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1.
Swiss Med Wkly ; 152: w30133, 2022 01 03.
Article in English | MEDLINE | ID: covidwho-1622738

ABSTRACT

BACKGROUND: Airborne transmission of SARS-CoV-2 is an important route of infection. For the wildtype (WT) only a small proportion of those infected emitted large quantities of the virus. The currently prevalent variants of concern, Delta (B1.617.2) and Omicron (B.1.1.529), are characterized by higher viral loads and a lower minimal infective dose compared to the WT. We aimed to describe the resulting distribution of airborne viral emissions and to reassess the risk estimates for public settings given the higher viral load and infectivity. METHOD: We reran the Monte Carlo modelling to estimate viral emissions in the fine aerosol size range using available viral load data. We also updated our tool to simulate indoor airborne transmission of SARS-CoV-2 by including a CO2 calculator and recirculating air cleaning devices. We also assessed the consequences of the lower critical dose on the infection risk in public settings with different protection strategies. RESULTS: Our modelling suggests that a much larger proportion of individuals infected with the new variants are high, very high or super-emitters of airborne viruses: for the WT, one in 1,000 infected was a super-emitter; for Delta one in 30; and for Omicron one in 20 or one in 10, depending on the viral load estimate used. Testing of the effectiveness of protective strategies in view of the lower critical dose suggests that surgical masks are no longer sufficient in most public settings, while correctly fitted FFP2 respirators still provide sufficient protection, except in high aerosol producing situations such as singing or shouting. DISCUSSION: From an aerosol transmission perspective, the shift towards a larger proportion of very high emitting individuals, together with the strongly reduced critical dose, seem to be two important drivers of the aerosol risk, and are likely contributing to the observed rapid spread of the Delta and Omicron variants of concern. Reducing contacts, always wearing well-fitted FFP2 respirators when indoors, using ventilation and other methods to reduce airborne virus concentrations, and avoiding situations with loud voices seem critical to limiting these latest waves of the COVID-19 pandemic.


Subject(s)
COVID-19 , Pandemics , Aerosols , Humans , SARS-CoV-2 , Viral Load
2.
J R Soc Interface ; 19(186): 20210819, 2022 01.
Article in English | MEDLINE | ID: covidwho-1621730

ABSTRACT

The outbreak of the COVID-19 pandemic highlighted the importance of accurately modelling the pathogen transmission via droplets and aerosols emitted while speaking, coughing and sneezing. In this work, we present an effective model for assessing the direct contagion risk associated with these pathogen-laden droplets. In particular, using the most recent studies on multi-phase flow physics, we develop an effective yet simple framework capable of predicting the infection risk associated with different respiratory activities in different ambient conditions. We start by describing the mathematical framework and benchmarking the model predictions against well-assessed literature results. Then, we provide a systematic assessment of the effects of physical distancing and face coverings on the direct infection risk. The present results indicate that the risk of infection is vastly impacted by the ambient conditions and the type of respiratory activity, suggesting the non-existence of a universal safe distance. Meanwhile, wearing face masks provides excellent protection, effectively limiting the transmission of pathogens even at short physical distances, i.e. 1 m.


Subject(s)
COVID-19 , Pandemics , Aerosols , Humans , SARS-CoV-2
3.
J Occup Environ Med ; 63(11): e783-e791, 2021 11 01.
Article in English | MEDLINE | ID: covidwho-1606229

ABSTRACT

OBJECTIVE: Health care professionals and governmental agencies are in consensus regarding contact and droplet transmission of infectious diseases. However, personal protective equipment (PPE) efficacy is not considered for aerosol or airborne transmission of infectious diseases. This review discusses the inhalation of virus-laden aerosols as a viable mechanism of transmission of various respiratory infectious diseases and PPE efficacy. METHODS: The Preferred Reporting Items for Systematic reviews, and Meta-Analysis (PRISMA) guidelines was used. RESULTS: The transmission of infectious disease is of concern for all respirable diseases discussed (SARS-CoV-1, SARS-CoV-2, MERS, influenza, and tuberculosis), and the effectiveness of facemasks is dependent on the efficiency of the filter, fit, and proper use. CONCLUSION: PPE should be the last resort in preventing the spread of infectious disease and should only be used for protection and not to control the transmission.


