounts of PAHs, OC and EC, but they can contain relevant amounts of metal oxides (Wiinikka et al., 2013). These metals have been linked to cytotoxic and inflammatory effects in vitro and in vivo (Warheit et al. 2009, Tapanainen et al. 2012, Uski, et al. 2014. The exact chemical properties of the PM emissions from modern pellet boilers are largely determined by the chemical composition of the pellets used in them . ...
... The chemical composition of this sample was dominated by ash-forming inorganic components, such as Na, K and SO4 2-. No associations between these components and sample toxicity have been found , Uski et al., 2014 in earlier studies either. Contrarily, the PM1 samples from the log wood combustions caused generally higher adverse effects than the pellet combustion sample. ...
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Residential heating contributes significantly to particulate air pollution. While emissions from fossil fuel heating have steadily declined in the last decade, those from biomass heating have constantly risen. Here particulate emissions from different scale heating systems fired with fuel oil, wood and alternative biomass were analyzed for their adverse health effects using in vitro models. Toxicity of emissions was greater if they contained high amounts of carbonaceous compounds and metals.
... Thus, for bark-containing fuels, there is also a higher relative zinc content in the fine fly ashes than for stem wood, which is due to the lower release factor of alkali metals in bark combustion. This enhanced zinc concentration likely increases the lung toxicity of inhaled particles, as shown in our previous studies [38,39]. Fig. 4b presents the most abundant metal emissions for the socalled ''dirty dozen" metals according to the European Waste Incineration Directive (Directive 2000/76/EC, 2000). ...
... Zinc formed the majority of the total PM 1 heavy metal emissions, and the zinc emissions were especially high in bark combustion. This is environmentally important since zinc particles were recently identified as the major constituent responsible for human health-related toxicity of emissions from automatic wood boilers [38,39]. Lastly, the usage of peat was found to considerably increase arsenic emissions. ...
... Cell viability and proliferation assays 2.5.1. MTT-assay The metabolic activity of the cells' mitochondria and endoplasmic reticulum was measured by the MTT (3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)-assay as described by Uski et al. (2014). ...
... Improvements in modern pellet-boilers have almost completely eliminated variation in combustion conditions and the emissions from these boilers generally contain only small amounts of PAHcompounds, but marked amounts of metal oxides . Especially zinc and zinc oxide can be found in the emissions, and it has been proven that these compounds can be responsible for short-term cytotoxic and inflammatory responses (Uski et al., 2014;Warheit et al., 2009). The emissions from the pellet boiler in this study contained very low amounts of PAHs and larger amounts of zinc. ...
Article
The use of wood instead of oil fuels in heating systems is strongly encouraged in many countries. Yet it is unknown to what extent such a large-scale change from oil to wood fuels in heating systems would contribute to any negative health effects from their emissions. We compared the toxicological properties of particulate matter (PM) emissions from wood and oil fuels from two small-scale and two medium-scale heating systems. To assess whether oil or wood combustion emissions cause adverse effects and which PM emissions' effects are more profound, we measured cell viability and proliferation, inflammatory markers, as well as DNA damage in RAW264.7 mouse macrophages. We found that the medium-scale oil-fueled heating system induced a dose-dependent increase of DNA damage, short-term cytotoxic effects, and a cell cycle arrest in the G2/M-phase. We did not detect an induction of DNA damage by the medium-scale wood-fired system. However, we detected significant short-term cytotoxicity. We found that both oil and wood combustion emission samples from the small-scale heating systems induced DNA damage. However, the short-term cytotoxic effects were greater for the PM emissions from the oil-fired heating system. PM mass emissions differed significantly between the tested heating systems. The lowest emissions, 0.1 mg/MJ, were produced by the small-scale oil-fired heating system; the highest emissions, 20.3 mg/MJ, by the medium-scale oil-fired heating system. The wood-fired heating systems' PM mass emissions were in between these concentrations, complicating the direct comparison of the emissions' health related toxic effects. Conclusively, our results indicate that the emissions from both the small- and the medium-scale wood-fueled heating systems cause overall less cytotoxicity and DNA damage in a cell model than the emissions from the corresponding oil-fueled heating systems. Hence, controlled wood-fueled heating systems may be good alternatives to heating systems fired with fuel oil.
... By filtering particles out of the sample, exposure to the gaseous phase can be studied separately from the particulate effects. In vitro studies show that biomass combustion particles from several sources can cause cytotoxicity, inflammation and genotoxicity in several cell types [29][30][31][32][33]. We have reported similar responses in our previous in vivo studies [13,34,35]. ...
... For instance, the NRF-2-mediated oxidative stress pathway was significantly regulated in both the transcript and proteome analyses after in vitro and in vivo combustion emission aerosol exposure. This activation could be caused by several compounds, including PAHs, transition metals or elemental carbon [33,67]. In our experiment, all of the above mentioned factors were detected in the aerosols, indicating the possibility of ROS induction. ...
Article
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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.
... It is important to understand the partitioning of metals between the bottom and fly ashes. First, trace metals in the fine particle fraction can significantly contribute to the toxic properties of particles [34][35][36]. Second, some trace metals (mainly Pb and Zn) are also known to promote the corrosion of heat exchangers [37]. ...
... Ultrafine particles (particle diameter b100 nm) are particularly harmful to human health, since they have a sufficiently small size to penetrate the membranes of the respiratory tract and enter the bloodstream or be transported by the olfactory nerves to the brain (Pöschl, 2005). Thus, health effects caused by particulate matter are dependent on its physical and chemical properties (Bølling et al., 2009), which have a clear relation with combustion appliances, fuels and combustion conditions (Happo et al., 2013;Kaivosoja et al., 2013;Lamberg et al., 2011;Uski et al., 2014;Vu et al., 2012). Aerosols generated by biomass burning, under poor combustion conditions, consist mainly of carbonaceous compounds, mostly OC and smaller amounts of EC (Reid et al., 2005;Tissari et al., 2008), while during efficient combustion conditions, particles are mainly formed by ash related material Torvela et al., 2014). ...
... The results from the cell exposures are in agreement with other in vitro and in vivo (animal) studies with wood combustion-derived particles, in which the PAHrich particles have been shown to induce decreased cell metabolic activity and viability [37][38][39], with an absence of a pronounced inflammatory response [40][41][42]. Moreover, significant DNA damage in vitro has been associated with the organic carbon (OC) content of PM samples [43][44][45]. ...
Article
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Background Smoke from combustion of biomass fuels is a major risk factor for respiratory disease, but the underlying mechanisms are poorly understood. The aim of this study was to determine whether exposure to wood smoke from incomplete combustion would elicit airway inflammation in humans. Methods Fourteen healthy subjects underwent controlled exposures on two separate occasions to filtered air and wood smoke from incomplete combustion with PM1 concentration at 314 μg/m³ for 3 h in a chamber. Bronchoscopy with bronchial wash (BW), bronchoalveolar lavage (BAL) and endobronchial mucosal biopsies was performed after 24 h. Differential cell counts and soluble components were analyzed, with biopsies stained for inflammatory markers using immunohistochemistry. In parallel experiments, the toxicity of the particulate matter (PM) generated during the chamber exposures was investigated in vitro using the RAW264.7 macrophage cell line. Results Significant reductions in macrophage, neutrophil and lymphocyte numbers were observed in BW (p < 0.01, <0.05, <0.05, respectively) following the wood smoke exposure, with a reduction in lymphocytes numbers in BAL fluid (<0.01. This unexpected cellular response was accompanied by decreased levels of sICAM-1, MPO and MMP-9 (p < 0.05, <0.05 and <0.01). In contrast, significant increases in submucosal and epithelial CD3+ cells, epithelial CD8+ cells and submucosal mast cells (p < 0.01, <0.05, <0.05 and <0.05, respectively), were observed after wood smoke exposure. The in vitro data demonstrated that wood smoke particles generated under these incomplete combustion conditions induced cell death and DNA damage, with only minor inflammatory responses. Conclusions Short-term exposure to sooty PAH rich wood smoke did not induce an acute neutrophilic inflammation, a classic hallmark of air pollution exposure in humans. While minor proinflammatory lymphocytic and mast cells effects were observed in the bronchial biopsies, significant reductions in BW and BAL cells and soluble components were noted. This unexpected observation, combined with the in vitro data, suggests that wood smoke particles from incomplete combustion could be potentially cytotoxic. Additional research is required to establish the mechanism of this dramatic reduction in airway leukocytes and to clarify how this acute response contributes to the adverse health effects attributed to wood smoke exposure. Trial registration NCT01488500
... Emissions from the combustion of standard softwood pellets generally contain only minimal amounts of carcinogenic PAH compared to emissions from fossil fuel combustion. However, they can contain considerable amounts of transition metals, namely zinc (Jalava et al. 2012; Tapanainen et al. 2011;Uski et al. 2014). In cases of almost complete combustion, zinc has been found to be the cause of most of the cytotoxic effects seen in vitro and in vivo studies (Leskinen findings, as the PM 1 sample from the standard softwood combustion contained the highest amount of Zn and also induced the largest cytotoxic responses. ...
