Airborne Dust Research Articles

Up in the air: Polyfluoroalkyl phosphate esters (PAPs) in airborne dust captured by air conditioning (AC) filters

Per- and polyfluoroalkyl substances (PFAS) are ubiquitously present in our indoor living environments. Dust is thought to accumulate PFAS released indoors and serve as an exposure pathway for humans. Here, we investigated whether spent air conditioning (AC) filters can be exploited as opportunistic samplers of airborne dust for assessing PFAS burden in indoor environments. Used AC filters from campus facilities (n = 19) and homes (n = 11) were analyzed for 92 PFAS via targeted ultra-high pressure liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS). While 27 PFAS were measured (in at least one filter), the predominant species were polyfluorinated dialkylated phosphate esters (diPAPs), with the sum of 6:2-, 8:2-, and 6:2/8:2diPAPs accounting for approximately 95 and 98 percent of ∑27PFAS in campus and household filters, respectively. Exploratory screening of a subset of the filters revealed the presence of additional species of mono-, di-, and tri-PAPs. Considering the constant human exposure to dust indoors and the potential of PAPs to degrade into terminal species with well-established toxicological risks, assessing dust for these precursor PFAS warrants further investigation with respect to both human health and PFAS loading to landfills from this under studied waste stream.

Combined Effects of Polluted Particles and Environmental Factors on Electrochemical Migration Failure

With the miniaturization of printed circuit board (PCB), the distance between the circuit traces or assembled component terminals is becoming smaller and smaller. Under the certain temperature, relative humidity, and bias voltage (THB), it is easier for the insulation performance between circuits to degrade due to electrochemical migration (ECM). The airborne dust deposited on the PCB during a long-term service may change the failure mechanism and time to failure (TTF) of ECM between circuits. In this paper, the mechanism and the characteristics of the combined effects of quartz particles in airborne dust, the temperature, the relative humidity and the bias voltage on the ECM failure of immersion silver finished PCB were studied by THB experiments. Then, the influencing significance of four factors on TTF of ECM were studied by the orthogonal test and range analysis. The results show that the silver cations migrate firstly but the exposed copper substrate on the positive electrode become the main migrated substance finally. The TTF of ECM changes non-monotonously with the increase of particle coverage density due to the bidirectional function of the insoluble particles, which can increase water condensation on PCB by the capillary action, but can extend the migration path of metal cations by physical barriers. The turning point is about the coverage density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$350~\mu \text{g}$ </tex-math></inline-formula> /cm 2. The insoluble particles with high coverage density can significantly shorten the TTF of ECM on the PCB than that with low coverage density under the same THB conditions.

Divergent TLR2 and TLR4 Activation by Fungal Spores and Species Diversity in Dust from Waste Sorting Plants.

This manuscript presents the results of an exploratory study on the relationships between NF-κB response through Toll-like receptor (TLR) activation by dust characterized by fungal spore concentrations and species diversity. Personal total dust samples were collected from Norwegian waste sorting plants and then characterized for fungal spores and fungal species diversity, as well as for other bioaerosol components, including endotoxins and actinobacteria. The ability of the dust to induce an NF-κB response by activating TLR2 and TLR4 in vitro was evaluated, as well as the relationship between such responses and quantifiable bioaerosol components. The average concentrations of bioaerosols were 7.23 mg total dust m-3, 4.49 × 105 fungal spores m-3, 814 endotoxin units m-3, and 0.6 × 105 actinobacteria m-3. The mean diversity measurements were 326, 0.59, and 3.39 for fungal richness, evenness, and Shannon index, respectively. Overall, fungal operational taxonomic units (OTUs) belonging to the Ascomycota phylum were most abundant (55%), followed by Basidiomycota (33%) and Mucoromycota (3%). All samples induced significant NF-κB responses through TLR2 and TLR4 activation. While fungal spore levels were positively associated with TLR2 and TLR4 activation, there was a trend that fungal species richness was negatively associated with the activation of these receptors. This observation supports the existence of divergent immunological response relationships between TLR activation and fungal spore levels on one hand and between TLR activation and fungal species diversity on the other. Such relationships seem to be described for the first time for dust from waste facilities. IMPORTANCE This manuscript presents results on multifactorial characterization of bioaerosol exposure in Norwegian waste sorting plants and the potential of such airborne dust to induce NF-κB reactions through TLR2 and TLR4 activations in an in vitro reporter cell model system. Our data revealed that increasing fungal spore levels in the dust is associated with increased activation of TLR2 and TLR4, whereas increasing fungal OTU richness is associated with decreasing activation of these receptors. The NF-κB-induced responses by the collected dust represent, therefore, effective measures of potential key immunological effects induced by a complex mixture of hazardous components, including characterized factors such as endotoxins, fungal spores, bacteria, and many other uncharacterized components. The key immunological events reported here are suggested as holistic alternatives to today's bioaerosol exposure characterization approaches for epidemiological studies in the future.

