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Airborne Virus Capture and Inactivation by an Electrostatic Particle Collector

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Abstract

Airborne virus capture and inactivation were studied in an electrostatic precipitator (ESP) at applied voltages from -10 to +10 kV using aerosolized bacteriophages T3 and MS2. For each charging scenario, samples were collected from the effluent air stream and assayed for viable phages using plaque assays and for nucleic acids using quantitative polymerase chain reaction (qPCR) assays. At higher applied voltages, more virus particles were captured from air with maximum log reductions of 6.8 and 6.3 for the plaque assay and 4.2 and 3.5 for the qPCR assay at -10 kV for T3 and MS2, respectively. Beyond corona inception (i.e., at applied voltages of -10, -8, +8, and +10 kV), log reduction values obtained with the plaque assay were much higher compared to those of the qPCR assay because nonviable particles, while present in the effluent were unaccounted for in the plaque assay. Comparisons of these assays showed that in-flight inactivation (i.e., inactivation without capture) was greater for the highest applied voltages with a log inactivation of 2.6 for both phages at -10 kV. We have demonstrated great potential for virus capture and inactivation via continual ion and reactive species bombardment when conditions in the ESP are enforced to generate a corona discharge.

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... Electric field-generation approaches have provided breakthrough techniques for controlling biotic and abiotic airborne nuisances causing public health problems. These nuisances have included infectious particles containing viruses [7][8][9], bacteria [9][10][11] and fungal spores [10][11][12][13], pollen grains that cause pollenosis [14], small flying insect pests that pass through a conventional insect net [15,16], some allergens [9], and tobacco smoke particles that can be inhaled passively [17]. All the works mentioned above presented methods for directly trapping targets in the electric field. ...
... In the corona discharge-generating electric field, non-insulated conductor poles that were properly electrified could generate corona discharge against the opposite poles placed at a proper distance and secondarily generate numerous charges in the ambient air; these charges were imparted to the target for its electrification [8][9][10][11]17]. In this electric field, the electrified targets could be attracted to the opposite collection pole. ...
... In the former case, that is, initial evaporation, the problem is whether the water-deprived phage particles can be ionised negatively in the electric field. However, to this point, some researchers have noted that in a corona discharge-generating electric field, numerous negative ions are generated in the ambient air of the field and imparted to biotic (viruses, bacteria and spores) [8][9][10][11] and abiotic (fine tobacco smoke particles) targets [17] that entered the electric field. Furthermore, in the present study, negative ions were produced abundantly in the electric field of the CDA (see Figure 4B). ...
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The purpose of this study was to develop a simple electrostatic apparatus to precipitate virus particles spread via droplet transmission, which is especially significant in the context of the recent coronavirus disease 2019 (COVID-19) pandemic. The bacteriophage φ6 of Pseudomonas syringae was used as a model of the COVID-19 virus because of its similar structure and safety in experiments. The apparatus consisted of a spiked, perforated stainless plate (S-PSP) linked to a direct-current voltage generator to supply negative charge to the spike tips and a vessel with water (G-water) linked to a ground line. The S-PSP and G-water surface were paralleled at a definite interval. Negative charge supplied to the spike tips positively polarised the G-water by electrostatic induction to form an electric field between them in which ionic wind and negative ions were generated. Bacteriophage-containing water was atomised with a nebuliser and introduced into the electric field. The mist particles were ionised by the negative ions and attracted to the opposite pole (G-water). This apparatus demonstrated a prominent ability to capture phage-containing mist particles of the same sizes as respiratory droplets and aerosols regardless of the phage concentration of the mist particles. The trapped phages were successfully sterilised using ozone bubbling. Thus, the present study provides an effective system for eliminating droplet transmission of viral pathogens from public spaces.
... Hogan et al. (23) demonstrated both enhanced charging and improved collection efficiency of aerosolized bacteriophage MS2. In a follow-up study, molecular microbiological techniques were used to quantify the level of in-flight inactivation of bacteriophages T3 and MS2 passing through a soft-X-ray-enhanced ESP system (24). ...
... The corona inception voltage is less clear under conditions when the X-ray was turned on (X-ray-on condition). However, based on the magnitude of reduction in applied voltage shown in previous studies incorporating in situ soft X-ray irradiation (19,23,24), a corona inception voltage of approximately Ϫ5.25 kV would be expected in the X-ray-on condition (Fig. 1A). ...
... In addition to charging the biological agents and removing them in the electrical field, the ions and O 3 in the system may act as both a bactericide and viricide as the ability of O 3 to inactivate microbes is well-established. The amount of viral inactivation occurring in an ESP has been reported for bacteriophages (24). Additionally, studies investigating the effect of reactive species (excluding O 3 ) from a corona discharge on dust mite and cat allergens have shown that these allergens, which differ structurally for one another, can be destroyed by exposure to the corona discharge prod-ucts (36,37). ...
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Protection of the human lung from infectious agents, allergens, and ultrafine particles is difficult with current technologies. HEPA filters remove airborne particles >0.3 μm with 99.97% efficiency, but are expensive to maintain. Electrostatic precipitation has been used as an inexpensive approach to remove large particles from airflows, but has a collection efficiency minimum in the sub-micrometer size range allowing for a penetration window for some allergens and ultrafine particles. Incorporating soft X-ray irradiation as an in-situ component of the electrostatic precipitation process greatly improves capture efficiency of ultrafine particles. Here we demonstrate the removal and inactivation capabilities of soft X-ray enhanced electrostatic precipitation technology targeting infectious agents (B. anthracis, M. bovis-BCG, and poxviruses), allergens, and ultrafine particles. Incorporation of in-situ soft X-ray irradiation at low-intensity corona conditions resulted in (i.) two-fold to nine-fold increase in capture efficiency of 200-600nm particles and (ii.) a considerable delay in the mean day of death as well as lower overall mortality rates in ECTV cohorts. At the high intensity corona conditions, nearly complete protection from viral and bacterial respiratory infection was afforded to the murine models for all biological agents tested. When optimized for combined efficient particle removal with limited ozone production, this technology could be incorporated into stand-alone indoor air cleaners or scaled for installation in aircraft cabin, office, and residential HVAC systems.
... The findings showed that the formation of disulfide bridges played a key role in RNA binding, providing a clarification of why infectious viruses cannot be rescued if cysteine residues are mutated, and that RNA binding can be promoted by multiple sites. Kettleson et al. [52] employed an Electrostatic precipitator (ESP) to study airborne virus capture and inactivation at applied voltages from À10 to þ10 kV by making use of aerosolized bacteriophages T3 and MS2. Samples were obtained from the effluent air stream for each charging scenario and assayed for viable phages using plaque assays and for nucleic acids using quantitative polymerase chain reaction (qPCR) assays. ...
... inactivation without capture) with a log inactivation of 2.6 for both phages at À10 kV given that conditions in the ESP are imposed to produce a corona discharge. Kettleson et al. [52] demonstrated that there is a significant potential for virus capture and inactivation through continual ion and reactive species bombardment. ...
... Kettleson et al. [52] Na/K pump's autoregulation and its role in metabolic control of semipermeable properties and excitability of neuronal membrane - ...
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This paper intends to contribute to the collaborative efforts of the scientific community by providing a literature review of the status of the coronavirus research by adding a multi-disciplinary perspective and looking into a broad spectrum of SARS-CoV-2 studies on virus molecular structure, biophysical approach, electrostatic interaction and UVC rays. The paper identifies future research directions for each group of studies and points out remaining questions on the way related to COVID-19. The summary of the literature review will intend to assist future studies; provide a biophysical understanding of the virus interaction with host cells and help better identify antiviral therapy and the development of new vaccines/drugs to tackle COVID-19 and any virus outbreak. In addition to the electrostatic interactions of SARS-CoV-2, this paper also discusses whether UVC rays are a safe alternative to many chemical sterilization methods which are frequently used in our daily life since the beginning of the COVID-19 outbreak and whose health effects are controversial. This article also briefly discusses the relationship of some trace elements with COVID-19 infection. In conclusion, focusing on biophysical mechanisms of virus–cell interactions with a broad perspective has potential to give a different approach to the reader for future treatment methods.
... Recently, technologies including electrostatic precipitator (ESP), mechanical heating system, and antimicrobial agent (such as tea tree, eucalyptus oil, and carbon nanotube (CNT))-coated air filter have been tested for controlling and inactivating airborne virus particles [11][12][13][14]. In our previous study, aerosolized bacteriophage MS2 virus was inactivated with synthesized SiO 2 -Ag nanoparticles, which were 400 nm silica particles decorated with 30 nm silver nanoparticles [15]. ...
... Two probes were placed downstream and upstream of the filter sample in order to measure the number concentrations of virus particles by the SMPS system. The filtration efficiency of the filter for virus aerosols was calculated as (11) where N is the number concentration of virus particles (particles/cm 3 ), and subscripts up and down represent upstream and downstream of the filter sample, respectively. ...
... The aerosolized virus particles were deposited onto an air filter sample for 15 mins at standard atmospheric conditions and a relative humidity of approximately 36%. Then, the elution process for virus particles from the filter sample was performed with reference to the work of Kettleson et al. [11]: Urea-arginine phosphate buffer (U-APB) solution was prepared by adding 0.9 g of urea, 0.4 mL of 0.2 M NaH 2 PO 4 , and 0.5 M l-arginine into 10 mL of DI water. The filter sample was placed into the solution for 10 min. ...
... Previous SXC studies, however, focused on using photoionization to charge particles and collect them using electric fields [15,17,18] or to investigate the achievement of the equilibrium charge-state of aerosol particles with low charge-state [13,19,20]. To the best of our knowledge, photoionization with an SXC has never been applied to neutralize (i.e., reduce the charge-state) highly charged particles generated by an electrospray, where the number of charges carried by particles scales with the square of particle size [21]. ...
... Initially, experiments were carried out using the Po-210 source incorporated in the EAG (Test 1), then the Po-210 source was removed and replaced with the SXC device, which was then attached to the chamber window, and the same set of experiments were conducted (Test 2). In the case of the SXC, a thin polyamide film (KaptonÔ 30HN, DuPont Corp., 30 mm thick) was used to seal the circular window where the Po-210 source is usually inserted to protect the X-ray emitter surface from the aerosol flow and to keep the neutralization chamber airtight [15,18]. ...
Article
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Electrospray size spectrometry analysis (ESSA), a mobility-based aerosol technique to characterize the size and charge-state of nanoparticles, uses a neutralizer to bring multiply charged particles to an equilibrium charge-state. Typical ESSA setups incorporate a Po-210 neutralizer that has short half-life time and its radioactive nature leads to safety concerns. This work demonstrates that a soft X-ray charger (SXC) effectively neutralizes electrosprayed bioparticles. Calculations show that the SXC generates bipolar ions with number concentrations one and two orders of magnitude higher than conventional Po-210 and Kr-85 sources, respectively. Additionally, we established that an SXC may be safely implemented in ESSA.
... Another type of sampler is the electrostatic precipitator (ESP), wherein electrostatic attraction is used to collect a wide size range of airborne particles (Jang et al., 2008, Kettleson et al., 2009, Dybwad et al., 2014. The ESP works by creating a corona discharge that places charges on airborne particles, resulting in an electrostatic attraction that draws the charged particles to electrodes ( Figure 2) (Hinds, 1998). ...
... The ESP has a size-dependent collection efficiency; total mass-based collection efficiencies are high (e.g. 99%), but typically low for submicrometer or nanometer particles (Yoo et al., 1997, Kettleson et al., 2009. Jang et al. (2007) developed a flow-swirling-based ESP without a corona discharger, and this device successfully collected Vaccinia viruses, which are brick shaped ...
Article
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Viruses that affect humans, animals, and plants are often dispersed and transmitted through airborne routes of infection. Due to current technological deficiencies, accurate determination of the presence of airborne viruses is challenging. This shortcoming limits our ability to evaluate the actual threat arising from inhalation or other relevant contact with aerosolized viruses. To improve our understanding of the mechanisms of airborne transmission of viruses, air sampling technologies that can detect the presence of aerosolized viruses, effectively collect them and maintain their viability, and determine their distribution in aerosol particles, are needed. The latest developments in sampling and detection methodologies for airborne viruses, their limitations, factors that can affect their performance, and current research needs, are discussed in this review. Much more work is needed on the establishment of standard air sampling methods and their performance requirements. Sampling devices that can collect a wide size range of virus‐containing aerosols and maintain the viability of the collected viruses are needed. Ideally, the devices would be portable and technology‐enabled for on‐the‐spot detection and rapid identification of the viruses. Broad understanding of the airborne transmission of viruses is of seminal importance for the establishment of better infection control strategies. This article is protected by copyright. All rights reserved.
