Impactor Samples Research Articles

Associations between airborne algae, ambient air pollution and lung function in a cross-sectional canadian population-based study.

Airborne algae have been associated with respiratory illness in the setting of coastal harmful algae blooms but little is known about their effects in urban populations distributed across a country, and whether ambient air pollution is an effect modifier. Using cross-sectional data from 11,256 participants of the Canadian Health Measures Survey (CHMS), we tested the association between lung function expressed as a forced expiratory volume (FEV1) and airborne concentrations of algae measured by a rotation impact sampler in the participant's city of residence on the day of spirometric testing. The daily upper 95th percentiles of algae ranged from 12.7 to 104.3 grains/m3. An interquartile range increase in algae was associated with a 2.55% (95%CI: 1.88, 3.23) decrease in percent predicted 1-s forced expiratory volume pp FEV1, and a 2.54% (95%CI: -2.93, -2.14) decrease in pp FEV1/forced vital capacity (FVC) after adjustment for participants' age, sex, education, annual income, active cigarette smoking, environmental tobacco smoke exposure, fine particulate air pollution (PM2.5), total fungal spores and total pollen grains. An interquartile increase in PM2.5 was associated with a 0.86% (95%CI: 0.78, 0.94) decrease in FEV1, but we found no significant interaction between air pollutants and algae. Our findings suggest that independent of air pollution, airborne algae may influence lung function in urban populations widely distributed across Canada, and the observed effect was of larger magnitude than that of air pollution.

Influencing factors analysis of infectious SARS-CoV-2 aerosols sampling

Assessing the potential infectivity of airborne viruses is critical for evaluating the risk of their transmission through air. This study investigated the factors influencing the collection of infectious SARS-CoV-2 aerosols using three common aerosol samplers: the impactor sampler AGI-30, the SKC Biosampler, and a cyclone sampler WA-400III. It was found that the sampling process over time significantly impacted the infectivity of SARS-CoV-2 captured in the sampler, and the infectivity loss of different SARS-CoV-2 variants in the process varied. Additionally, adding newborn calf serum in the collection suspension could effectively preserve viral infectivity in the sampler. Further tests conducted under various ventilation occasions indicated that ventilation can reduce the virus concentration in the environment and rapidly clear viral particles after aerosol generation. Although the flow rate of WA-400III is higher, it only could collect higher concentrations of viral RNA instead of live viruses than AGI-30 or SKC Biosampler when aerosol was generated constantly in the environment. After aerosol generation stopped, the WA-400III collected more infectious viruses and viral RNA. This study highlights the impact of the sampling process on captured virus should be assessed and protective agent is needed to preserve viral viability. And it is crucial to select appropriate sampler based on environmental characteristics and research objectives for obtaining optimal results. The AGI-30 and SKC Biosampler are preferable for collecting infectious viruses in environments with high aerosol concentrations, while the cyclone sampler WA-400III is more effective for collecting viral nucleic acids and enriching virus samples in confined spaces with lower viral loads.

It's a Trap! Part I: Exploring the Applications of Rotating-Arm Impaction Samplers in Plant Pathology.

Although improved knowledge on the movement of airborne plant pathogens is likely to benefit plant health management, generating this knowledge is often far more complicated than anticipated. This complexity is driven by the dynamic nature of environmental variables, diversity among pathosystems that are targeted, and the unique needs of each research group. When using a rotating-arm impaction sampler, particle collection is dependent on the pathogen, environment, research objectives, and limitations (monetary, environmental, or labor). Consequently, no design will result in 100% collection efficiency. Fortunately, it is likely that multiple approaches can succeed despite these constraints. Choices made during design and implementation of samplers can influence the results, and recognizing this influence is crucial for researchers. This article is for beginners in the art and science of using rotating-arm impaction samplers; it provides a foundation for designing a project, from planning the experiment to processing samples. We present a relatively nontechnical discussion of the factors influencing pathogen dispersal and how placement of the rotating-arm air samplers alters propagule capture. We include a discussion of applications of rotating-arm air samplers to demonstrate their versatility and potential in plant pathology research as well as their limitations.