Application of quantitative mineralogy to determine sources of airborne particles at a European copper smelter

Copper processing operations, such as smelters and refineries, can produce airborne particles that may impact the health of workers. At these operations, worker exposure to chemicals are regularly monitored to ensure that regulatory compliance with occupational exposure limit values (OELVs) are maintained. Determining the type of airborne particles present is important for characterizing the composition of dust exposures and better understanding the relationship between worker exposure and health. Routine methods of analysis (e.g., chemical assay) are unable to differentiate between phases containing the same elements and may result in ambiguity. A novel approach of a combination of Quantitative Evaluation of Materials by Scanning Electron Microscope (QEMSCAN) and chemical characterization was used here to evaluate airborne and settled dust collected at key locations throughout a copper smelter in Europe. The copper (Cu) phases present in the airborne dust are indicative of the activities performed at specific locations. In the batch preparation area where Cu concentrate is received, significant amounts of Cu were carried in sulfidic minerals (chalcocite, chalcopyrite/bornite, >40%), whereas near the anode and electric furnace, the majority of Cu in dust was carried in metallic and oxidic phases (60–70%). Particle size analysis of the settled dust indicates that the sulfidic and oxidic Cu minerals are more likely to become airborne over metallic Cu. Furthermore, overall Cu concentrations decreased with particle size where metallic and oxidic Cu dominate, which suggests that differences in the proportion of Cu forms present in the dust will impact how much Cu ends up in the respirable fraction. These results highlight the need to understand the characterization of Cu in dust in order to set better OELVs.

Assessment of Lung Efficiency of Individuals Exposed to Various Foundry Industries in Satara City

The airborne dust as pollutants plays a major role in the overall atmospheric pollution. Silica is a chemical term for silicon dioxide (SiO2). The term crystalline silica refers to a crystallized form of SiO2 known as quartz, crystobalite or tridymite; it is the most abundant compound on the earth’s crust capable of causing silicosis and lung cancer upon inhaling large doses in course of occupational exposure. The present study was aim to evaluate the lung efficiency of individuals who worked in various foundry industries in Satara city. Around 300 individuals were enrolled. From selected three locations, 100 individuals were enrolled. All the individuals from the test were given a pulmonary function test. Before the test, a questionnaire was given to them to collect their basic information. Their age, height and weight were also entered in the spirometer. The spirometer gives two values; one is the expected value and the other is actual value. The predicted values are based upon the age, height and weight of the person while the actual values are dependent upon the maximal inspiration and expiration of the person. All the parameters, i.e. FVC, SVC and MVV showed impairment in the large industry workers compared to other two industries workers. A significant difference (p &lt; 0.01) in the actual and expected values was observed in the pulmonary function test individuals of all the three selected industries. The percentage efficiency for all parameters for small industry workers, i.e. FVC (96.42 %), SVC (95.71 %) and MVV (88.69 %) was also good as compared to large and medium industries. At large industry, MVV efficiency was very less (59.66 %) as compared to the medium industry (68.61 %) and small industry (88.69 %) workers. In the SVC also, a large industry worker (69.72 %) showed less value as compared to the medium industry (79.99 %) and small industry (95.71 %) workers. Restrictive defect was 14 %, 36 %, 33 % and 17 % in the large industry workers which was normal, mild, moderate and severe, respectively. These values were very low as compared to small industry workers. Individuals exposed to heavy load of pollutants in air are susceptible for many respiratory disorders. Decrease in the FVC, MVV and SVC parameters were observed in the individuals of large industry assz compared to medium and small industry. This impairment in the pulmonary test parameters are indications of an accumulation of pollutants in the airways, which intern reduces inhalation and exhalation force. So, the people exposing continuously to such silica or particulate matter pollution should be made aware about pulmonary disorders.