... When it comes to the effect of negative ions on various viruses and the prevention of their transmission, there are many studies and analyses [22][23][24]. In this paper, the focus is on the triple deactivation treatment of two types of viruses those within liquid droplets and those within porous solid particles. ...
... where R u 8314,47 J kmol −1 K −1 is universal gas constant, and M w 18 kg kmol −1 is relative molecular mass of water, while ρ d is the density of water droplet. Combining Eq. (24) with expression (7) gives ...
Article
Various viruses can hide within fluid and solid structures and thus successfully cross different distances, causing the spread of viral infections. Analytical modeling of the triple treatment of virus within a small liquid droplet and within a solid porous particle is the basic research polygon of this paper. The three-stage treatment aims to maximize the efficacy of deactivating viruses indoors. In order to achieve this, viruses undergo treatment by infrared heating, ultraviolet deactivation and ionization–electrostatic deactivation by negative ions. When the droplets are treated with infrared heating, incomplete evaporation occurs, reducing their initial diameter by 10 times; an initial diameter of droplets is 0.01 mm, 0.03 mm and 0.05 mm. Thermal inactivation of viruses inside the droplets is almost negligible, due to short exposure time and a maximum temperature of 100 °C. On the other hand, when solid porous particles are heated to a much higher temperature at the same exposure time, this causes significant thermal inactivation of viruses inside them. Reducing the diameter of the droplet (due to evaporation) by 10 times causes a multiple increase in UV-C deactivation of viruses inside the droplets. The effect of UV-C radiation on viruses within solid porous particles is not included in this paper.Graphic abstract
... Such a statement, unlike what has been stated in former studies [7], is true especially for indoor spaces, which leads to an assumption that the infectivity of the virus may be possibly reduced if indoor hygrothermal conditions hostile to the virion could be properly established using a suitable HVAC (heating, ventilation, and air conditioning) system [8]. Nonetheless, the pursuit of this objective must consider a number of other aspects: (i) the vulnerability of human mucous membranes tends to increase in decreasing relative humidity (RH) below 30% [9]; (ii) the presence of humans inside indoor spaces for a long time (many hours) requires adequate, or at least bearable, comfort conditions [10]; (iii) to avoid the potential for mould and moisture threat, RH cannot exceed specific values (at most 80%) in the coldest and least ventilated corners [11]; and (iv) to offset the risk of electrical static charge on electronic devices in office or healthcare environments, RH cannot be extremely low [12]. All of these statements highlight the need to identify a domain of RH and temperature values that could result in a decrease in the virus strength, being at the same time suitable for long-term human presence, building-structure preservation, and critical-devices operation [13]. ...
... There are two possible ways of achieving this result. One is quantitative, i.e., at the source level, based on the dilution of the infectious agent load via air changes [63][64][65], their capture through devices such as ultra-low particulate air (ULPA) filters or electrostatic precipitators (ESPs) [12], or the use of UV radiation [6]. The other is qualitative, i.e., at the ambient level, reachable through the surrounding of the infectious agents with adverse thermodynamic conditions. ...
Article
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In the CoViD-19 pandemic, the precautionary approach suggests that all possible measures should be established and implemented to avoid contagion, including through aerosols. For indoor spaces, the virulence of SARS-CoV-2 could be mitigated not only via air changes, but also by heating, ventilation, and air conditioning (HVAC) systems maintaining thermodynamic conditions possibly adverse to the virus. However, data available in literature on virus survival were never treated aiming to this. In fact, based on comparisons in terms of specific enthalpy, a domain of indoor comfort conditions between 50 and 60 kJ/kg is found to comply with this objective, and an easy-to-use relationship for setting viable pairs of humidity and temperature using a proper HVAC plant is proposed. If confirmed via further investigations on this research path, these findings could open interesting scenarios on the use of indoor spaces during the pandemic.
... Ozone and other reactive species are generated during corona discharging, which usually inactivates the viruses. 21 However, the concentration of the generated ozone was approximately 4 ppb with corresponding ozone dose less than 0.1 min-ppb under the test conditions ( Figure S6). This ozone concentration was too low to inactivate the phages, considering that 90% inactivation of MS2 and T7 requires an ozone dose of 652 and 1009 min-ppb, respectively, at 55% RH. 31 The T7 phage, which is similar to the T3 phage in structure, was more resistant to ozone than the MS2 phage; thus ozone inactivation may not be an explanation for the decreased PFU level for T3. ...
... Therefore, it is more likely that the T3 phages were damaged when they were exposed to the high electric field intensity. 21 Since both the head and tail of T3 can be charged with the same polarity and hence can form strong repulsive force, 36 they might be more easily separated under the high electric field. MS2 viruses do not have the head and tail structure, and their RIVC and recovery rate did not decrease significantly as the magnitude of the electric field was increased from 2 kV to 10 kV (p = 0.449 and 0.387, respectively). ...
Article
Measurements of airborne viruses via sampling have been critical issues. Most electrostatic samplers have been assessed for bacterial aerosols or micrometer-sized viral particles; however, sampling of submicrometer-sized airborne viruses is necessary, especially because of the high probability of their staying airborne and their deposition in the lower respiratory tract. Here, we present a novel personal electrostatic particle concentrator (EPC) for gentle sampling of submicrometer airborne virus particles. Owing to the enhanced electric field designed in this EPC, the collection efficiencies reached values as high as 99.3-99.8% for 0.05-2 μm diameter polystyrene particles at a flow rate of 1.2 L/min. Submicrometer-sized MS2 and T3 virus particles were also collected in the EPC, and the concentrations relative to their respective initial suspensions were more than 10 times higher than those in the SKC BioSampler. Moreover, the recovery rate of T3 was 982 times higher in the EPC (-2 kV) than in the BioSampler at 12.5 L/min because of the gentle sampling of the EPC. Gentle sampling is desirable because many bioaerosols suffer from significant viability losses during sampling. The influence of ozone generated, applied electrostatic field, and the flow rate on the viability of the viruses will also be discussed.
... Furthermore, compared to liquid impingers, electrostatic samples have demonstrated 5-10 times higher concentration output (Yao et al., 2009;Wei et al., 2014;Rufino de Sousa et al., 2020). There is potential to develop this technology for clinical use as an alternative sampling technique for exhaled breath aerosols (Han and Mainelis, 2008;Kettleson et al., 2009;Miller et al., 2010;Christensen et al., 2011;Tan et al., 2011;Lancereau et al., 2013); however, we found no reports yet of direct exhaled breath sampling using electrostatic methods. ...
Article
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Collecting samples for diagnosis of respiratory infections can be invasive and highly uncomfortable for patients; with sampling techniques ranging from nasal or throat swabs to bronchoalveolar lavage. In this work, we explore the electrostatic capture of exhaled pathogens as a non-invasive sampling method for rapid diagnosis in a primary care setting. A pilot study at primary care centers in Belgium enrolled 20 patients presenting with flu-like symptoms whose diagnosis was determined by nasopharyngeal (NP) swabs. We collected exhaled aerosol particles from infected patients using a breath electrostatic sampler (BESS) and using filters, following an extremely light procedure consisting of five normal exhales. All samples were analyzed using a commercial multiplex q-RT-PCR panel assay. Staphylococcus aureus (S. aureus) was detected from BESS samples of seven patients; three of whom were in agreement with their corresponding diagnoses. The BESS method was negative for exhaled viruses. We detected viruses, but no bacteria, with the filters, but the results showed no correlation with the corresponding diagnosis. Our results indicate that electrostatic sampling of exhaled breath is a technique and approach potentially suited for the primary care setting, where it might constitute a helpful diagnostic device.
... Although precipitation to sites other than THOR does not contribute to pathogen detection it helps nevertheless to remove infectious particles from the air. Ionization has been shown to prevent transmission of airborne TB [39] and to inactivate viruses and bacteria [40][41][42]. These observations are in line with poor re-growth of mycobacteria from THOR in our laboratory experiments. ...
Article
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Tuberculosis (TB) infects about 25% of the world population and claims more human lives than any other infectious disease. TB is spread by inhalation of aerosols containing viable Mycobacterium tuberculosis expectorated or exhaled by patients with active pulmonary disease. Air-sampling technology could play an important role in TB control by enabling the detection of airborne M. tuberculosis, but tools that are easy to use and scalable in TB hotspots are lacking. We developed an electrostatic air sampler termed the TB Hotspot DetectOR (THOR) and investigated its performance in laboratory aerosol experiments and in a prison hotspot of TB transmission. We show that THOR collects aerosols carrying microspheres, Bacillus globigii spores and M. bovis BCG, concentrating these microparticles onto a collector piece designed for subsequent detection analysis. The unit was also successfully operated in the complex setting of a prison hotspot, enabling detection of a molecular signature for M. tuberculosis in the cough of inmates. Future deployment of this device may lead to a measurable impact on TB case-finding by screening individuals through the aerosols they generate.
... On the other hand, the same personal cyclone successfully recovered viral RNA in the cough aerosols from 32 of 38 influenza-positive patients (Lindsley et al. 2010). Efficient capture of viruses was achieved using ESPs with a novel charging system (Hogan, Lee, and Biswas 2004;Kettleson et al. 2009), including for the use of plaque assays and qPCR. An ESP with 150 mL of collection fluid was used to capture influenza viruses for point-of-care applications (Ladhani et al. 2017). ...
Article
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Bioaerosol sampling is an essential and integral part of any bioaerosol investigation. Since bioaerosols are very diverse in terms of their sizes, species, biological properties, and requirements for their detection and quantification, bioaerosol sampling is an active, yet challenging research area. This paper was inspired by the discussions during the 2018 International Aerosol Conference (IAC) (St. Louis, MO) regarding the need to summarize the current state of the art in bioaerosol research, including bioaerosol sampling, and the need to develop a more standardized set of guidelines for protocols used in bioaerosol research. The manuscript is a combination of literature review and perspectives: it discusses the main bioaerosol sampling techniques and then overviews the latest technical developments in each area; the overview is followed by the discussion of the emerging trends and developments in the field, including personal sampling, application of passive samplers, and advances toward improving bioaerosol detection limits as well as the emerging challenges such as collection of viruses and collection of unbiased samples for bioaerosol sequencing. The paper also discusses some of the practical aspects of bioaerosol sampling with particular focus on sampling aspects that could lead to bioaerosol determination bias. The manuscript concludes by suggesting several goals for bioaerosol sampling and development community to work towards and describes some of the grand bioaerosol challenges discussed at the IAC 2018.
... However, studies point out that for aerosol 30-100 nm, AGI-30 and BioSampler® have physical collection efficiency less than 10% (Hogan et al. 2005). Using filter and electrostatic precipitators can lead to higher physical collection efficiency for viral aerosol, but can damage the viability of viral aerosol (Kettleson et al. 2009;Roux et al. 2016;Yang et al. 2011). Recently, condensation growth method gained significant attention in viral aerosol collection due to its ability to possess high physical collection efficiency and viability preservation. ...
Article
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Viral aerosol infection through cough generates large amounts of viral aerosol and can result in many adverse health effects such as influenza flu and severe acute respiratory syndrome (SARS). To characterize the coughed viral aerosol, the sampler needs to sample at higher flow rate and possess high physical collection efficiency as well as high viral preservation. However, most current inertia-based high flow bioaerosol samplers are not suited for viral aerosol sampling since the viability will be lost doing the sampling process. Current condensation growth methods only have good physical collection efficiency and viral preservation at low flow rate (< 10 LPM). In this study, we developed a viral aerosol sampling system using a cooler and steam-jet aerosol collector (SJAC) for bioaerosol collection for the first time. The system is based on mixing condensation growth method and has high viral preservation at a higher flow rate (12.5 LPM). We control the inlet aerosol flow temperature and the SJAC mixing reservoir temperature to improve the physical collection efficiency and viability preservation of the viral aerosol. Results indicate that the physical collection efficiency is 70–99% for aerosol 30–100 nm when the aerosol flow and mixing reservoir temperature was 19 and 50 °C, respectively. In addition, the system was 7 and 22 times more efficient for viability preservation of MS2 bacteriophage than the commonly used All Glass Impinger 30 (AGI-30) and BioSampler®, respectively. Finally, the system can be applied to sample at a lower concentration (105 PFU/m3), and results shows the system was 4.7 times more efficient for viability preservation than using AGI-30 alone. The developed viral collection system will improve our understanding of the characteristics of coughed aerosol and can be used for future evaluation of respiratory protective equipment and environmental sampling.
