Total Particle Concentration Research Articles

An Amorphous Phase Precedes Crystallization: Unraveling the Colloidal Synthesis of Zirconium Oxide Nanocrystals.

One can nowadays readily generate monodisperse colloidal nanocrystals, but the underlying mechanism of nucleation and growth is still a matter of intense debate. Here, we combine X-ray pair distribution function (PDF) analysis, small-angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM) to investigate the nucleation and growth of zirconia nanocrystals from zirconium chloride and zirconium isopropoxide at 340 °C, in the presence of surfactant (tri-n-octylphosphine oxide). Through E1 elimination, precursor conversion leads to the formation of small amorphous particles (less than 2 nm in diameter). Over the course of the reaction, the total particle concentration decreases while the concentration of nanocrystals stays constant after a sudden increase (nucleation). Kinetic modeling suggests that amorphous particles nucleate into nanocrystals through a second order process and they are also the source of nanocrystal growth. There is no evidence for a soluble monomer. The nonclassical nucleation is related to a precursor decomposition rate that is an order of magnitude higher than the observed crystallization rate. Using different zirconium precursors (e.g., ZrBr4 or Zr(OtBu)4), we can tune the precursor decomposition rate and thus control the nanocrystal size. We expect these findings to help researchers in the further development of colloidal syntheses.

Characterizing a Year-Round Particulate Matter Concentration and Variation under Different Environmental Controls in a Naturally Ventilated Dairy Barn

A mixing fan and spraying system is commonly used to control the indoor environment of naturally ventilated dairy barns worldwide. However, its impact on particulate matter (PM) concentration and variation is still unclear due to the lack of year-round field data. To systematically characterize the PM dynamics under different environmental controls (namely, EC1: No Fans and No Spraying; EC2: Fans; EC3: Fans and Spraying), a year-round continuous monitoring of PM less than 2.5 μm in aerodynamic diameter (PM2.5) and total suspended particle (TSP) concentrations, as well as indoor environmental factors, was carried out inside a naturally ventilated dairy barn using an IoT-based sensor monitoring network. Results showed that the hourly mean TSP and PM2.5 concentrations were 94.7 μg m−3 and 49.8 μg m−3, respectively. EC2 had a higher TSP content (116.6 μg m−3) than EC1 (98.0 μg m−3) and EC3 (81.9 μg m−3). EC1 had the greatest PM2.5 concentration (57.1 μg m−3), followed by EC2 (48.3 μg m−3) and EC3 (44.7 μg m−3). EC1 showed clear TSP and PM2.5 fluctuations during the daily operations at 07:00 to 08:00 and 18:00 to 19:00, while irregular peaks in EC2 and a relatively steady diurnal variation in EC3 were found. Daily Tsp concentrations in the three ECs did not exceed 300 μg m−3. However, 17.8%, 11.5%, and 4.8% of the observed days in EC1, EC2, and EC3 had daily mean PM2.5 concentrations above the healthy threshold (75 μg m−3), mostly from 07:00 to 08:00 and 22:00–07:00. In conclusion, the mixing fan and spraying system had significant effects on PM concentration and variation, and more protection procedures should be taken for farm workers to prevent long-term health risk exposure, to EC1 in particular.

Markers of Chemical and Microbiological Contamination of the Air in the Sport Centers.

