Toxicity of particles derived from combustion of Ethiopian traditional biomass fuels in human bronchial and macrophage-like cells.

The combustion of traditional fuels in low-income countries, including those in sub-Saharan Africa, leads to extensive indoor particle exposure. Yet, the related health consequences in this context are understudied. This study aimed to evaluate the in vitro toxicity of combustion-derived particles relevant for Sub-Saharan household environments. Particles (< 2.5 µm) were collected using a high-volume sampler during combustion of traditional Ethiopian biomass fuels: cow dung, eucalyptus wood and eucalyptus charcoal. Diesel exhaust particles (DEP, NIST 2975) served as reference particles. The highest levels of particle-bound polycyclic aromatic hydrocarbons (PAHs) were found in wood (3219 ng/mg), followed by dung (618 ng/mg), charcoal (136 ng/mg) and DEP (118 ng/mg) (GC-MS). BEAS-2B bronchial epithelial cells and THP-1 derived macrophages were exposed to particle suspensions (1-150 µg/mL) for 24 h. All particles induced concentration-dependent genotoxicity (comet assay) but no pro-inflammatory cytokine release in epithelial cells, whereas dung and wood particles also induced concentration-dependent cytotoxicity (Alamar Blue). Only wood particles induced concentration-dependent cytotoxicity and genotoxicity in macrophage-like cells, while dung particles were unique at increasing secretion of pro-inflammatory cytokines (IL-6, IL-8, TNF-α). In summary, particles derived from combustion of less energy dense fuels like dung and wood had a higher PAH content and were more cytotoxic in epithelial cells. In addition, the least energy dense and cheapest fuel, dung, also induced pro-inflammatory effects in macrophage-like cells. These findings highlight the influence of fuel type on the toxic profile of the emitted particles and warrant further research to understand and mitigate health effects of indoor air pollution.

Coronavirus Disease 2019 and Airborne Transmission: Science Rejected, Lives Lost. Can Society Do Better?

This is an account that should be heard of an important struggle: the struggle of a large group of experts who came together at the beginning of the COVID-19 pandemic to warn the world about the risk of airborne transmission and the consequences of ignoring it. We alerted the World Health Organization about the potential significance of the airborne transmission of SARS-CoV-2 and the urgent need to control it, but our concerns were dismissed. Here we describe how this happened and the consequences. We hope that by reporting this story we can raise awareness of the importance of interdisciplinary collaboration and the need to be open to new evidence, and to prevent it from happening again. Acknowledgement of an issue, and the emergence of new evidence related to it, is the first necessary step towards finding effective mitigation solutions.

Effects of cleaning spray use on eyes, airways, and ergonomic load.

BACKGROUND: Cleaning workers are exposed to chemicals and high physical workload, commonly resulting in airway problems and pain. In this study the response in the upper airways and the physical workload following airborne and ergonomic exposure of cleaning spray was investigated. METHODS: A survey was answered by professional cleaning workers to investigate their use of cleaning sprays and the perceived effects on eyes, airways and musculoskeletal pain. A human chamber exposure study was then conducted with 11 professional cleaning workers and 8 non-professional cleaning workers to investigate the airborne exposure, acute effects on eyes and airways, and physical load during cleaning with sprays, foam application and microfiber cloths premoistened with water. All cleaning products used were bleach, chlorine, and ammonia free. The medical assessment included eye and airway parameters, inflammatory markers in blood and nasal lavage, as well as technical recordings of the physical workload. RESULTS: A high frequency of spray use (77%) was found among the 225 professional cleaning workers that answered the survey. Based on the survey, there was an eight times higher risk (p < 0.001) of self-experienced symptoms (including symptoms in the nose, eyes and throat, coughing or difficulty breathing) when they used sprays compared to when they cleaned with other methods. During the chamber study, when switching from spray to foam, the airborne particle and volatile organic compound (VOC) concentrations showed a decrease by 7 and 2.5 times, respectively. For the whole group, the peak nasal inspiratory flow decreased (-10.9 L/min, p = 0.01) during spray use compared to using only water-premoistened microfiber cloths. These effects were lower during foam use (-4.7 L/min, p = 0.19). The technical recordings showed a high physical workload regardless of cleaning with spray or with water. CONCLUSION: Switching from a spraying to a foaming nozzle decreases the exposure of both airborne particles and VOCs, and thereby reduces eye and airway effects, and does not increase the ergonomic load. If the use of cleaning products tested in this study, i.e. bleach, chlorine, and ammonia free, cannot be avoided, foam application is preferable to spray application to improve the occupational environment.