... Alternatively, electrostatic precipitators (ESPs) have been reported recently as bioaerosol samplers for the collection of airborne microorganisms [3,[12][13][14][15]. ESPs benefit from low power consumption and a gentler sampling that is potentially less damaging for pathogens [14]. ...
Article
Flu is caused by the influenza virus that, due to mutations, keeps our body vulnerable for infections, making early diagnosis essential. Although immuno-based diagnostic tests are available, they have low sensitivity and reproducibility. In this paper, the prospect of detecting influenza A virus using digital ELISA has been studied. To appropriately select bioreceptors for this bioassay, seven commercial antibodies against influenza A nucleoprotein were methodically tested for their reactivity and binding affinity. The study has been performed on two markedly different platforms, being an enzyme-linked immunosorbent assay and a surface plasmon resonance system. The selected antibodies displayed completely different behavior on the two platforms and in various assay configurations. Surprisingly, the antibodies that showed overall good reactivity on both platforms had the highest dissociation constant among the tested antibodies, suggesting that, although important, binding affinity is not the only parameter to be considered when selecting antibodies. Moreover, only one antibody had the capacity to capture nucleoprotein directly in lysis buffer used for releasing this viral protein, which might pose huge advantage when developing assays with fast time-to-result. This antibody was implemented on an in-house developed digital ELISA platform for ultrasensitive detection of recombinant nucleoprotein, reaching a detection limit of 4 ± 1 fM in buffer and 10 ± 2 fM in 10 fold diluted nasopharyngeal swabs which is comparable to currently available fast molecular detection techniques. These results point to a great potential for ultrasensitive immuno-based influenza detection.
... Alternatively, electrostatic precipitators (ESPs) have been reported recently as bioaerosol samplers for the collection of airborne microorganisms [3,[12][13][14][15]. ESPs benefit from low power consumption and a gentler sampling that is potentially less damaging for pathogens [14]. ...
Article
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Airborne transmission of the influenza virus contributes significantly to the spread of this infectious pathogen, particularly over large distances when carried by aerosol droplets with long survival times. Efficient sampling of virus-loaded aerosol in combination with a low limit of detection of the collected virus could enable rapid and early detection of airborne influenza virus at the point-of-care setting. Here, we demonstrate a successful sampling and detection of airborne influenza virus using a system specifically developed for such applications. Our system consists of a custom-made electrostatic precipitation (ESP)-based bioaerosol sampler that is coupled with downstream quantitative polymerase chain reaction (qPCR) analysis. Aerosolized viruses are sampled directly into a miniaturized collector with liquid volume of 150 μL, which constitutes a simple and direct interface with subsequent biological assays. This approach reduces sample dilution by at least one order of magnitude when compared
... Inactivation of viruses by electrostatic attraction has only been briefly investigated 35 . In the present study, rotavirus and CaCV lost significant (> 97%) infectivity (ratio; CaCV from 3.0 × 10 −2 to < 7.8 × 10 −4 and rotavirus from 4.9 × 10 −1 to < 7.6 × 10 −3 ) in ionized air as determined by a ratio of infectivity versus gene copies. ...
Article
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By the use of a modified ionizer device we describe effective prevention of airborne transmitted influenza A (strain Panama 99) virus infection between animals and inactivation of virus (>97%). Active ionizer prevented 100% (4/4) of guinea pigs from infection. Moreover, the device effectively captured airborne transmitted calicivirus, rotavirus and influenza virus, with recovery rates up to 21% after 40 min in a 19 m(3) room. The ionizer generates negative ions, rendering airborne particles/aerosol droplets negatively charged and electrostatically attracts them to a positively charged collector plate. Trapped viruses are then identified by reverse transcription quantitative real-time PCR. The device enables unique possibilities for rapid and simple removal of virus from air and offers possibilities to simultaneously identify and prevent airborne transmission of viruses.
... Miller et al. [38] demonstrated a hand-held ESP device for breath sampling relying on transmission electron microscopy (TEM) for sample analysis, which is not a suitable detection method for PoC applications. Alternatively, Kettleson et al. [39] demonstrated inactivation of aerosolized viruses using an ESP. Christensen et al. [40] utilized a commercial, chip-based ESP to analyze breath from cattle for detection of foot-and-mouth disease . ...
... Studies showed that large-scale infectious disease outbreaks, such as the outbreaks of severe acute respiratory syndrome in 2003 and influenza virus H1N1 in 2009, were triggered by airborne transmission of the viral agents (4)(5)(6)(7). To reduce exposure to viruses, various methods have been developed and evaluated, including UV irradiation (8)(9)(10)(11), chemical agents (12), electrical fields (13,14), ion emission (15)(16)(17)(18), ozone generation (19), and microwave irradiation (20)(21)(22)(23). In recent years, atmospheric-pressure cold plasma (APCP), a low-temperature decontamination technology, has gained increased attention for the inactivation of microbial agents due to its high degree of effectiveness and low cost (24). ...
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In this study, airborne MS2 bacteriophages were exposed for sub-second time intervals to the atmospheric pressure cold plasma (APCP) produced using different power levels (20, 24, and 28 Watts) and gas carriers [ambient air, Ar/O2 (2 vol %), and He/O2 (2 vol %)]. In addition, water-borne MS2 viruses were directly subjected to the APCP treatment for up to 3 min. The MS2 viruses with and without the APCP exposure were examined by scanning electron microscope (SEM), reverse transcription polymerase chain reaction (RT-PCR) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The viral inactivation was shown to exhibit linear relationships with the APCP generation power and exposure time (all R(2)>0.95), up to 95% (1.3 log) after sub-second airborne exposure at 28 Watts; about the same inactivation level was achieved for water-borne viruses with an exposure of less than 1 min. A greater amount of reactive oxygen species (ROS) such as atomic oxygen in the APCP was detected for higher generation power with Ar/O2 and He/O2 gas carriers. SEM images, SDS-Page and agarose gel analysis of exposed water-borne viruses showed various damages to both surface proteins and their related RNA genes after the APCP exposure, thus leading to the loss of their viability and infectivity. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
... Several research groups studied the inactivation of airborne viruses via various technologies. Kettleson et al. [38] used an electrostatic precipitator (ESP) for capturing and inactivating aerosolized bacteriophages T3 and MS2. Grinshpun et al. [39] investigated inactivation of aerosolized bacteriophage MS2 in a continuous air flow chamber with axial heating for periods of 0.1-1 s. ...
... Phages pose no significant risk to humans, they are easy to propagate in laboratory and their similarities with eukaryote viruses make them interesting models for aerovirology research. For these reasons, the coliphage MS2 (Golmohammadi et al. 1993), a small non-enveloped bacterial virus (Leviviridae family) with a capsid diameter of 25 nm and a genome made of a single-stranded RNA (ssRNA) molecule (3569 nucleotides), has been used as an airborne viral model in many aerosol studies (Barker and Jones 2005;Burton et al. 2007;Eninger et al. 2009;Grinshpun et al. 2007;Hogan et al. 2005;Hogan et al. 2006;Hogan et al. 2004;Holton and Webb 1994;Kettleson et al. 2009;Li et al. 2009;Perrott et al. 2009;Tseng and Li, 2005;Walker and Ko, 2007;Wang and Brion 2007). The Pseudomonas syringae virulent phage phi 6 is another well characterized bacterial virus that has some interesting features as a surrogate for RNA viruses, although it has been used only sporadically in aerosol studies (Ellis and Schlegel 1974). ...
Article
This study exploits the virulent bacteriophages phi 6 (dsRNA) and MS2 (ssRNA) as surrogates for airborne RNA viruses. Two different filter types, polytetrafluoroethylene (PTFE) and polycarbonate (PC), were tested for their efficiency in collecting aerosolized RNA phages. Two commercial kits were tested for total RNA isolation. Also, heat shock treatments were performed in three different media to obtain the most favorable conditions for reverse transcription assays of dsRNA. Our findings suggest that PC filters are more suitable to recover infectious airborne RNA viruses as determined by plaque assays. Both types of filters were equally efficient in recovering RNA from aerosolized phage phi 6 as established by qRT-PCR. Viral samples should be treated with QIAamp Viral RNA Mini Kit and a 5 min heat shock treatment at 110°C in TE buffer before RT-PCR to maximize detection of phage phi 6. Overall, the infectivity of the recovered phages was severely affected by the aerosolization/air sampling process and the presence of RNA viruses in air samples should be determined by qRT-PCR.
... The smoke is precipitated out of the aerosolized form and sediments on the peritoneal and viscera surfaces. 24,25 The device can be connected to any standard electrosurgical system. To eliminate smoke, a stainless steel microfilament brush, the Ionwand, is inserted percutaneously into the abdomen through a hollow needle. ...
Article
Introduction Given the propensity of severe acute respiratory syndrome coronavirus 2 to spread, it is imperative that those continuing to perform surgery take precautions to limit the potential generation of contaminated aerosols in smoke from energy‐based instruments. The aim of this study was to report current data regarding insufflators with desufflation mode and similar options to safely remove CO2 in minimal access surgery. Methods A non‐systematic review of the scientific literature was conducted using the PubMed database, and the main companies that provide surgical devices were contacted for information. Results Most commercially available smoke evacuators use a combination of suction and mechanical filtering. There are also electrostatic precipitators that charge surgical smoke and retain the particles via electrostatic attraction. The search identified three insufflators with desufflation mode, four modular smoke evacuators using mechanical filtration, and only one device using electrostatic precipitation. However, none of these devices has been tested with viruses. Conclusion This review identified commercially available equipment that employs mechanical filtering and electrostatic attraction principles that can be used for pneumoperitoneum evacuation during the present coronavirus disease 2019 pandemic. This pandemic should assist in raising awareness regarding protection measures and the risk of occupational exposure in surgery.
... The use of an active smoke evacuator connected to a proper filter has been recommended by SAGES for laparoscopic or robotic procedures during the COVID-19 pandemic [24]. Another innovative suggestion for additional safety is the addition of a system of intra-abdominal electrostatic precipitation, [25,26] which is able to sediment the aerosolized virus to the peritoneum, thereby precipitating 99.7% of the particles (Fig. 2). ...
Article
Aim: The rapid spread of the COVID-19 pandemic has created unprecedented challenges for the medical and surgical healthcare systems. With the ongoing need for urgent and emergency colorectal surgery, including surgery for colorectal cancer, several questions pertaining to operating room (OR) utilization and techniques needed to be rapidly addressed. Method: This manuscript discusses knowledge related to the critical considerations of patient and caregiver safety relating to personal protective equipment (PPE) and the operating room environment. Results: During the COVID-19 pandemic, additional personal protective equipment (PPE) may be required contingent upon local availability of COVID-19 testing and the incidence of known COVID-19 infection in the respective community. In addition to standard COVID-19 PPE precautions, a negative-pressure environment, including an OR, has been recommended, especially for the performance of aerosol-generating procedures (AGPs). Hospital spaces ranging from patient wards to ORs to endoscopy rooms have been successfully converted from standard positive-pressure to negative-pressure spaces. Another important consideration is the method of surgical access; specifically, minimally invasive surgery with pneumoperitoneum is an AGP and thus must be carefully considered. Current debate centres around whether it should be avoided in patients known to be infected with SARS-CoV-2 or whether it can be performed under precautions with safety measures in place to minimize exposure to aerosolized virus particles. Several important lessons learned from pressurized intraperitoneal aerosolized chemotherapy procedures are demonstrated to help improve our understanding and management. Conclusion: This paper evaluates the issues surrounding these challenges including the OR environment and AGPs which are germane to surgical practices around the world. Although there is no single universally agreed upon set of answers, we have presented what we think is a balanced cogent description of logical safe approaches to colorectal surgery during the COVID-19 pandemic.
... Several particle control technologies have been developed over the years to reduce our exposure to airborne particles that cause various health problems. Commercially, high-efficiency particulate air (HEPA) filtration and electrostatic precipitators (ESPs) are used to remove aerosol particles and inactivate bioaerosols (including several viruses) from the air in many indoor environments, including hospitals, offices, and aircraft cabins (Kettleson et al. 2009). However, both of these technologies have serious limitations. ...
... Electrostatic precipitation has been used in the collection of a variety of airborne particulate 15,16 including viruses. 17 Surface samples were collected on doors leading into each of the air sampling spaces. Extracted samples were analyzed by RT-PCR for the SARS-CoV-2 E gene as previously described. ...