Review on Sampling Methods and Health Impacts of Fine (PM2.5, ≤2.5 µm) and Ultrafine (UFP, PM0.1, ≤0.1 µm) Particles

Airborne particulate matter (PM) is of great concern in the modern-day atmosphere owing to its association with a variety of health impacts, such as respiratory and cardiovascular diseases. Of the various size fractions of PM, it is the finer fractions that are most harmful to health, in particular ultrafine particles (PM0.1; UFPs), with an aerodynamic diameter ≤ 100 nm. The smaller size fractions, of ≤2.5 µm (PM2.5; fine particles) and ≤0.1 µm (PM0.1; ultrafine particles), have been shown to have numerous linkages to negative health effects; however, their collection/sampling remains challenging. This review paper employed a comprehensive literature review methodology; 200 studies were evaluated based on the rigor of their methodologies, including the validity of experimental designs, data collection methods, and statistical analyses. Studies with robust methodologies were prioritised for inclusion. This review paper critically assesses the health risks associated with fine and ultrafine particles, highlighting vehicular emissions as the most significant source of particulate-related health effects. While coal combustion, diesel exhaust, household wood combustors’ emissions, and Earth’s crust dust also pose health risks, evidence suggests that exposure to particulates from vehicular emissions has the greatest impact on human health due to their widespread distribution and contribution to air pollution-related diseases. This article comprehensively examines current sampling technologies, specifically focusing on the collection and sampling of ultrafine particles (UFP) from ambient air to facilitate toxicological and physiochemical characterisation efforts. This article discusses diverse approaches to collect fine and ultrafine particulates, along with experimental endeavours to assess ultrafine particle concentrations across various microenvironments. Following meticulous evaluation of sampling techniques, high-volume air samplers such as the Chem Vol Model 2400 High Volume Cascade Impactor and low-volume samplers like the Personal Cascade Impactor Sampler (PCIS) emerge as effective methods. These techniques offer advantages in particle size fractionation, collection efficiency, and adaptability to different sampling environments, positioning them as valuable tools for precise characterisation of particulate matter in air quality research and environmental monitoring.

Characterization and decontamination of deposited dust: a management regime at a museum

Deposited dust represents a nutritional niche for microflora. Inhibiting microflora-associated deposited dust is a critical approach to manage cultural heritage buildings. Knowledge on the effectiveness of commercial disinfection on microflora in a real field environment is limited. The present study aims to: (1) characterize deposited dust composition, and (2) assess the effectiveness of several commercial biocides/and an air ionizer on microflora-associated floor surface and air before and after treatment. Deposited dust was collected using a dust collector and microbial air sampling was conducted via a volumetric impactor sampler. Susceptibility of microorganisms to biocide/ionizer was performed in a naturally ventilated unoccupied room with a floor area of 18 m2. One-treatment protocol, a daily disinfection mode, was applied to each biocide/ionizer. The surface floor was adjacently sprayed by a biocide, and the ionizer was turned on for 30 min. Indoor deposited dust rates varied between 0.75 and 8.7 mg/m2/day with indoor/outdoor ratio of ~ 1:100. Ion concentrations of NH4+, Cl−, SO42− and NO3− were higher indoor than outdoor. The concentration of microorganisms-associated deposited dust averaged 106 CFU/g; 105 CFU/g and 104 CFU/g for bacteria, fungi and actinomycetes, respectively. A total of 23 fungal taxa were identified, with Aspergillus flavus, Asp. fumigatus and Asp. niger were the predominant taxa. Biocides quickly reduced floor surface and airborne microbial loads. The biocidal effect was time limited, as microflora loads increased again after ~ 4 days of the treatment protocol. Benzalkonium chloride (BAC) out-performed other biocides, showed a relatively permanent microbial inhibiting effect. The air ionizer reduced airborne microorganisms and increased surface floor ones. Characterizing of deposited dust (rate and composition) and choice an appropriate biocide may effectively reduce biodeterioration. Further real field treatment trials under various microenvironmental conditions are needed to determine the effectiveness of disinfection treatment.