Characterization of fine particulate matter from indoor cooking with solid biomass fuels.

Household burning of solid biomass fuels emits pollution particles that are a huge health risk factor, especially in low-income countries (LICs) such as those in Sub-Saharan Africa. In epidemiological studies, indoor exposure is often more challenging to assess than outdoor exposure. Laboratory studies of solid biomass fuels, performed under real-life conditions, are an important path toward improved exposure assessments. Using on- and offline measurement techniques, particulate matter (PM) from the most commonly used solid biomass fuels (charcoal, wood, dung, and crops residue) was characterized in laboratory settings using a way of burning the fuels and an air exchange rate that is representative of real-world settings in low-income countries. All the fuels generated emissions that resulted in concentrations which by far exceed both the annual and the 24-hour-average WHO guidelines for healthy air. Fuels with lower energy density, such as dung, emitted orders of magnitude more than, for example, charcoal. The vast majority of the emitted particles were smaller than 300 nm, indicating high deposition in the alveoli tract. The chemical composition of the indoor pollution changes over time, with organic particle emissions often peaking early in the stove operation. The chemical composition of the emitted PM is different for different biomass fuels, which is important to consider both in toxicological studies and in source apportionment efforts. For example, dung and wood yield higher organic aerosol emissions, and for dung, nitrogen content in the organic PM fraction is higher than for the other fuels. We show that aerosol mass spectrometry can be used to differentiate stove-related emissions from fuel, accelerant, and incense. We argue that further emission studies, targeting, for example, vehicles relevant for LICs and trash burning, coupled with field observations of chemical composition, would advance our understanding of air pollution in LIC. We believe this to be a necessary step for improved air quality policy.

A controlled chamber study of effects of exposure to diesel exhaust particles and noise on heart rate variability and endothelial function.

BACKGROUND: Adverse cardiovascular effects are associated with both diesel exhaust and road traffic noise, but these exposures are hard to disentangle epidemiologically. We used an experimental setup to evaluate the impact of diesel exhaust particles and traffic noise, alone and combined, on intermediary outcomes related to the autonomic nervous system and increased cardiovascular risk. METHODS: In a controlled chamber 18 healthy adults were exposed to four scenarios in a randomized cross-over fashion. Each exposure scenario consisted of either filtered (clean) air or diesel engine exhaust (particle mass concentrations around 300 µg/m3), and either low (46 dB(A)) or high (75 dB(A)) levels of traffic noise for 3 h at rest. ECG was recorded for 10-min periods before and during each exposure type, and frequency-domain heart rate variability (HRV) computed. Endothelial dysfunction and arterial stiffness were assessed after each exposure using EndoPAT 2000. RESULTS: Compared to control exposure, HRV in the high frequency band decreased during exposure to diesel exhaust, both alone and combined with noise, but not during noise exposure only. These differences were more pronounced in women. We observed no synergistic effects of combined exposure, and no significant differences between exposure scenarios for other HRV indices, endothelial function or arterial stiffness. CONCLUSION: Three-hour exposure to diesel exhaust, but not noise, was associated with decreased HRV in the high frequency band. This indicates activation of irritant receptor-mediated autonomic reflexes, a possible mechanism for the cardiovascular risks of diesel exposure. There was no effect on endothelial dysfunction or arterial stiffness after exposure.

Air Quality in Africa: Public Health Implications.