Article
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Wood pellets have been used in domestic heating appliances for three decades. However, because the share of renewable energy for heating will likely rise over the next several years, alternative biomass fuels, such as short-rotation coppice or energy crops, will be utilized. We tested particulate emissions from the combustion of standard softwood pellets and three alternative pellets (poplar, Miscanthus sp., and wheat straw) for their ability to induce inflammatory, cytotoxic, and genotoxic responses in a mouse macrophage cell line. Our results showed clear differences in the chemical composition of the emissions, which was reflected in the toxicological effects. Standard softwood and straw pellet combustion resulted in the lowest PM1 mass emissions. Miscanthus sp. and poplar combustion emissions were approximately three times higher. Emissions from the herbaceous biomass pellets contained higher amounts of chloride and organic carbon than the emissions from standard softwood pellet combustion. Additionally, the emissions of the poplar pellet combustion contained the highest concentration of metals. The emissions from the biomass alternatives caused significantly higher genotoxicity than the emissions from the standard softwood pellets. Moreover, straw pellet emissions caused higher inflammation than the other samples. Regarding cytotoxicity, the differences between the samples were smaller. Relative toxicity was generally highest for the poplar and Miscanthus sp. samples, as their emission factors were much higher. Thus, in addition to possible technical problems, alternative pellet materials may cause higher emissions and toxicity. The long-term use of alternative fuels in residential-scale appliances will require technological developments in both burners and filtration.Copyright © 2016 American Association for Aerosol Research
... The environmental and health effects of particulate matter are dependent on its physical and chemical properties. Although good combustion conditions lead to lowest particulate emissions, several studies have reported highest oxidative stress, inflammatory, cytotoxic and genotoxic activities and decreased cellular metabolic activity from particles generated under efficient combustion conditions rather than particles resulting from inefficient combustion (Happo et al., 2013;Uski et al., 2014). The size of the particles generated during combustion is a very important factor. ...
Article
Interest in renewable energy sources has increased in recent years due to environmental concerns about global warming and air pollution, reduced costs and improved efficiency of technologies. Under the European Union (EU) energy directive, biomass is a suitable renewable source. The aim of this study was to experimentally quantify and characterize the emission of particulate matter (PM2.5) resulting from the combustion of two biomass fuels (chipped residual biomass from pine and eucalypt), in a pilot-scale bubbling fluidized bed (BFB) combustor under distinct operating conditions. The variables evaluated were the stoichiometry and, in the case of eucalypt, the leaching of the fuel. The CO and PM2.5 emission factors were lower when the stoichiometry used in the experiments was higher (0.33 ± 0.1 g CO/kg and 16.8 ± 1.0 mg PM2.5/kg, dry gases). The treatment of the fuel by leaching before its combustion has shown to promote higher PM2.5 emissions (55.2 ± 2.5 mg/kg, as burned). Organic and elemental carbon represented 3.1 to 30 wt.% of the particle mass, while carbonate (CO32 −) accounted for between 2.3 and 8.5 wt.%. The particulate mass was mainly composed of inorganic matter (71% to 86% of the PM2.5 mass). Compared to residential stoves, BFB combustion generated very high mass fractions of inorganic elements. Chloride was the water soluble ion in higher concentration in the PM2.5 emitted by the combustion of eucalypt, while calcium was the dominant water soluble ion in the case of pine.
... Airborne particles arising from residential combustion have harmful effects on public health [9][10][11]. Some studies have been conducted to evaluate the toxicity and mutagenicity of particulate matter resulting from domestic biomass combustion [12][13][14]. Epidemiologic studies have linked fine particulate air pollution with negative health effects like respiratory and heart diseases or even premature dead [15,16]. Several studies have shown that the submicrometer sized particles (b 1 μm) are predominant in PM emissions from this source [17]. ...
... More data are available on the acute toxicity of wood stove emissions using submerged exposure. While the majority of researchers report several biological effects, but no acute toxicity of collected wood smoke particles ( Kocbach Bølling et al., 2009), some found toxic effects on murine macrophages after high particle doses, particularly from efficient combustions ( Jalava et al., 2012;Uski et al., 2014). The doses which induced toxicity under submerged conditions assuming that all particles in the suspension deposit on the cells still are a factor of 2-10 higher than particle doses achieved with our ALI experimental set-up. ...
Article
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In vitro toxicity testing of airborne particles usually takes place in multi-well plates, where the cells are exposed to a suspension of particles in cell culture medium. Due to the artefacts caused by particle collection and preparation of suspensions, the air-liquid interface (ALI) exposure is challenging this conventional exposure technique to become the method of choice. The ALI technique allows for direct sampling of an aerosol and exposure of cell cultures to airborne particles. At the same time, it reflects the physiological conditions in the lung to a greater extent. So far, the available ALI systems have mostly been laboratory set-ups of the single components. Here, we present a mobile and complete system providing all process technology required for cell exposure experiments at dynamic aerosol sources. The system is controlled by a human machine interface (HMI) with standard routines for experiments and internal testing to assure reproducibility. It also provides documentation of the exposure experiment regarding process parameters and measured doses. The performance of this system is evaluated using fluorescein-sodium dosimetry, which is also used to determine the factor of dose enhancement by optional electrostatic deposition. The application of the system is shown for two different technical aerosol sources: wood smoke particles emitted by a household log wood stove and emissions from a ship diesel engine. After exposure of lung cells, cytotoxicity and gene regulation on a genome-wide scale were analysed.
... In 2010, wood amounted for 38%, 50% and 30% of renewable energy consumption in the three most heavily populated EU countries Germany, France and United Kingdom [1]. Previous studies has been shown that wood combustion contributes significantly to indoor and outdoor air pollution, especially to ambient air fine particle concentrations [2][3][4], known for inducing adverse health effects [5][6][7]. In addition to particulate emissions, wood combustion is also a significant source of volatile organic compound (VOC) emissions which are known for their deleterious effect on human health and as precursors for atmospheric secondary organic aerosol formation [8][9][10]. ...
... 1 In residential heating, even the most modern biomass combustion technologies may generate considerably higher fine particle emissions than fossil fuel-operated appliances, 2 and there is some evidence that fine particles from complete wood combustion also can be harmful to human health. 3,4 As a consequence, there is a clear need to develop methods for the reduction of particle emissions from small-scale biomass-fired appliances. ...
Article
There is a need to develop feasible PM reduction methods for small-scale biomass combustion installations due to their high PM emissions. In this work, we evaluated the potential of a novel prototype small-scale heat exchanger (PHX) designed for high particle emission reduction. In addition, the role of the different deposition mechanisms in such an application was studied. The PHX was connected to a wood-fired unit, and both particle and gas emissions and thermal efficiencies were evaluated. In addition, a scrubbing system, for keeping the PHX walls clean, was connected to the system. The thermal efficiency reached over 100% due to the recovered heat by water condensation, when operating the PHX at temperatures typical for floor heating. The usage of the scrubber for cleaning the PHX increased the PM1 emissions, compared to the heat exchanger (HX) reference case, but prevented fouling of the PHX tubes. The PHX was found to have fine particle precipitation efficiencies of 45% and 48%, depending on applied water temperatures. The particle reduction was mainly a result of thermophoretic deposition in the heat exchanger tubes.
... Although good combustion conditions lead to lowest particulate emissions, several studies have reported highest oxidative stress, inflammatory, cytotoxic and genotoxic activities and decreased cellular metabolic activity from particles generated under efficient combustion conditions rather than particles resulting from smouldering combustion (Happo et al., 2013;Uski et al., 2014). Besides the health effects, biomass combustion particles are efficient cloud condensation nuclei and can influence the formation of precipitation (P€ oschl, 2005;Rose et al., 2010). ...
... Studies have associated long-term exposure to smoke from the burning of firewood with reduced pulmonary function, the development of asthma and chronic bronchitis, heart problems, and premature mortality. Shortterm exposure has been associated with acute bronchitis, asthma attacks, worsening of pulmonary diseases, and greater susceptibility to respiratory infections (Naeher et al. 2007; Díaz- Robles et al. 2014;Uski et al. 2014;Shao et al. 2016). In Chile, estimated health costs associated with the combustion of firewood and PM emissions are between US$270 and US$364 million/year (CNE 2008). ...
Article
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This study analyzed air quality in terms of the concentrations of sub-10 µm and sub-2.5 µm particulate matter (PM10 and PM2.5, respectively) recorded at 23 automated public monitoring stations located in 16 cities in south-central Chile (Rancagua, Rengo, San Fernando, Curicó, Talca, Maule, Chillán and Chillán Viejo, Gran Concepción, Coronel, Los Ángeles, Temuco and Padre Las Casas, Valdivia, Osorno, Puerto Montt, Coyhaique and Punta Arenas). In each city, the spatial and temporal distributions of the PM10 and PM2.5 concentrations were recorded at daily, monthly, and yearly intervals. Air quality was evaluated by comparing the annual average concentrations and the maximum daily concentrations of PM10 and PM2.5 with the World Health Organization (WHO) and national standards. The results showed that the limits established in the WHO guidelines and the national standards were systematically exceeded at all the study sites. The highest concentrations of both PM10 and PM2.5 were observed during the fall and winter months (April to September), i.e., the cold period of the year, whereas the lowest concentrations were recorded in the spring and summer months (October to March), i.e., the warm period of the year. Analysis of variance (ANOVA) of the data collected in the warm and cold periods showed that all stations in this study exhibited statistically significant differences between these two periods. During cold periods, burning firewood for heating produces emissions that are a main source of PM. Furthermore, firewood is primarily burned at night when the lowest temperatures occur and when the atmospheric conditions are generally unfavorable for dispersion; thus, pollution accumulates above cities. The levels of PM2.5, the most important type of pollution, exceeded the limit established by the WHO on at least one-third of the days of the year (>120 days) in the cities of Rancagua, Rengo, Curicó, Talca, Chillan, Los Angeles, Temuco, Valdivia, Osorno, Puerto Montt and Coyhaique. Therefore in the cities in southern Chile, the population is exposed to particulate matter concentrations that can have negative health impacts. To improve the air quality conditions in the studied cities, research on heaters and combustion techniques should be promoted, home energy efficiency should be increased to reduce firewood consumption, the firewood certification process should be improved at the national level with a better auditing processes, and the introduction of alternative fuels should be considered for greater energy efficiency at competitive costs.
... Many studies underlined that the type of combustion appliance has an important role on the toxicological effects of PM emissions (Canha et al., 2016;Corsini et al., 2017;Jalava et al., 2012;Tapanainen et al., 2011;Vu et al., 2012). Additionally, the fuel burned (Arif et al., 2017;Canha et al., 2016;Corsini et al., 2017;Kasurinen et al., 2017;Vu et al., 2012) and the combustion conditions (Canha et al., 2016;Jalava et al., 2010;Uski et al., 2014;Vu et al., 2012) were also investigated. ...