Fungal Spore Richness and Abundance of Allergenic Taxa: Comparing a Portable Impactor and Passive Trap Indoors and Outdoors in an Urban Setting

Fungal spores are common airborne allergens, and fungal richness has been implicated in allergic disease. Amplicon sequencing of environmental DNA from air samples is a promising method to estimate fungal spore richness with semi-quantification of hundreds of taxa and can be combined with quantitative PCR to derive abundance estimates. However, it remains unclear how the choice of air sampling method influences these estimates. This study compared active sampling with a portable impactor and passive sampling with a passive trap over different durations to estimate fungal spore richness and the abundance of allergenic taxa. Air sampling was conducted indoors and outdoors at 12 residences, including repeated measurements with a portable impactor and passive traps with 1-day and 7-day durations. ITS2 amplicon sequence data were transformed to spore equivalents estimated by quantitative PCR, repeated active samples were combined, and abundance-based rarefaction was performed to standardize sample coverage for estimation of genus-level richness and spore abundance. Rarefied fungal richness was similar between methods indoors but higher for passive traps with a 7-day duration outdoors. Rarefied abundance of allergenic genera was similar between methods but some genera had lower abundance for passive traps with a 1-day duration, which differed indoors and outdoors indicating stochasticity in the collection of spores on collocated samplers. This study found that similar estimates of fungal spore richness and abundance of allergenic taxa can be obtained using a portable impactor or a passive trap within one day and that increased passive sample duration provides limited additional information.

Environmental DNA analysis of airborne poaceae (grass) pollen reveals taxonomic diversity across seasons and climate zones

BackgroundGrasses populate most biogeographical zones, and their diversity influences allergic sensitisation to pollen. Previously, the contribution of different Poaceae subfamilies to airborne pollen has mostly been inferred from historical herbarium records. We recently applied environmental (e)DNA metabarcoding at one subtropical site revealing that successive airborne grass pollen peaks were derived from repeated flowering of Chloridoid and Panicoid grasses over a season. This study aimed to compare spatiotemporal patterns in grass pollen exposure across seasons and climate zones. MethodsAirborne pollen concentrations across two austral pollen seasons spanning 2017–2019 at subtropical (Mutdapilly and Rocklea, Queensland) and temperate (Macquarie Park and Richmond, New South Wales) sites, were determined with a routine volumetric impaction sampler and counting by light microscopy. Poaceae rbcL metabarcode sequences amplified from daily pollen samples collected once per week were assigned to subfamily and genus using a ribosomal classifier and compared with Atlas of Living Australia sighting records. ResultseDNA analysis revealed distinct dominance patterns of grass pollen at various sites: Panicoid grasses prevailed in both subtropical Mutdapilly and temperate Macquarie Park, whilst Chloridoid grasses dominated the subtropical Rocklea site. Overall, subtropical sites showed significantly higher proportion of pollen from Chloridoid grasses than temperate sites, whereas the temperate sites showed a significantly higher proportion of pollen from Pooideae grasses than subtropical sites. Timing of airborne Pooid (spring), Panicoid and Chloridoid (late spring to autumn), and Arundinoid (autumn) pollen were significantly related to number of days from mid-winter. Proportions of eDNA for subfamilies correlated with distributions grass sighting records between climate zones. ConclusionseDNA analysis enabled finer taxonomic discernment of Poaceae pollen records across seasons and climate zones with implications for understanding adaptation of grasslands to climate change, and the complexity of pollen exposure for patients with allergic respiratory diseases.

Identifying urban emission sources and their contribution to the oxidative potential of fine particulate matter (PM2.5) in Kuwait.