Composition of Culturable Microorganisms in Dusts Collected from Sport Facilities in Finland during the COVID-19 Pandemic.

Sport facilities represent extreme indoor environments due to intense cleaning and disinfection. The aim of this study was to describe the composition of the cultivated microbiota in dust samples collected in sport facilities during the COVID-19 pandemic. A dust sample is defined as the airborne dust sedimented on 0.02 m2 within 28 d. The results show that the microbial viable counts in samples of airborne dust (n = 9) collected from seven Finnish sport facilities during the pandemic contained a high proportion of pathogenic filamentous fungi and a low proportion of bacteria. The microbial viable counts were between 14 CFU and 189 CFU per dust sample. In seven samples from sport facilities, 20-85% of the microbial viable counts were fungi. Out of 123 fungal colonies, 47 colonies belonged to the potentially pathogenic sections of Aspergillus (Sections Fumigati, Nigri, and Flavi). Representatives of each section were identified as Aspergillus fumigatus, A. flavus, A. niger and A. tubingensis. Six colonies belonged to the genus Paecilomyces. In six samples of dust, a high proportion (50-100%) of the total fungal viable counts consisted of these potentially pathogenic fungi. A total of 70 isolates were considered less likely to be pathogenic, and were identified as Aspergillus section Nidulantes, Chaetomium cochliodes and Penicillium sp. In the rural (n = 2) and urban (n = 7) control dust samples, the microbial viable counts were >2000 CFU and between 44 CFU and 215 CFU, respectively, and consisted mainly of bacteria. The low proportion of bacteria and the high proportion of stress tolerant, potentially pathogenic fungi in the dust samples from sport facilities may reflect the influence of disinfection on microbial communities.

Molecular Identification, Isolation, Morphologic and Serologic of Acanthamoeba sp. Throw the Ovary of Sprague-Dawley Rats.

&lt;b&gt;Background and Objective:&lt;/b&gt; Typically, free-living amoebae, members of the genus &lt;i&gt;Acanthamoeba&lt;/i&gt; can exist in a range of biological niches, such as fresh and brackish water, filters for heating, soil, airborne dust, ventilation, in addition to air conditioning, as well as pools and hot tubs. On rare occasions, these can be linked to infections of the central nervous system in both people in addition to animals. This study aimed to identify the cause of rats' death by isolating and identifying &lt;i&gt;Acanthamoeba&lt;/i&gt; sp., from the ovary of Sprague-Dawley rats. &lt;b&gt;Materials and Methods:&lt;/b&gt; An amoeba was identified and cultured from the ovary of Sprague-Dawley rats that succumbed to an amoebic illness. Considering culture attributes, growth shape and immunofluorescence measures, &lt;i&gt;Acanthamoeba&lt;/i&gt; sp., was determined as the infecting amoeba. &lt;b&gt;Results:&lt;/b&gt; &lt;i&gt;Acanthamoeba&lt;/i&gt; sp., the contaminating single adaptable cell, was discovered. Furthermore, by sequencing a symptomatic part of the atomic little subunit ribosomal RNA gene to recognize the one-celled critter as &lt;i&gt;Acanthamoeba&lt;/i&gt; sp., &lt;b&gt;Conclusion:&lt;/b&gt; An &lt;i&gt;Acanthamoeba&lt;/i&gt; strain was demonstrated that has a wide range of genotypes and is capable of infecting people and other species can also infect rats fatally.