This review highlights the importance of air quality in the African urban development process. We address connections between air pollution and (a) rapid urbanization, (b) social problems, (c) health impacts, (d) climate change, (e) policies, and (f) new innovations. We acknowledge that air pollution levels in Africa can be extremely high and a serious health threat. The toxic content of the pollution could relate to region-specific sources such as low standards for vehicles and fuels, cooking with solid fuels, and burning household waste. We implore the pursuit of interdisciplinary research to create new approaches with relevant stakeholders. Moreover, successful air pollution research must regard conflicts, tensions, and synergies inherent to development processes in African municipalities, regions, and countries. This includes global relationships regarding climate change, trade, urban planning, and transportation. Incorporating aspects of local political situations (e.g., democracy) can also enhance greater political accountability and awareness about air pollution.

Sources of Airborne Norovirus in Hospital Outbreaks.

BACKGROUND: Noroviruses are the major cause of viral gastroenteritis. Disease transmission is difficult to prevent and outbreaks in health-care facilities commonly occur. Contact with infected persons and contaminated environments are believed to be the main routes of transmission. However, noroviruses have recently been found in aerosols and airborne transmission has been suggested. The aim of our study was to investigate associations between symptoms of gastroenteritis and the presence of airborne norovirus, and to investigate the size of norovirus-carrying particles. METHODS: Air sampling was repeatedly performed close to 26 patients with norovirus infections. Samples were analyzed for norovirus RNA by reverse transcription quantitative polymerase chain reaction. The times since each patient's last episodes of vomiting and diarrhea were recorded. Size-separating aerosol particle collection was performed. RESULTS: Norovirus RNA was found in 21 (24%) of 86 air samples from 10 different patients. Only air samples during outbreaks, or before a succeeding outbreak, tested positive for norovirus RNA. Airborne norovirus RNA was also strongly associated with a shorter time period since the last vomiting episode (odds ratio 8.1; P = .04 within 3 hours since the last vomiting episode). The concentrations of airborne norovirus ranged from 5-215 copies/m3, and detectable amounts of norovirus RNA were found in particles <0.95 µm and >4.51 µm. CONCLUSIONS: The results suggest that recent vomiting is the major source of airborne norovirus and imply a connection between airborne norovirus and outbreaks. The presence of norovirus RNA in submicrometre particles indicates that airborne transmission can be an important transmission route.

Characterization of airborne particles from cleaning sprays and their corresponding respiratory deposition fractions.

Cleaning workers are exposed to many risk factors, including handling of cleaning products. Epidemiological studies show that they have a high incidence of asthma and other respiratory symptoms. Some studies have indicated an even higher incidence of asthma in individuals using cleaning sprays regularly. It is known that sprays produce an aerosol that can expose the respiratory system to chemicals. Knowledge of the physical characteristics of the airborne particles, as well as the characteristics of the gas phase, is needed to determine how they affect the respiratory tract and why they cause airway symptoms. The aim of this study was to characterize the aerosols from seven different ready-to-use trigger cleaning sprays in terms of total airborne mass fraction, particle size distribution, and new particle formation from ozone reactions. An additional aim was to calculate the respiratory deposition fraction of the measured particles. The total airborne mass fraction was determined by comparing the mass deposited on the chamber wall with the mass emitted from the bottle during spraying. Particle number concentration and size distribution of the airborne particles were measured using an aerodynamic particle sizer and a fast aerosol mobility size spectrometer. The total airborne mass fraction was between 2.7% and 32.2% of the mass emitted from the bottle, depending on the product. Between 0.0001% and 0.01% of the total airborne mass fraction consisted of residual particles. However, these particles had a mass median aerodynamic diameter between 1.9 µm and 3.7 µm, constituting a total respiratory deposition of up to 77%. New particle formation in the presence of ozone was also shown to vary between 5,000 cm-3 and 35,000 cm-3 depending on the product, in the studied settings. These findings confirm that a substantial part (up to 1/3) of the mass sprayed from the bottle does not reach the intended surface. Thus, the use of cleaning sprays can result in chemical airway exposure, with particles in the relevant size range for both nasal and alveolar deposition.

Comprehensive proteome analysis of nasal lavage samples after controlled exposure to welding nanoparticles shows an induced acute phase and a nuclear receptor, LXR/RXR, activation that influence the status of the extracellular matrix.