In this study, we investigated the seasonal variations, chemical composition, sources, and oxidative potential of ambient PM2.5 (particles with a diameter of less than 2.5 μm) in Kuwait City. The sampling campaign was conducted within the premises of Kuwait Institute for Scientific Research from June 2022 to May 2023, covering different seasons throughout the year. The personal cascade impactor sampler (PCIS) operated at flow rate of 9 L/min was employed to collect weekly PM2.5 samples on PTFE and quarts filters. These collected samples were analyzed for carbonaceous species (i.e., elemental and organic carbon), metals and transition elements, inorganic ions, and DTT (dithiothreitol) redox activity. Furthermore, principal component analysis (PCA) and multi-linear regression (MLR) were used to identify the predominant emission sources and their percentage contribution to the redox activity of PM2.5 in Kuwait. The results of this study highlighted that the annual-averaged ambient PM2.5 mass concentrations in Kuwait (59.9 μg/m3) substantially exceeded the World Health Organization (WHO) guideline of 10 μg/m3. Additionally, the summer season displayed the highest PM2.5 mass concentration (75.2 μg/m3) compared to other seasons, primarily due to frequent dust events exacerbated by high-speed winds. The PCA identified four primary PM2.5 sources: mineral dust, fossil fuel combustion, road traffic, and secondary aerosols. The mineral dust was found to be the predominant source, contributing 36.1% to the PM2.5 mass, followed by fossil fuel combustion and traffic emissions with contributions of 23.7% and 20.3%, respectively. The findings of MLR revealed that road traffic was the most significant contributor to PM2.5 oxidative potential, accounting for 47% of the total DTT activity. In conclusion, this comprehensive investigation provides essential insights into the sources and health implications of PM2.5 in Kuwait, underscoring the critical need for effective air quality management strategies to mitigate the impacts of particulate pollution in the region.

Airborne grass pollen and thunderstorms influence emergency department asthma presentations in a subtropical climate

BackgroundGrass pollen is considered a major outdoor aeroallergen source worldwide. It is proposed as a mechanism for thunderstorm asthma that lightning during thunderstorms promotes electrical rupture of pollen grains that leads to allergic airway inflammation. However, most evidence of associations between grass pollen and asthma comes from temperate regions. The objective of this study was to investigate short-term associations between airborne grass pollen exposure and asthma emergency department presentations in a subtropical population. MethodsEpisode level public hospital presentations for asthma (2016–2020) were extracted for greater Brisbane, Australia, from Queensland Health's Emergency Data Collection. Concentrations of airborne pollen were determined prospectively using a continuous flow volumetric impaction sampler. Daily time series analysis using a generalised additive mixed model were applied to determine associations between airborne grass pollen concentrations, and lightning count data, with asthma presentations. ResultsAirborne grass pollen showed an association with asthma presentations in Brisbane; a significant association was detected from same day exposure to three days lag. Grass pollen exposure increased daily asthma presentations up to 48.5% (95% CI: 12%, 85.9%) in female children. Lightning did not modify the effect of grass pollen on asthma presentations, however a positive association was detected between cloud-to-cloud lightning strikes and asthma presentations (P = 0.048). ConclusionAirborne grass pollen exposure may exacerbate symptoms of asthma requiring urgent medical care of children and adults in a subtropical climate. This knowledge indicates an opportunity for targeted management of respiratory allergic disease to reduce patient and health system burden. For the first time, an influence of lightning on asthma was detected in this context. The outcomes support a need for continued pollen monitoring and surveillance of thunderstorm asthma risk in subtropical regions.

Assessment of indoor bioaerosol exposure using direct-reading versus traditional methods—potential application to home health care

Home healthcare workers (HHCWs) can be occupationally exposed to bioaerosols in their clients’ homes. However, choosing the appropriate method to measure bioaerosol exposures remains a challenge. Therefore, a systematic comparison of existing measurement approaches is essential. Bioaerosol measurements with a real-time, fluorescence-based Wideband Integrated Bioaerosol Sensor (WIBS) were compared to measurements with four traditional off-line methods (TOLMs). The TOLMS included optical microscopic counting of spore trap samples, microbial cultivation of impactor samples, qPCR, and next-generation sequencing (NGS) of filter samples. Measurements were conducted in an occupied apartment simulating the environments that HHCWs could encounter in their patients’ homes. Descriptive statistics and Spearman’s correlation test were computed to compare the real-time measurement with those of each TOLM. The results showed that the geometric mean number concentrations of the total fluorescent aerosol particles (TFAPs) detected with the WIBS were several orders of magnitude higher than those of total fungi or bacteria measured with the TOLMs. Among the TOLMs, concentrations obtained with qPCR and NGS were the closest to the WIBS detections. Correlations between the results obtained with the WIBS and TOLMs were not consistent. No correlation was found between the concentrations of fungi detected using microscopic counting and any of the WIBS fluorescent aerosol particle (FAP) types, either indoors or outdoors. In contrast, the total concentrations detected with microbial cultivation correlated with the WIBS TFAP results, both indoors and outdoors. Outdoors, the total concentration of culturable bacteria correlated with FAP-type AC. In addition, fungal and bacterial concentrations obtained with qPCR correlated with FAP types AB and AC. For a continuous, high-time resolution but broad scope, the real-time WIBS could be considered, whereas a TOLM would be the best choice for specific and more accurate microbial characterization. HHCWs’ activities tend to re-aerosolize bioaerosols causing wide temporal variation in bioparticle concentrations. Thus, the advantage of using the real-time instrument is to capture those variations. This study lays a foundation for future exposure assessment studies targeting HHCWs.