Dry air intrusions link Rossby wave breaking to large-scale dust storms in Northwest Africa: Four extreme cases

Large dust storms in the Saharan desert and the subsequent transport of airborne dust over large distances are a major meteorological hazard. Several mechanisms associated to dust emission, occurring on a range of scales, have been previously documented, notably involving Rossby wave breaking and a low-level jet. However, the mechanistic link between the different features and actual dust concentrations has not been coherently established. Here, using a Lagrangian approach, and the conceptual view of extratropical cyclone airstreams, the role of the dry intrusion airstream for translating the influence of the upper-tropospheric Rossby wave perturbation to near-surface flow conductive for the highest dust concentrations is examined. To this end, four large-scale dust storms that were accompanied by dry intrusions in west Africa are studied. Data from the Copernicus Atmospheric Monitoring Service (validated against AERONET station data) are combined with atmospheric data from reanalysis and objectively-identified Lagrangian trajectories of dry intrusions. Common, coherent structures highlighting the role of dry intrusions link the upper-tropospheric Rossby wave breaks with the lower-tropospheric dry and cold jets. These conditions favor dust uplift and transport along an arc-shaped cold front trailing from a Mediterranean cyclone. Consequently, the southwest side of the front is characterized by the highest near-surface dust concentrations ahead of the dry intrusion outflow, where the Intertropical Discontinuity shifts equatorward by 3 to 7°. The northeast part of the front is, however, accompanied by southerly, warm conveyor belt-like flow transporting the dust northward to the Mediterranean, Middle East and/or Europe at mid and upper-tropospheric levels. While case-to-case variations exists, the central role of dry intrusions in all cases calls for systematic investigation of its occurrence as a predictive tool for large dust transport events.

Exposure sources and pathways of micro- and nanoplastics in the environment, with emphasis on potential effects in humans: A systematic review.

Microplastics (MPs) are emerging pollutants that are ubiquitous in the environment, and may be a potential threat to human health. This review describes the MP exposure sources and pathways through drinking water, food intake, and air inhalation. The unregulated discharge of MPs in water sources and the absence of required MP filter technology in water treatment plants are important routes of MP exposure through drinking water. The presence of MPs in food may lead to the accumulation of MPs in the body. Exposure to MPs can occur through airborne fallout and dust inhalation in both indoor and outdoor environments. This review summarizes the MP exposure sources and possible pathways in the human body, and illustrates that the intake of drinking water, food consumption, and air inhalation should be assessed in during routine activities. Integr Environ Assess Manag 2023;19:1422-1432. © 2023 SETAC.

Evaluation of transport processes over North China Plain and Yangtze River Delta using MAX-DOAS observations

Abstract. Pollutant transport has a substantial impact on the atmospheric environment in megacity clusters. However, owing to the lack of knowledge of vertical pollutant structure, quantification of transport processes and understanding of their impacts on the environment remain inadequate. In this study, we retrieved the vertical profiles of aerosols, nitrogen dioxide (NO2), and formaldehyde (HCHO) using multi-axis differential optical absorption spectroscopy (MAX-DOAS) and analyzed three typical transport phenomena over the North China Plain (NCP) and Yangtze River Delta (YRD). We found the following: (1) the main transport layers (MTL) of aerosols, NO2, and HCHO along the southwest–northeast transport pathway in the Jing-Jin-Ji region were approximately 400–800, 0–400, and 400–1200 m, respectively. The maximum transport flux of HCHO appeared in Wangdu (WD), and aerosol and NO2 transport fluxes were assumed to be high in Shijiazhuang (SJZ), both urban areas being significant sources feeding regional pollutant transport pathways. (2) The NCP was affected by severe dust transport on 15 March 2021. The airborne dust suppressed dissipation and boosted pollutant accumulation, decreasing the height of high-altitude pollutant peaks. Furthermore, the dust enhanced aerosol production and accumulation, weakening light intensity. For the NO2 levels, dust and aerosols had different effects. At the SJZ and Dongying (DY) stations, the decreased light intensity prevented NO2 photolysis and favored NO2 concentration increase. In contrast, dust and aerosols provided surfaces for heterogeneous reactions, resulting in reduced NO2 levels at the Nancheng (NC) and Xianghe (XH) stations. The reduced solar radiation favored local HCHO accumulation in SJZ owing to the dominant contribution of the primary HCHO. (3) Back-and-forth transboundary transport between the NCP and YRD was found. The YRD-to-NCP and NCP-to-YRD transport processes mainly occurred in the 500–1500 and 0–1000 m layers, respectively. This transport, accompanied by the dome effect of aerosols, produced a large-scale increase in PM2.5, further validating the haze-amplifying mechanism.