BACKGROUND: Epidemiological studies have shown that many welders experience respiratory symptoms. During the welding process a large number of airborne nanosized particles are generated, which might be inhaled and deposited in the respiratory tract. Knowledge of the underlying mechanisms behind observed symptoms is still partly lacking, although inflammation is suggested to play a central role. The aim of this study was to investigate the effects of welding fume particle exposure on the proteome expression level in welders suffering from respiratory symptoms, and changes in protein mediators in nasal lavage samples were analyzed. Such mediators will be helpful to clarify the pathomechanisms behind welding fume particle-induced effects. METHODS: In an exposure chamber, 11 welders with work-related symptoms in the lower airways during the last month were exposed to mild-steel welding fume particles (1 mg/m3) and to filtered air, respectively, in a double-blind manner. Nasal lavage samples were collected before, immediately after, and the day after exposure. The proteins in the nasal lavage were analyzed with two different mass spectrometry approaches, label-free discovery shotgun LC-MS/MS and a targeted selected reaction monitoring LC-MS/MS analyzing 130 proteins and four in vivo peptide degradation products. RESULTS: The analysis revealed 30 significantly changed proteins that were associated with two main pathways; activation of acute phase response signaling and activation of LXR/RXR, which is a nuclear receptor family involved in lipid signaling. Connective tissue proteins and proteins controlling the degradation of such tissues, including two different matrix metalloprotease proteins, MMP8 and MMP9, were among the significantly changed enzymes and were identified as important key players in the pathways. CONCLUSION: Exposure to mild-steel welding fume particles causes measurable changes on the proteome level in nasal lavage matrix in exposed welders, although no clinical symptoms were manifested. The results suggested that the exposure causes an immediate effect on the proteome level involving acute phase proteins and mediators regulating lipid signaling. Proteases involved in maintaining the balance between the formation and degradation of extracellular matrix proteins are important key proteins in the induced effects.

Acute respiratory effects and biomarkers of inflammation due to welding-derived nanoparticle aggregates.

PURPOSE: Welders are exposed to airborne particles from the welding environment and often develop symptoms work-related from the airways. A large fraction of the particles from welding are in the nano-size range. In this study we investigate if the welders' airways are affected by exposure to particles derived from gas metal arc welding in mild steel in levels corresponding to a normal welding day. METHOD: In an exposure chamber, 11 welders with and 10 welders without work-related symptoms from the lower airways and 11 non-welders without symptoms, were exposed to welding fumes (1 mg/m3) and to filtered air, respectively, in a double-blind manner. Symptoms from eyes and upper and lower airways and lung function were registered. Blood and nasal lavage (NL) were sampled before, immediately after and the morning after exposure for analysis of markers of oxidative stress. Exhaled breath condensate (EBC) for analysis of leukotriene B4 (LT-B4) was sampled before, during and immediately after exposure. RESULTS: No adverse effects of welding exposure were found regarding symptoms and lung function. However, EBC LT-B4 decreased significantly in all participants after welding exposure compared to filtered air. NL IL-6 increased immediately after exposure in the two non-symptomatic groups and blood neutrophils tended to increase in the symptomatic welder group. The morning after, neutrophils and serum IL-8 had decreased in all three groups after welding exposure. Remarkably, the symptomatic welder group had a tenfold higher level of EBC LT-B4 compared to the two groups without symptoms. CONCLUSION: Despite no clinical adverse effects at welding, changes in inflammatory markers may indicate subclinical effects even at exposure below the present Swedish threshold limit (8 h TWA respirable dust).

Carbon Nanotube Emissions from Arc Discharge Production: Classification of Particle Types with Electron Microscopy and Comparison with Direct Reading Techniques.