Direct analysis of airborne microplastics collected on quartz filters by pyrolysis-gas chromatography/mass spectrometry

This paper reports the direct analysis of polymer components in the airborne particulates collected on quartz filters by pyrolysis (Py)-GC/MS. The airborne microplastics (AMPs) were collected with three classification stages depending on different aerodynamic diameters using a multi-nozzle cascade impact (MCI) sampler. The quartz filter holding AMPs was punched directly into several pieces without pretreatment procedures. Three pieces were introduced into a sample cup, and Py-GC/MS measurements were done to analyze AMPs. Evolved gas analysis (EGA) of AMPs showed the volatilization of phthalates, the generation of sulfur dioxide and nitrogen oxide, and the thermal decomposition of polymer components as the heating temperature increased. In thermal desorption (TD)-GC/MS prior to Py-GC/MS, polycyclic aromatic hydrocarbons were detected in addition to phthalates and some aliphatic carboxylic acids. The following Py-GC/MS results indicated the presence of polyethylene, polypropylene (PP), polystyrene (PS), styrene-butadiene rubber (SBR), and natural rubber in AMPs. Among these polymers, PS, PP, and SBR were quantified using the indicator ions of their characteristic pyrolysis products. The analytical results showed that PS and PP seem to accumulate in the smaller aerodynamic diameter stage, while SBR appears to collect in the larger one. The analytical method using Py-GC/MS described herein is a powerful one that requires no pretreatment of the AMP samples.

Quantitative chemical assay of nanogram-level particulate matter using aerosol mass spectrometry: characterization of particles collected from uncrewed atmospheric measurement platforms

Abstract. Aerosol generation techniques have expanded the utility of aerosol mass spectrometry (AMS) for offline chemical analysis of airborne particles and droplets. However, standard aerosolization techniques require relatively large liquid volumes (e.g., several milliliters) and high sample masses that limit their utility. Here we report the development and characterization of a micronebulization AMS (MN-AMS) technique that requires as low as 10 µL of sample and can provide the quantification of the nanogram level of organic and inorganic substances via the usage of an isotopically labeled internal standard (34SO42-). Using standard solutions, the detection limits for this technique were determined at 0.19, 0.75, and 2.2 ng for sulfate, nitrate, and organics, respectively. The analytical recoveries for these species are 104 %, 87 %, and 94 %, respectively. This MN-AMS technique was applied successfully to analyze filter and impactor samples collected using miniature particulate matter (PM) samplers deployable on uncrewed atmospheric measurement platforms, such as uncrewed aerial systems (UASs) and tethered balloon systems (TBSs). Chemical composition of PM samples collected from a UAS field campaign conducted at the Department of Energy's (DOE) Southern Great Plains (SGP) observatory was characterized. The offline MN-AMS data compared well with the in situ PM composition measured by a co-located aerosol chemical speciation monitor (ACSM). In addition, the MN-AMS and ion chromatography (IC) agreed well for measurements of sulfate and nitrate concentrations in the PM extracts. This study demonstrates the utility of combining MN-AMS with uncrewed measurement platforms to provide quantitative measurements of ambient PM composition.