Article
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.
... It was shown by some authors that the toxicity of the PM emission is influenced by the combustion quality and that particles emitted during incomplete combustion are more toxic than those emitted during complete combustion [20,21]. There are only very few studies [1,14,22,23] dealing with the influence of ESP on the particle composition and the resulting health effects of the PM still released into the atmosphere after the flue gas has passed the precipitator. ...
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Many studies showed that there are associations between particulate matter (PM) emissions and negative health effects. Sources for particulate matter PM emissions are, in addition to industry and traffic, residential wood combustion. Such PM emissions consist typically of non-combustible impurities contained naturally within the wood fuels (e.g., ash). Additionally, heavy metals from the wood fuel and/or polycyclic aromatic hydrocarbons (PAHs) formed during incomplete combustions may condense on the surface of these particulate matter and may increase the toxicity of these particles. To reduce negative health effects, wood combustion appliances are forced to emit less PM emissions. This may lead to an increased use of electrostatic precipitators to meet the valid threshold values. Against this background, the overall goal of this paper is it to compare biological effects of PM emissions released under full- and partial-load conditions of a wood pellet boiler with and without a flue gas treatment with an electrostatic precipitator in bacterial assays. The results show that PM emissions emitted under full-load conditions show a lower cytotoxic potential than those collected under partial load. No difference for the genotoxicity between full-load and partial-load conditions could be identified. However, significantly lower genotoxicity during full-load operation and precipitation but higher genotoxicity during partial load and precipitation have been found. Conclusively, the results indicate that the PM emissions emitted under full-load conditions show overall less cytotoxicity and genotoxicity than the emissions from partial-load operation. The PAH concentration doubles between full load and partial load with separator and quadruples between full load and partial load without precipitator.
... Moreover, the contents of the easily volatile metals Zn, Pb, and Cd in emissions increased for wood fuels (standard softwood pellets, poplar). However, they can contain considerable amounts of transition metals, namely zinc [57][58][59] . In cases of just about complete combustion, zinc is the reason behind most of the cytotoxic studies [60][61][62] . ...
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Industrial development and increased energy requirements have led to high consumption of fossil fuels. Thus, environmental pollution has become a profound problem. Every year, a large amount of agro-industrial, municipal and forest residues are treated as waste, but they can be recovered and used to produce thermal and electrical energy through biological or thermochemical conversion processes. Among the main types of agro-industrial waste, soluble coffee residues represent a significant quantity all over the world. Silver skin and spent coffee grounds (SCG) are the main residues of the coffee industry. The many organic compounds contained in coffee residues suggest that their recovery and use could be very beneficial. Indeed, thanks to their composition, they can be used in the production of biodiesel, as a source of sugar, as a precursor for the creation of active carbon or as a sorbent for the removal of metals. After a careful evaluation of the possible uses of coffee grounds, the aim of this research was to show a broad characterization of coffee waste for energy purposes through physical and chemical analyses that highlight the most significant quality indexes, the interactions between them and the quantification of their importance. Results identify important tools for the qualification and quantification of the effects of coffee waste properties on energy production processes. They show that (SCG) are an excellent raw material as biomass, with excellent values in terms of calorific value and low ash content, allowing the production of 98% coffee pellets that are highly suitable for use in thermal conversion systems. Combustion tests were also carried out in an 80kWth boiler and the resulting emissions without any type of abatement filter were characterized.
... Furthermore, the increased inflammatory response was better correlated with the ash component of emissions, more prevalent in newer technologies, than with PAH concentrations, emitted in higher concentrations in the older technologies. Uski et al. (2014) compared the toxicity of PM from smoldering and efficient combustion in heating appliances and found that, while the PM emitted under smoldering conditions caused greater DNA damage and cell death, those emitted from more efficient combustion were more effective in decreasing metabolic activity and causing oxidative stress. Leskinen et al. (2014) reported that the PM emissions from more efficient wood combustion (higher temperatures) caused more cell death, which they attributed to the high concentrations of ash and metals. ...
Article
Light-absorbing organic particulate matter (PM), or brown carbon (BrC), may constitute an important fraction of combustion PM. Here, we investigate the effect of combustion conditions on the molecular sizes of BrC, their light-absorption properties, and their cytotoxicity. We used toluene in a combustion reactor with highly controlled conditions to produce two different types of BrC under two conditions corresponding to smoldering and near-flaming combustion, with temperatures of 670 °C and 1035 °C, respectively. We performed online measurements of the size distributions and light-absorption properties of the BrC. The BrC produced at 1035 °C was more light absorbing, with an imaginary component of the refractive index at 532 nm (k532) an order of magnitude larger than that of the BrC produced at 670 °C. We also collected samples for offline chemical characterization using laser desorption ionization (LDI) mass spectrometry. The LDI mass spectra showed that the BrC produced at 1035 °C was composed of species with significantly larger molecular sizes than the BrC produced at 670 °C. Using human lung epithelial cells, we conducted in vitro cytotoxicity analysis on the two types of BrC with doses ranging from 3.5 to 136.0 μg of BrC/ml. After 24-h exposure, the viability of the cells was assessed using a WST-8 assay. The cytotoxicity analysis showed that, for both BrC samples, the cells exhibited a clear dose-dependent response with significant BrC cytotoxicity that plateaued at the higher doses. However, while the viability of cells exposed to the BrC produced at 1035 °C reached a minimum of around 65% at the highest dose, the BrC produced at 670 °C proved to be significantly more toxic, with the viability dropping asymptotically to 25%. The results presented here suggest that organic PM of smaller molecular sizes produced under lower temperature, smoldering combustion could be significantly more toxic than those of larger molecular sizes produced under higher temperature, flaming conditions. The use of a single-molecule fuel in a highly controlled combustion setup distinguishes this work from experiments that rely on real-life sources and combustion setups, where different combustion conditions could be occurring simultaneously and clouding the conclusions.
... We have previously reported that PM released by cashew nut roasting generates genotoxic effects in a plant model ) and in exposed workers . However, despite the establishment of a causal relationship between exposure to different biomass burning pollutants and DNA damage is already well-known (Corsini et al., 2013;Danielsen et al., 2011;de Oliveira Alves et al., 2014;de Oliveira Galvão et al., 2018;Dong et al., 2017;Peixoto et al., 2019;S anchez-P erez et al., 2009;Uski et al., 2014), the underlying molecular mechanism involved in the genotoxicity observed remains unclear and needs to be elucidated. ...
Article
Approximately 3 billion people world-wide are exposed to air pollution from biomass burning. Herein, particulate matter (PM) emitted from artisanal cashew nut roasting, an important economic activity worldwide, was investigated. This study focused on: i) chemical characterization of polycyclic aromatic hydrocarbons (PAHs) and oxygenated (oxy-) PAHs; ii) intracellular levels of reactive oxygen species (ROS); iii) genotoxic effects and time- and dose-dependent activation of DNA damage signaling, and iv) differential expression of genes involved in xenobiotic metabolism, inflammation, cell cycle arrest and DNA repair, using A549 lung cells. Among the PAHs, chrysene, benzo[a]pyrene (B[a]P), benzo[b]fluoranthene, and benz[a]anthracene showed the highest concentrations (7.8-10 ng/m3), while benzanthrone and 9,10-anthraquinone were the most abundant oxy-PAHs. Testing of PM extracts was based on B[a]P equivalent doses (B[a]Peq). IC50 values for viability were 5.7 and 3.0 nM B[a]Peq at 24 h and 48 h, respectively. At these low doses, we observed a time- and dose-dependent increase in intracellular levels of ROS, genotoxicity (DNA strand breaks) and DNA damage signaling (phosphorylation of the protein checkpoint kinase 1 - Chk1). In comparison, effects of B[a]P alone was observed at micromolar range. To our knowledge, no previous study has demonstrated an activation of pChk1, a biomarker used to estimate the carcinogenic potency of PAHs in vitro, in lung cells exposed to cashew nut roasting extracts. Sustained induction of expression of several important stress response mediators of xenobiotic metabolism (CYP1A1, CYP1B1), ROS and pro-inflammatory response (IL-8, TNF-α, IL-2, COX2), and DNA damage response (CDKN1A and DDB2) was also identified. In conclusion, our data show high potency of cashew nut roasting PM to induce cellular stress including genotoxicity, and more potently when compared to B[a]P alone. Our study provides new data that will help elucidate the toxic effects of low-levels of PAH mixtures from air PM generated by cashew nut roasting.
... Several studies related the exposure to PM emitted from biomass burning with DNA damage (Corsini et al., 2013;Danielsen et al., 2011;de Oliveira Alves et al., 2017de Oliveira Galvão et al., 2018Dong et al., 2017;Longhin et al., 2016;Uski et al., 2014). A study carried out by Kašuba et al. (2012) reported increase in frequency of apoptotic, necrotic cells, and MN in peripheral blood lymphocytes of pottery-glaze workers. ...
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The ceramics manufacturing in northeastern Brazil has been dominated by archaic procedures, in which the consumption of native wood extracted from the natural Caatinga biome is used as fuel in the process of clay burning. The aims of this study were to assess particulate matter (PM) physico-chemical characteristics and atmospheric modeling analyses, as well as the genotoxic potential using Tradescantia micronucleus assay associated to the emissions from the ceramic industry complex. The average PM concentration for all analyzed periods was 65 ± 26.2 μg m ⁻³ for total suspended particles, and 23.4 ± 19.9 μg m ⁻³ for PM 10 . Furthermore, the morphological analysis showed particles typical from biomass burning, such as soot carbon, spherical organic carbon and inorganic ash. The major elemental components were identified as Ba, Zn, Al, K, and Ca. Enrichment factor values showed that Ba and Zn were highly enriched in the ceramic production areas. Modeling analysis suggested that these particles can reach regions farther away from the emission sources. The frequency of micronuclei was 2.7–7.2 times higher than in the non-exposed area for all analyzed months. Moreover, a negative correlation between micronucleus and wind speed (r = −0.91; p = 0.04) was verified. This study addressed the effects of PM emitted from the ceramic industry on DNA damage and showed its genotoxic effects in meiotic cells despite the PM 10 concentrations being within the upper WHO limits. The particulate air pollutants emitted from the wood burning by ceramics manufacturing are able to induce DNA damage in T. pallida, suggesting a required higher control of these air pollution emissions.