Airborne antibiotic resistome and human health risk in railway stations during COVID-19 pandemic

Antimicrobial resistance is recognized as one of the greatest public health concerns. It is becoming an increasingly threat during the COVID-19 pandemic due to increasing usage of antimicrobials, such as antibiotics and disinfectants, in healthcare facilities or public spaces. To explore the characteristics of airborne antibiotic resistome in public transport systems, we assessed distribution and health risks of airborne antibiotic resistome and microbiome in railway stations before and after the pandemic outbreak by culture-independent and culture-dependent metagenomic analysis. Results showed that the diversity of airborne antibiotic resistance genes (ARGs) decreased following the pandemic, while the relative abundance of core ARGs increased. A total of 159 horizontally acquired ARGs, predominantly confering resistance to macrolides and aminoglycosides, were identified in the airborne bacteria and dust samples. Meanwhile, the abundance of horizontally acquired ARGs hosted by pathogens increased during the pandemic. A bloom of clinically important antibiotic (tigecycline and meropenem) resistant bacteria was found following the pandemic outbreak. 251 high-quality metagenome-assembled genomes (MAGs) were recovered from 27 metagenomes, and 86 genera and 125 species were classified. Relative abundance of ARG-carrying MAGs, taxonomically assigned to genus of Bacillus, Pseudomonas, Acinetobacter, and Staphylococcus, was found increased during the pandemic. Bayesian source tracking estimated that human skin and anthropogenic activities were presumptive resistome sources for the public transit air. Moreover, risk assessment based on resistome and microbiome data revealed elevated airborne health risks during the pandemic.

Answers blowing in the wind: Detection of birds, mammals, and amphibians with airborne environmental DNA in a natural environment over a yearlong survey

AbstractAnalysis of environmental DNA (eDNA) from passively collected airborne dust has demonstrated broad success for sensitive and robust detection of plants. Recent experiments at small spatial scales have suggested that animals can also be detected using airborne eDNA. However, airborne eDNA analysis has never been used for a long‐term whole‐community assessment of a natural terrestrial community or with passive dust collectors. We conducted a metabarcoding survey targeting vertebrate eDNA from dust carried in the air on an approximately 130‐acre shortgrass prairie passively collected over the course of a year. Our survey detected a wide variety of animal forms including an amphibian species, several bird species, and both small and large mammals. We found that airborne eDNA signals changed with known patterns of animal activity, wind speed, and rainfall. Overall, we demonstrate that passively collected airborne dust carries eDNA from terrestrial animals and could be used to detect a wide variety of terrestrial vertebrate species in a natural environment with minimal effort. To develop this as a valuable monitoring tool, research needs to focus on the ecology of eDNA carried in the air, which includes the origin, state, transport, dispersal, and fate of eDNA in the environment.

Airborne Dust and Associated Metals: A Link between its impact and sink rate within different roadside plants