Distribution of Bacterial Concentration and Viability in Atmospheric Bioaerosols Under Different Weather Conditions in the Coastal Region of Qingdao

Bacteria are the most abundant microorganisms in atmospheric bioaerosols, widely distributed in the environment. Bioaerosol samples were collected using the FA-1 impact sampler from October 2013 to January 2021 in the coastal city of Qingdao, and samples stained with a BacLightTM bacterial viability kit were used to measure the concentrations of viable and non-viable bacteria with an epifluorescence microscope. The viable and non-viable bacteria in bioaerosols were characterized during different seasons, with particular attention paid to the distribution characteristics of bacteria on foggy, hazy, and dust days. The results showed that the mean concentrations of total bacteria were (1.06±0.68)×105 cells·m-3 in Qingdao during the sampling period, and those of viable and non-viable bacteria were (8.20±4.88)×103 cells·m-3and (9.74±6.72)×104 cells·m-3, respectively. The seasonal concentrations of non-viable bacteria were the highest in spring and winter and the lowest in summer, whereas that of viable bacteria was highest in spring, followed by those in summer and autumn, and the lowest in winter. Atmospheric bacterial concentrations fluctuated with by month, and total bacteria presented a similar variation pattern with that of non-viable bacteria. The monthly average concentration of non-viable bacteria showed the highest value in March during the spring and the lowest in June during the summer in 2021, whereas the highest value for viable bacteria occurred in May during the spring in 2021 and the lowest in December during the winter in 2020. Viable bacteria concentrations were significantly positively correlated with temperature and significantly negatively correlated with NO2, SO2, and CO. Non-viable bacteria were significantly positively correlated with PM. The bacteria in bioaerosol particles showed bimodal, unimodal, and skewed size distributions, varying with season and month. Under different weather conditions, the concentration of non-viable bacteria on dusty days was significantly higher than that on sunny, foggy, or hazy days, but the bacteria viability was as low as 6.85% due to long-distance transport. Anthropogenic pollution resulted in the lowest viability of bacteria at 4.10% on hazy days, whereas the highest viability in bacteria was 16.26% on foggy days due to high humidity. The size distribution of bacteria in bioaerosol particles under different pollution days showed a bimodal distribution, and the peak size depended on the weather type.

Characterization of aerosolized particles in effluents from carbon fibre composites incorporating nanomaterials during simultaneous fire and impact

This work investigates the aerosols emitted from carbon fibre-reinforced epoxy composites (CFC) incorporating nanomaterials (nanoclays and nanotubes), subjected to simultaneous fire and impact, representing an aeroplane or automotive crash. Simultaneous fire and impact tests were performed using a previously described bespoke testing methodology with the capability to collect particles released from the front/back faces of the impacted composites plus the effluents. In this work the methodology has been further developed by connecting the Dekati Low Pressure Impactor (DLPI) and Mini Particle Sampler (MPS) sampling system in the extraction chimney. The aerosols emitted have been characterized using various devices devoted to the analysis of aerosols. The influence of the nanoadditives in the matrix on the number concentration and the size distribution of airborne particles produced, was studied with a cascade impactor in the 5 nm–10 μm range. The morphology of the separated soot fractions was examined by SEM. The measurement of aerodynamic size of particles that can deposit in human respiratory tract indicate that 75% of the soot and particles released from CFC could deposit in the lungs reaching the bronchi region at a minimum. There was however, a minimal difference between the number particle concentrations or particle-size mass distribution of particles from CFC and CFC containing nanoadditives. Moreover, no fibres were found in the effluents.

Aerosol exposure of live bird market workers to viable influenza A/H5N1 and A/H9N2 viruses, Cambodia.

Live bird markets (LBMs) have been identified as key factors in the spread, persistence and evolution of avian influenza viruses (AIVs). In addition, these settings have been associated with human infections with AIVs of pandemic concern. Exposure to aerosolised AIVs by workers in a Cambodian LBM was assessed using aerosol impact samplers. LBM vendors were asked to wear an air sampler for 30 min per day for 1week while continuing their usual activities in the LBM during a period of high AIV circulation (February) and a period of low circulation (May). During the period of high circulation, AIV RNA was detected from 100% of the air samplers using molecular methods and viable AIV (A/H5N1 and/or A/H9N2) was isolated from 50% of air samplers following inoculation into embryonated chicken eggs. In contrast, AIV was not detected by molecular methods or successfully isolated during the period of low circulation. This study demonstrates the increased risk of aerosol exposure of LBM workers to AIVs during periods of high circulation and highlights the need for interventions during these high-risk periods. Novel approaches, such as environmental sampling, should be further explored at key high-risk interfaces as a potentially cost-effective alternative for monitoring pandemic threats.