Subject(s)
COVID-19 , Communicable Diseases , Aerosols , Humans , Personal Protective Equipment , SARS-CoV-2
4.
Rev Peru Med Exp Salud Publica ; 38(3): 391-398, 2021.
Article in Spanish, English | MEDLINE | ID: covidwho-1599823

ABSTRACT

OBJECTIVE: To develop a methodology for evaluating the level of respiratory protection provided by respirators, surgical masks and community face masks used by the Peruvian population; protection was evaluated against particles of a size similar to those containing active SARS-CoV-2 virus. MATERIALS AND METHODS: A direct linear relationship has been determined between the logarithm of the concentration of airborne particles and the elapsed time; thus, it is possible to compare the quantity of particles inside and outside of the mask or respirator in the same time period, as well as to obtain the percentage of respiratory protection for each evaluated sample. RESULTS: A methodology was established to evaluate the level of respiratory protection against aerosols smaller than 5.0 µm. Also, the use of accessories such as rubber bands or adjusters behind the head and neck, and the use of robust nasal clips, significantly increased the level of respiratory protection against particles with a high probability of containing SARS-CoV-2. CONCLUSIONS: We found concordance between the obtained respiratory protection values and those expected, considering the filtration level of the material used for each surgical mask or respirator, as well as the tightness. A significant increase in the levels of respiratory protection was observed.


OBJETIVO: Desarrollar una metodología para evaluar el nivel de protección respiratoria de respiradores, mascarillas quirúrgicas y mascarillas comunitarias que usa la población peruana, usando partículas de un tamaño similar a las que contienen al virus activo del SARS-CoV-2. MATERIALES Y MÉTODOS: Se ha determinado una relación lineal directa entre el logaritmo de la concentración de partículas suspendidas en aire y el tiempo transcurrido; por lo cual es posible comparar la cantidad de partículas internas y externas a la mascarilla o respirador en un mismo periodo y conocer el porcentaje de protección respiratoria de cada muestra evaluada. RESULTADOS: Se ha logrado implementar una metodología para evaluar el nivel de protección respiratoria ante aerosoles menores a 5,0 µm. Asimismo, el empleo de accesorios como ligas o ajustadores detrás de cabeza y nuca, y el uso de clips nasales robustos, incrementan significativamente el nivel de protección respiratoria ante partículas con alta probabilidad de contener al SARS-CoV-2. CONCLUSIONES: Se observa una concordancia entre los valores de protección respiratoria obtenidos y los esperados, considerando el nivel de filtración del material empleado de cada mascarilla quirúrgica o respirador, y su nivel de ajuste. Se observó un incremento significativo en los niveles de protección respiratoria.


Subject(s)
COVID-19 , Masks , Aerosols , Humans , SARS-CoV-2 , Ventilators, Mechanical
5.
Sci Rep ; 11(1): 24490, 2021 12 29.
Article in English | MEDLINE | ID: covidwho-1594104

ABSTRACT

During the first wave of Covid-19 infections in Germany in April 2020, clinics reported a shortage of filtering face masks with aerosol retention> 94% (FFP2 & 3, KN95, N95). Companies all over the world increased their production capacities, but quality control of once-certified materials and masks came up short. To help identify falsely labeled masks and ensure safe protection equipment, we tested 101 different batches of masks in 993 measurements with a self-made setup based on DIN standards. An aerosol generator provided a NaCl test aerosol which was applied to the mask. A laser aerosol spectrometer measured the aerosol concentration in a range from 90 to 500 nm to quantify the masks' retention. Of 101 tested mask batches, only 31 batches kept what their label promised. Especially in the initial phase of the pandemic in Germany, we observed fluctuating mask qualities. Many batches show very high variability in aerosol retention. In addition, by measuring with a laser aerosol spectrometer, we were able to show that not all masks filter small and large particles equally well. In this study we demonstrate how important internal and independent quality controls are, especially in times of need and shortage of personal protection equipment.


Subject(s)
COVID-19/prevention & control , COVID-19/transmission , Masks/statistics & numerical data , Aerosols , Filtration/instrumentation , Germany , Humans , Masks/standards , Masks/trends , N95 Respirators/standards , N95 Respirators/statistics & numerical data , Occupational Exposure/prevention & control , Pandemics/prevention & control , Personal Protective Equipment/standards , Quality Control , Respiratory Protective Devices/standards , SARS-CoV-2/pathogenicity
6.
Int J Environ Res Public Health ; 19(1)2021 Dec 25.
Article in English | MEDLINE | ID: covidwho-1580817

ABSTRACT

There is uncertainty about the viral loads of infectious individuals required to transmit COVID-19 via aerosol. In addition, there is a lack of both quantification of the influencing parameters on airborne transmission and simple-to-use models for assessing the risk of infection in practice, which furthermore quantify the influence of non-medical preventive measures. In this study, a dose-response model was adopted to analyze 25 documented outbreaks at infection rates of 4-100%. We show that infection was only possible if the viral load was higher than 108 viral copies/mL. Based on mathematical simplifications of our approach to predict the probable situational attack rate (PARs) of a group of persons in a room, and valid assumptions, we provide simplified equations to calculate, among others, the maximum possible number of persons and the person-related virus-free air supply flow necessary to keep the number of newly infected persons to less than one. A comparison of different preventive measures revealed that testing contributes the most to the joint protective effect, besides wearing masks and increasing ventilation. In addition, we conclude that absolute volume flow rate or person-related volume flow rate are more intuitive parameters for evaluating ventilation for infection prevention than air exchange rate.