Preprint
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Importance. Scalable programs for school-based SARS-CoV-2 testing and surveillance are needed to guide in-person learning practices and inform risk assessments in K-12 settings. Objectives. To characterize SARS-CoV-2 infections in staff and students in an urban public school setting and evaluate test-based strategies to support ongoing risk assessment and mitigation for K-12 in-person learning. Design, Setting, and Participants. The pilot program engaged three schools for weekly saliva PCR testing of staff and students participating in in-person learning over a 5-week period. Wastewater, air, and surface samples were collected weekly and tested for SARS-CoV-2 RNA to determine surrogacy for case detection and interrogate transmission risk of in-building activities. Main Outcomes and Measures. SARS-CoV-2 detection in saliva and environmental samples and risk factors for SARS-CoV-2 infection. Results. 2,885 supervised self-collected saliva samples were tested from 773 asymptomatic staff and students during November and December, 2020. 46 cases (22 students, 24 staff) were detected, representing a 5.8- and 2.5-fold increase in case detection rates among students and staff, respectively, compared to conventional reporting mechanisms. SARS-CoV-2 RNA was detected in wastewater samples from all pilot schools, as well as in air samples collected from two choir rooms. Sequencing of 21 viral genomes in saliva specimens demonstrated minimal clustering associated with one school. Geographic analysis of SARS-CoV-2 cases reported district-wide demonstrated higher community risk in zip codes proximal to the pilot schools. Conclusions and Relevance. Weekly screening of asymptomatic staff and students by saliva PCR testing dramatically increased SARS-CoV-2 case detection in an urban public-school setting, exceeding infection rates reported at the county level. Experiences differed among schools, and virus sequencing and geographic analyses suggest a dynamic interplay of school-based and community-derived transmission risk. Environmental testing for SARS-CoV-2 RNA in air and surface samples enabled real-time risk assessment of in-school activities and allowed for interventions in choir classes. Wastewater testing demonstrated the utility of school building-level SARS-CoV-2 surveillance. Collectively, these findings provide insight into the performance and community value of test-based SARS-CoV-2 screening and surveillance strategies in the K-12 educational setting.
... Electrostatic precipitation has been used in the collection of a variety of airborne particulates, 19,20 including viruses. 21 Surface samples were collected on doors leading into each of the air sampling spaces. Extracted samples were analyzed by RT-PCR for the SARS-CoV-2 E gene as previously described. ...
Article
Full-text available
Importance: Scalable programs for school-based SARS-CoV-2 testing and surveillance are needed to guide in-person learning practices and inform risk assessments in kindergarten through 12th grade settings. Objectives: To characterize SARS-CoV-2 infections in staff and students in an urban public school setting and evaluate test-based strategies to support ongoing risk assessment and mitigation for kindergarten through 12th grade in-person learning. Design, setting, and participants: This pilot quality improvement program engaged 3 schools in Omaha, Nebraska, for weekly saliva polymerase chain reaction testing of staff and students participating in in-person learning over a 5-week period from November 9 to December 11, 2020. Wastewater, air, and surface samples were collected weekly and tested for SARS-CoV-2 RNA to evaluate surrogacy for case detection and interrogate transmission risk of in-building activities. Main outcomes and measures: SARS-CoV-2 detection in saliva and environmental samples and risk factors for SARS-CoV-2 infection. Results: A total of 2885 supervised, self-collected saliva samples were tested from 458 asymptomatic staff members (mean [SD] age, 42.9 [12.4] years; 303 women [66.2%]; 25 Black or African American [5.5%], 83 Hispanic [18.1%], 312 White [68.1%], and 35 other or not provided [7.6%]) and 315 students (mean age, 14.2 [0.7] years; 151 female students [48%]; 20 Black or African American [6.3%], 201 Hispanic [63.8%], 75 White [23.8%], and 19 other race or not provided [6.0%]). A total of 46 cases of SARS-CoV-2 (22 students and 24 staff members) were detected, representing an increase in cumulative case detection rates from 1.2% (12 of 1000) to 7.0% (70 of 1000) among students and from 2.1% (21 of 1000) to 5.3% (53 of 1000) among staff compared with conventional reporting mechanisms during the pilot period. SARS-CoV-2 RNA was detected in wastewater samples from all pilot schools as well as in air samples collected from 2 choir rooms. Sequencing of 21 viral genomes in saliva specimens demonstrated minimal clustering associated with 1 school. Geographical analysis of SARS-CoV-2 cases reported district-wide demonstrated higher community risk in zip codes proximal to the pilot schools. Conclusions and relevance: In this study of staff and students in 3 urban public schools in Omaha, Nebraska, weekly screening of asymptomatic staff and students by saliva polymerase chain reaction testing was associated with increased SARS-CoV-2 case detection, exceeding infection rates reported at the county level. Experiences differed among schools, and virus sequencing and geographical analyses suggested a dynamic interplay of school-based and community-derived transmission risk. Collectively, these findings provide insight into the performance and community value of test-based SARS-CoV-2 screening and surveillance strategies in the kindergarten through 12th grade educational setting.
... The studies summarized above highlight plasma as a promising technology with similar advantages as electrostatic precipitation [209], but possibly superior to filters. Plasma will directly inactivate the airborne virus with efficacies in excess of 99.9%, comparable to HEPA efficacies. ...
Article
Full-text available
Pathogenic viruses cause many human, animal, and plant diseases that are associated with substantial morbidity, mortality and socio-economic impact. Although effective strategies for combatting virus transmission and associated disease are available, global outbreaks of viral pathogens such as the virus responsible for the COVID-19 pandemic demonstrate that there is still a critical need for new approaches that can be used to interrupt the chain of viral infection and mitigate virus-associated pathogenesis. Recent studies point to non-thermal plasma (NTP), a partly ionized gas comprised of a complex mixture of reactive oxygen and nitrogen species along with physical effectors, as the potential foundation for new antiviral approaches. A more thorough understanding of the antiviral properties and safety of NTP has stimulated explorations of NTP as the basis for treatments of viral diseases. The recently described immunomodulatory properties of NTP are also being evaluated for potential use in immunotherapies of viral diseases as well as in antiviral vaccination strategies. In this review, we present the current state-of-the-art in addition to compelling arguments that NTP merits further exploration for use in the prevention and management of viral infections and associated diseases.
... Collection and inactivation can be distinguished from one another via the simultaneous use of virus titration to detect upstream and downstream viable viruses, RT-qPCR to detect viral RNA, and assays for an independent physical tracer (eg fluorescent dye) to examine physical removal on a mass basis. Differences between virus titer-based measurements and either the RT-qPCR or physical tracer measurements provide evidence for the inactivation of uncollected viruses by the tested unit; if the titer-based removal is largest, then the difference in log reduction on a titer-basis and physical tracer basis is the inactivation log reduction.31 Furthermore, differences between RT-qPCR and physical tracer results provide evidence for RNA degradation in particles passing through the unit, which should also coincide with inactivation. ...
Article
Full-text available
Recirculating air purification technologies are employed as potential means of reducing exposure to aerosol particles and airborne viruses. Toward improved testing of recirculating air purification units, we developed and applied a medium-scale single-pass wind tunnel test to examine the size-dependent collection of particles and the collection and inactivation of viable bovine coronavirus (BCoV, a betacoronavirus), porcine respiratory coronavirus (PRCV, an alphacoronavirus), and influenza A virus (IAV), by a commercial air purification unit. The tested unit, the Molekule Air Mini, incorporates a MERV 16 filter as well as a photoelectrochemical oxidating layer. It was found to have a collection efficiency above 95.8% for all tested particle diameters and flow rates, with collection efficiencies above 99% for supermicrometer particles with the minimum collection efficiency for particles smaller than 100 nm. For all three tested viruses, the physical tracer-based log reduction was near 2.0 (99% removal). Conversely, the viable virus log reductions were found to be near 4.0 for IAV, 3.0 for BCoV, and 2.5 for PRCV, suggesting additional inactivation in a virus family- and genus-specific manner. In total, this work describes a suite of test methods which can be used to rigorously evaluate the efficacy of recirculating air purification technologies.
... Liquid and dry impaction are the most common sampling methods used to study viral bioaerosol behavior, characteristics or destruction (Verreault, Moineau, and Duchaine 2008). The advantages and limitations of sampling using liquid impingers such as AGI-30 or AGI-4 (All Glass Impinger), SKC Biosampler V R ) and frit bubblers are well described (Hermann et al. 2006;Hogan et al. 2005;Hogan et al. 2006;Kettleson et al. 2009;Tseng and Li 2005;Walls et al. 2016). Collecting samples in liquid allows for better preservation of microorganisms and facilitates downstream analyses. ...
Article
A better description of airborne transmission routes of viruses that are responsible for nosocomial infections requires efficient and accurate sampling methods that allow the preservation of viral integrity and infectivity. The aim of this project was to compare the virus collection efficiency of traditional filter sampling using cassettes with water-based condensation sampling through laminar flow. Bacteriophages MS2, PhiX174, Phi6, and PR772 as well as an influenza virus were nebulized in an aerosol chamber. Bioaerosols were simultaneously collected on polycarbonate (PC) filters (0.8 μm pore diameter) loaded into 37-mm closed-face cassettes (CFCs) and with a condensation-based sampler (Spot Sampler™) which collected bioaerosols in a liquid buffer. Concentrations of bacteriophages and influenza were analyzed at two different sampling times (60 min and 4 h) both by culture (infectivity preservation) and qPCR (efficiency of recovery) to compare the performance of the two samplers. PhiX174 showed better recovery with the Spot Sampler™ for both sampling times and PR 772 showed better relative genome recovery with CFC sampling after 60 min. In addition, use of the Spot Sampler™ led to better preservation of infectivity for all the viruses including influenza, with the exception of phage MS2 after 4 h of sampling. In future work, the Spot Sampler™ could be tested in hospital environments to better understand airborne transmission routes of viruses, or in in-vitro setups to assess the efficiency of virucidal air treatment. Copyright © 2021 American Association for Aerosol Research
... The tested duct unit, though similar to units described and applied previously, 15,16 is distinct in design from more common UV−C HVAC units, where UV−C lights are typically placed near filtration systems and designed to inactivate infectious particles collected by the filter media. That said, we do believe such UV−C flow tube reactors would be best incorporated into systems integrating multiple control technologies, such as fibrous filters (for efficient particle removal, after the UV−C unit), activated carbon filters (for VOC removal upstream, to mitigate gas phase reactions catalyzed by the UV−C unit), or electrostatic precipitators (also for particle collection and possibly virus inactivation 41 ). ...
Article
Control technologies to inactivate airborne viruses effectively are needed during the ongoing SARS-CoV-2 pandemic, and to guard against airborne transmitted diseases. We demonstrate that sealed UV−C flow reactors operating with fluences near 253 ± 1 nm of 13.9−49.6 mJ cm −2 efficiently inactivate coronaviruses in an aerosol. For measurements, porcine respiratory coronavirus (PRCV) was nebulized in a custom-built, 3.86 m wind tunnel housed in a biosafety level class II facility. The single pass log 10 reduction of active coronavirus was in excess of 2.2 at a flow rate of 2439 L min −1 (13.9 mJ cm −2) and in excess of 3.7 (99.98% removal efficiency) at 684 L min −1 (49.6 mJ cm −2). Because virus titers resulting from sampling downstream of the UV−C reactor were below the limit of detection, the true log reduction is likely even higher than measured. Comparison of virus titration results to reverse transcriptase quantitative PCR and measurement of fluorescein concentrations (doped into the nebulized aerosol) reveals that the reduction in viable PRCV is primarily due to UV−C based inactivation, as opposed to physical collection of virus. The results confirm that UV−C flow reactors can efficiently inactivate coronaviruses through incorporation into HVAC ducts or recirculating air purifiers.
... The computer simulation of these respiratory aerosols is relevant, given that essential workers very often share close spaces. It would be convenient to simulate far-UVC light [20] and electrostatic precipitators [21,22] to eliminate SARS-CoV-2 in virulent PM 2.5 to control the air quality in such spaces. This new realistic computer simulation could help to capture real-world situations and thus examine more effective measures to prevent and control infectious spreading among essential workers during the COVID-19 pandemic. ...
Article
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Because there is a rapidly emerging risk that essential supply chains could collapse during the COVID-19 pandemic, new strategies are urgently needed by governments to protect workers regardless of whether or not they have symptoms. We propose a “stochastic filtrate” of such workers to reduce the risk of physical interactions with workers infected with SARS-CoV-2. Here, we suggest the random real-time-RT-PCR test of SARS-CoV-2 as a filtrating agent, although other more useful tests developed in the future to detect SARS-CoV-2 could also be used instead. Such a focused strategy, when combined with other preventive measures, could be successfully replicated in many countries to reactivate the world's economy safely. Our stochastic filtrate concept includes a mathematical framework and conceptual model. The simulations of this stochastic filtrate process support its viability.