Development and performance evaluation of a two-stage cascade impactor equipped with gelatin filter substrates for the collection of multi-sized particulate matter

This study presents the development and evaluation of a high flow rate gelatin cascade impactor (GCI) to collect different PM particle sizes on water-soluble gelatin substrates. The GCI operates at a flow rate of 100 lpm, and consists of two impaction stages, followed by a filter holder to separate particles in the following diameter ranges: >2.5 μm, 0.2–2.5 μm, and <0.2 μm. Laboratory characterization of the GCI performance was conducted using monodisperse polystyrene latex (PSL) particles as well as polydisperse ammonium sulfate, sodium chloride, and ammonium nitrate aerosols to obtain the particle collection efficiency curves for both impaction stages. In addition to the laboratory characterization, we performed concurrent field experiments to collect PM2.5 employing both GCI equipped with gelatin filter and personal cascade impactor sampler (PCIS) equipped with PTFE filter for further toxicological analysis using macrophage-based reactive oxygen species (ROS) and dithiothreitol consumption (DTT) assays. Our results showed that the experimentally determined cut-point diameters for the first and second impaction stages were 2.4 μm and 0.21 μm, respectively, which agreed with the theoretical predictions. Although the GCI has been developed primarily to collect particles on gelatin filters, the use of a different type of substrate (i.e., quartz) led to similar particle separation characteristics. The findings of the field tests demonstrated the advantage of using the GCI in toxicological studies due to its ability to collect considerable PM-toxic constituents, as corroborated by the DTT and ROS values for the GCI-collected particles which were 26.44 nmol/min/mg PM and 8813.2 μg Zymosan Units/mg PM, respectively. These redox activity values were more than twice those of particles collected concurrently on PTFE filter using the PCIS. This high-flow-rate impactor can collect considerable amounts of size-fractionated PM on water-soluble filters (i.e., gelatin), which can completely dissolve in water allowing for the extraction of soluble and insoluble PM species for further toxicological analysis.

Methods for Elemental Analysis of Size-Resolved PM Samples Collected on Aluminium Foils: Results of an Intercomparison Exercise.

Aluminium is the most common substrate in studies using impactors for the measurement of the number or the weight of size-segregated atmospheric particulate matter (PM), as its characteristics perfectly fit impactor requirements. However, its use is not recommended by manufacturers when one of the purposes of the study is the determination of the metal content in the sample. The aim of this work was to develop an efficient analytical procedure for the removal and acid digestion of PM samples collected on aluminium foils by a cascade impactor to perform the determination of metals. The possibility of performing the trace metal analysis of PM samples collected using aluminium foils is of great importance, as it allows the determination of an accurate size distribution and the elemental composition of the PM collected on each impactor stage. Two procedures were optimised by using different digestion and analysis techniques. Both procedures were then applied to the two halves of several Dekati low-pressure impactor (DLPI) samples, and the results were critically compared. The two procedures proved to be effective in the determination of extremely low concentrations of a large suite of analytes in different size fractions of PM emitted by a brake system.

Alkali emissions characterization in chemical looping combustion of wood, wood char, and straw fuels