INTRODUCTION: An increased production and use of carbon nanotubes (CNTs) is occurring worldwide. In parallel, a growing concern is emerging on the adverse effects the unintentional inhalation of CNTs can have on humans. There is currently a debate regarding which exposure metrics and measurement strategies are the most relevant to investigate workplace exposures to CNTs. This study investigated workplace CNT emissions using a combination of time-integrated filter sampling for scanning electron microscopy (SEM) and direct reading aerosol instruments (DRIs). MATERIAL AND METHODS: Field measurements were performed during small-scale manufacturing of multiwalled carbon nanotubes using the arc discharge technique. Measurements with highly time- and size-resolved DRI techniques were carried out both in the emission and background (far-field) zones. Novel classifications and counting criteria were set up for the SEM method. Three classes of CNT-containing particles were defined: type 1: particles with aspect ratio length:width >3:1 (fibrous particles); type 2: particles without fibre characteristics but with high CNT content; and type 3: particles with visible embedded CNTs. RESULTS: Offline sampling using SEM showed emissions of CNT-containing particles in 5 out of 11 work tasks. The particles were classified into the three classes, of which type 1, fibrous CNT particles contributed 37%. The concentration of all CNT-containing particles and the occurrence of the particle classes varied strongly between work tasks. Based on the emission measurements, it was assessed that more than 85% of the exposure originated from open handling of CNT powder during the Sieving, mechanical work-up, and packaging work task. The DRI measurements provided complementary information, which combined with SEM provided information on: (i) the background adjusted emission concentration from each work task in different particle size ranges, (ii) identification of the key procedures in each work task that lead to emission peaks, (iii) identification of emission events that affect the background, thereby leading to far-field exposure risks for workers other than the operator of the work task, and (iv) the fraction of particles emitted from each source that contains CNTs. CONCLUSIONS: There is an urgent need for a standardized/harmonized method for electron microscopy (EM) analysis of CNTs. The SEM method developed in this study can form the basis for such a harmonized protocol for the counting of CNTs. The size-resolved DRI techniques are commonly not specific enough to selective analysis of CNT-containing particles and thus cannot yet replace offline time-integrated filter sampling followed by SEM. A combination of EM and DRI techniques offers the most complete characterization of workplace emissions of CNTs today.

Detection of Multi-walled Carbon Nanotubes and Carbon Nanodiscs on Workplace Surfaces at a Small-Scale Producer.

BACKGROUND: The industrial use of novel-manufactured nanomaterials such as carbon nanotubes and carbon nanodiscs is increasing globally. Occupational exposure can occur during production, downstream use, and disposal. The health effects of many nanomaterials are not yet fully characterized and to handle nano-objects, their aggregates and agglomerates >100nm (NOAA), a high degree of control measures and personal protective equipment are required. The emission of airborne NOAA during production and handling can contaminate workplace surfaces with dust, which can be resuspended resulting in secondary inhalation exposures and dermal exposures. This study surveys the presence of carbon-based nanomaterials, such as multi-walled carbon nanotubes (MWCNTs) and carbon nanodiscs, as surface contamination at a small-scale producer using a novel tape sampling method. METHODS: Eighteen different surfaces at a small-scale producer were sampled with an adhesive tape sampling method. The surfaces selected were associated with the production and handling of MWCNT powder in the near-field zone. Surfaces in the far-field zone were also sampled. In addition, tape stripping of the skin was performed on one worker. The tape samples were analysed with scanning electron microscopy to detect the carbon-based NOAA. Air sampling with a personal impactor was also performed on a worker who was producing MWCNTs the same day as the tape samples were collected. RESULTS: MWCNTs were detected in 50% of the collected tape samples and carbon nanodiscs in 17%. MWCNTs and carbon nanodiscs were identified in all parts of the workplace, thus, increasing the risk for secondary inhalation and dermal exposure of the workers. Both airborne MWCNTs and carbon nanodiscs were detected in the personal impactor samples. The tape-strip samples from the worker showed no presence of carbon-containing nanoparticles. CONCLUSIONS: Tape sampling is a functional method for detecting surface contamination of carbon-based NOAA and for exposure control during production at potentially any workplace that produces or handles such manufactured nanomaterials. With the tape method, it is possible to monitor if a potential for secondary inhalation exposure or dermal exposure exists through resuspension of dust deposited on workplace surfaces. By means of air sampling, we could confirm that carbon nanodiscs were resuspended into the air at the workplace even though they were not handled during that particular work shift. MWCNTs were detected in the air samples, but can have been derived from either resuspension or from the work tasks with MWCNTs that were performed during the air sampling. Tape sampling is a complementary method to air sampling and together these two methods provide a better view of the hygienic situation in workplaces where NOAA can be emitted into work environments.