&lt;p&gt;Transportation driven by fossil fuels increases air pollution induced by urbanisation. Heavy metals such as Cadmium (Cd), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), and Zinc (Zn) are life-threatening elements and their concentration is increasing alarmingly in soil in various countries. Air pollution and associated metals contaminate the environment and affect nature's abiotic and biotic components. The significance of tree species originates from their connection to the effects of pollution and the solution approach to their biological cycle. Nineteen distinct tree species dominate the region, with heavy metals sinking in the range of Cd&amp;lt;0.4, Cr&amp;lt;1, Cu&amp;lt;15, Fe&amp;lt;2, Pb&amp;lt;5, and Zn&amp;lt;2 mg/kg or parts per million. According to the findings of this study, tree species can sink heavy metals. The different trees have distinct metals-sink ratios. The competence results showed the order of heavy metal sink as Delonix Regia-red (4) &amp;gt; Delonix Regia-yellow (4) &amp;gt; Syzygium Cumini (3) &amp;gt; Muntingic Calabura (3) of the trees with the highest sink rates and nine species had absorbed lead metal. The nine tree species were unsuitable for heavy metal absorption or deposition. There, Albizia Lebbeck (T02), Biancaca Decapetela (T05), Brucea Javanica (T06), Ficus Elastica (T09), Ficus Religiosa (T10), Pithecellobium Dulce (T13), Tamarind (T17), Terminalia Catappa (T18), and Thespesia Populnea (T19) were very low, less than 10% of other dominant tree species. Syzygium cumini (T16) is a high-yielding tree species that absorb significant quantities of Lead (Pb) and Copper (Cu). These studies confirm that, tree species can capture several heavy metals simultaneously from the polluted environment.&lt;/p&gt;&#x0D;

Assessing Environmental Mitigation Strategies in Controlled Cage-Free Aviary Housing Systems: Effect on Air Quality and Bioaerosols

Highlights Three mitigation strategies were tested in experimental chambers fitted as small-scale aviaries. Particle monitor and high-flow air samplers were used to sample airborne dust (PM) and bioaerosols. Oil emulsion sprinkling on the litter surface of aviaries was effective in reducing PM emissions in experimental chambers. Abstract. Alternative housing systems for laying hens are gradually replacing battery cages. Though these systems provide more space per animal and enrichments, higher concentrations of ammonia and airborne dust have been reported in those environments. In this project, three environmental control strategies and a control condition were tested in twelve experimental chambers fitted as small-scale aviaries. The experiment was conducted during three periods spanning 18 weeks, during which PM and bioaerosols were sampled in each chamber in three separate sampling campaigns. Emissions of PM, culturable bacteria and molds, total bacteria, Penicillium, and Aspergillus molds and selected fecal indicators (Campylobacter coli, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Enterococcus spp., Salmonella spp.) were assessed in each experimental chamber. Strategies that included oil emulsion sprinkling on litter surface were effective at reducing PM emissions, while no significant effect (p &amp;gt; 0.05) was observed on ammonia emissions, and the effect on bioaerosol was variable under the evaluated conditions. Keywords: Airborne dust, Aviaries, Bioaerosol, Laying hen alternative housing, Mitigation.

Quality control of endotoxin measurement in dust samples/Qualitätskontrolle der Endotoxinmessung in Staubproben

Endotoxin activity determination is a common tool and a surrogate marker for bioaerosol assessment and is used at workplaces especially for this purpose. The reliability of the methods used for quantification in airborne dust samples is important for exposure estimation and thus for assessing the workplace situation. Within the scope of this study, the reproducibility of the endotoxin activity values determined with the two common methods, the LAL test and the rFC test, should be determined and compared. 21 water-based dust extracts from electrostatic dust collectors (EDC) were used for repeated endotoxin quantification using LAL and rFC test. As a result, twelve independent standard curves (0-50 EU/ml) were applied showing a median coefficient of variation (CV) of 9% for rFC and 12% for LAL test. The measured endotoxin activities of the samples could be reproduced within one test as well on three consecutive days. The CV of the 7- and 8-fold measured samples was below 20%. in 92% (LAL) and 93% (rFC) of the samples. Multiple measurements of the same sample showed that the results of LAL and rFC tests are highly reproducible. To eliminate interfering factors detected by recovery of spiked samples, dilutions of the samples are valuable methodological tools. This study demonstrates that quality-assured quantification of endotoxin activity is possible with both methods and is suitable for workplace measurements using the respective Standard Operation Procedure (SOP).