Chemical looping combustion of wood pellets (WP), wood char (WC), and straw pellets (SP) was conducted in a 60 kW CLC pilot with ilmenite and braunite oxygen carriers (OCs). Alkali emissions were investigated with impactor-based and surface ionization detector (SID) measurements. Particle size distributions for WP and WC fuels were dominated by coarse particles formed by refractory species. For SP fuel, the distribution was bimodal with a distinct fine particle mode formed by nucleation of volatile ash species. Thermodynamic modelling of stable alkali species at 800 °C predicted that high KOH(g) and lower concentrations of KCl(g) are stable for WP and WC fuels. For SP fuel, equilibrium K species were dominated by condensed-phase K species, followed by KCl(g), and KOH(g). Modelling of fuel-OC interactions showed that ilmenite decreases equilibrium levels of KOH(g) and KCl(g). Braunite impacted only KOH(g) levels. Impactor sample leachate analysis showed that for WP-braunite operation, the leachate contained KCl, NaCl, KOH, and NaOH, in decreasing order. For WC-ilmenite operation, the samples contained KOH and KCl. For SP fuel, most detected alkalis were KCl. For most cases, speciation of impactor samples qualitatively agreed with modelling predictions. Impactor and SID alkali measurements showed reasonable agreement for WC-braunite and SP-braunite tests.

SARS-CoV-2 air sampling: A systematic review on the methodologies for detection and infectivity.

This systematic review aims to present an overview of the current aerosol sampling methods (and equipment) being used to investigate the presence of SARS‐CoV‐2 in the air, along with the main parameters reported in the studies that are essential to analyze the advantages and disadvantages of each method and perspectives for future research regarding this mode of transmission. A systematic literature review was performed on PubMed/MEDLINE, Web of Science, and Scopus to assess the current air sampling methodologies being applied to SARS‐CoV‐2. Most of the studies took place in indoor environments and healthcare settings and included air and environmental sampling. The collection mechanisms used were impinger, cyclone, impactor, filters, water‐based condensation, and passive sampling. Most of the reviewed studies used RT‐PCR to test the presence of SARS‐CoV‐2 RNA in the collected samples. SARS‐CoV‐2 RNA was detected with all collection mechanisms. From the studies detecting the presence of SARS‐CoV‐2 RNA, fourteen assessed infectivity. Five studies detected viable viruses using impactor, water‐based condensation, and cyclone collection mechanisms. There is a need for a standardized protocol for sampling SARS‐CoV‐2 in air, which should also account for other influencing parameters, including air exchange ratio in the room sampled, relative humidity, temperature, and lighting conditions.

Road tunnel-derived coarse, fine and ultrafine particulate matter: physical and chemical characterization and pro-inflammatory responses in human bronchial epithelial cells

BackgroundTraffic particulate matter (PM) comprises a mixture of particles from fuel combustion and wear of road pavement, tires and brakes. In countries with low winter temperatures the relative contribution of mineral-rich PM from road abrasion may be especially high due to use of studded tires during winter season. The aim of the present study was to sample and characterize size-fractioned PM from two road tunnels paved with different stone materials in the asphalt, and to compare the pro-inflammatory potential of these fractions in human bronchial epithelial cells (HBEC3-KT) in relation to physicochemical characteristics.MethodsThe road tunnel PM was collected with a vacuum pump and a high-volume cascade impactor sampler. PM was sampled during winter, both during humid and dry road surface conditions, and before and after cleaning the tunnels. Samples were analysed for hydrodynamic size distribution, content of elemental carbon (EC), organic carbon (OC) and endotoxin, and the capacity for acellular generation of reactive oxygen species. Cytotoxicity and pro-inflammatory responses were assessed in HBEC3-KT cells after exposure to coarse (2.5–10 μm), fine (0.18–2.5 μm) and ultrafine PM (≤ 0.18 μm), as well as particles from the respective stone materials used in the pavement.ResultsThe pro-inflammatory potency of the PM samples varied between road tunnels and size fractions, but showed more marked responses than for the stone materials used in asphalt of the respective tunnels. In particular, fine samples showed significant increases as low as 25 µg/mL (2.6 µg/cm2) and were more potent than coarse samples, while ultrafine samples showed more variable responses between tunnels, sampling conditions and endpoints. The most marked responses were observed for fine PM sampled during humid road surface conditions. Linear correlation analysis showed that particle-induced cytokine responses were correlated to OC levels, while no correlations were observed for other PM characteristics.ConclusionsThe pro-inflammatory potential of fine road tunnel PM sampled during winter season was high compared to coarse PM. The differences between the PM-induced cytokine responses were not related to stone materials in the asphalt. However, the ratio of OC to total PM mass was associated with the pro-inflammatory potential.