... EAP is currently the most efficient method for aerosol evacuation and elimination. In the light that a previous study reported the efficient capture of viruses and its concomitant deactivation using electrostatic precipitation technology [33], EAP should become even more promising in the future. ...
Article
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Objective In the COVID-19 crisis, laparoscopic surgery is in the focus as a relevant source of bioaerosol release. The efficacy of electrostatic aerosol precipitation (EAP) and continuous aerosol evacuation (CAE) to eliminate bioaerosols during laparoscopic surgery was verified. Methods Ex-vivo laparoscopic cholecystectomies (LCs) were simulated +/- EAP or CAE in a pelvitrainer equipped with swine gallbladders. Release of bioaerosols was initiated by performing high-frequency electrosurgery with a monopolar electro hook (MP-HOOK) force at 40 W (MP-HOOK40) and 60 W (MP-HOOK60), as well as by ultrasonic cutting (USC). Particle number concentrations (PNC) of arising aerosols were analyzed with a condensation particle counter (CPC). Aerosol samples were taken i) within the pelvitrainer near to the source, ii) outside the pelvitrainer at the working trocar and iii) in the breathing zone of the surgeon. Results Within the pelvitrainer, MP-HOOK40 (6.4 x 105 cm-3) and MP-HOOK60 (7.3 x 105 cm-3) showed significant higher median PNCs compared to USC (4.4 x 105 cm-3) (p = 0.001). EAP lead to a significant decrease of the median PNCs in all three groups. A high linear correlation with Pearson correlation coefficients of 0.852, 0.825 and 0.759 were observed by comparing MP-HOOK40 (+/- EAP), MP-HOOK60 (+/- EAP) and USC (+/- EAP), respectively. During ex-vivo LC and CAE, significant bioaerosol contaminations of the operating room occurred. Ex-vivo LC with EAP lead to a considerable reduction of the bioaerosol concentration. Conclusion EAP was found to be efficient for intraoperative bioaerosol elimination and reducing the risk of bioaerosol exposure for surgical staff.
Article
In this study, single-walled carbon nanotube (SWNT) filters were prepared using mixed cellulose ester (MCE) filters and carbon nanotubes with three levels of loading: 0.02, 0.16 and 0.64mg/cm2. Both MCE and SWNT filters were used to collect bacterial and fungal aerosols with a total volume of 200L air sampled in indoor and outdoor environments. After sampling, the filters were directly placed on agar plates at 26°C for culturing. The culturable aerosol counts were manually obtained both for MCE and SWNT filters, and the resulting bacterial colony forming units (CFUs) were washed off and subjected to the culturable bioaerosol diversity analysis using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). For fungal CFUs, microscopy method was used to study the diversity obtained using different filter types.The results showed that use of SWNT filters with medium and high CNT loadings resulted in significant reduction (up to 2 logs) of culturable bacterial and fungal aerosol counts compared to MCE filters in both environments. For low CNT loading (0.02mg/cm2), very limited inactivation effects were observed for fungal aerosols, while more bacterial counts were obtained possibly due to increased sampling efficiency. PCR-DGGE analysis revealed that SWNT filters at high CNT loading (0.64mg/cm2) resulted in lowest culturable bioaerosol diversity, especially pronounced for outdoor bacterial aerosols. For low and medium CNT loading, the culturable bacterial aerosol diversity remained similar. Fungal aerosol analysis showed that the use of SWNT filters with medium to high CNT loading also resulted in significant reduction of fungal species diversity. The results here demonstrated great promise of the SWNT hybrid filter in controlling biological aerosols, and suggested its potential to impact current air conditioning system.
Article
Air purification through fiber-based filters has become a fundamental requirement for air contamination control. However, conventional filters depend on polymeric fibrous filters with adequate particulate matter removal ability but fewer degassing and biocidal effects. This study presents the photocatalytic volatile organic compound (VOC) oxidation and antimicrobial properties of zinc oxide (ZnO) nano-spines sprouted activated-carbon nanofibers (I@ZnO/ACNFs) and their potential for air contamination control and infection prevention. By developing a novel technique that can induce phase separation of inorganic salts during electrospinning, nanofibers with zinc (Zn) components concentrated on the surface could be synthesized. I@ZnO/ACNFs exhibit a surface densely covered with high aspect-ratio ZnO nano-spines with significant lethality to airborne pathogens and enhanced photocatalytic activity toward VOCs. Moreover, excellent adhesion stability of ZnO to ACNFs under rapid airflow was observed in I@ZnO/ACNFs. In combination with intriguing antimicrobial activity and strong VOC removal capability derived from their unique morphology, novel I@ZnO/ACNFs hold potential for airborne microbial disinfection, effective and sustainable VOC purification, and the design of photomicrobicidal and photocatalytic materials.
Article
A numerical analysis on the electrostatic capture of airborne viruses and nanoparticles in a homemade particle concentrator without a unipolar charger using commercial CFD software (CFD-ACE+) was presented. We simulated the effects of inlet/outlet configurations and particle diameters on the collection efficiency of the particle concentrator, and the simulation was in good agreement with the experimental measurements. We investigated the effects of the electrode arrangement on the collection efficiency. We also discussed the maximum collection efficiency and the relationship between the electric field intensity, the positions of the simulated particles on the inlet surface, and the collection efficiency.
Article
This communication describes a novel water-soluble membrane prepared from chitosan intended for SARS-CoV-2 viral nucleic acid collection and detection. The CSH membrane formed from nanofibers shows promising potential in the quantitative determination of the SARS-CoV-2 viral nucleic acids at a concentration of 102 copies per L in air. The sponge-like structure which allows gas to pass through for collection of viral nucleic acids potentially provides simple, fast, and reliable sampling as well as detection of various types of airborne viruses.
Article
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Bacteriophages are perceived as good models for the study of airborne viruses because they are safe to use, some of them display structural features similar to human and animal viruses, and they are relatively easy to produce in large quantities. Yet, only few studies have investigated them as models. It has been previously demonstrated that aerosolization, environmental conditions, and sampling conditions affect viral infectivity but this is virus-dependent. Thus, several viral models are likely needed to study their general behavior in aerosols. The aim of this study was to compare the effect of aerosolization and sampling on the infectivity of five tail-less bacteriophages and two pathogenic viruses: MS2 (ssRNA/Leviviridae family), Φ6 (segmented dsRNA/Cystoviridae), ΦX174 (ssDNA/Microviridae), PM2 (dsDNA/Corticoviridae), PR772 (dsDNA/Tectiviridae), human influenza A H1N1 (ssRNA/Orthomyxoviridae), and poultry Newcastle disease virus (NDV, ssRNA, Paramyxoviridae). Three nebulizer and two nebulization salt buffers (with or without organic fluid) were tested as well as two aerosol-sampling devices, a liquid cyclone (SKC BioSampler) and a dry cyclone (NIOSH two-stage cyclone). The presence of viruses in collected air samples was detected by culture and quantitative PCR (qPCR). Our results showed that these selected five phages behave differently when aerosolized and sampled. RNA phage MS2 and ssDNA phage ΦX174 were the most resistant to aerosolization and sampling. The presence of organic fluid in the nebulization buffer protected RNA phages PR772 and Φ6 throughout aerosolization and sampling with dry cyclones. In this experimental setup, the behavior of the influenza virus resembled that of phages PR772 and Φ6 while the NDV was closer to phages MS2 and ΦX174. These results provide critical information for the selection of appropriate phage models to mimic the behavior of specific human and animal viruses in aerosols.
Article
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Severe acute respiratory syndrome coronavirus-2 may cause low oxygen saturation (SpO2) and respiratory failure in patients with coronavirus disease (COVID-19). Hence, increased SpO2 levels in COVID-19 patients could be crucial for their quality of life and recovery. This study aimed to demonstrate that a 30-minute single session of dorsal low-field thoracic magnetic stimulation (LF-ThMS) can be employed to increase SpO2 levels in COVID-19 patients significantly. Furthermore, we hypothesized that the variables associated with LF-ThMS, such as frequency, magnetic flux density, and temperature in the dorsal thorax, might be correlated to SpO2 levels in these patients. Here we employed an LF-ThMS device to noninvasively deliver a pulsed magnetic field from 100 to 118 Hz and 10.5 to 13.1 milliTesla (i.e., 105 to 131 Gauss) to the dorsal thorax. These values are within the intensity range of several pulsed electromagnetic field devices employed in physical therapy worldwide. We designed a single-blind, sham-controlled, crossover study on 5 COVID-19 patients who underwent 2 sessions of the study (real and sham LF-ThMS) and 12 patients who underwent only the real LF-ThMS. We found a statistically significant positive correlation between magnetic flux density, frequency, or temperature, associated with the real LF-ThMS and SpO2 levels in all COVID-19 patients. However, the 5 patients in the sham-controlled study did not exhibit a significant change in their SpO2 levels during sham stimulation. The employed frequencies and magnetic flux densities were safe for the patients. We did not observe adverse events after the LF-ThMS intervention. This study is a proof-of-concept that a single session of LF-ThMS applied for 30 minutes to the dorsal thorax of 17 COVID-19 patients significantly increased their SpO2 levels. However, future research will be needed to understand the physiological mechanisms behind this finding. The study was registered at ClinicalTrials.gov (Identifier: NCT04895267, registered on May 20, 2021) retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT04895267.
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The World Health Organization (WHO) has declared the 2019 novel coronavirus outbreak (COVID-19) as a pandemic on March 11th. As of the end of April 2020, more than 3 million COVID-19 cases and 200 thousands death have been reported from more than 200 countries. It is therefore important to know what to expect in terms of the growth of the number of cases, and to understand what is needed to arrest the very worrying trends. In this disruptive period of the COVID-19 pandemic, scientists are investing an unprecedented effort to try to forecast and suggest measures to mitigate the ill-fated effects of the pandemic. Although recent literature indicates that travel control and restrictions of public activities are effective in delaying the spreading of the COVID-19 epidemic in China (Heory et al. 2020; Chinazzi et al. 2020), there is still an urgent need for greater understanding of the intrinsic dynamics and effective control methods which can offer in emergency and pandemic management. This Research Topic aims to extend the angles and collect articles which propose data driven mathematical or statistical models of the spread of the COVID-19, and/or of its foreseen consequences on public health, society, industry, economics and technology. It also focuses on collecting the real-time big data of COVID-19 spreading, and further helps the scientists to establish the efficient databases for the risk management. Furthermore, we also want to understand the impact of the pandemic on the economy and society of the whole world, and provide efficient suggestions for economic recovery and social order maintenance. The editors and reviewers of this special issue will guarantee a fast, but fair, peer-to-peer review procedure, in order to provide to society a reliable injection of scientific insights. The scopes and topics include but are not limited to: • nonlinear dynamics and non-equilibrium processes of COVID-19; • complex system and complex networks modeling of COVID-19; • computational epidemiology, biophysics, systems biology and computational biology aspects of COVID-19; • artificial intelligence, machine learning and big data analytics of COVID-19; • self-organization and emergent phenomena of social organization with COVID-19 pandemics; • applications to social science, Public health, economics, engineering and other aspects related to COVID-19 pandemics.
Article
Electrostatic precipitators (ESPs) have been widely used for air purification applications as they have no degradation issues and do not need to be replaced periodically. However, the generation of ozone by ESPs has been regarded as one of their most serious drawbacks. This paper presents the development of an ozone emission free ESP comprising a carbon brush ionizer and a polymeric arrayed collector (PAC). The collector consisted of sixty layers, where each layer had three stratums: polyethylene terephthalate (PET) film, conductive ink (CI), and PET film. The performance of the ESP was evaluated for three CI resistance levels: 107, 1010, and 1013 Ω/m2. The ESP was evaluated for particle filtration efficiency in a wind tunnel with a 0.3 μm challenge aerosol for an applied voltage ranging from 3 to 9 kV. The clean air delivery rate (CADR) was evaluated by coupling the ESP to a commercial air purifier to deliver purified air to a controlled 30-m 3 chamber in which particle concentration and ozone monitoring instruments were placed. Single pass ESP efficiency peaked at 89.5% for a high voltage (9 kV), high resistance (1013 Ω/m2), and low face velocity (1 m/s). The CADR for the ESP was 1.2 times higher than that for a standard high efficiency particulate air filter, with no ozone generation in a 24-h test. Thus, the proposed PAC-based ESP provides a viable solution for an ozone-free ESP, one that retains the benefits while eliminating the risk.