This study aimed to assess the markers of chemical and microbiological contamination of the air at sport centers (e.g., the fitness center in Poland) including the determination of particulate matter, CO2, formaldehyde (DustTrak™ DRX Aerosol Monitor; Multi-functional Air Quality Detector), volatile organic compound (VOC) concentration (headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry), the number of microorganisms in the air (culture methods), and microbial biodiversity (high-throughput sequencing on the Illumina platform). Additionally the number of microorganisms and the presence of SARS-CoV-2 (PCR) on the surfaces was determined. Total particle concentration varied between 0.0445 mg m-3 and 0.0841 mg m-3 with the dominance (99.65-99.99%) of the PM2.5 fraction. The CO2 concentration ranged from 800 ppm to 2198 ppm, while the formaldehyde concentration was from 0.005 mg/m3 to 0.049 mg m-3. A total of 84 VOCs were identified in the air collected from the gym. Phenol, D-limonene, toluene, and 2-ethyl-1-hexanol dominated in the air at the tested facilities. The average daily number of bacteria was 7.17 × 102 CFU m-3-1.68 × 103 CFU m-3, while the number of fungi was 3.03 × 103 CFU m-3-7.34 × 103 CFU m-3. In total, 422 genera of bacteria and 408 genera of fungi representing 21 and 11 phyla, respectively, were detected in the gym. The most abundant bacteria and fungi (>1%) that belonged to the second and third groups of health hazards were: Escherichia-Shigella, Corynebacterium, Bacillus, Staphylococcus, Cladosporium, Aspergillus, and Penicillium. In addition, other species that may be allergenic (Epicoccum) or infectious (Acinetobacter, Sphingomonas, Sporobolomyces) were present in the air. Moreover, the SARS-CoV-2 virus was detected on surfaces in the gym. The monitoring proposal for the assessment of the air quality at a sport center includes the following markers: total particle concentration with the PM2.5 fraction, CO2 concentration, VOCs (phenol, toluene, and 2-ethyl-1-hexanol), and the number of bacteria and fungi.

Exploiting kaolinite-alumina heteroaggregation in Pickering emulsion stabilisation and porous mullite fabrication

Clay particles have gained considerable attention as a potential option for stabilising Pickering emulsions in recent years, which are promising templates for the development of porous ceramics intended for high temperature applications. However, the development of porous ceramics using this approach requires control over a number of factors such as stability, microstructure, rheology, and processability of the Pickering emulsions. In this work, we discuss a versatile approach for formulating porous mullite ceramics from emulsions stabilised by oppositely charged kaolinite and alumina particles. In this process, we exploit the electrostatic heteroaggregation phenomena in the oppositely charged mixed colloidal particle system. The aggregates formed by electrostatic interaction readily adsorb to the interface created during emulsification and favor the formation of highly stable Pickering emulsions. The influence of parameters such as concentration of each particle in the mixture, pH, and total particle concentration on the microstructure of Pickering emulsions are studied. We further show that processable Pickering emulsions can be engineered by in-situ surface modification of the hetero-aggregates using a short-chain amphiphile. Porous mullite ceramic is obtained by drying and sintering the optimised emulsion formulation. The phase evolution, microstructure, and porosity of the resulting ceramic are characterised. The macroporous mullite developed through this approach can be used as thermal insulator due to low thermal conductivity and tailored microstructure.

К новым методам измерения и распознавания микрочастиц пылей в атмосферном воздухе

Established health hazards posed by dust microparticles require automated and mobile devices for their assessment. Such devices should provide an opportunity to analyze component and disperse structures of the solid component in ambient air pollution operatively and in real time. In future, they will replace labor-consuming sampling and separate identification of fraction structure and chemical composition of dusts. The aim of this study was to develop and test new methodical, procedural and instrumental approaches to monitoring of solid particles in ambient air. We suggest a hardware and software complex that implements a two-stage scheme for identifying solid particles sampled in ambient air according to the from-coarse-to-fine principle. The first stage involves identifying the total concentration of solid particles by laser diffraction. Microphotographs are taken with iMicro Q2 mini portable microscope with magnification x800. The microscope lens is connected to a camera, which is linked to nVidia Jetson Nano micro PC. The micro PC classifies particles, identifies their contours by using a neural network and deals with image segmentation. The second stage relies on using computer vision that makes it possible to automate routine recognition of particle images created by the microscope in order to calculate levels of different substances in a sample. All the data are analyzed by the second neural network that performs preset calculations in accordance with mathematical logic (model). The network is trained using a library that contains attributed microphotographs of dusts with different qualitative and disperse structures. The algorithm has been tested with some promising results. Identified disperse structures and chemical composition of dusts turn out to be quite similar to those identified by conventional approaches and measurement methods. The method has been shown to offer wide opportunities to identify dust composition and structure, to create dust pollution profiles, and to estimate a contribution made by a specific source to overall pollution. The study results ensure more correct and precise health risk assessment under exposure to dusts in ambient air.

