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Diagram of G-II exhaled breath bioaerosol collection system (U = upstream sampling location; D = downstream sampling location; T = temperature sensor; M = Magnehelic R pressure gauge; RH/T = relative humidity and temperature sensor; V = voltage controller; F = flow controller).
Source publication
The importance of the aerosol mode for transmission of influenza is unknown. Understanding the role of aerosols is essential to developing public health interventions such as the use of surgical masks as a source control to prevent the release of infectious aerosols. Little information is available on the number and size of particles generated by i...
Contexts in source publication
Context 1
... device was designed, built, and is shown in Figure 1. It is called the Gesundheit II (G-II) to acknowledge the pioneering work of Knight and colleagues on whose cough collection device the word Gesundheit can be seen in a photograph published with their work (Gerone et al. 1966). ...
Context 2
... grown by condensation are subsequently drawn through a 1.0 μm slit impactor. The impactor is sealed into a reservoir into which particles and condensate are collected ( Figure 1). There is ample room between the bottom of the im- pactor and the bottom of the reservoir to allow condensate to collect without interfering with the operation of the impactor. ...
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Citations
... The Gesundheit-II (G-II) is a sampler that collects exhaled respiratory particles for use in infectivity analyses and assays for genomic material [30]. A sample is diluted in a buffer, and RNA is extracted and resuspended in a known volume of a transport media, an aliquot of which is used to quantify the genomic material in the sample using RT-qPCR. ...
... Despite numerous studies reporting the detection of influenza viral RNA in the air, few have been able to recover infectious viruses, owing largely to the limitations of the sampling device. Here, using the Gesundheit-II (G-II) exhaled breath sampler [17], we sought to characterize the emission of influenza virus in exhaled breath generated by community-acquired influenza cases in a university cohort in Singapore, a dense citystate situated in the tropics. In addition, we discuss our findings in comparison with SARS-CoV-2 infection, whose aerosol transmission was met with initial controversy [18]. ...
... A second nasopharyngeal specimen and a throat swab were collected for analysis using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and influenza virus culture. Exhaled breath was collected using the Gesundheit-II sampler, which can separate aerosols into fine (≤5 µm) and coarse (>5 µm) fractions, as described previously [17,19]. Exhaled particles were collected for 30 min during tidal breathing, with intermittent recitation of the alphabet at the 5-, 15-, and 25 min marks. ...
... However, many of these droplets were lost due to settling onto unsampled surfaces, or because only specific droplet parameters were measured. In this study, we utilized a high-efficiency particulate breath collector (G-II) to capture most of the exhaled aerosols during tidal breathing [17]. ...
Influenza is a highly contagious respiratory illness that commonly causes outbreaks among human communities. Details about the exact nature of the droplets produced by human respiratory activities such as breathing, and their potential to carry and transmit influenza A and B viruses is still not fully understood. The objective of our study was to characterize and quantify influenza viral shedding in exhaled aerosols from natural patient breath, and to determine their viral infectivity among participants in a university cohort in tropical Singapore. Using the Gesundheit-II exhaled breath sampling apparatus, samples of exhaled breath of two aerosol size fractions (“coarse” > 5 µm and “fine” ≤ 5 µm) were collected and analyzed from 31 study participants, i.e., 24 with influenza A (including H1N1 and H3N2 subtypes) and 7 with influenza B (including Victoria and Yamagata lineages). Influenza viral copy number was quantified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Infectivity of influenza virus in the fine particle fraction was determined by culturing in Madin–Darby canine kidney cells. Exhaled influenza virus RNA generation rates ranged from 9 to 1.67 × 105 and 10 to 1.24 × 104 influenza virus RNA copies per minute for the fine and coarse aerosol fractions, respectively. Compared to the coarse aerosol fractions, influenza A and B viruses were detected more frequently in the fine aerosol fractions that harbored 12-fold higher viral loads. Culturable virus was recovered from the fine aerosol fractions from 9 of the 31 subjects (29%). These findings constitute additional evidence to reiterate the important role of fine aerosols in influenza transmission and provide a baseline range of influenza virus RNA generation rates.
... McDevitt et al. designed and built a new sampler, Gesundheit II (G-II); using an amplifier, the water vapor in the air condenses on the particles to form large droplets, and later the amplified droplets (because of deliquescence and condensation) are collected using an impinger. This device provides a collection efficiency of >85% for PMs larger than 50 nm for viral aerosols [36]. ...