Exposure and emission measurements during production, purification, and functionalization of arc-discharge-produced multi-walled carbon nanotubes.

BACKGROUND: The production and use of carbon nanotubes (CNTs) is rapidly growing. With increased production, there is potential that the number of occupational exposed workers will rapidly increase. Toxicological studies on rats have shown effects in the lungs, e.g., inflammation, granuloma formation, and fibrosis after repeated inhalation exposure to some forms of multi-walled CNTs (MWCNTs). Still, when it comes to health effects, it is unknown which dose metric is most relevant. Limited exposure data for CNTs exist today and no legally enforced occupational exposure limits are yet established. The aim of this work was to quantify the occupational exposures and emissions during arc discharge production, purification, and functionalization of MWCNTs. The CNT material handled typically had a mean length <5 µm. Since most of the collected airborne CNTs did not fulfil the World Health Organization fibre dimensions (79% of the counted CNT-containing particles) and since no microscopy-based method for counting of CNTs exists, we decided to count all particle that contained CNTs. To investigate correlations between the used exposure metrics, Pearson correlation coefficient was used. METHODS: Exposure measurements were performed at a small-scale producer of MWCNTs and respirable fractions of dust concentrations, elemental carbon (EC) concentrations, and number concentrations of CNT-containing particles were measured in the workers' breathing zones with filter-based methods during work. Additionally, emission measurements near the source were carried out during different work tasks. Respirable dust was gravimetrically determined; EC was analysed with thermal-optical analysis and the number of CNT-containing particles was analysed with scanning electron microscopy. RESULTS: For the personal exposure measurements, respirable dust ranged between <73 and 93 µg m(-3), EC ranged between <0.08 and 7.4 µg C m(-3), and number concentration of CNT-containing particles ranged between 0.04 and 2.0 cm(-3). For the emission measurements, respirable dust ranged between <2800 and 6800 µg m(-3), EC ranged between 0.05 and 550 µg C m(-3), and number concentration of CNT-containing particles ranged between <0.20 and 11cm(-3). CONCLUSIONS: The highest exposure to CNTs occurred during production of CNTs. The highest emitted number concentration of CNT-containing particles occurred in the sieving, mechanical work-up, pouring, weighing, and packaging of CNT powder during the production stage. To be able to quantify exposures and emissions of CNTs, a selective and sensitive method is needed. Limitations with measuring EC and respirable dust are that these exposure metrics do not measure CNTs specifically. Only filter-based methods with electron microscopy analysis are, to date, selective and sensitive enough. This study showed that counting of CNT-containing particles is the method that fulfils those criteria and is therefore the method recommended for future quantification of CNT exposures. However, CNTs could be highly toxic not only because of their length but also because they could contain, for example transition metals and polycyclic aromatic hydrocarbons, or have surface defects. Lack of standardized counting criteria for CNTs to be applied at the electron microscopy analysis is a limiting factor, which makes it difficult to compare exposure data from different studies.

Large-eddy simulation of aerosol concentrations in a realistic urban environment: Model validation and transport mechanism.

Air pollution in urban environments exhibits large spatial and temporal variations due to high heterogeneous air flow and emissions. To address the complexity of local air pollutant dynamics, a comprehensive large-eddy simulation using the PALM model system v6.0 was conducted. The distribution of flow and vehicle emitted aerosol particles in a realistic urban environment in Malmö, Sweden, was studied and evaluated against on-site measurements made using portable instrumentation on a spring morning in 2021. The canyon transport mechanisms were investigated, and the convective and turbulent mass-transport rates compared to clarify their role in aerosol transport. The horizontal distribution of aerosols showed acceptable evaluation metrics for both mass and number. Flow and pollutant concentrations were more complex than those in idealized street canyon networks. Vertical turbulent mass-transport rate was found to dominate the mass transport process compared with the convective transport rate, contributing more than 70% of the pollutant transport process. Our findings highlight the necessity of examining various aerosol metric due their distinct dispersion behaviour. This study introduces a comprehensive high-resolution modelling framework that accounts for dynamic meteorological and aerosol background boundary conditions, real-time traffic emission, and detailed building features, offering a robust toll for local urban air quality assessment.