Plasma Parameters and Kinetics of Reactive Ion Etching of SiO2 and Si3N4 in an HBr/Cl2/Ar Mixture

The parameters of the gas phase and the kinetics of reactive ion etching of SiO2 and Si3N4 under conditions of an induction RF (13.56 MHz) discharge with a varying HBr/Cl2 ratio is studied. The study includes plasma diagnostics using Langmuir probes, plasma modeling to find stationary concentrations of active particles, measuring velocities, and analyzing etching mechanisms in the effective interaction prob-ability approximation. It is found that the substitution of HBr by Cl2 at a constant argon content (a) is accompanied by a noticeable change in the electrical parameters of the plasma; (b) leads to a weak increase in the intensity of ion bombardment of the treated surface; and (c) causes a significant increase in the total concentration and flux density of reactive particles. It is shown that the etching rates of SiO2 and Si3N4 increase monotonically as the proportion of Cl2 increases in a mixture, while the main etching mechanism is an ion-stimulated chemical reaction. The model description of the kinetics of such a reaction in the first approximation assumes (a) the additive contribution of bromine and chlorine atoms and (b) the direct pro-portional dependence of their effective interaction probabilities on the intensity of ion bombardment. The existence of an additional channel of heterogeneous interaction with the participation of HCl molecules is proposed.

On new methods for measuring and identifying dust microparticles in ambient air

Established health hazards posed by dust microparticles require automated and mobile devices for their assessment. Such devices should provide an opportunity to analyze component and disperse structures of the solid component in ambient air pollution operatively and in real time. In future, they will replace labor-consuming sampling and separate identification of fraction structure and chemical composition of dusts. The aim of this study was to develop and test new methodical, procedural and instrumental approaches to monitoring of solid particles in ambient air. We suggest a hardware and software complex that implements a two-stage scheme for identifying solid particles sampled in ambient air according to the from-coarse-to-fine principle. The first stage involves identifying the total concentration of solid particles by laser diffraction. Microphotographs are taken with iMicro Q2 mini portable microscope with magnification x800. The microscope lens is connected to a camera, which is linked to nVidia Jetson Nano micro PC. The micro PC classifies particles, identifies their contours by using a neural network and deals with image segmentation. The second stage relies on using computer vision that makes it possible to automate routine recognition of particle images created by the microscope in order to calculate levels of different substances in a sample. All the data are analyzed by the second neural network that performs preset calculations in accordance with mathematical logic (model). The network is trained using a library that contains attributed microphotographs of dusts with different qualitative and disperse structures. The algorithm has been tested with some promising results. Identified disperse structures and chemical composition of dusts turn out to be quite similar to those identified by conventional approaches and measurement methods. The method has been shown to offer wide opportunities to identify dust composition and structure, to create dust pollution profiles, and to estimate a contribution made by a specific source to overall pollution. The study results ensure more correct and precise health risk assessment under exposure to dusts in ambient air.

Quantifying the Potential Water Filtration Capacity of a Constructed Shellfish Reef in a Temperate Hypereutrophic Estuary

Shellfish reefs have been lost from bays and estuaries globally, including in the Swan-Canning Estuary in Western Australia. As part of a national program to restore the ecosystem services that such reefs once provided and return this habitat from near extinction, the mussel Mytilus galloprovincialis was selected for a large-scale shellfish reef construction project in this estuary. To assess the potential filtration capacity of the reef, estuary seston quality, mussel feeding behavior, and valve gape activity were quantified in the laboratory and field during winter and summer. In general, estuary water contained high total particulate concentrations (7.9–8.7 mg L−1). Standard clearance rates were greater in winter (1.9 L h−1; 17 °C) than in summer (1.3 L h−1; 25 °C), the latter producing extremely low absorption efficiencies (37%). Mussel valves remained open ~97% and ~50% of the time in winter and summer, respectively. They often displayed erratic behavior in summer, possibly due to elevated temperatures and the toxic microalgae Alexandrium spp. Despite numerous stressors, the reef, at capacity, was estimated to filter 35% of the total volume of the estuary over winter, incorporating 42.7 t of organic matter into mussel tissue. The reefs would thus make a substantial contribution to improving estuary water quality.