... Such lower metal content, together with the relatively high PAH content may be re- sponsible of the reduced cytotoxicity and the slightly increased apopto- tic event in charcoal and wood exposed cells. This is also in agreement with previous studies, showing that high concentrations of PAHs in urban PM are strongly associated with apoptosis ( Uski et al., 2014;Yang et al., 2016), and that PAH-coated carbon particles are able to in- duce apoptosis in tracheal epithelial cells, while pristine particles are not ( Lindner et al., 2017). All together, these observations suggest that the particle-adsorbed chemicals might activate different cell death mechanisms. ...
Article
Biomass combustion significantly contributes to indoor and outdoor air pollution and to the adverse health effects observed in the exposed populations. Besides, the contribution to toxicity of the particles derived from combustion of different biomass sources (pellet, wood, charcoal), as well as their biological mode of action, are still poorly understood. In the present study, we investigate the toxicological properties of PM10 particles emitted indoor from a stove fueled with different biomasses. PM10 was sampled by gravimetric methods and particles were chemically analyzed for Polycyclic Aromatic Hydrocarbons (PAHs) and elemental content. Human lung A549 cells were exposed for 24 h to 1–10 μg/cm² PM and different biological endpoints were evaluated to comparatively estimate the cytotoxic, genotoxic and pro-inflammatory effects of the different PMs. Pellet PM decreased cell viability, inducing necrosis, while charcoal and wood ones mainly induced apoptosis. Oxidative stress-related response and cytochrome P450 enzymes activation were observed after exposure to all the biomasses tested. Furthermore, after pellet exposure, DNA lesions and cell cycle arrest were also observed. The severe genotoxic and pro-necrotic effects observed after pellet exposure were likely the consequence of the high metal content. By administering the chelating agent TPEN, the genotoxic effects were indeed rescued. The higher content in PAHs measured in wood and charcoal PMs was likely the reason of the enhanced expression of metabolizing and oxidative stress-related enzymes, like CYP1B1 and HO-1, and the consequent increase in apoptotic cell death. These data suggest that combustion particles from different biomass sources may impact on lung cells according to different pathways, finally producing different toxicities. This is strictly related to the PM chemical composition, which reflects the quality of the combustion and the fuel in particular. Further studies are needed to clarify the role of particle dimension and the molecular mechanisms behind the harmful effects observed.
... The environmental and health effects of APM are related to their physical and chemical properties. Some studies have indicated a relation between particles generated from combustion processes and inflammatory, cytotoxic and genotoxic effects and also oxidative stress (Happo et al., 2013;Uski et al., 2014). Hata et al. (2014) identified that the size range of particles resulting from biomass combustion is < 100 nm (specifically 0.43 μm), which contains high levels of toxic polycyclic aromatic hydrocarbons (PAHs) and water-soluble organic carbon (WSOC). ...
Article
The inorganic and organic geochemistry of aerosol particulate matter (APM) was studied in a major olive grove area from Southwest Europe (Baena, Spain). The biomass consists of olive tree branches and the solid waste resulting of the olive oil production. Moreover, high PM10 levels were obtained (31.5 μg m− 3), with two days of exceedance of the daily limit of 50 μg m− 3 (2008/50/CE; EU, 2008) during the experimental period. A high mean levoglucosan concentration was obtained representing up 95% of the total mass of the isomers analysed (280 ng m− 3), while galactosan and mannosan mean concentrations were lower (8.64 ng m− 3 and 7.86 ng m− 3, respectively). The contribution of wood smoke in Baena was estimated, representing 19% of OC and 17% of OM total mass. Positive matrix factor (PMF) was applied to the organic and inorganic aerosols data, which has permitted the identification of five source categories: biomass burning, traffic, mineral dust, marine aerosol and SIC (secondary inorganic compounds). The biomass burning category reached the highest mean contribution to the PM10 mass (41%, 17.6 μg m− 3). In light of these results, the use of biomass resulting from the olive oil production for residential heating and industry must be considered the most important aerosol source during the winter months. The results of this paper can be extrapolated to other olive oil producing areas in the Mediterranean basin. Therefore, a fuller understanding of this type of biomass combustion is required in order to be able to establish appropriate polices and reduce the environmental impact on the population.
... These toxic effects range from increased short-term morbidity in individuals with preexisting respiratory and cardiovascular disease to excess mortality rates over life-long exposure durations [15,16]. Given the extreme chemical and physical heterogeneity of TRP, however, it is not clear which components or mixtures are most responsible for driving the observed adverse responses [17][18][19][20], nor which specific biological pathways contribute to PM-specific disease etiology [20][21][22][23][24][25]. Metabolomics may provide much needed insight into these gaps that traditional exposure assessments conducted to date have been unable to address. ...
Article
Introduction: Advances in the development of high-resolution metabolomics (HRM) have provided new opportunities for their use in characterizing exposures to environmental air pollutants and air pollution-related disease etiologies. Exposure assessment studies have considered blood, breath, and saliva as biological matrices suitable for measuring responses to air pollution exposures. The current study examines comparability among these three matrices using HRM and explored their potential for measuring mobile source air toxics. Methods: Four participants provided saliva, exhaled breath concentrate (EBC), and plasma before and after a 2-hour road traffic exposure. Samples were analyzed on a Thermo Scientific QExactive MS system in positive electrospray ionization (ESI) mode and resolution of 70,000 FHWM with C18 chromatography. Data were processed using apLCMS and xMSanalyzer on the R statistical platform. Results: The analysis yielded 7,110, 6,019, and 7,747 reproducible features in plasma, EBC, and saliva, respectively. Correlations were moderate-to-strong (R = 0.41 - 0.80) across all pairwise comparisons of feature intensity within profiles, with the strongest between EBC and saliva. The associations of mean intensities between matrix pairs were positive and significant, controlling for subject and sampling time effects. Six out of 20 features shared in all three matrices putatively matched a list of known mobile-source air toxics. Conclusions: Plasma, saliva, and EBC have largely comparable metabolic profiles measurable through HRM. These matrices have the potential to be used in identification and measurement of exposures to mobile source air toxics, though further, targeted study is needed.
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The bioactivity of the extractable organic matter (EOM) of particulate matter (PM) exhausted from major urban combustion sources, including residential heating installations (wood-burning fireplace and oil-fired boiler) and vehicular exhaust from gasoline and diesel cars), was investigated in vitro by employing multiple complementary cellular and bacterial assays. Cytotoxic responses were investigated by applying the MTT ((3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide)) bioassay and the lactate dehydrogenase (LDH) release bioassay on human lung cells (MRC-5). Sister Chromatids Exchange (SCE) genotoxicity was measured on human peripheral lymphocytes. Lipid peroxidation potential via reactive oxygen species (ROS) was evaluated on E. coli bacterial cells by measuring the malondialdehyde (MDA) end product. Furthermore, the DNA damage induced by the organic PM fractions was evaluated by the reporter (β-galactosidase) gene expression assay in the bacterial cells, and, by examining the fragmentation of chromosomal DNA on agarose gel electrophoresis. The correlations between the source PM-induced biological endpoints and the PM content in polycyclic aromatic hydrocarbons (PAHs), as typical molecular markers of combustion, were investigated. Fireplace wood smoke particles exhibited by far the highest content in total and carcinogenic PAHs followed by oil boilers, diesel and gasoline emissions. However, in all bioassays, the total EOM-induced toxicity, normalized to PM mass, was highest for diesel cars equipped with Diesel Particle Filter (DPF). No correlation between the toxicological endpoints and the PAHs content was observed suggesting that cytotoxicity and genotoxicity are probably driven by other extractable organic compounds than the commonly measured unsubstituted PAHs. Clearly, further research is needed to elucidate the role of PAHs in the biological effects induced by both, combustion emissions, and ambient air particles.
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Experimental results are presented on the emissions from a single combustion chamber stove burning wood, coal and processed fuels. This technique was used to permit comparisons to be made of the influence of different fuel types without it being influenced by the effects of secondary combustion. Measurements were made of CO, NOx and fine particulates during the major phases of combustion, namely flaming and smouldering. Measurements of the particulates were made in two ways: firstly using a gravimetric total particulate measurement and secondly using a cyclone technique to give PM2.5 and PM10 size fractions. Smoke emissions from the different fuels were very dependent on the phase of combustion especially for the total particulate results, where flaming phase emissions were much higher than in the smouldering phase. It was found that the particulate emission factors for the wood fuels were dependent on the volatile content whilst the coals followed a different pattern. NOx was linearly dependent on the fuel-N content for all the fuel types, but the relationship for biomass is different from that for coal. CO emissions were very dependent on the combustion phase.
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Nanomaterials (NM) exhibit novel physicochemical properties that determine their interaction with biological substrates and processes. Recent nano-technological advances are leading to wide usage of metallic nanoparticles (NPs) in various fields. However, the increasing use of NPs has led to their release into environment and the toxicity of NPs on human health has become a concern. Moreover, there are inadvertently generated metallic NPs which are formed during various human activities (e.g. metal processing and energy production). Unfortunately, there are still widespread controversies and ambiguities with respect to the toxic effects and mechanisms of metallic NPs, e.g. metal oxides including ZnO.