Airborne viruses, such as COVID-19, cause pandemics all over the world. Virus-containing particles produced by infected individuals are suspended in the air for extended periods, actually resulting in viral aerosols and the spread of infectious diseases. Aerosol collection and detection devices are essential for limiting the spread of airborne virus diseases. This review provides an overview of the primary mechanisms and enhancement techniques for collecting and detecting airborne viruses. Indoor virus detection strategies for scenarios with varying ventilations are also summarized based on the excellent performance of existing advanced comprehensive devices. This review provides guidance for the development of future aerosol detection devices and aids in the control of airborne transmission diseases, such as COVID-19, influenza and other airborne transmission viruses.
... Direct sampling of respiratory droplets released by COVID-19 patients and subsequent virological analysis of the samples could have been the most effective way for virus content analysis, which, however, is hampered by the limitations of existing respiratory droplet sampling devices. Due to the inertial impaction and gravitational deposition losses of larger droplets, efficient sampling of droplets larger than 10 μm is rather difficult for existing respiratory droplets samplers such as G-II developed by the Harvard University (McDevitt et al 2013) and the three-stage cyclone-based bioaerosol sampler developed by NIOSH (Lindsley et al. 2006), though droplets up to 100 μm can be readily exhaled during talking and coughing (Johnson et al. 2011). Besides, they collect and classify relatively fine droplets into 2-3 categories by size. ...
Origin of differently sized respiratory droplets is fundamental for clarifying their viral loads and the sequential transmission mechanism of SARS-CoV-2 in indoor environments. Transient talking activities characterized by low (0.2 L/s), medium (0.9 L/s), and high (1.6 L/s) airflow rates of monosyllabic and successive syllabic vocalizations were investigated by computational fluid dynamics (CFD) simulations based on a real human airway model. SST k−ω model was chosen to predict the airflow field, and the discrete phase model (DPM) was used to calculate the trajectories of droplets within the respiratory tract. The results showed that flow field in the respiratory tract during speech is characterized by a significant laryngeal jet, and bronchi, larynx, and pharynx-larynx junction were main deposition sites for droplets released from the lower respiratory tract or around the vocal cords, and among which, over 90% of droplets over 5 µm released from vocal cords deposited at the larynx and pharynx-larynx junction. Generally, droplets’ deposition fraction increased with their size, and the maximum size of droplets that were able to escape into external environment decreased with the airflow rate. This threshold size for droplets released from the vocal folds was 10–20 µm, while that for droplets released from the bronchi was 5–20 µm under various airflow rates. Besides, successive syllables pronounced at low airflow rates promoted the escape of small droplets, but do not significantly affect the droplet threshold diameter. This study indicates that droplets larger than 20 µm may entirely originate from the oral cavity, where viral loads are lower; it provides a reference for evaluating the relative importance of large-droplet spray and airborne transmission route of COVID-19 and other respiratory infections.
... McDevitt et al. designed and built a new sampler, Gesundheit II (G-II), using the amplifier and impactor principles to amplify PM and then secondarily collect the particulate matter to enhance the collection efficiency of small particles. This device provides a collection efficiency of >85% for particles larger than 50 nm for influenza viruses [26]. ...
Airborne virus, such as COVID-19, caused pandemics all over the world. Virus-containing particles produced by infected individuals are suspended in the air for extended periods of time, actually results in viral aerosols and the spread of infectious diseases. Aerosol collection and detection devices are essential for limiting the spread of airborne virus diseases. This review provides an overview of the primary mechanisms and enhancement techniques for collecting and detecting airborne viruses. Indoor virus detection strategies for scenarios with varying ventilations are also summarized based on the excellent performance of existing advanced comprehensive devices. This review provides guidance for the development of future aerosol detection devices and aids in the control of airborne transmission diseases, such as COVID-19, monkeypox, and other airborne transmission viruses.
... 目前已有针对呼出气溶胶的 形成机制及溶质进入呼出气部位的研究 [105] , 并已发布 了EBC样本采集程序和分析技术标准建议以对EBC样 本的收集检测进行规范 [106] . 研究者也关注从采样技 术 [107] 和检测技术 [108] 两方面解决采样效率低的问题. 基于高通量测序技术的MST新工具的出现正在解 决上述微生物追踪所面临的问题. ...