Abstract 13404: Novel Sized-Based HDL Subspecies Demonstrate Inverse Associations With Incident Vascular Events

Recent studies suggest that total high-density lipoprotein particle concentration (HDL-P) outperforms HDL cholesterol (HDL-C) in predicting atherosclerotic cardiovascular disease (ASCVD). Whether specific size-based HDL subspecies contribute to the atheroprotective effects of HDL-P remains unknown. Our objective was to assess size-based HDL subspecies for association with both incident myocardial infarction (MI) and ischemic stroke in a large, diverse cohort, expecting heterogeneous associations regarding subspecies and vascular endpoints. Participants without prior ASCVD enrolled in the Dallas Heart Study, MESA, ARIC, and PREVEND were included as a single pooled cohort (N=15,371). Seven HDL size-based subspecies were quantified by NMR (LP4 algorithm; H1=smallest; H7=largest). The primary adjudicated outcomes over an average of 8-10 years of follow up were first MI and first ischemic stroke. Cox proportional hazards models included traditional ASCVD risk factors (except HDL-C) and all seven HDL subspecies. As continuous variables, higher H1, H2 and H4 concentrations were associated with lower risk of MI (Panel A), whereas higher H2 and H4 concentrations were associated with lower risk of ischemic stroke (Panel B). The top vs bottom quartiles of H2 and H4 had 27-32% lower incidence of MI (HR Q4 vs. Q1 [95% CI]: H1 0.73 [0.58-0.91]; H2 0.69 [0.54-0.89]; H4 0.68 [0.54-0.86]) and no significant associations with ischemic stroke. Serial adjustment for HDL-C attenuated all associations with ischemic stroke. However, H1 and H4 retained significant inverse associations with MI adjusted for HDL-C (HR/SD [95% CI]: H1 0.88 [0.81-0.94]; H4 0.89 [0.82-0.97]). H1 (small HDL) and H4 (medium HDL), but no large subspecies, demonstrated inverse associations with MI in a large multi-ethnic pooled cohort. Next steps include assessment of interactions by sex and race as well as incremental clinical utility of H1 and H4 compared to both HDL-C and total HDL-P in predicting MI.

Relationships of APOE Genotypes With Small RNA and Protein Cargo of Brain Tissue Extracellular Vesicles From Patients With Late-Stage AD.

Variants of the apolipoprotein E (APOE) gene are the greatest known risk factors for sporadic Alzheimer disease (AD). Three major APOE isoform alleles, ε2, ε3, and ε4, encode and produce proteins that differ by only 1-2 amino acids but have different binding partner interactions. Whereas APOE ε2 is protective against AD relative to ε3, ε4 is associated with an increased risk for AD development. However, the role of APOE in gene regulation in AD pathogenesis has remained largely undetermined. Extracellular vesicles (EVs) are lipid bilayer-delimited particles released by cells to dispose of unwanted materials and mediate intercellular communication, and they are implicated in AD pathophysiology. Brain-derived EVs (bdEVs) could act locally in the tissue and reflect cellular changes. To reveal whether APOE genotype affects EV components in AD brains, bdEVs were separated from patients with AD with different APOE genotypes for parallel small RNA and protein profile. bdEVs from late-stage AD brains (BRAAK stages 5-6) from patients with APOE genotypes ε2/3 (n = 5), ε3/3 (n = 5), ε3/4 (n = 6), and ε4/4 (n = 6) were separated using our published protocol into a 10,000g pelleted extracellular fraction (10K) and a further purified EV fraction. Counting, sizing, and multiomic characterization by small RNA sequencing and proteomic analysis were performed for 10K, EVs, and source tissue. Comparing APOE genotypes, no significant differences in bdEV total particle concentration or morphology were observed. Overall small RNA and protein profiles of 10K, EVs, and source tissue also did not differ substantially between different APOE genotypes. However, several differences in individual RNAs (including miRNAs and tRNAs) and proteins in 10K and EVs were observed when comparing the highest and lowest risk groups (ε4/4 and ε2/3). Bioinformatic analysis and previous publications indicate a potential regulatory role of these molecules in AD. For patients with late-stage AD in this study, only a few moderate differences were observed for small RNA and protein profiles between APOE genotypes. Among these, several newly identified 10K and EV-associated molecules may play roles in AD progression. Possibly, larger genotype-related differences exist and are more apparent in or before earlier disease stages.