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The Ministry of the Environment of the Czech Republic within the Operational Programme Environment of the European Union (EU) has supported a ‘grant to replace old boilers’ from 2015 to 2020. The aim was to replace outdated, non-ecological, solid-fuel boilers with modern low-emission boilers (for the combustion of biomass, coal, or a combination), heat pumps, gas boilers, or solar systems. All heat sources must comply with the Ecodesign Directive of the EU. According to the Air Protection Act in the Czech Republic, commencing in 2022, outdated boilers of the 1st and 2nd emission classes will no longer be operable in households. The grant also aimed to reduce particulate matter (PM), organic gaseous compounds, and CO and NOx emissions. Our goal was to compare the PM emissions of four boilers: an outdated overfire boiler (B1), an outdated boiler with down-draft combustion (B2), a new gasification boiler (B3), and a new automatic boiler (B4). A Dekati low-pressure cascade impactor was used to determine the mass concentration of individual dust fractions; a scanning mobility particle sizer SMPS 3936 was utilized to determine the particle size distributions of the dust particles. Dry and wet spruce wood and wood pellets were combusted. Regarding the mass concentration of the PM and specific emissions (SE) of individual size fractions, they were much higher in boilers of older types (B1 and B2), while the reduction in SE of PM was very significant in boilers of newer types (B3 and B4). However, the SE of ultrafine particles (PM0.1) from the newer boilers remained in a range similar to that of B1 at Pmin and B2.
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Fine particles are the most important type of pollutant affecting urban air quality. Recent studies have highlighted the relevance for health effects of the zinc component of these particles. Zinc is traditionally associated with industrial and waste combustion plant emissions, although not covered by current regulations (e.g. the EU Waste Incineration Directive). However, pure wood combustion also produces substantial amounts of zinc particles. In this study, pure wood pellet fuels doped with three doses of Zn powder were combusted in a small grate boiler. The emissions were then analysed by a broad array of techniques to shed light on the health-related properties of particles originating from Zn-rich fuel combustion. In addition, reference pellets without Zn doping (during efficient and poor combustion conditions) were studied.
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Toxicological characterisation of combustion emissions in vitro are often conducted with macrophage cell lines, and the majority of these experiments are based on responses measured at 24 h after the exposure. The aim of this study was to investigate how significant role time course plays on toxicological endpoints that are commonly measured in vitro. The RAW264.7 macrophage cell line was exposed to PM1 samples (150 μg/ml) from biomass combustion devices representing old and modern combustion technologies for 2, 4, 8, 12, 24 and 32 h. After the exposure, cellular metabolic activity, cell membrane integrity, cellular DNA content, DNA damage and production of inflammatory markers were assessed. The present study revealed major differences in the time courses of the responses, statistical differences between the studied samples mostly limiting to differences between modern and old technology samples. Early stage responses consisted of disturbances in metabolic activity and cell membrane integrity. Middle time points revealed increases in chemokine production, whereas late-phase responses exhibited mostly increased DNA-damage, decreased membrane integrity and apoptotic activity. Altogether, these results implicate that the time point of measurement has to be considered carefully, when the toxicity of emission particles is characterised in in vitro study set-ups.
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(https://doi.org/10.1016/j.atmosenv.2017.05.019) Inhalation of particulate matter (PM) from residential biomass combustion is epidemiologically associated with cardiovascular and pulmonary diseases. This study investigates PM0.4-1 emissions from combustion of commercial Miscanthus straw (MS), softwood chips (SWC) and beech wood chips (BWC) in a domestic-scale boiler (40 kW). The PM0.4-1 emitted during combustion of the MS, SWC and BWC were characterized by ICP-MS/OES, XRD, SEM, TEM, and DLS. Cytotoxicity and genotoxicity in human alveolar epithelial A549 and human bronchial epithelial BEAS-2B cells were assessed by the WST-1 assay and the DNA-Alkaline Unwinding Assay (DAUA). PM0.4-1 uptake/translocation in cells was investigated with a new method developed using a confocal reflection microscope.
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A series of photo-oxidation smog chamber experiments were performed to investigate the primary emissions and secondary aerosol formation from two different log wood burners and a residential pellet burner under different burning conditions: starting and flaming phase. Emissions were sampled from the chimney and injected into the smog chamber leading to primary organic aerosol (POA) concentrations comparable to ambient levels. The composition of the aerosol was measured by an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and black carbon (BC) instrumentation. The primary emissions were then exposed to xenon light to initiate photo-chemistry and subsequent secondary organic aerosol (SOA) production. After correcting for wall losses, the average increase in organic matter (OM) concentrations by SOA formation for the starting and flaming phase experiments with the two logwood burners was found to be a factor of 4.1 ± 1.4 after five hours of aging. No SOA formation was observed for the stable burning phase of the pellet burner. The startup emissions of the pellet burner showed an increase in OM concentration by a factor of 3.3. Average emission factors of BC + POA + SOA, calculated from CO2 emission, were found to be in the range of 0.04 to 3.9 g kg-1 wood for the stable burning pellet burner and an old log wood burner during startup respectively. SOA contributed significantly to the ion C2H4O2+ at mass to charge ratio m/z 60, a commonly used marker for primary emissions of wood burning. The primary organic emissions from the three different burners showed a wide range in O/C atomic ratio (0.19-0.60) for the starting and flaming conditions, which also increased during aging. Primary wood burning emissions have a rather low relative contribution at m/z 43 (f43) to the total organic mass spectrum. The non-oxidized fragment C3H7+ has a considerable contribution at m/z 43 for the fresh OA with an increasing contribution of the oxygenated ion C2H3O+ during aging. After five hours of aging, the OA has a rather low C2H3O+ signal for a given CO2+ fraction, possibly indicating a higher ratio of acid to non-acid oxygenated compounds in wood burning OA compared to other OOA.
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Inflammation is regarded as an important mechanism behind mortality and morbidity experienced by cardiorespiratory patients exposed to urban air particulate matter (PM). Small-scale biomass combustion is an important source of particulate air pollution. In this study, we investigated association between inflammatory responses and chemical composition of PM(1) emissions from seven different small-scale wood combustion appliances representing old and modern technologies. Healthy C57Bl/6J mice were exposed by intratracheal aspiration to single dose (10 mg/kg) of particulate samples. At 4 and 18 h after the exposure, bronchoalveolar lavage fluid (BALF) as well as serum was collected for subsequent analyses of inflammatory indicators (interleukin (IL)-6, IL-1β, IL-12, and IL-10; tumor necrosis factor-α (TNF-α); keratinocyte-derived chemoattractant (KC), and interferon-γ (IFN-γ)) in multiplexing assay. When the responses to the PM(1) samples were compared on an equal mass basis, the PM from modern technology appliances increased IL-6, KC, and IL-1β levels significantly in BALF at 4 and 18 h after the exposure. In contrast, these responses were seen only at 4 h time point in serum. Increased cytokine concentrations correlated with metal-rich ash related compounds which were more predominant in the modern technology furnaces emissions. These particles induced both local and systemic inflammation. Instead, polycyclic hydrocarbon (PAH) rich PM(1) samples from old technology (OT) evoked only minor inflammatory responses. In conclusion, the combustion technology largely affects the toxicological and chemical characteristics of the emissions. The large mass emissions of old combustion technology should be considered, when evaluating the overall harmfulness between the appliances. However, even the small emissions from modern technologies may pose significant toxic risks.
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Background Exposure to particulate matter (PM) has been linked to several adverse cardiopulmonary effects, probably via biological mechanisms involving inflammation. The pro-inflammatory potential of PM depends on the particles’ physical and chemical characteristics, which again depend on the emitting source. Wood combustion is a major source of ambient air pollution in Northern countries during the winter season. The overall aim of this study was therefore to investigate cellular responses to wood smoke particles (WSPs) collected from different phases of the combustion cycle, and from combustion at different temperatures. Results WSPs from different phases of the combustion cycle induced very similar effects on pro-inflammatory mediator release, cytotoxicity and cell number, whereas WSPs from medium-temperature combustion were more cytotoxic than WSPs from high-temperature incomplete combustion. Furthermore, comparisons of effects induced by native WSPs with the corresponding organic extracts and washed particles revealed that the organic fraction was the most important determinant for the WSP-induced effects. However, the responses induced by the organic fraction could generally not be linked to the content of the measured polycyclic aromatic hydrocarbons (PAHs), suggesting that also other organic compounds were involved. Conclusion The toxicity of WSPs seems to a large extent to be determined by stove type and combustion conditions, rather than the phase of the combustion cycle. Notably, this toxicity seems to strongly depend on the organic fraction, and it is probably associated with organic components other than the commonly measured unsubstituted PAHs.
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Particulate matter (PM) has been identified as a major environmental pollutant causing severe health problems. Large amounts of the harmful particulate matter (PM) are emitted from residential wood combustion, but the toxicological properties of wood combustion particles are poorly known. To investigate chemical and consequent toxicological characteristics of PM(1) emitted from different phases of batch combustion in four heating appliances. Mouse RAW264.7 macrophages and human BEAS-2B bronchial epithelial cells were exposed for 24 h to different doses (15-300 µg/mL) of wood combustion particles. After the exposure, cytotoxicity, genotoxicity, production of the inflammatory mediators (TNF-α and MIP-2) and effects on the cell cycle were assessed. Furthermore, the detected toxicological responses were compared with the chemical composition of PM(1) samples including PAHs, metals and ions. All the wood combustion samples exerted high cytotoxicity, but only moderate inflammatory activity. The particles emitted from the inefficient phase of batch combustion in the sauna stove (SS) induced the most extensive cytotoxic and genotoxic responses in mammalian cells. Polycyclic aromatic hydrocarbons (PAHs) and other organic compounds in PM(1) samples might have contributed to these effects. Instead, water-soluble metals seemed to participate in the cytotoxic responses triggered by the particles from more efficient batch combustion in the masonry heaters. Overall, the toxicological responses were decreased when the combustion phase was more efficient. Efficiency of batch combustion plays a significant role in the harmfulness of PM even under incomplete wood combustion processes.