Airborne dust pollution due to mechanised scaling in underground metalliferous mine cross-cut drive under buoyancy-driven airflow

ABSTRACT Nowadays, mechanised scaling is extensively used in fully mechanised underground metalliferous mines (FMUMM) for removing potentially dangerous loose rocks from the mine roof and side walls. This study measures and analyses the generation and dispersion of airborne dust due to mechanised scaling operation by scaler in cross-cut (X-cut) drive of an underground mine using real-time aerosol spectrometers. The airborne dust is analysed in terms of the concentration of various size particles in total airborne dust (TAD). The analyses of different dust sizes, viz. ≤20 μm, ≤15 μm, ≤10 μm, ≤5 μm and ≤1 μm revealed that the per cent proportion of ≤1 μm and ≤10 μm varies from 2.6 to 22.4% and 60.5 to 88.3%, respectively, in the cross-cut. Moreover, the concentration proportions of alveolic and thoracic dusts in TAD during the 20-min retention time are assessed. This study can aid in developing safe re-entry periods and efficient dust control appliances.

Urbanization increases the range, but not the depth, of forest edge influences on Pinus sylvestris bark pH

The influence of forest edge on Pinus sylvestris bark pH was evaluated in urban and suburban pine forests in Yekaterinburg (South Taiga subzone, Central Urals, Russia). The measurements was conducted in 18 transects (rows of 6–10 sample plots arranged in pairs along a 100–260 m line perpendicular to the forest boundary); 12 transects (110 plots) were located in the urban forest and 6 transects (58 plots) in the suburban forest. All the characteristics studied (degree of urbanization, distance from forest boundary, and type and age of boundary), were found to have a significant effect on the pH of P. sylvestris bark. Bark alkalinization increased on average by 0.2 to 0.5 pH units above background along a gradient from the forest interior to the forest edge. In urban forests, the edge influence was about twice greater (0.6–0.8 pH units) than in suburban forests (0.2–0.3 pH units), while the depth ranged between 70 and 160 m. Little variation in the depth of the edge influence observed due to transect characteristics, and no differences were noted due to degree of urbanization. The range of the edge influence was cumulative over the time that had elapsed since forest fragmentation and highway construction. The results show that urban airborne dust pollution affects southern taiga pine forests to a depth of about 100 to 150 meters from forest boundary. This circumstance is important to take into account when planning the locations of the borders of forests, roads, residential and social areas.

Evaluation of a self-cleaning portable dust collector for reducing worker exposures to silica at hydraulic-fracturing sites

ABSTRACT National Institute for Occupational Safety and Health (NIOSH) researchers continue to study worker exposure to respirable crystalline silica (RCS) and develop interventions to reduce these exposures. Occupational overexposures to RCS continue to cause illness and deaths in many industries and RCS has been identified as a serious exposure risk associated with hydraulic- fracturing operations during oil and gas extraction. In 2016 the Occupational Safety and Health Administration (OSHA) reduced the permissible exposure limit (PEL) to 0.05 milligrams of silica per cubic meter of air, averaged over an 8-hour day. This mandate requires hydraulic-fracturing operations to implement dust controls and safer work methods to protect workers from silica exposures above this PEL by June 23, 2021. At hydraulic-fracturing sites utilizing sand movers, pneumatic transfer of fracking sand is the primary source of aerosolized RCS. Currently, there are limited commercially available engineering controls for the collection of dust emitted from thief hatches on sand movers. The goal of this research is to develop a robust, cost-effective, weather resistant, portable, self-cleaning dust collection system that can be retrofitted onto sand mover thief hatches. A prototype was designed, built, and tested, and it was determined that the system could handle flows in the range of 600 to 1300 cfm with loading/cleaning cycle times of 40 and 5 minutes respectively and demonstrated operating efficiencies of 97–99%. Further development of this NIOSH prototype is being done in collaboration with an industry partner with the goal of developing a commercially viable, cost-effective solution to reduce RCS at hydraulic-fracturing sites around the world. Implications: This research has verified that airborne dust created by pneumatic transfer of fracking sand can be effectively collected using a passive cartridge filter system, and that the filters can be cleaned using blasts of air. Mounting these units to the thief hatches of sand movers will significantly reduce dust emissions from sand movers on hydraulic fracturing sites. Thus, this system offers the Oil and Gas Industry a method to reduce worker exposure to RCS on hydraulic fracturing sites that utilize sand movers. The success of this prototype has led researchers to devise a modified version for collecting dust at conveyor transfer points.