Lipoprotein profiles of fat distribution and its association with insulin sensitivity.

Fat deposition is associated with adverse outcomes. Waist-to-hip (WHR) ratio is a simple feasible index to assess fat distribution. Lipoprotein particle composition in relation to WHR and to what extent their association is mediated by insulin sensitivity are less investigated. In 504 randomly recruited Flemish (mean age: 48.9 years; women: 51.6%), we analyzed the lipoprotein particle constitutions using nuclear magnetic resonance spectroscopy. WHR obesity described a WHR of ≥ 0.85 for women or 0.9 for men. Insulin sensitivity was evaluated by the homeostasis model assessment-estimated insulin resistance (HOMA-IR). SCORE-2 risk algorithm was applied to estimate 10-year cardiovascular risk. Statistical methods included multivariable-adjusted linear regression analysis, logistic regression analysis, and mediation analysis. The prevalence of WHR obesity was 54.6%, approximately 3 times of BMI-determined obesity (19.1%). Individuals with WHR obesity had significantly higher metabolic complications, such as hypertension (57.1%), dyslipidemia (61.8%), and insulin resistance (14.2%). WHR and WHR obesity were positively associated with total very-low-density lipoprotein (VLDL) particle concentration, remnant cholesterol, and triglycerides, but were negatively associated with VLDL particle size (P ≤ 0.027), independent of body mass index and other covariates. WHR was inversely associated with total high-density lipoprotein (HDL) particle concentration, whereas WHR obesity was inversely associated with HDL cholesterol (P ≤ 0.039). Neither WHR nor WHR obesity was associated with the concentration of total low-density lipoprotein (LDL) particles, LDL particle size, and LDL cholesterol (P ≥ 0.089). In the mediation analysis, insulin sensitivity significantly mediated the effect of WHR on total VLDL particle concentration (mediation percentage: 37.0%), remnant cholesterol (47.7%), and HDL cholesterol (41.1%). Individuals with WHR obesity were at increased cardiovascular risk, regardless of LDL cholesterol (P ≤0.028). In WHR obesity, higher total VLDL particle concent36ration and remnant cholesterol, and lower HDL cholesterol were associated with an increased cardiovascular risk (P≤ 0.002). Upper-body fat deposition was independently associated with an unfavorable lipoprotein profile, and insulin sensitivity significantly mediated this association. LDL cholesterol might underestimate lipid abnormality for people with upper-body obesity and lowering VLDL particles and remnant cholesterol might potentially reduce the residual cardiovascular risk.

Mass quantification of microplastic at wastewater treatment plants by pyrolysis-gas chromatography–mass spectrometry

Municipal wastewater treatment plants (WWTPs) are a central point of collection of plastic particles from households and industry and for their re-distribution into the environment. Existing studies evaluating levels of plastics in WWTPs, and their removal rates have reported and used data on polymer type, size, shape, colour, and number of plastic particles, while the total mass concentration of plastic particles (especially >1 μm) remains unclear and unknown. To address this knowledge gap, raw influent, effluent, and reference water samples from three WWTPs in Australia were collected to analyse the mass concentrations and removal rates of seven common plastics (>1 μm in size) across the treatment schemes. Quantitative analysis was performed by pressurized liquid extraction followed by pyrolysis coupled to gas chromatography mass spectrometry. Results showed that the total plastic content in the WWTPs raw influent samples was between 840 and 3116 μg/L, resulting in an inflow of between about 2.1 and 196.4 kg/day of the total measured plastics. Overall, >99 % by mass of the plastics entering the three WWTPs from the raw influent was removed during the pre-treatment stages, presumably ending up in the sewage sludge, which means emissions (via treated effluent) from the treatment plants are low. Compared with the raw influent, the plastic mass concentrations in the treated effluents (i.e., Class C, A, and final effluent) from the three WWTPs, as well as the reference water samples within their catchments were below the limits of reporting. Of the five quantified plastic types, polyethylene (PE, 76.4 %), and polyvinylchloride (PVC, 21 %) dominated by mass, while polyethylene terephthalate (PET, 1.9 %), polypropylene (PP, 0.4 %) and polymethyl methacrylate (PMMA, 0.3 %) accounted for a small proportion of the total. Overall, this study investigated the mass concentrations of plastic particles above 1 μm in wastewater and their removal, which provided valuable information regarding the pollution level and distribution characteristics of plastic polymers in Australian WWTPs.