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Several studies have shown that combustion-derived fine particles cause adverse health effects. Previous toxicological studies on combustion-derived fine particles have rarely involved multiple endpoints and a detailed characterization of chemical composition. In this study, we developed a novel particle sampling system for toxicological and chemical characterization (PSTC), consisting of the Dekati Gravimetric Impactor (DGI) and a porous tube diluter. Physico-chemical and toxicological properties of the particles emitted from various combustion sources were evaluated in two measurement campaigns. First, the DGI was compared with the High-Volume Cascade Impactor (HVCI) and to the Dekati Low-Pressure Impactor (DLPI), using the same dilution system and the same sampling conditions. Only small differences were observed in the mass size distributions, total particulate matter (PM), and particulate matter with diameter smaller than 1 um (PM(1)) concentrations and geometric mass mean diameters (GMMD) between these three impactors. Second, the PSTC was compared with the HVCI sampling system, which has been optimal for collection of particulate samples for toxicological and chemical analyses. Differences were observed in the mass size distributions, total PM and PM(1) emissions, and GMMDs, probably due to the different sampling and dilution methods as well as different sampling substrates which affected the behavior of semi-volatile and volatile organic compounds. However, no significant differences were detected in the in vitro measurements of cytotoxicity between the samples collected with the PSTC and the HVCI systems. In measurements of genotoxicity, significant differences between the two sampling systems were seen only with the particles emitted from the sauna stove. In conclusion, due to compact size, PSTC is an applicable method for use in particle sampling as part of the toxicological and chemical characterization of particulate emissions from different combustion sources. It offers some advantages compared to the previously used high-volume sampling methods including compactness for field measurements, simple preparation of sample substrates and high extraction efficiency.
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Atmospheric ultrafine particles (diameter < 0.1 μm) are under study by inhalation toxicologists to determine whether they pose a threat to public health, yet, little is known about the chemical composition of ultrafine particles in the atmosphere of cities. In the present work, the number concentration, size distribution, and chemical composition of atmospheric ultrafine particles is determined under wintertime conditions in Pasadena, CA, near Los Angeles. These experiments are conducted using a scanning differential mobility analyzer, laser optical counter, and two micro-orifice impactors. Samples are analyzed to create a material balance on the chemical composition of the ultrafine particles. The number concentration of ultrafine particles in the size range 0.017 < d_p < 0.1 μm, analyzed over 24-h periods, is found to be consistently in the range 1.3 × 10^4 ± 8.9 × 10^3 particles cm^(-3) air. Ultrafine particle mass concentrations are in the range 0.80−1.58 μg m^(-3). Organic compounds are the largest contributors to the ultrafine particle mass concentration. A small amount of sulfate is present in these particles, at concentrations too low to tell whether it exists as unneutralized sulfuric acid. Iron is the most prominent transition metal found in the ultrafine particles. These data may assist the health effects research community in constructing realistic animal or human exposure studies involving ultrafine particles.
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Although some consensus has emerged among the scientific and regulatory communities that the urban ambient atmospheric mix of combustion related pollutants is a determinant of population health, the relative toxicity of the chemical and physical components of this complex mixture remains unclear. Daily mortality rates and concurrent data on sizefractionated particulate mass and gaseous pollutants were obtained in eight of Canada's largest cities from 1986 to 1996 inclusive in order to examine the relative toxicity of the components of the mixture of ambient air pollutants to which Canadians are exposed. Positive and statistically significant associations were observed between daily variations in both gas- and particulate-phase pollution and daily fluctuations in mortality rates. The association between air pollution and mortality could not be explained by temporalvariation in either mortality rates or weather factors. Fine particulate mass (less than 2.5 μm in average aerometric diameter) was a stronger predictor of mortality than coarse mass (between 2.5 and 10 μm). Size-fractionated particulate mass explained 28% of the total health effect of the mixture, with the remaining effects accounted for by the gases. Forty-seven elemental concentrations were obtained for the fine and coarse fraction using nondestructive x-ray fluorescence techniques. Sulfate concentrations were obtained by ion chromatography. Sulfate ion, iron, nickel, and zinc from the fine fraction were most strongly associated with mortality. The total effect of these four components was greater than that for fine mass alone, suggesting that the characteristics of the complex chemical mixture in the fine fraction maybe a better predictor of mortality than mass alone. However,the variation in the effects of the constituents of the fine fraction between cities was greater than the variation in the mass effect, implying that there are additional toxic components of fine particulate matter not examined in this study whose concentrations and effects vary between locations. One of these components, carbon, represents half the mass of fine particulate matter. We recommend that measurements of elemental and organiccarbon be undertaken in Canadian urban environments to examine their potential effects on human health.
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Diesel exhaust and wood burning are important sources of ambient atmospheric particles due to increasing numbers of diesel cars and the importance of wood as a source of renewable energy. Inhalation is the predominant route of entry and uptake for fine and ultrafine particles into the body. Health effects of atmospheric particles are still not completely understood. There is consistent evidence from epidemiology that particle exposure contributes to respiratory and cardiovascular diseases.This study aimed at examining acute responses of airway epithelial cells and luminal macrophages after exposure to freshly emitted and photochemically aged carbonaceous aerosols under realistic atmospheric conditions. In addition to a bronchial epithelial cell line advanced cell cultures namely fully differentiated respiratory epithelia and primary surface macrophages were used.Our results demonstrate that a single exposure of the cells to realistic particle doses of 0.3–3 ng diesel or 3–9 ng wood aerosol per cm2 cell surface induces small, particle-specific responses. The release of interleukin-6 and -8 was found to be decreased in differentiated airway epithelia but not in the other cell models studied. Aerosol exposure decreased macrophage phagocytic activity by 45–90%. Cell and tissue integrity remained unaffected. Overall, primary and aged particles from the same combustion induced similar responses in the cell models tested, whereby particles from diesel exhaust affected the cells more than those from wood combustion.
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Residential wood combustion causes major effects on the air quality on a global scale. The ambient particulate levels are known to be responsible for severe adverse health effects that include e.g. cardio-respiratory illnesses and cancer related effects, even mortality. It is known that biomass combustion derived emissions are affected by combustion technology, fuel being used and user-related practices. There are also indications that the health related toxicological effects are influenced by these parameters. This study we evaluated toxicological effects of particulate emissions (PM1) from seven different residential wood combusting furnaces. Two appliances i.e. log wood boiler and stove represented old batch combustion technology, whereas stove and tiled stove were designated as new batch combustion as three modern automated boilers were a log wood boiler, a woodchip boiler and a pellet boiler. The PM1 samples from the furnaces were collected in an experimental setup with a Dekati® gravimetric impactor on PTFE filters with the samples being weighed and extracted from the substrates and prior to toxicological analyses. The toxicological analyses were conducted after a 24-hour exposure of the mouse RAW 264.7 macrophage cell line to four doses of emission particle samples and analysis of levels of the proinflammatory cytokine TNFα, chemokine MIP-2, cytotoxicity with three different methods (MTT, PI, cell cycle analysis) and genotoxicity with the comet assay. In the correlation analysis all the toxicological results were compared with the chemical composition of the samples. All the samples induced dose-dependent increases in the studied parameters. Combustion technology greatly affected the emissions and the concomitant toxicological responses. The modern automated boilers were usually the least potent inducers of most of the parameters while emissions from the old technology log wood boiler were the most potent. In correlation analysis, the PAH and other organic composition and inorganic ash composition affected the toxicological responses differently. In conclusion, combustion technology largely affects the particulate emissions and their toxic potential this being reflected in substantially larger responses in devices with incomplete combustion. These differences become emphasized when the large emission factors from old technology appliances are taken into account.
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Residential wood combustion appliances emit large quantities of fine particles which are suspected to cause a substantial health burden worldwide. Wood combustion particles contain several potential health-damaging metals and carbon compounds such as polycyclic aromatic hydrocarbons (PAH), which may determine the toxic properties of the emitted particles. The aim of the present study was to characterize in vitro immunotoxicological and chemical properties of PM1 (Dp ≤ 1 μm) emitted from a pellet boiler and a conventional masonry heater. Mouse RAW264.7 macrophages were exposed for 24 h to different doses of the emission particles. Cytotoxicity, production of the proinflammatory cytokine TNF-α and the chemokine MIP-2, apoptosis and phases of the cell cycle as well as genotoxic activity were measured after the exposure. The type of wood combustion appliance had a significant effect on emissions and chemical composition of the particles. All the studied PM1 samples induced cytotoxic, genotoxic and inflammatory responses in a dose-dependent manner. The particles emitted from the conventional masonry heater were 3-fold more potent inducers of programmed cell death and DNA damage than those emitted from the pellet boiler. Furthermore, the particulate samples that induced extensive DNA damage contained also large amounts of PAH compounds. Instead, significant differences between the studied appliances were not detected in measurements of inflammatory mediators, although the chemical composition of the combustion particles differed considerably from each other. In conclusion, the present results show that appliances representing different combustion technology have remarkable effects on physicochemical and associated toxicological and properties of wood combustion particles. The present data indicate that the particles emitted from incomplete combustion are toxicologically more potent than those emitted from more complete combustion processes.
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An inventory of annual and monthly emissions from small-scale residential wood combustion in Switzerland was prepared. Emissions from seven single room appliance classes (<15 kW) were included in the inventory. These systems were classified by technology (current or modern) and include batch fired and automatic systems. The inventory was developed using a novel method incorporating heating degree-days and appliance usage estimates. Emission factors used in the inventory are representative of normal combustion (NC) conditions for both current and modern appliances and poor combustion (PC) conditions for current appliances. Emissions factors for hard- and softwood combustion were incorporated where available. Particulate matter (PM), particle bound black carbon (BC), particle bound organic matter (POM), inorganic material, total organic carbon (roc) and carbon monoxide (CO) emissions were included in the inventory. PM was characterised by size as total particulate emissions (TPE), and as particulate matter having diameter less than 10, 2.5 and 1 mu m (PM10, PM2.5 and PM1, respectively). Annual emissions were determined for each emissions species (base year 2009). The hardwood softwood mix was assumed to be 57:43 and the mix of current and modern appliances was assumed to be 70:30. For the current emission scenario, annual TPE was calculated to be similar to 4.35 kt y(-1), of which 39% was BC and 42% POM. TOC emissions were calculated to be similar to 3.82 kt y(-1) for the same period and scenario. Analysis of the size dependency of PM was also made. PM2 5 dominated all combustion scenarios, contributing 76-85% of TPE.