Article
Corona discharge based techniques are promising approaches for oxidizing elemental mercury (Hg(0)) in flue gas from coal combustion. In this study, in-situ soft X-rays were coupled to a DC (direct current) corona-based electrostatic precipitator (ESP). The soft X-rays significantly enhanced Hg(0) oxidation, due to generation of electrons from photoionization of gas molecules and the ESP electrodes. This coupling technique worked better in the positive corona discharge mode because more electrons were in the high energy region near the electrode. Detailed mechanisms of Hg(0) oxidation are proposed and discussed based on ozone generation measurements and Hg(0) oxidation behavior observations in single gas environments (O2, N2, and CO2). The effect of O2 concentration in flue gas, as well as the effects of particles (SiO2, TiO2, and KI) was also evaluated. In addition, the performance of a soft X-rays coupled ESP in Hg(0) oxidations was investigated in a lab-scale coal combustion system. With the ESP voltage at +10 kV, soft X-ray enhancement, and KI addition, mercury oxidation was maximized. Mercury is a significant-impact atmospheric pollutant due to its toxicity. Coal-fired power plants are the primary emission sources of anthropogenic releases of mercury; hence, mercury emission control from coal-fired power plant is important. This study provides an alternative mercury control technology for coal-fired power plants. The proposed electrostatic precipitator with in situ soft X-rays has high efficiency on elemental mercury conversion. Effects of flue gas conditions (gas compositions, particles, etc.) on performance of this technology were also evaluated, which provided guidance on the application of the technology for coal-fired power plant mercury control.
Article
A portable cantilever-based airborne nanoparticle detector (CANTOR) was designed and manufactured for detecting engineered nanoparticles (ENPs) in workplace air by monitoring the resonant frequency shift induced by the mass of the particles trapped on the cantilever resonator. The CANTOR consists of two main modules, i.e., a silicon resonant cantilever sensor and a miniaturized electrostatic ENP sampler. Tested in 15-min aerosol sampling with ∼100 nm carbon-based ENPs having a concentration of ∼6000 NPs/cm3, the sensor exhibited a mass sensitivity of 36.51 Hz/ng when the second resonant mode was used. Two simple cleaning methods, i.e., dry and wet cleanings, to remove the attached ENPs were successfully demonstrated in order to extend the operating life of the sensor.
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Exposure to pathogenic microorganisms, especially viruses, can lead to various diseases, allergies, and hospital infections. The application of sampling procedure is still a challenge to sample viruses from different environments such as air, water, wastewater, etc. However, there are many procedures such as filtration, impactor, impinger, cyclone, electrostatic separator, and MD-8 airscan that are applied for sampling and measuring viruses from air. Among conventional filters, the gelatin type can be readily dissolved in a liquid for molecular counting or cell culture without significant changes in virus tissue. Liquid impingers are the most frequent devices that are applied for the collection of viral aerosols. Also, many methods including precipitation, ultracentrifugation, electronegative membrane, and ultrafiltration have been used to prepare samples of food, wastewater, feces, urine, and surfaces. In many studies, the aforementioned methods have been employed to sample the coronaviruses such as SARS-CoV-2 in various environments. Also, various PCR procedures have been commonly used to identify the virus from the environmental samples.
Article
Airborne influenza viruses are responsible for serious respiratory diseases, and most detection methods for airborne viruses are based on extraction of nucleic acids. Herein, vertical-flow-assay-based electrochemical paper immunosensors were fabricated to rapidly quantify the influenza H1N1 viruses in air after sampling with a portable electrostatic particle concentrator (EPC). The effects of antibodies, anti-influenza nucleoprotein antibodies (NP-Abs) and anti-influenza hemagglutinin antibodies (HA-Abs), on the paper sensors as well as nonpulsed high electrostatic fields with and without corona charging on the virus measurement were investigated. The antigenicity losses of the surface (HA) proteins were caused by H2O2 via lipid oxidation-derived radicals and 1O2 via direct protein peroxidation upon exposure of a high electrostatic field. However, minimal losses in antigenicity of NP of the influenza viruses were observed, and the concentration of the H1N1 viruses was more than 160 times higher in the EPC than the BioSampler upon using NP-Ab based paper sensors after 60 min collection. This NP-Ab-based paper sensors with the EPC provided measurements comparable to quantitative polymerase chain reaction (qPCR) but much quicker, specific to the influenza H1N1 viruses in the presence of other airborne microorganisms and beads, and more cost-effective than enzyme-linked immunosorbent assay and qPCR.
Chapter
The coronavirus disease 2019 (COVID-19) pandemic shook the world in ways not seen since the pandemic influenza of 1918–1919. As of late August 2020, over 25 million persons had been infected, and we will see the global death toll exceed one million by the end of 2020. Both are minimum estimates. All segments of society have been drastically affected. Schools worldwide have been forced to close due to illness and absenteeism, transmission and risk to vulnerable members of the school community, and community concerns. The decision to reopen school during a pandemic will have a tremendous impact on children’s safety, growth, and well-being. Not opening invites social isolation and suboptimal educational experiences, especially for youth whose computing assets and online access are limited and those with special needs. The opening has hazards as well, and the mitigation of these risks is the topic of this chapter. Opening schools requires careful considerations of benefits, risks, and precautions. Guiding principles for safety and strategic application of the principles in each educational niche are critical issues to consider during school reopening. The fundamental principles of disease control involve school-directed initiatives (physical distancing and mask use, hand/face and surface cleansing, administrative controls, engineering controls) and individual-level risk reduction approaches to maximize adherence to new guidelines. The school-initiated “top-down” approaches and the individual-level “bottom-up” approaches must be synergized, as no single method will ensure safety. We discuss how to effectively layer strategies in each educational space to increase safety. Since the vulnerability of children has been heightened during this pandemic crisis, we highlight the special considerations for mental health support that should be considered by schools. The safety principles, disease control strategies, and other critical issues discussed here will serve as a starting point for developing a safe, comprehensive, and feasible reopening plan.
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Air quality has a direct influence on the health, welfare and performance of animals as well as on the health of farm workers undertaking different tasks in livestock buildings. Furthermore, air pollutants emitted from livestock buildings can reduce air, water and soil quality and potentially undermine the health of nearby residents. There is ample evidence that the respiratory health of various livestock species can be compromised by poor air quality. High concentrations of noxious gases, dust and airborne microorganisms might reduce production efficiency and the general welfare of farm animals. In some herds, a large portion of the lungs of slaughter pigs may show signs of acute or chronic pneumonia, pleuritis or other respiratory diseases. In broilers, birds with lung lesions account for about 30% of all rejections at meat inspection. Farm workers can be exposed to a range of noxious gases in animal buildings and above slurry pits, causing illness and, in some exceptional cases, mortality through suffocation or poisoning during agitation of slurry that can release toxic hydrogen sulfide gas. Long-term exposure to particulates in pig and poultry buildings might affect the respiratory health of farm workers. Dust in animal buildings contains many biologically active substances such as bacteria, fungi, endotoxins and residues of antibiotics (as a result of veterinary treatments) that are suspected to be hazardous to human health. Epidemiological studies have demonstrated that working in pig confinement buildings is associated with symptoms of chronic bronchitis (cough and phlegm), asthma-like symptoms such as wheezing and shortness of breath during work. Exposure to dust in piggery buildings causes an immediate inflammation of the airways in many individuals. Longterm studies indicate that work inside pig buildings doubles or triples the incidence of respiratory symptoms. Residents living close to livestock buildings can be exposed to dust and bacteria, which might produce negative health effects. It is well-documented (within and outside of this book) that livestock farming is a source of many different emissions. Airborne emissions include ammonia, methane, nitrous oxide, and particulates such as dust and microorganisms. In addition, other potentially harmful substances such as heavy metals, antibiotic residues and components of disinfectants might be emitted from livestock building via air ventilation, slurry and/or solid manure. The impacts of these emissions are potentially damaging to ecosystems, even at considerable distances away from the farms. Livestock farming also contributes significantly to total anthropogenic greenhouse gas emissions, which are thought by many to influence climate, and many countries have now undertaken steps to reduce these emissions. This book concentrates on the nature and amounts of aerial pollutants arising from livestock production and their impacts on the health and welfare of farm animals, and the workforce, as well as on the environment. We hope that this book will be useful for farming professionals, academics, students, policy makers, business leaders, regulatory bodies and agricultural consultants.
Article
This case report summarises the investigation of a death scene in the trunk of a car. Air sampling, laser-induced breakdown spectroscopy, and gas chromatography/mass spectrometry on samples of carpet and tyre well scrapings from the vehicle’s trunk were utilised to confirm the presence of a human decompositional event even though no human remains were discovered in the vehicle. Air sampling has been used in numerous industries for many decades, but only recently has been applied to forensic investigations although it has been at the centre of controversy over the use of this technique in such cases. This report also describes the value of such investigative tools and points to the discovery of evidence, which, without the use of these techniques, would not have been identified.
Article
Recently, various studies have reported the prevention and treatment of respiratory infection outbreaks caused by lethal viruses. Consequently, a variety of air filters coated with antimicrobial agents have been developed to capture and inactivate virus particles in continuous airflow conditions. However, since aerosolized infectious viral-testing is inadvisable due to safety concerns, their anti-viral capability has only been tested by inserting the filters into liquid media, where infectious virus particles disperse. In this study a novel method of determining anti-viral performance of an air filter against airborne infectious viruses is presented. Initially, anti-viral air filter tests were conducted. Firstly, by an air-media test, in which the air filter was placed against an aerosolized non-infectious virus. Secondly, by a liquid-media test, in which the filter was inserted into a liquid medium containing a non-infectious virus. Subsequently, a correlation was established by comparing the susceptibility constants obtained between the two medium tests and an association was found for the air medium test with infectious virus. After ensuring the relationship did not depend on the virus species, the correlation was used to derive the results of the air-medium test from the results of the liquid-medium test.
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Transmission mechanisms for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) are incompletely understood. In particular, aerosol transmission remains unclear, with viral detection in air and demonstration of its infection potential being actively investigated. To this end, we employed a novel electrostatic collector to sample air from rooms occupied by COVID‐19 patients in a major Swedish hospital. Electrostatic air sampling in conjunction with extraction‐free, reverse‐transcriptase polymerase chain reaction (hid‐RT‐PCR) enabled detection of SARS‐CoV‐2 in air from patient rooms (9/22; 41%) and adjoining anterooms (10/22; 45%). Detection with hid‐RT‐PCR was concomitant with viral RNA presence on the surface of exhaust ventilation channels in patients and anterooms more than 2 m from the COVID‐19 patient. Importantly, it was possible to detect active SARS‐CoV‐2 particles from room air, with a total of 496 plaque‐forming units (PFUs) being isolated, establishing the presence of infectious, airborne SARS‐CoV‐2 in rooms occupied by COVID‐19 patients. Our results support circulation of SARS‐CoV‐2 via aerosols and urge the revision of existing infection control frameworks to include airborne transmission.
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The applicability of electrostatic precipitation as a method for bioaerosol collection was investigated by using a modified Electrostatic Aerosol Sampler (EAS) (Model 3100, TSI Inc., St. Paul, MN). The physical and biological efficiencies of this method were determined. The tests were performed using three bacterial species which were collected onto agar, into water, and onto filters. The physical collection efficiency was higher than 80% when using a sampling flow rate of 1 L/min. When the Bacillus subtilis var niger (BG) spores were collected on agar, about 50-60% of the collected culturable organisms formed colonies. The bioefficiency exceeded 90% when the BG spores were collected on a filter, but was only 15-22% when collected into water. The Mycobacterium bovis BCG bacteria recovered at the 0-8% level on all three collection media. The least number of colonies were formed when Pseudomonas fluorescens bacteria were collected on any of the collection media. The data show that the process of electrostatic collection is very complex for sensitive airborne bacteria and thus several effects should be considered when assessing its bioefficiency. In separate tests conducted without aerosol flow through the sampler, bacteria placed onto the collection media did not show any significant reduction in bacterial recovery while exposed to a strong electric field. It was found that evaporation from the collection media, such as agar or water, increases the humidity inside the EAS and may affect the size distribution of the particles being collected, resulting in decreased physical and biological efficiencies of the electrostatic precipitation method. For hardy microorganisms such as BG spores, the bioefficiency for electrostatic collection is high, thus encouraging further explorations of the electrostatic method for sampling bioaerosols.