PAH atmospheric log(KP) values in Great Lakes samples are related to black carbon levels near each site

Many semi-volatile organic pollutants are present in the atmosphere both in the vapor and particle phases. About 50 years ago, a partition coefficient (KP) was defined as the compound's concentration in the particle phase (Cpart, in ng/m3 or pg/m3) divided by its concentration in the vapor phase (Cvapor, also in ng/m3 or pg/m3) divided by the atmospheric concentration of total suspended particles (TSP, in μg/m3) or, more recently, by the concentration of particulate matter with aerodynamic diameters less than 2.5 μm (PM2.5, also in μg/m3). The original point of this term was to account for surface adsorption of pollutants to the particles, but over the years it has become apparent that absorption, particularly to black carbon (BC, also known as elemental carbon) in the particles, may also be important. This study investigates the importance of this particle term using about 3000 polycyclic aromatic hydrocarbon (PAH) concentrations measured from 1997 to 2018 (inclusive) in 24-h samples collected once every 12 days at five sites on the shores of the North American Great Lakes and using U.S. Environmental Protection Agency PM2.5 concentrations at the same sites. Analyses of variance of the annual mean log(KP) values show significant differences for all six compounds among the five sites, which we attribute to the composition of the particles at the five sites. For example, the particles from the urban sites are likely to have higher black carbon levels compared to those from the more rural and remote sites. With an additional term for black carbon in these samples, these new ratios are similar across sites for a given compound. These results suggest that a black carbon term is useful and potentially important.

SARS-CoV-2 in the Air Surrounding Patients during Nebulizer Therapy.

Nebulizer therapy is commonly used for patients with obstructive pulmonary disease or acute pulmonary infections with signs of obstruction. It is considered a “potential aerosol-generating procedure,” and the risk of disease transmission to health care workers is uncertain. The aim of this pilot study was to assess whether nebulizer therapy in hospitalized COVID-19 patients is associated with increased dispersion of SARS-CoV-2. Air samples collected prior to and during nebulizer therapy were analyzed by RT-PCR and cell culture. Total aerosol particle concentrations were also quantified. Of 13 patients, seven had quantifiable virus in oropharynx samples, and only two had RT-PCR positive air samples. For both these patients, air samples collected during nebulizer therapy had higher SARS-CoV-2 RNA concentrations compared to control air samples. Also, for particle sizes 0.3–5 µm, particle concentrations were significantly higher during nebulizer therapy than in controls. We were unable to cultivate virus from any of the RT-PCR positive air samples, and it is therefore unknown if the detected virus were replication-competent; however, the significant increase in smaller particles, which can remain airborne for extended periods of time, and increased viral RNA concentrations during treatment may indicate that nebulizer therapy is associated with increased risk of SARS-CoV-2 transmission.

Experimental development of a lake spray source function and its model implementation for Great Lakes surface emissions

Abstract. Lake spray aerosols (LSAs) are generated from freshwater breaking waves in a mechanism similar to their saltwater counterparts, sea spray aerosols (SSAs). Unlike the well-established research field pertaining to SSAs, studying LSAs is an emerging research topic due to their potential impacts on regional cloud processes and their association with the aerosolization of freshwater pathogens. A better understanding of these climatic and public health impacts requires the inclusion of LSA emission in atmospheric models, yet a major hurdle to this inclusion is the lack of a lake spray source function (LSSF), namely an LSA emission parameterization. Here, we develop an LSSF based on measurements of foam area and the corresponding LSA emission flux in a marine aerosol reference tank (MART). A sea spray source function (SSSF) is also developed for comparison. The developed LSSF and SSSF are then implemented in the Community Multiscale Air Quality (CMAQ) model to simulate particle emissions from the Great Lakes surface from 10 to 30 November 2016. Measurements in the MART revealed that the average SSA total number concentration was 8 times higher than that of LSA. Over the 0.01–10 µm aerosol diameter size range, the developed LSSF was around 1 order of magnitude lower than the SSSF and around 2 orders of magnitude lower for aerosols with diameters between 1 and 3 µm. Model results revealed that LSA emission flux from the Great Lakes surface can reach ∼105 m−2 s−1 during an episodic event of high wind speeds. These emissions only increased the average total aerosol number concentrations in the region by up to 1.65 %, yet their impact on coarse-mode aerosols was much more significant, with up to a 19-fold increase in some areas. The increase in aerosol loading was mostly near the source region, yet LSA particles were transported up to 1000 km inland. Above the lakes, LSA particles reached the cloud layer, where the total and coarse-mode particle concentrations increased by up to 3 % and 98 %, respectively. Overall, this study helps quantify LSA emission and its impact on regional aerosol loading and the cloud layer.