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Fine-particle and gaseous emissions from a modem small-scale pellet boiler were studied with different air-staging settings and under different load operations. Commercial wood pellets were used in the boiler, which worked with a top-feed fuel input. Partial load operation experiments included half-load 12.5 kW and low-load 7 kW. In air-staging experiments, the amounts of primary air were decreased by 71 and 82% while simultaneously keeping constant total air/fuel ratios. This was found to result in considerably lower emissions than during normal full-load operation with factory settings. The reduction in fine-particle emissions was based on both a decrease in alkali metal emissions and emissions of unburnt carbonaceous particles. However, when the amounts of secondary air were decreased by 17 and 33%, there were higher emissions of both fine particles and gases during full-load operation, especially of emission components originating from incomplete combustion. The primary air/secondary air ratio correlated with CO, PM(1), K, EC, and SO(4) emissions. Furthermore, correlations were found between the primary air/fuel ratio and particle geometric mean diameter (GMD) and between the secondary air supply and GMD. These correlations were seen with all measured points, which indicates that they apply to all of the operational situations that were studied. The results show that there is significant potential for decreasing particle emissions from automated pellet combustion systems by optimizing combustion air staging in the furnace.
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The impact of biomass combustion on atmospheric particulate matter was investigated at Central and Northern European urban background sites (Duisburg, Prague, Amsterdam, Helsinki) in 2002–2003. In Helsinki, additional 4-week sampling campaigns were carried out during the four seasons in 2003–2004. During campaigns fine particles (PM2.5) and size-segregated samples were collected with a virtual impactor and a ten-stage Berner low-pressure impactor, respectively. From the aerosol samples monosaccharide anhydrides (MA) were determined as source specific tracers for biomass combustion. MA comprised 0.29–6.3% of the PM2.5 mass and 0.45–7.3% of its organic carbon content. According to size-segregated samples, the mean diameter of a prominent MA mode coincided with the accumulation mode of particulate mass, except for Prague where the MA mode appeared in a slightly smaller particle size range than the mass. The estimated contribution of biomass combustion to the OC and PM2.5 mass concentration was the highest in wintertime Prague, 79% and 37%, respectively. It seems that, in addition to traffic in densely populated areas, incomplete biomass combustion with current heating appliances can be a major source of particulate pollution both at local and regional scales.
Article
Current levels of ambient air fine particulate matter (PM(2.5)) are associated with mortality and morbidity in urban populations worldwide. In residential areas wood combustion is one of the main sources of PM(2.5) emissions, especially during wintertime. However, the adverse health effects of particulate emissions from the modern heating appliances and fuels are poorly known. In this study, health related toxicological properties of PM(1) emissions from five modern and two old technology appliances were examined. The PM(1) samples were collected by using a Dekati® Gravimetric Impactor (DGI). The collected samples were weighed and extracted with methanol for chemical and toxicological analyses. Healthy C57BL/6J mice were intratracheally exposed to a single dose of 1, 3, 10 or 15mg/kg of the particulate samples for 4, 18 or 24h. Thereafter, the lungs were lavaged and bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation, cytotoxicity and genotoxicity. Lungs of 24h exposed mice were collected for inspection of pulmonary tissue damage. There were substantial differences in the combustion qualities of old and modern technology appliances. Modern technology appliances had the lowest PM(1) (mg/MJ) emissions, but they induced the highest inflammatory, cytotoxic and genotoxic activities. In contrast, old technology appliances had clearly the highest PM(1) (mg/MJ) emissions, but their effect in the mouse lungs were the lowest. Increased inflammatory activity was associated with ash related components of the emissions, whereas high PAH concentrations were correlating with the smallest detected responses, possibly due to their immunosuppressive effect.
Article
Atmospheric ultrafine particles (diameter < 0.1 μm) are under study by inhalation toxicologists to determine whether they pose a threat to public health, yet, little is known about the chemical composition of ultrafine particles in the atmosphere of cities. In the present work, the number concentration, size distribution, and chemical composition of atmospheric ultrafine particles is determined under wintertime conditions in Pasadena, CA, near Los Angeles. These experiments are conducted using a scanning dif ferential mobility analyzer, laser optical counter, and two micro-orifice impactors. Samples are analyzed to create a material balance on the chemical composition of the ultrafine particles. The number concentration of ultrafine particles in the size range 0.017 < dp < 0.1 μm, analyzed over 24-h periods, is found to be consistently in the range 1.3 × 104 ± 8.9 × 103 particles cm-3 air. Ultrafine particle mass concentrations are in the range 0.80−1.58 μg m-3. Organic compounds are the largest contributors to the ultrafine particle mass concentration. A small amount of sulfate is present in these particles, at concentrations too low to tell whether it exists as unneutralized sulfuric acid. Iron is the most prominent transition metal found in the ultrafine particles. These data may assist the health effects research community in constructing realistic animal or human exposure studies involving ultrafine particles.
Article
Particle and gaseous emissions of a top-feed pellet stove were studied in laboratory conditions. Pellets made of separate stem and bark materials of five different wood species and a commercial pellet product were used as fuels. The study included the determination of the particle number concentration, size distribution, fine-particle mass (PM1.0), CO, CO2, NOx, and volatile organic compounds (VOC). The PM1.0 emission was analyzed for inorganic substances, organic carbon, and elemental carbon. Thermodynamic equilibrium calculations were performed to interpret the results from chemical analysis and to estimate the chemical composition of the PM1.0 mass emitted with various fuels. The bark fuels produced higher PM, VOC, and CO emissions than stem fuels. This was evidently related to the higher ash content of the bark fuels and was found to increase both the fly ash emission and the products of incomplete combustion. The fuel ash content correlated linearly with the PM1.0 emission. Among stem fuels, willow and alder produced higher PM1.0 emissions than birch, pine, spruce, and the commercial fuel. An exceptionally low PM1.0 emission was measured from pine bark combustion, which can be explained by the low ash content of the fuel. The main components in the PM1.0 were K2SO4, KCl, K2CO3, KOH, and organic material. Except birch fuels, around 60−80 mass % of potassium species were K2SO4 based on the equilibrium calculations. In the case of birch fuels, because of the high chlorine content and low S/Cl ratios, around half of the potassium was KCl.
Article
Polycyclic aromatic hydrocarbon (PAH) extracts of fine particles (PM(2.5)) collected from combustion of seven wood species and briquettes were tested for mutagenic activities using Ames test with Salmonella typhimurium TA98 and TA100. The woods were Pinus pinaster (maritime pine), Eucalyptus globulus (eucalypt), Quercus suber (cork oak), Acacia longifolia (golden wattle), Quercus faginea (Portuguese oak), Olea europea (olive), and Quercus ilex rotundifolia (Holm oak). Burning experiments were done using woodstove and fireplace, hot start and cold start conditions. A mutagenic response was recorded for all species except golden wattle, maritime pine, and briquettes. The mutagenic extracts were not correlated with high emission factors of carcinogenic PAHs. These extracts were obtained both from two burning appliances and start-up conditions. However, fireplace seemed to favour the occurrence of mutagenic emissions. The negative result recorded for golden wattle was interesting, in an ecological point of view, since after confirmation, this invasive species, can be recommended for domestic use.
Article
Residential heating is an important local source of fine particles and may cause significant exposure and health effects in populations. We investigated the cytotoxic and inflammatory activity of particulate emissions from normal (NC) and smouldering (SC) combustion in one masonry heater. The PM1–0.2 and PM0.2 samples were collected from the dilution tunnel with a high-volume cascade impactor (HVCI). Mouse RAW 264.7 macrophages were exposed to the PM-samples for 24 h. Inflammatory mediators, (IL-6, TNFα and MIP-2), and cytotoxicity (MTT-test), were measured. Furthermore, apoptosis and cell cycle of macrophages were analyzed. The HVCI particulate samples were characterized for ions, elements and PAH compounds. Assays of elemental and organic carbon were conducted from parallel low volume samples. All the samples displayed mostly dose-dependent inflammatory and cytotoxic activity. SC samples were more potent than NC samples at inducing cytotoxicity and MIP-2 production, while the order of potency was reversed in TNFα production. SC-PM1–0.2 sample was a significantly more potent inducer of apoptosis than the respective NC sample. After adjustment for the relative toxicity with emission factor (mg MJ−1), the SC-PM emissions had clearly higher inflammatory and cytotoxic potential than the NC-PM emissions. Thus, operational practice in batch burning of wood and the resultant combustion condition clearly affect the toxic potential of particulate emissions.
Article
The influence of residential wood-combustion on local air quality was studied during two periods in 2002 and 2003/04 in a small rural town with widespread use of wood combustion for heating. During one 6-week winter period, particle levels (PM2.5) in the residential area were about 4 μg m−3 higher than at a nearby background site. This was comparable to the local traffic contribution observed at a busy street (about 70,000 vehicles per day) in the city of Copenhagen. The diurnal variation in the residential area showed increased particle levels (PM2.5) in the evening and night as expected from local heating sources. Particle size distributions showed highest volume concentrations of particles with diameters of 400–500 nm, and the diurnal variation of particle volume was similar to PM2.5. The particle measurements were supported by measurements of combustion gases in both the residential area and at a background site. Receptor modelling and source apportionment of the results confirmed that the most important sources to particles were long-range transport (both organic and inorganic compounds) and local heating (particularly organic compounds) in addition to regional traffic emissions. Local wood combustion sources affected especially the organic particle component.