Development of analytical methods for the determination of 3-hydroxy fatty acids and muramic acid as bacterial markers in airborne particles and settled dust

Inhalation of airborne bacteria in indoor environments is known to be associated with respiratory diseases. Analytical methods for the determination of 3-hydroxy fatty acids (3-OHFAs) and muramic acid (MA) as chemical markers of gram-negative and gram-positive bacteria, respectively, were developed for airborne particle and dust samples in this study. 3-OHFAs as markers of endotoxin were released and esterified during the hydrolysis process under methanolic acid conditions, and their hydrolysates, i.e., 3-OHFA methyl esters, were cleaned up by solid-phase extraction using silica sorbent that provided more effective separation from interferents than polymeric sorbent through elution pattern. The SPE eluent was analyzed by GC-MS/MS measurement after the trimethylsilylation reaction. The recovery of the method ranged from 82.1 % to 103.2 %, with a limit of detection ranging from 0.5 to 1.1 ng/filter and good linearity (R2 > 0.991). For the analysis of MA, muramic acid methyl ester (MAME), a product formed during methanolic hydrolysis, was selected as a specific marker of peptidoglycan. It was the first proposed compound identified and confirmed with MS and MS/MS spectra using high-resolution measurement. In particular, the measurement of MAME providing 12.5 times greater sensitivity than MA with the application of the LC-MS/MS method is one of the notable findings of this study. The recovery by simple liquid extraction was 99.4 % following the removal of the hydrophobic matrix and neutralization with solvent reconstruction. The method displayed a LOD of 0.7 ng/filter and linearity (R2) of 0.997 through a simple pretreatment process. Both developed methods were applied and evaluated by determining 3-OHFAs and MA in airborne particles collected from multipurpose facilities and settled dust in the laboratory and office.

Soil heavy metal contamination in the vicinity of the abandoned Zeïda mine in the Upper Moulouya Basin, Morocco. Implications for airborne dust pollution under semi-arid climatic conditions

For thirteen years, the Zeïda mine was one of Morocco's biggest lead reserves. The mining activities produced a huge volume of waste stored as tailings and subjected to meteoric agents. To better understand the impact of the past mining activity on the soil ecosystem in the vicinity of the abandoned mine, several physical and chemical analysis were done to identify the level of soil contamination. A total of 27 surface soil samples were collected from a depth of about 0–20 cm from crop areas and analysed for Pb, Zn, Cu, Co, Cd, and As total concentrations (aqua regia extraction) using the ICP-MS method. Results showed that soils have high to medium levels of metal concentrations, especially close to the tailings, compared to the non-contaminated soil sample taken as a geochemical background reference. Analysis of physicochemical parameters (pH, electrical conductivity, total calcium, phosphorus, potassium, and organic matter) has shown high alkalinity levels related to carbonates, varying organic matter content, and electrical conductivity values ranging from 4.12 to 1466 μS/cm. Most of the studied soils share the same mineralogical composition that includes: carbonates (Calcite and Dolomite), Quartz, Orthoclase, and Muscovite. Lead mineral phases (cerussite and wulfenite) have been found in 3 samples (ZAM17, ZAM18, and ZAM21). The Illite and the Kaolinite are the main clay minerals. Descriptive and multivariate statistics were carried out to investigate the distribution of the studied metals. Comparing the obtained results with International Standard Limits (ISL), soils especially those close to the mine tailings show high heavy metals content. Pb, Zn, Cu, As, and Cd contents in Zeïda soils are usually linked to anthropogenic origins. Results have shown correlation values between As, Cu, and Cd and Pb and Zn indicating that they come from the same origin and react similarly throughout transport.