Health Risk Assessment of Human Exposure to Dust Exposure on Communities Around Weaving Industry in Palembang, Indonesia

Air pollution due to industrial activities is increasing worldwide, including in Indonesia. Particulate Matter (PM) is one of the air pollutant parameters that can cause health problems, especially respiratory problems in communities living at the weaving industrial area. The aimed of this study was to analyze the environmental health risk of human exposure due to dust exposure in communities around the weaving industry center. This research was an observational study using an environmental health risk analysis approach. Dust parameters were measured in as many as ten indoors and five outdoors around the weaving industry. The dust parameters measured were PM 2.5, PM 10, and Total Solid Particulate (TSP) concentration indoor and outdoor around the weaving industry areas. Dust measurements were carried out in the morning and afternoon using an Aerocet. The average results of dust measurement indoor were PM 2.5 (0.182 mg/m3), PM 10 (0.443 mg/m3), TSP (0.556 mg/m3), while for outdoor PM 2.5 (0.185 mg/m3). PM 10 (0.381 mg/m3), TSP (0.419 mg/m3). The average indoor of PM 2.5 intake was 0.013 mg/kg-day, PM10 (0.031 mg/kg-day), and TSP (0.038 mg/kg-day), and outdoor were PM 2.5 (for adult 0.064 mg/kg-day, for children 0.014 mg/kg-day), PM10 (for adult 0.132 mg/kg-day and for children 0.292 mg/kg-day), TSP (for adult 0.146 mg/kg-day and for children 0.322 mg/kg-day). All of them were more than Reference Concentration (RfC), and the Risk Quotient of PM10 and PM2.5 were more than 1. Exposure to PM10 and PM2.5 are unsafe or likely to result in non-carcinogenic effects on the residents in the next 30 years. The finding of this study is to provide information the dust concentration in the environment, the Risk Quotient of dust exposure in the communities around the weaving industry, and strategies for managing risks due to dust exposure in the traditional weaving industry center. Therefore, it is necessary to conduct a risk management scenario.

Characterisation of Particles Emitted during Laser Cutting of Various Metal Sheets and an Exposure Assessment for the Laser Operators

Laser cutting is used in many industrial settings to achieve precise cuts of metal sheets. Laser operators may be exposed to particles formed during cutting when opening the cabinet or when metal sheets are exchanged. To characterise the potential exposure, particles formed during laser cutting were studied with scanning electron microscopy equipped with an energy dispersive X-ray detector and an energy backscatter diffraction detector. The total concentration of particles (11–615 nm) was determined online with a scanning mobility particle sizer. The chemical composition of the particles formed during the cutting of the different metal sheets was determined by inductively coupled plasma mass spectrometry (ICP-MS). X-ray diffraction was applied to determine the phase composition. The occupational exposure was assessed gravimetrically and by ICP-MS for five laser operators handling different laser cutters, and materials and were found to be low. Agglomerates and aggregates of condensation particles were formed during laser cutting, independent of the sheet type. Iron, present as both magnetite and α-Fe, was the main element found in the particles formed when cutting steel sheets. The size of the particles generated was mainly below 300 nm. Open laser cutters may lead to higher metal exposures, which is especially relevant when cutting metal sheets containing heavy metals.