Characterization of airborne dust emissions from three types of crushed multi-walled carbon nanotube-enhanced concretes.

Dispersing Multi-Walled Carbon Nanotubes (MWCNTs) into concrete at low (<1 wt% in cement) concentrations may improve concrete performance and properties and provide enhanced functionalities. When MWCNT-enhanced concrete is fragmented during remodelling or demolition, the stiff, fibrous and carcinogenic MWCNTs will, however, also be part of the respirable particulate matter released in the process. Consequently, systematic aerosolizing of crushed MWCNT-enhanced concretes in a controlled environment and measuring the properties of this aerosol can give valuable insights into the characteristics of the emissions such as concentrations, size range and morphology. These properties impact to which extent the emissions can be inhaled as well as where they are expected to deposit in the lung, which is critical to assess whether these materials might constitute a future health risk for construction and demolition workers. In this work, the impact from MWCNTs on aerosol characteristics was assessed for samples of three concrete types with various amounts of MWCNT, using a novel methodology based on the continuous drop method. MWCNT-enhanced concretes were crushed, aerosolized and the emitted particles were characterized with online and offline techniques. For light-weight porous concrete, the addition of MWCNT significantly reduced the respirable mass fraction (RESP) and particle number concentrations (PNC) across all size ranges (7 nm - 20 µm), indicating that MWCNTs dampened the fragmentation process by possibly reinforcing the microstructure of brittle concrete. For normal concrete, the opposite could be seen, where MWCNTs resulted in drastic increases in RESP and PNC, suggesting that the MWCNTs may be acting as defects in the concrete matrix, thus enhancing the fragmentation process. For the high strength concrete, the fragmentation decreased at the lowest MWCNT concentration, but increased again for the highest MWCNT concentration. All tested concrete types emitted <100 nm particles, regardless of CNT content. SEM imaging displayed CNTs protruding from concrete fragments, but no free fibres were detected.

Mandating indoor air quality for public buildings.

If some countries lead by example, standards may increasingly become normalized.

Quantifying the influence of urban biotic and abiotic environmental factors on great tit nestling physiology.

There is a long history of avian studies investigating the impacts of urbanization. While differences in several life-history traits have been documented, either between urban and rural populations or across generalized urbanization gradients, a detailed understanding of which specific environmental variables cause these phenotypic differences is still lacking. Here, we quantified several local environmental variables coupled to urbanization (air pollution, tree composition, ambient temperature, and artificial light at night [ALAN]) within territories of breeding great tits (Parus major). We linked the environmental variables to physiological measures of the nestlings (circulating fatty acid composition [FA], antioxidant capacity and an oxidative damage marker [malondialdehyde; MDA]), to garner a mechanistic understanding of the impact of urbanization. We found that the antioxidant capacity of nestlings decreased with higher numbers of oak trees and levels of PM2.5 (airborne particulate matter with a diameter < 2.5 µm). Furthermore, the ratio of ω6:ω3 polyunsaturated FAs, important for immune function, was positively correlated with PM2.5 concentration, while being negatively associated with ambient temperature and number of non-native trees in the territory. Body mass and wing length both increased with the number of local oak trees. We also show, through a principal component analysis, that while the environmental variables fall into an urbanization gradient, this gradient is insufficient to explain the observed physiological responses. Therefore, accounting for individual environmental variables in parallel, and thus allowing for interactions between these, is crucial to fully understand the urban ecosystem.

Size-resolved characterization of particles >10 nm emitted to air during metal recycling.