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In this work, in order to investigate the particle loading effects on the performance of an electrostatic precipitator (ESP), simultaneous measurements of the dust cake thickness accumulated on the collection plates, ESP's collection efficiency, corona discharge characteristics, and ozone concentration were conducted experimentally. A laboratory scale single stage wire-plate ESP was used for the aerosol loading test. Two kinds of particulate matter, cement and aluminum oxide (Al 2 O 3 ), were generated by using a Palas Powder Disperser. A displacement meter was used to monitor the dust cake thickness accumulated on the collection plates. A scanning mobility particle sizer was used to measure the particle size distribution and number concentration upstream and downstream of the ESP. Ozone generated by the ESP was sampled 20 cm downstream of the ESP exit and measured with an ozone analyzer. The Dioctyl Phthalate (DOP) was also used as a liquid challenge agent in order to investigate the loading effects of liquid particles on the ESP performance. The results showed that when challenged with cement particles, the ion current decreased with increasing dust cake thickness under a constant electrical field strength. Moreover, the collection efficiency and ozone generated by corona discharge decreased as the loading test progressed. For example, when the dust layer was about 5 mm in thickness, the output current and the ozone concentration decreased about 33 and 44%, respectively, and the collection efficiency (300 nm particle) decreased about 4% at a fixed electrical field strength of m 4.2 kV/cm. However, the ion current increased as aluminum oxide particles deposited on the collection plates. The increase in ozone concentration and aerosol penetration was mainly due to the occurrence of back corona, evidenced by the existence of the caves on the surface of the dust layers. In the case of testing with cement particles, the ion current rises after about 20 min of loading test and then decreases with time, while ozone concentration increases synchronously.
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We have studied the efficiency of ozone production by pulsed positive corona discharge in coaxial wire-cylinder geometry at atmospheric pressure. A corona discharge was generated by short (~150 ns) high voltage pulses applied between a silver coated copper wire anode and stainless steel cylinder cathode in synthetic air. A pyrex probe and Teflon tube was used for collecting discharge products and an ozone concentration was monitored outside of the discharge chamber by a non-dispersive UV absorbtion technique. The production of ozone was investigated as a function of energy density (10-4-3×10-1 Wh l-1) delivered to the discharge volume by combining the discharge frequency (0.1-10 Hz) and airflow rate (1-32 l min-1). From ozone concentration measurements we have evaluated the ozone production, yield and production energy cost. The ozone production yield and cost vary in the range of 15-55 g kWh-1 and 35-110 eV/molecule.
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We have investigated the parameters affecting the magnitude and polarity of the electric charges carried by biological particles in the airborne state. A recently developed experimental setup through which we analyzed the electric charges imposed on airborne particles by a means of induction charging (Mainelis et al. (Aerosol Sci. Technol. 2001, submitted for publication)) was utilized for this research. In this study, the microorganisms were aerosolized under controlled conditions and an electric mobility analyzer extracted particles of specific electric mobility. The extracted microorganisms were then analyzed by an optical particle size spectrometer. The amount of electric charge carried by airborne microorganisms was found to depend on the dispersion method and can be more than 10,000 elementary electric charges. This finding contrasts with the low electric charge levels carried by non-biological particles. Our data show that repeated pneumatic dispersion of sensitive bacteria affects their structural integrity, which, in turn, changes the magnitude of electric charges carried by these bacteria. We have concluded that the amount of electric charge carried by aerosolized bacteria may be used as an indicator of mechanical stress. It was also found that the electrical conductivity and the pH level of a bacterial suspension increase during aerosolization from a Collison nebulizer. Thus, these two parameters may be used as indicators of the mechanical stress, injury and loss in viability, endured by bacteria during aerosolization, i.e., measuring the electrical conductivity and pH level of bacterial suspensions may be a simple and convenient method for monitoring the “wear and tear” of the bacteria suspended in deionized water.
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Bioaerosol exposure assessment and the protection of civil/governmental/military establishments from bioterrorism require the development of low-power bioaerosol collectors that are able not only to efficiently collect airborne microorganisms, but also to preserve their biological integrity. In search for such a method, a new bioaerosol sampler was evaluated. In this device, the airborne microorganisms are imparted electrical charges and are then deposited in an electrical field onto a growth medium (agar). Experiments were conducted with Pseudomonas fluorescens vegetative cells, Bacillus subtilis var. niger (BG) endospores (used to simulate the spores of anthrax-causing Bacillus anthracis when testing bioaerosol sensors) and Penicillium brevicompactum fungal spores. It was found that 80–90% of initially “charge-neutralized” biological particles were removed from the air, when a small amount of ionization was generated in the electrostatic precipitator's (ESP) inlet and a precipitation voltage of was applied across the agar plates. Over 70% of viable BG and P. brevicompactum spores entering the ESP were enumerated as colony forming units. The bioefficiency of the new sampler was about the same as that of the Biosampler, which was tested in parallel. In experiments with sensitive P. fluorescens vegetative cells, the ESP enumerated twice as many cells as the Biosampler. The latter result indicates that the electrostatic collection method may be especially useful for the collection and enumeration of sensitive airborne microorganisms. Experiments investigating the effect of aging time on the amount of electrical charge carried by the airborne microorganisms showed that the level of electrical charge gradually decreases with increasing aging time. However, even after the P. fluorescens cells had remained airborne for an hour, they retained enough electrical charge to be collected with efficiency higher than 70%.
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We have recently developed a new personal sampler and demonstrated its feasibility for detection of viable airborne microorganisms including bacteria, fungi and viruses. To accelerate the time-consuming analytical procedure involving 2-5 days of biological testing, we employed a real-time PCR protocol in conjunction with the personal sampler for collection of airborne viruses. The advantage of this approach is that if the presence of a particular pathogen in the air is detected by the PCR, the remaining collecting liquid can be further analysed by more time-consuming biological methods to estimate the number of airborne infectious/live microorganisms. As sampling of bioaerosols in natural environments is likely to be associated with substantial contamination by a range of microorganisms commonly existing in an ambient air, an investigation of the specificity of detection by targeted PCR analysis is required. Here we present the results of the study on the detection of Influenza virus in the ambient air contaminated with high concentrations of bacteria and fungi using real-time PCR protocol. The combined sampling PCR detection method was found to be fully feasible for the rapid (similar to 2.5 h) and highly specific (no cross-reactivity) identification of the labile airborne virus in the air containing elevated concentrations of other microorganisms.
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Thesis (Ph. D.)--University of Cincinnati, 2000. Includes bibliographical references (leaves 86-102). Includes abstract.
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Bacteriophage MS2 RNA is 3,569 nucleotides long. The nucleotide sequence has been established for the third and last gene, which codes for the replicase protein. A secondary structure model has also been proposed. Biological properties, such as ribosome binding and codon interactions can now be discussed on a molecular basis. As the sequences for the other regions of this RNA have been published already, the complete, primary chemical structure of a viral genome has now been established.
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Because human activities impact the timing, location, and degree of pollutant exposure, they play a key role in explaining exposure variation. This fact has motivated the collection of activity pattern data for their specific use in exposure assessments. The largest of these recent efforts is the National Human Activity Pattern Survey (NHAPS), a 2-year probability-based telephone survey ( n=9386) of exposure-related human activities in the United States (U.S.) sponsored by the U.S. Environmental Protection Agency (EPA). The primary purpose of NHAPS was to provide comprehensive and current exposure information over broad geographical and temporal scales, particularly for use in probabilistic population exposure models. NHAPS was conducted on a virtually daily basis from late September 1992 through September 1994 by the University of Maryland's Survey Research Center using a computer-assisted telephone interview instrument (CATI) to collect 24-h retrospective diaries and answers to a number of personal and exposure-related questions from each respondent. The resulting diary records contain beginning and ending times for each distinct combination of location and activity occurring on the diary day (i.e., each microenvironment). Between 340 and 1713 respondents of all ages were interviewed in each of the 10 EPA regions across the 48 contiguous states. Interviews were completed in 63% of the households contacted. NHAPS respondents reported spending an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles. These proportions are fairly constant across the various regions of the U.S. and Canada and for the California population between the late 1980s, when the California Air Resources Board (CARB) sponsored a state-wide activity pattern study, and the mid-1990s, when NHAPS was conducted. However, the number of people exposed to environmental tobacco smoke (ETS) in California seems to have decreased over the same time period, where exposure is determined by the reported time spent with a smoker. In both California and the entire nation, the most time spent exposed to ETS was reported to take place in residential locations.
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Annual influenza epidemics in the United States result in an average of >36,000 deaths and 114,000 hospitalizations. Influenza can spread rapidly to patients and health care personnel in health care settings after influenza is introduced by visitors, staff, or patients. Influenza outbreaks in health care facilities can have potentially devastating consequences, particularly for immunocompromised persons. Although vaccination of health care personnel and patients is the primary means to prevent and control outbreaks of influenza in health care settings, antiviral influenza medications and isolation precautions are important adjuncts. Although droplet transmission is thought to be the primary mode of influenza transmission, limited evidence is available to support the relative clinical importance of contact, droplet, and droplet nuclei (airborne) transmission of influenza. In this article, the results of studies on the modes of influenza transmission and their relevant isolation precautions are reviewed.
Article
Liquid impingers, filter papers, and fritted bubblers were partial viable collectors of radioactive submicron T1 bacteriophage aerosols at 30, 55, and 85% relative humidity. Sampler differences for viable collection were due to incomplete physical collection (slippage) and killing of phage by the samplers. Dynamic aerosols of a mass median diameter of 0.2 μ were produced with a Dautrebande generator from concentrated aqueous purified phage suspensions containing extracellular soluble radioactive phosphate as a physical tracer. There was considerable destruction of phage by the Dautrebande generator; phage titers of the Dautrebande suspension decreased exponentially, but there was a progressive (linear) increase in tracer titers. Liquid impingers recovered the most viable phage but allowed considerable (30 to 48%) slippage, which varies inversely with the aerosol relative humidity. Filter papers were virtually complete physical collectors of submicron particles but were the most destructive. Fritted bubbler slippage was more than 80%. With all samplers, phage kill was highest at 85% relative humidity and lowest at 55% relative humidity. An electrostatic precipitator was used to collect aerosol samples for particle sizing with an electron microscope. The particle size was slightly larger at 85% relative humidity than at 30 or 55% relative humidity.
Article
Senala los lineamientos para las precauciones de aislamientos en los hospitales. Describe los razonamientos y responsabilidades para las precauciones del aislamiento, las tecnicas, recomendaciones y modificaciones. Dichas precauciones estan disenadas para prevenir la difusion de microorganismos entre pacientes, personal y visitantes
Article
Because there is an increasing incidence of microorganism infections, more concerns are made in microorganism engineering control for airborne infectious diseases. Electrostatic was considered to be promising to inactivate or kill microorganisms. In this investigation, the influences of microorganism species, relative humidity, gas flowrates, and electric voltage on control effectiveness of electrostatic precipitator (ESP) were evaluated in a laboratory test chamber. A Collison nebulizer generated Escherichia coli, Bacillus subtilis spores, cells of C. famata var. flareri, and Penicillium citrinum. The control effectiveness of this negative ESP was determined as the ratio, N-S/N-0, where N-S and N-0 were the colony concentrations collected by Anderson one-stage samplers with and without ESP operation. The experimental results indicated that control effectiveness of ESP varied in a wide range. The microorganism penetration through the ESP decreased (from 81% to 42%) as the voltage of the discharge electrode increased (from +5 kV to +10 kV) at a flowrate of 60 L/min. At a fixed electrode voltage (+10 kV), microorganism penetration increased from 42% to 70% as the flowrate increased from 60 to 90 L/min. Regarding microorganism species, it was indicated that bacterial removal effectiveness was lower than those of fungus aerosols. This might be related to smaller aerodynamics sizes of bacterial aerosols. In regard to relative humidity effects, it was observed that control effectiveness of ESP at 85% relative humidity were higher than those observed at 65% relative humidity. This might be related to higher corona current observed at higher relative humidity at the same voltage. In addition, control effectiveness of ESP was demonstrated to be lower at higher gaseous flowrates and lower electric voltage.
Chapter
Classifying PollutionThe Pollution EnvironmentPollution Control StrategiesPractical Toxicity IssuesPractical Applications to Pollution Control‘Clean’ TechnologyProcess ChangesBiological ControlBio-SubstitutionsClosing RemarksReferences
Article
As tested using a commercially available differential mobility classifier and condensation nuclei counter, the SEMS is well suited for the measurement of size distributions at typical ambient aerosol concentrations. With this dramatic improvement in time resolution, details of the dynamics of small aerosol particles that would have been interpreted as instrumental noise can now be resolved. In an extensive series of smog chamber experiments that will be described in a later paper, the SEMS has allowed resolution of nucleation bursts as they occur, and has overcome many of the instrumental limitations that have plagued previous studies of aerosol dynamics in smog chamber experiments. The SEMS has additional important advantages over the stepping mode operation of the DMA. Since all particle mobilities are sampled, even highly monodisperse aerosols can be detected in rapid scans. This is critically important in the study of classified aerosols, as in tandem differential mobility analyzer measurements of vapor pressures over aerosols particles and in the study of aerosols that have grown primarily by condensation. By collecting complete particle size distribution data in rapid scans, both size and time resolution can be used to maximum advantage. Signal averaging can be applied after data collection in either particle size or time domains if aerosol concentrations are too low to be resolved in a single high resolution scan.