Retrieval of the sea spray aerosol mode from submicron particle size distributions and supermicron scattering during LASIC

Abstract. Improved quantification of sea spray aerosol concentration and size is important for determining aerosol effects on clouds and the climate, though attempts to accurately capture the size distribution of the sea spray mode remain limited by the availability of supermicron size distributions. In this work, we introduce a new approach to retrieving lognormal mode fit parameters for a sea spray aerosol mode by combining submicron size distributions with supermicron scattering measurements using a Mie inversion. Submicron size distributions were measured by an ultra-high-sensitivity aerosol spectrometer (UHSAS), and supermicron scattering was taken as the difference between <10 µm and <1 µm three-wavelength integrating nephelometer measurements (NEPH). This UHSAS-NEPH method was applied during background marine periods of the Department of Energy Atmospheric Radiation Measurement Layered Atlantic Smoke Interactions with Clouds (LASIC) campaign on Ascension Island (November 2016–May 2017), when the contribution of sea spray aerosol was expected to represent a large fraction of the aerosol mass and total scattering. Lognormal sea spray modal parameters were retrieved from comparisons between nephelometer measurements and a lookup table of Mie theory-simulated scattering coefficients for low-error solutions that minimized the 0.4–1 µm residual in the UHSAS size distribution. We evaluated the UHSAS-NEPH method with a set of clean marine measurements in the North Atlantic that included supermicron size and chemical measurements, showing that measured supermicron size distributions are needed to constrain the sea spray number concentration but that mass concentration was reasonably characterized using supermicron scattering. For LASIC, the UHSAS-NEPH method retrieved sea spray mode properties for approximately 88 % of the background marine times when the scattering variability and total particle concentration were low (<± 5 Mm−1 and <400 cm−3, respectively), with mass mean diameter ranging from 0.6 to 1.9 µm (1.47 ± 0.17 µm), modal width ranging from 1.1 to 3.97 (2.4±0.3), and mass concentration ranging from 0.18 to 23.0 µg m−3 (8.37. ± 4.1 µg m−3). The measured nephelometer scattering at three wavelengths was found to constrain the mode width marginally at the largest particle sizes in the absence of additional size and chemical measurements for defining parameters for the Mie solutions. Comparing UHSAS-NEPH retrievals to those of a fitting algorithm applied only to the submicron UHSAS number size distribution showed that correlations between retrieved mass concentration and the available mass-based sea spray tracers (coarse scattering, wind speed, and chloride) are low when supermicron measurements are not considered. This work demonstrates the added value of supermicron scattering measurements for retrieving reasonable sea spray mass concentrations, providing the best-available observationally constrained estimate of the sea spray mode properties when supermicron size distribution measurements are not available.

Short-term study on in-use stability of opened bevacizumab biosimilar PF-06439535 vials

ObjectivesAggregation is one of the key critical points limiting the stability of monoclonal antibodies in solution. The present study aimed to investigate the in-use stability of a residual monoclonal antibody...

Experiment and numerical investigation of inhalable particles and indoor environment with ventilation system

After the outbreak of COVID-19, the indoor environment has become particularly important in closed spaces, being a common concern in environmental science and public health, and of great significance for the building environment. To improve the indoor air quality and control the spread of viruses, the analysis of inhalable particles in indoor environments is critical. In this research, we study standards focused on inhalable particles and indoor environmental quality, as well as analyzing the movement and diffusion of indoor particles. Based on our analysis, we conduct an experimental study to determine the distribution of indoor inhalable particles of different sizes before and after diffusion under the conditions of underfloor air distribution. Furthermore, the mathematical modeling method is adopted to simulate the indoor flow field, particle trajectories, and pollutant dispersion process. The k-ε two-equation model is applied as the turbulence model in the numerical simulation, while the Lagrangian discrete phase model is adopted to trace the motion of particles and analyze the distribution characteristics of indoor particles. The results demonstrate that fine particles (i.e., those with size less than 0.5 μm) have a significant impact on the indoor particle concentration, while coarse particles (i.e., with size above 2.5 μm) have a greater influence on the total mass concentration of indoor particles. Small-sized particles can easily follow the airflow and diffuse to upper parts of the room. Overall, the effects of indoor particles on indoor air quality, including the potential threat of aerosol transmission of respiratory infectious diseases, are non-negligible. Application of the presented research can contribute to improving the health-related aspects of the building environment.