... The G-II uses a slit impactor to remove particles >5 μm and then grows the remaining particles <1 μm to be captured by another slit impactor, with collection efficiencies for influenza virus similar to that of the BioSampler (McDevitt et al., 2013). ...
Bioaerosols are suspensions of airborne particulate matter of biological origin (BioPM) which includes microorganisms and the products of these organisms. Bioaerosols are ubiquitous in indoor and outdoor environments and can become dispersed by attaching to other particles. Bioaerosols are diverse in terms of their size, composition and biological properties and are an important transmission route for infectious and sensitization agents. More recently, bioaerosols have received significant scientific and societal attention from industry, academia, government and the wider public due to the emergence and global spread of COVID-19 and the threat of bioterrorism. Yet despite their importance for human health, the microbiological components of aerosols and their species dispersal from various environments remains poorly understood. Moreover, there is a lack of understanding of the ecology and role that bioaerosols play in the environment.
As a result of these knowledge gaps, health officials and regulators have been hindered in their assessment of public and occupational health exposures and risk. For example, a better understanding of the concentrations and composition of bioaerosols in a particular environment, and the transmission dynamics of pathogens and their components, can inform on the appropriate ventilation rates and hygiene procedures to maintain good air quality and reduce human health risk. However, there are currently many uncertainties still remaining with regard to exposure assessment.
To better understand the impact of bioaerosol exposure on human health, comprehensive methods to detect, characterise and quantify bioaerosols are needed. Although significant advances in technologies for bioaerosol sampling and analysis have been achieved over the last two decades or so, a consensus on air sampling methods for a particular context or environment and a universal analysis method still does not exist. This makes it difficult for researchers to compare data across studies, and for regulators to set meaningful exposure limits.
BioAirNet is a UKRI NERC-funded project which acts as a leading voice for the UK BioPM science community and operates around four themes: Theme (1) BioPM sources and dynamics; Theme (2) BioPM sampling and characterisation; Theme (3) Human health, behaviour and wellbeing; and Theme (4) Policy and public engagement. As part of Theme 2, researchers, regulators, and public health officials have developed this compendium and Fig. 1 presents an overview of BioAirNet Theme 2.
This compendium aims to provide a comprehensive toolbox of current techniques, workflows, and technologies for bioaerosol sampling, characterisation, and monitoring across different environments for researchers, epidemiologists, regulators, public health officials and regulators involved in bioaerosols. The overall goal of this text is to support the development of useful standards to better regulate and monitor bioaerosols worldwide.
... William Wells described the quantum theory of airborne infection [7] whereby infection risk is described by exposure to infectious doses, or quanta (which is, more specifically, the dose that would infect 63% of those exposed), generated by infectious individuals over time. Studies quantifying influenza virus and SARS-CoV-2 virus shed into exhaled breath aerosols using a Gesundheit-II (G-II) bioaerosol sampler support an understanding of airborne contamination by infectious individuals, provides a way forward for precisely estimating airborne infection risk in terms of virions with infectious potential and genome copies measured by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) [8][9][10][11]. Human challenge transmission trials offer one way forward to quantifying the airborne transmission risk between infectious and susceptible individuals with known levels of inhalation exposure to exhaled breath, paired with measurements of viral load in exhaled breath. Real-world study in congregate settings where exposure may be unavoidable, including in healthcare or other public gathering places offers another approach that may provide more generalizable findings, yet may be more logistically challenging to achieve valid estimates of exposure [12]. ...
Despite uncertainty about the specific transmission risk posed by airborne, spray-borne, and contact modes for influenza, SARS-CoV-2, and other respiratory viruses, there is evidence that airborne transmission via inhalation is important and often predominates. An early study of influenza transmission via airborne challenge quantified infectious doses as low as one influenza virion leading to illness characterized by cough and sore throat. Other studies that challenged via intranasal mucosal exposure observed high doses required for similarly symptomatic respiratory illnesses. Analysis of the Evaluating Modes of Influenza Transmission (EMIT) influenza human-challenge transmission trial-of 52 H3N2 inoculated viral donors and 75 sero-susceptible exposed individuals-quantifies airborne transmission and provides context and insight into methodology related to airborne transmission. Advances in aerosol sampling and epidemiologic studies examining the role of masking, and engineering-based air hygiene strategies provide a foundation for understanding risk and directions for new work.