Article
The measurement of particle size distributions using electrical mobility can be accelerated significantly by an alternate mode of operating mobility instruments. Rather than changing the electric field in discrete steps to select particles in a given mobility range, the electric field can be scanned continuously. The particles are classified in a time-varying electric field, but for an exponential ramp in the field strength there remains a one-to-one correspondence between the time a particle enters the classifier and the time it leaves. By this method, complete scans of mobility with as many as 100 mobility measurements have been made in 30 seconds using a differential mobility classifier with a condensation nuclei counter as a detector.
Article
This manuscript describes the coupling of bioaerosol collection and the use of real-time PCR (RT-PCR) to quantify the airborne bacteria. The quantity of collected bacteria determined by RT-PCR is compared with conventional quantification techniques, such as culturing, microscopy and airborne microorganism counting by using optical particle counter (OPC). Our data show that an experimental approach used to develop standard curves for use with RT-PCR is critical for accurate sample quantification. Using universal primers we generated 12 different standard curves which were used to quantify model organism Escherichia coli (Migula) Catellani from air samples. Standard curves prepared using a traditional approach, where serially diluted genomic DNA extracted from pure cultured bacteria were used in PCR reaction as a template DNA yielded significant underestimation of sample quantities compared to airborne microorganism concentration as measured by an OPC. The underestimation was especially pronounced when standard curves were built using colony forming units (CFUs). In contrast, the estimate of cell concentration in an air sample by RT-PCR was more accurate (∼60% compared to the airborne microorganism concentration) when the standard curve was built using aerosolized E. coli. The accuracy improved even further (∼100%) when air samples used to build the standard curves were diluted first, then the DNA extracted from each dilution was amplified by the RT-PCR—to mimic the handling of air samples with unknown and possibly low concentration. Therefore, our data show that standard curves used for quantification by RT-PCR needs to be prepared using the same environmental matrix and procedures as handling of the environmental sample in question. Reliance on the standard curves generated with cultured bacterial suspension (a traditional approach) may lead to substantial underestimation of microorganism quantities in environmental samples.
Article
Small-angle neutron scattering (SANS) has been used to extend the structural characterization of the MS2 phage by examining its physical characteristics in solution. Specifically, the contrast variation technique was employed to determine the molecular weight of the individual components of the MS2 virion (protein shell and genomic RNA) and the spatial relationship of the genomic RNA to its protein shell. A consequence of this work was to evaluate a novel particle counting instrument, the integrated virus detection system (IVDS) that, in combination with SANS, has the potential to provide rapid quantitative physical characterization of unidentified viruses and phage.
Article
A well-defined two-stage ESP experiment was carried out in the submicron particle size range. The experimental setup consisted of five components: a clean wind tunnel, a submicron particle generation system, an aerosol sampling and transport system, a submicron particle number concentration measurement system, and a pilot-scale two-stage parallel-plate ESP. Experimental collection efficiency data were obtained with a GMD of 0.03–0.2 μm and a GSD of about 1.67 for air velocities between 1.9 and 4.1 m/s under the nominal operation condition of two-stage ESP. The experimental data were then compared with the results of a numerical collection efficiency model which takes into consideration charging rate equations, particle equations of motion, and collection performance models. The comparison showed good agreement. It was confirmed from the comparison that the partial charging regime, where a portion of incoming particles is not charged, exists when the particle size range is below about 0.03 μm This partial charging effect causes a significant decrease in the ESP efficiency.
Article
The charge distribution of airborne MS2 bacteriophage nanoparticles and the efficiency of electrical-mobility–based capture mechanisms with bipolar charging were studied. MS2 virions form large agglomerated particles in a suspension. The average charge on airborne MS2 virions can be as high as one unit charge (negatively charged). The application of both soft X-ray irradiation and alpha rays from a Po-210 bipolar charger was shown to not only reduce the average charge on MS2 virion particles but also partially fragment the larger MS2 virion agglomerates, thereby increasing the number of ultrafine MS2 virion particles. A cylindrical electrostatic precipitator with a mounted soft X-ray emitter was used to determine the effectiveness of electrical capture methods for virus particles. At low applied voltages, it was found that the capture efficiency of ultrafine virus particles can be increased by applying in situ soft X-ray irradiation with electrostatic precipitation. It has also been shown that in the presence of both a positive and negative corona, virus particles are readily captured with log removal values exceeding 4. The unit developed and demonstrated in this work is a compact, low-pressure drop system that can be readily mounted in ventilation ducts or air supply systems to remove ultrafine particles such as viruses.
Article
A nanoparticle charging model considering simultaneous diffusion, direct photoionization and thermionization charging was developed. The model included a balance expression for the positive and negative ions, and one for each charge level of the particles. Three comparable parameters: attachment coefficient, β±(v,q), photoelectric yield coefficient, α+(v,q), and thermionic yield coefficient, γ+(v,q), were identified that govern different charging mechanisms. By comparing these parameters, the importance of different mechanisms was explored. Analytical (closed-form) solutions under certain unipolar and bipolar conditions were proposed. Literature reported experimental data on a soft-X-ray based unipolar charger was used to verify this model and fair agreement was achieved. A numerical algorithm was developed to solve the governing equations for a soft-X-ray enhanced electrostatic precipitator (ESP) system. The role of soft-X-ray irradiation at improving nanoparticle average charge and enhancing the ESP capture efficiency was demonstrated. Experimental tests with this system were also conducted. Measured capture efficiency showed excellent agreement with theoretical results.
Article
A new bipolar charger for nanometer aerosols using soft X-ray photoionization was developed. The concentrations and mobility distributions of the positive and negative ions generated by the X-ray charger were investigated, and then the charging probability of nanoparticles was evaluated experimentally and theoretically. All experimental data of the X-ray charger were compared with those of a 241Am α-ray bipolar charger. It was found that the X-ray bipolar charger could produce at least about 3.5 times as high concentration of gaseous ions as the α-ray charger and thus could have particles attain the equilib-rium bipolar charging state in shorter residence time than the α-ray charger. The charging state of particles attained by the X-ray charger was explained by theoretical calculations as well as α-ray bipolar charging. It was concluded that the X-ray charger would be a useful instrument for charging high number concentration nanoparticles in the electrical aerosol measurements.
Article
Ozone production in a negative corona discharge has been studied experimentally at atmospheric pressure in mixtures of N2O+O2 at ambient temperature. Ozone formation was found to be dramatically reduced with increase in the content of N2O in the mixture. The reaction of O(1D) with nitrous oxide is the most likely process reducing the rate of ozone generation. A considerable decrease in the mean discharge current at a constant voltage was also observed with increasing content of nitrous oxide in the mixture and is attributed to the formation of anions in the discharge. The low values of the calculated mobility of negative charge carriers in the drift region of the discharge is caused by the formation of O- · (N2O)n and NO-·(N2O)n cluster anions in the drift region of the negative corona discharge.
Article
Because there is an increasing incidence of microorganism infections, more concerns are made in microorganism engineering control for airborne infectious diseases. Electrostatic was considered to be promising to inactivate or kill microorganisms. In this investigation, the influences of microorganism species, relative humidity, gas flowrates, and electric voltage on control effectiveness of electrostatic precipitator (ESP) were evaluated in a laboratory test chamber. A Collison nebulizer generated Escherichia coli , Bacillus subtilis spores , cells of C. famata var. flareri , and Penicillium citrinum . The control effectiveness of this negative ESP was determined as the ratio, N S /N 0 , where N S and N 0 were the colony concentrations collected by Anderson one-stage samplers with and without ESP operation. The experimental results indicated that control effectiveness of ESP varied in a wide range. The microorganism penetration through the ESP decreased (from 81% to 42%) as the voltage of the discharge electrode increased (from +5 kV to +10 kV) at a flowrate of 60 L/min. At a fixed electrode voltage (+10 kV), microorganism penetration increased from 42% to 70% as the flowrate increased from 60 to 90 L/min. Regarding microorganism species, it was indicated that bacterial removal effectiveness was lower than those of fungus aerosols. This might be related to smaller aerodynamics sizes of bacterial aerosols. In regard to relative humidity effects, it was observed that control effectiveness of ESP at 85% relative humidity were higher than those observed at 65% relative humidity. This might be related to higher corona current observed at higher relative humidity at the same voltage. In addition, control effectiveness of ESP was demonstrated to be lower at higher gaseous flowrates and lower electric voltage.
Book
Airborne particles are present throughout our environment. They come in many different forms, such as dusts, fumes, mists, smoke, smog, or fog. These aerosols affect visibility, climate, and our health and quanlity of life. This book covers the properties, behaviour, and measurement of aerosols. This is a basic textbook for people engaged in industrial hygiene, air pollution control, radiation protection, or environmental science who must, in the practice of their profession, measure, evaluate, or control airborne particles. It is written at a level suitable for professionals, graduate students, or advanced undergraduates. It assumes that the student has a good background in chemistry and physics and understands the concepts of calculus. Although not written for aerosol scientists, it will be useful to them in their experimental work and will serve as an introduction to the field for students starting such careers. Decisions on what topics to include were based on their relevance to the pratical application of aerosol science, which includes an understanding of the physical and chemical prinicples that underlie the behaviour of aerosols and the instruments used to measure them. (from preface)
Book
The properties and behavior of suspended particles (dust, smoke, clouds), and the physical principles underlying their behavior are covered. Applications such as filtration, respiratory deposition, sampling, and the production of test aerosols are discussed. Physical analysis rather than mathematical analysis is emphasized.
Article
The products of a negative corona discharge in both pure CO2 and mixtures of CO2 + O2 have been studied using a coaxial cylindrical electrode geometry with particular emphasis on the production of ozone. The discharge current in pure CO2 was found to be highly sensitive to the presence of trace concentrations of molecular oxygen and to changes in the flow speed through the discharge. The effect of dissociative electron attachment to ozone on the discharge current was studied by measurements of ozone and CO production. The ozone concentration increases monotonically with increasing content of oxygen in the mixture with carbon dioxide, whereas the CO concentration exhibits a flat maximum for oxygen concentrations of around 4%. A simple kinetic model of the dominant chemical processes is described and compared with the experimental results.
Article
A non-stationary reactive gas dynamics model in a mono-dimensional geometry, including radial mass diffusion, gas temperature variation and chemical kinetics, is developed in this paper. The aim is to analyse the spatio-temporal evolution of the main neutral species involved in a corona discharge used for NO pollution control in polluted air at atmospheric pressure and ambient temperature. The present reactive gas dynamics model takes into account 16 neutral chemical species (including certain metastable species) reacting following 110 selected chemical reactions. The initial concentration of each neutral species is obtained from a 1.5D electrical discharge model. The gas temperature variations are due to direct Joule heating during the discharge phase, and also result from the delayed heating due to the relaxation of the vibrational energy into a random thermal energy during the post-discharge phase. The simulation conditions are those of an existing experimental setup (anode voltage of 10 kV in the case of a point to plane geometry with an interelectrode distance of 10 mm). The obtained results show that the diffusion phenomena and the gas temperature rise affect quite well the gas reactivity and the neutral species evolution. This allows us to better understand the different reaction processes and transport phenomena affecting the NO concentration magnitude inside the discharge channel.
Article
Aims: The aerosolization and collection of submicrometre and ultrafine virus particles were studied with the objective of developing robust and accurate methodologies to study airborne viruses. Methods and Results: The collection efficiencies of three sampling devices used to sample airborne biological particles – the All Glass Impinger 30, the SKC BioSampler® and a frit bubbler – were evaluated for submicrometre and ultrafine virus particles. Test virus aerosol particles were produced by atomizing suspensions of single-stranded RNA and double-stranded DNA bacteriophages. Size distribution results show that the fraction of viruses present in typical aqueous virus suspensions is extremely low such that the presence of viruses has little effect on the particle size distribution of atomized suspensions. It has been found that none of the tested samplers are adequate in collecting submicrometre and ultrafine virus particles, with collection efficiencies for all samplers below 10% in the 30–100 nm size range. Plaque assays and particle counting measurements showed that all tested samplers have time-varying virus particle collection efficiencies. A method to determine the size distribution function of viable virus containing particles utilizing differential mobility selection was also developed. Conclusions: A combination of differential mobility analysis and traditional plaque assay techniques can be used to fully characterize airborne viruses. Significance and Impact of the Study: The data and methods presented here provide a fundamental basis for future studies of submicrometre and ultrafine airborne virus particles.