BACKGROUND: In the strive towards a circular economy, metal waste recycling is a growing industry. During the recycling process, particulate matter containing toxic and allergenic metals will be emitted to the air causing unintentional exposure to humans and environment. OBJECTIVE: In this study detailed characterization of particle emissions and workplace exposures were performed, covering the full size range from 10 nm to 10 µm, during recycling of three different material flows: Waste of electrical and electronic equipment (WEEE), metal scrap, and cables. METHODS: Both direct-reading instruments (minute resolution), and time-integrated filter measurements for gravimetric and chemical analysis were used. Additionally, optical sensors were applied and evaluated for long-term online monitoring of air quality in industrial settings. RESULTS: The highest concentrations, in all particle sizes, and with respect both to particle mass and number, were measured in the WEEE flow, followed by the metal scrap flow. The number fraction of nanoparticles was high for all material flows (0.66-0.86). The most abundant metals were Fe, Al, Zn, Pb and Cu. Other elements of toxicological interest were Mn, Ba and Co. SIGNIFICANCE: The large fraction of nanoparticles, and the fact that their chemical composition deviate from that of the coarse particles, raises questions that needs to be further addressed including toxicological implications, both for humans and for the environment.

Characterization and Toxic Potency of Airborne Particles Formed upon Waste from Electrical and Electronic Equipment Waste Recycling: A Case Study.

Manual dismantling, shredding, and mechanical grinding of waste from electrical and electronic equipment (WEEE) at recycling facilities inevitably lead to the accidental formation and release of both coarse and fine particle aerosols, primarily into the ambient air. Since diffuse emissions to air of such WEEE particles are not regulated, their dispersion from the recycling plants into the adjacent environment is possible. The aim of this interdisciplinary project was to collect and characterize airborne WEEE particles smaller than 1 µm generated at a Nordic open waste recycling facility from a particle concentration, shape, and bulk and surface composition perspective. Since dispersed airborne particles eventually may reach rivers, lakes, and possibly oceans, the aim was also to assess whether such particles may pose any adverse effects on aquatic organisms. The results show that WEEE particles only exerted a weak tendency toward cytotoxic effects on fish gill cell lines, although the exposure resulted in ROS formation that may induce adverse effects. On the contrary, the WEEE particles were toxic toward the crustacean zooplankter Daphnia magna, showing strong effects on survival of the animals in a concentration-dependent way.

Ambient and indoor air pollution exposure and adverse birth outcomes in Adama, Ethiopia.

Air pollution poses a threat to human health, with pregnant women and their developing fetuses being particularly vulnerable. A high dual burden of ambient and indoor air pollution exposure has been identified in Ethiopia, but studies investigating their effects on adverse birth outcomes are currently lacking. This study explores the association between ambient air pollution (NOX and NO2) and indoor air pollution (cooking fuel type) and fetal and neonatal death in Adama, Ethiopia. A prospective cohort of mothers and their babies was used, into which pregnant women were recruited at their first antenatal visit (n = 2085) from November 2015 to February 2018. Previously developed land-use regression models were utilized to assess ambient concentrations of NOX and NO2 at the residential address, whereas data on cooking fuel type was derived from questionnaires. Birth outcome data was obtained from self-reported questionnaire responses during the participant's postnatal visit or by phone if an in-person meeting was not possible. Binary logistic regression was employed to assess associations within the final study population (n = 1616) using both univariate and multivariate models; the latter of which adjusted for age, education, parity, and HIV status. Odds ratios (OR) and their corresponding 95% confidence intervals (CI) were reported. Within the cohort, 69 instances of fetal death (n = 16 miscarriages; n = 53 stillbirths) and 16 cases of neonatal death were identified. The findings suggest a tendency towards an association between ambient NOX and NO2 exposure during pregnancy and an increased risk of fetal death overall as well as stillbirth, specifically. However, statistical significance was not observed. Results for indoor air pollution and neonatal death were inconclusive. As limited evidence on the effects of exposure to ambient air pollution on adverse birth outcomes exists in Sub-Saharan Africa and Ethiopia, additional studies with larger study populations should be conducted.