... Recent studies have confirmed the presence of these pulmonary surfactants through a combination of various processes such as sodium dodecyl sulfate poly-acrylamide gel electrophoresis (SDS-PAGE) [58], liquid chromatography-mass spectrometry (LC-MS), and triple quadrupole mass spectrometry (TQMS). Apart from this, Gesundheit II (G-II) which was manufactured to detect the Influenza virus in exhaled breath can be used to study the properties of viral aerosol particles with SARS-CoV-2 inside the exhaled breath [59]. Recently, a European network has initiated examining viral particles' chemical composition for the identification of COVID-19 disease using mass spectrometers in real time within seconds [60]. ...
The airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified as a potential pandemic challenge, especially in poorly ventilated indoor environments, such as certain hospitals, schools, public buildings, and transports. The impacts of meteorological parameters (temperature and humidity) and physical property (droplet size) on the airborne transmission of coronavirus in indoor settings have been previously investigated. However, the impacts of chemical properties of viral droplets and aerosol particles (i.e., chemical composition and acidity (pH)) on viability and indoor transmission of coronavirus remain largely unknown. Recent studies suggest high organic content (proteins) in viral droplets and aerosol particles supports prolonged survival of the virus by forming a glassy gel-type structure that restricts the virus inactivation process under low relative humidity (RH). In addition, the virus survival was found at neutral pH, and inactivation was observed to be best at low (<5) and high pH (>10) values (enveloped bacteriophage Phi6). Due to limited available information, this article illustrates an urgent need to research the impact of chemical properties of exhaled viral particles on virus viability. This will improve our fundamental understanding of indoor viral airborne transmission mechanisms.
... ; https://doi.org/10.1101/2022.05.25.22275435 doi: medRxiv preprint head, and into an aerosol capture array (95). The system relies on humidified air supply at the cone perimeters which in Coleman et al. was ambient, 68% relative humidity HEPA-filtered air in a COVID-19 ward (Coleman K, personal communication). ...
... Ambient air influx and mixing within the cone would exacerbate this effect (96). In their seminal paper on this sampling method, McDevitt et al (95) reported no ambient air FA particle size changes on account of the device cone and pump operation, but <50% capture efficiency for mechanical aerosol particles <30µm; no particle data was reported for human breath aerosols which differ in humidity and temperature to environmental aerosols. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint ...
Rationale
Exhaled breath condensate (EBC) promises a valuable, non-invasive, and easy to obtain clinical sample. However, it is not currently used diagnostically due to poor reproducibility, sample contamination, and sample loss.
Objective
We evaluated whether a new, hand-held EBC collector (PBM-HALE™) that separates inertially impacted large droplets (LD) before condensing the fine aerosol (FA) fraction, in distinct self-sealing containers, overcomes current limitations.
Methods
Sampling consistency was determined in healthy volunteers by microbial culture, 16S phylogenetics, spectrophotometry, RT-PCR, and HILIC-MS. Capture of aerosolised polystyrene beads, liposomes, virus-like particles, or pseudotyped virus was analysed by nanoparticle tracking analysis, reporter expression assays, and flow cytometry. Acute symptomatic COVID-19 case tidal FA EBC viral load was quantified by RT-qPCR. Exhaled particles were counted by laser light scattering.
Measurements and Main Results
Salivary amylase-free FA EBC capture was linear (R ² =0.9992; 0.25-30 min) yielding RNA (6.03 μg/mL) containing eukaryotic 18S rRNA (RT-qPCR; p<0.001) but not human GAPDH or beta actin mRNA, and 141 non-volatile metabolites including eukaryotic cell membrane components, and cuscohygrine 3 days after cocaine abuse. Culturable aerobe viability was condensation temperature-dependent. Breath fraction-specific microbiota were stable, identifying Streptococcus enrichment in a mild dry cough case. Nebulized pseudotyped virus infectivity loss <67% depended on condensation temperature, and particle charge-driven aggregation. No SARS-CoV-2 genomes were detected in convalescent or acute COVID-19 patient tidal breath FA EBC.
Conclusions
High purity alveolar fraction FA EBC can reproducibly and robustly inform on contamination-free infectious agent emission sources, and be quantitatively assayed for multiple host, microbial, and lifestyle biomarker classes.