Article
The fine particle and gas emissions from the residential wood combustion (RWC) appear to be a major contributor to winter-time pollution in Europe. In this study, we characterised the effect of two different combustion conditions on particulate and gaseous emissions from a conventional masonry heater. Normal combustion (NC) is the best available operational practice for the heater, whereas smouldering combustion (SC) mimicked slow heating combustion. It was found that the operational practice in RWC can significantly influence the quantity and quality of particle and gaseous emissions into the atmosphere. In SC, the emissions of carbon monoxide were 3.5-fold, total volatile organics 14-fold and PM1 6-fold to those of NC, whereas the mass of the inorganic compounds (“fine ash”) and particle number emissions were lower from SC than from NC. According to electron microscopy analyses, the observed fine ash particles seemed to occur mainly as separate spherical or irregularly shaped particles but not as agglomerates. Ultrafine (<100 nm) fine ash particles were composed mainly of K, S and Zn, but also in a lesser extent of C, Ca, Fe, Mg, Cl, P and Na. Large agglomerates were found to contain mainly carbon and are considered to be primarily soot particles. The larger spherical and irregularly shaped particles were composed of same alkali metal compounds as ultrafine particles, but they were probably covered with heavy organic compounds. From SC, particles were composed mainly of carbon compounds and they had a more closed structure than the particles from NC, due to organic matter on the particles. In the present experiments, the ultrafine mode in the particle number distributions seemed to be determined mainly by the amount of released ash forming material in combustion, and the shifting of particle size during different combustion conditions seemed to be determined by the amount of condensed organic vapour in the flue gas.
Article
Genotoxic effects of traffic-generated particulate matter (PM) are well described, whereas little data are available on PM from combustion of biomass and wood, which contributes substantially to air pollution world wide. The aim of this study was to compare the genotoxicity of wood smoke particulate matter (WSPM), authentic traffic-generated particles, mineral PM and standard reference material (SRM2975) of diesel exhaust particles in human A549 lung epithelial and THP-1 monocytic cell lines. DNA damage was measured as strand breaks (SB) and formamidopyrimidine DNA glycosylase (FPG) sites by the comet assay, whereas cell cytotoxicity was determined as lactate dehydrogenase release. The exposure to WSPM generated SB and FPG sites in both cell lines at concentrations from 2.5 or 25 μg/ml, which were not cytotoxic. Compared to all other studied particles, WSPM generated greater responses in terms of both SB and FPG sites. Organic extracts of WSPM and SRM2975 elicited higher levels of SB than native and washed PM at 25 and 100 μg/ml, whereas assay saturation precluded reliable assessment of FPG sites. During a 6 h post-exposure period, in which the medium with PM had been replaced by fresh medium, 60% of the DNA lesions generated by WSPM were removed. In conclusion, WSPM generated more DNA damage than traffic-generated PM per unit mass in human cell lines, possibly due to the high level of polycyclic aromatic hydrocarbons in WSPM. This suggests that exposure to WSPM might be more hazardous than PM collected from vehicle exhaust with respect to development of lung cancer.
Article
Flue gas emissions of wood and heavy fuel oil (HFO) fired district heating units of size range 4–15 MW were studied. The emission measurements included analyses of particle mass, number and size distributions, particle chemical compositions and gaseous emissions. Thermodynamic equilibrium calculations were carried out to interpret the experimental findings.In wood combustion, PM1 (fine particle emission) was mainly formed of K, S and Cl, released from the fuel. In addition PM1 contained small amounts of organic material, CO3, Na and different metals of which Zn was the most abundant. The fine particles from HFO combustion contained varying transient metals and Na that originate from the fuel, sulphuric acid, elemental carbon (soot) and organic material. The majority of particles were formed at high temperature (>800 °C) from V, Ni, Fe and Na. At the flue gas dew point (125 °C in undiluted flue gas) sulphuric acid condensed forming a liquid layer on the particles. This increases the PM1 substantially and may lead to partial dissolution of the metallic cores.Wood-fired grate boilers had 6–21-fold PM1 and 2–23-fold total suspended particle (TSP) concentrations upstream of the particle filters when compared to those of HFO-fired boilers. However, the use of single field electrostatic precipitators (ESP) in wood-fired grate boilers decreased particle emissions to same level or even lower as in HFO combustion. On the other hand, particles released from the HFO boilers were clearly smaller and higher in number concentration than those of wood boilers with ESPs. In addition, in contrast to wood combustion, HFO boilers produce notable SO2 emissions that contribute to secondary particle formation in the atmosphere. Due to vast differences in concentrations of gaseous and particle emissions and in the physical and chemical properties of the particles, HFO and wood fuel based energy production units are likely to have very different effects on health and climate.
Article
Literature data on particle emissions are compared with emissions from combustion of wood pellets and wood briquettes in commercial small-scale combustion devices: a pellet stove, two pellet burners and two smaller district heating boilers. The influence of operating parameters and fuel quality was investigated. Mass concentration, number concentration and number size distribution of particles were determined. The mass size distribution was analysed as well as the inorganic components. Gaseous compounds were recorded to give information about the combustion conditions. The mass concentrations of particles were between 34 and , increasing during unsatisfactory operation conditions. The number concentration was in the range of 107–108 particles per Ncm−3. The particle emission was dominated by submicron particles (size ), both from number and mass perspective. The main inorganic components of the submicron particles were potassium, sulphur, chlorine and oxygen. Small amounts of sodium, magnesium and zinc were also found. The contents of potassium, chlorine, and sulphur in the fuel are important for the composition of the emitted inorganic submicron particles.
Article
The wide scale use of Zinc oxide (ZnO) nanoparticles in the world consumer market makes human beings more prone to the exposure to ZnO nanoparticles and its adverse effects. The liver, which is the primary organ of metabolism, might act as a major target organ for ZnO nanoparticles after they gain entry into the body through any of the possible routes. Therefore, the aim of the present study was to assess the apoptotic and genotoxic potential of ZnO nanoparticles in human liver cells (HepG2) and the underlying molecular mechanism of its cellular toxicity. The role of dissolution in the toxicity of ZnO nanoparticles was also investigated. Our results demonstrate that HepG2 cells exposed to 14-20 μg/ml ZnO nanoparticles for 12 h showed a decrease in cell viability and the mode of cell death induced by ZnO nanoparticles was apoptosis. They also induced DNA damage which was mediated by oxidative stress as evidenced by an increase in Fpg sensitive sites. Reactive oxygen species triggered a decrease in mitochondria membrane potential and an increase in the ratio of Bax/Bcl2 leading to mitochondria mediated pathway involved in apoptosis. In addition, ZnO nanoparticles activated JNK, p38 and induced p53(Ser15) phosphorylation. However, apoptosis was found to be independent of JNK and p38 pathways. This study investigating the effects of ZnO nanoparticles in human liver cells has provided valuable insights into the mechanism of toxicity induced by ZnO nanoparticles.
Article
There is excess mortality in the winter. To minimise this it is important that an adequate indoor temperature is maintained and this is dependent on affordable energy supplies. Standards adopted by the Ministry for the Environment in relation to levels of small particles (PM10) in the air and the Regulations to enforce their implementation are based on inadequate scientific evidence. They are likely to make heating less affordable and have a negative net effect rather than a positive one on general health. Whilst the attainment and maintenance of clean air is laudable, regulations should be based on sound scientific evidence. The costs, benefits, and equity for individuals need careful consideration, as do the implications for energy security.
Article
Combustion of biomass and wood for residential heating and/or cooking contributes substantially to both ambient air and indoor levels of particulate matter (PM). Toxicological characterization of ambient air PM, especially related to traffic, is well advanced, whereas the toxicology of wood smoke PM (WSPM) is poorly assessed. We assessed a wide spectrum of toxicity end points in human A549 lung epithelial and THP-1 monocytic cell lines comparing WSPM from high or low oxygen combustion and ambient PM collected in a village with many operating wood stoves and from a rural background area. In both cell types, all extensively characterized PM samples (1.25-100 μg/mL) induced dose-dependent formation of reactive oxygen species and DNA damage in terms of strand breaks and formamidopyrimidine DNA glycosylase sites assessed by the comet assay with WSPM being most potent. The WSPM contained more polycyclic aromatic hydrocarbons (PAH), less soluble metals, and expectedly also had a smaller particle size than PM collected from ambient air. All four types of PM combined increased the levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine dose-dependently in A549 cells, whereas there was no change in the levels of etheno-adducts or bulky DNA adducts. Furthermore, mRNA expression of the proinflammatory genes monocyte chemoattractant protein-1, interleukin-8, and tumor necrosis factor-α as well as the oxidative stress gene heme oxygenase-1 was upregulated in the THP-1 cells especially by WSPM and ambient PM sampled from the wood stove area. Expression of oxoguanine glycosylase 1, lymphocyte function-associated antigen-1, and interleukin-6 did not change. We conclude that WSPM has small particle size, high level of PAH, low level of water-soluble metals, and produces high levels of free radicals, DNA damage as well as inflammatory and oxidative stress response gene expression in cultured human cells.
Article
Abstract Book, Aerosols from solid biomass combustion and their health effects P3Q1/4A0 IAC, 8th International Aerosol Conference 2010, 29th Aug. - 3rd Sept. 2010, Helsinki
Article
During the winters of 2006/2007 and 2007/2008, PM2.5 source apportionment programs were carried out within five western Montana valley communities. Filter samples were analyzed for mass and chemical composition. Information was utilized in a Chemical Mass Balance (CMB) computer model to apportion the sources of PM2.5. Results showed that wood smoke (likely residential woodstoves) was the major source of PM2.5 in each of the communities, contributing from 56% to 77% of the measured wintertime PM2.5. Results of 14C analyses showed that between 44% and 76% of the measured PM2.5 came from a new carbon (wood smoke) source, confirming the results of the CMB modeling. In summary, the CMB model results, coupled with the 14C results, support that wood smoke is the major contributor to the overall PM2.5 mass in these rural, northern Rocky Mountain airsheds throughout the winter months.