Subject(s)
COVID-19 , SARS-CoV-2 , Aerosols , Humans , Masks , Viral Load
7.
Drug Deliv ; 29(1): 10-17, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-1577575

ABSTRACT

Aerosol therapy is used to deliver medical therapeutics directly to the airways to treat respiratory conditions. A potential consequence of this form of treatment is the release of fugitive aerosols, both patient derived and medical, into the environment and the subsequent exposure of caregivers and bystanders to potential viral infections. This study examined the release of these fugitive aerosols during a standard aerosol therapy to a simulated adult patient. An aerosol holding chamber and mouthpiece were connected to a representative head model and breathing simulator. A combination of laser and Schlieren imaging was used to non-invasively visualize the release and dispersion of fugitive aerosol particles. Time-varying aerosol particle number concentrations and size distributions were measured with optical particle sizers at clinically relevant positions to the simulated patient. The influence of breathing pattern, normal and distressed, supplemental air flow, at 0.2 and 6 LPM, and the addition of a bacterial filter to the exhalation port of the mouthpiece were assessed. Images showed large quantities of fugitive aerosols emitted from the unfiltered mouthpiece. The images and particle counter data show that the addition of a bacterial filter limited the release of these fugitive aerosols, with the peak fugitive aerosol concentrations decreasing by 47.3-83.3%, depending on distance from the simulated patient. The addition of a bacterial filter to the mouthpiece significantly reduces the levels of fugitive aerosols emitted during a simulated aerosol therapy, p≤ .05, and would greatly aid in reducing healthcare worker and bystander exposure to potentially harmful fugitive aerosols.


Subject(s)
Aerosols , COVID-19 , Drug Delivery Systems , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Nebulizers and Vaporizers , Respiratory Therapy , Aerosols/administration & dosage , Aerosols/adverse effects , COVID-19/prevention & control , COVID-19/transmission , Computer Simulation , Drug Delivery Systems/instrumentation , Drug Delivery Systems/methods , Equipment Design , Humans , Infection Control/methods , Models, Biological , Particle Size , Respiratory Therapy/adverse effects , Respiratory Therapy/instrumentation , Respiratory Therapy/methods , SARS-CoV-2
8.
Med Hypotheses ; 159: 110753, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-1586985

ABSTRACT

For respiratory infections treatment and prevention, we analyze for the first time the possibility of providing a broad range medication based on metallic nanoparticles colloids (NpC) delivery by controlled aerosol inhalation. (i) Based on in-vitro data combined with aerosol deposition characteristics in the respiratory system, we calculate the required effective formulations, dosages and delivery parameters for an aerosol inhalation treatment. The goal is to achieve an effective NpC inhibitory concentration (IC) in the target airway surface liquid (ASL); (ii) We evaluate the clinical safety of such dosages, drawing on information from animal testing data and regulatory limits in the USA for such nanoparticles aerosol inhalation safety. Our analysis indicates a wide range of potentially safe and effective dosages that can be clinically explored, targeting the upper respiratory and bronchial tree system. Similar dosages can also provide antibacterial effectiveness for prophylactic treatment in hospital intensive care units to lower the risk of ventilator-associated pneumonia (VAP). Our calculations are phenomenological, independent of mechanisms. Nevertheless, we highlight a mechanism of action by which any suitably designed NpC, with nanoparticles sized 2-10 nm and having a large negative zeta-potential, preferentially bind to viruses with predominantly positively-charged spike proteins. These will be ineffective against viruses with predominantly negatively-charged spike proteins. Accordingly, the popular silver metal base for NpC serves just as a construction ingredient, and other metal or metal-oxides which can serve to construct the noted nanoparticle properties would be similarly effective. We suggest that inhalation delivery of the proposed antiviral formulations could be applied as a first-line intervention while respiratory infections are primarily localized to the upper respiratory system and bronchial tree.


Subject(s)
COVID-19 , Administration, Inhalation , Aerosols , Animals , Humans , Lung , Nanomedicine , SARS-CoV-2
10.
Biomed Res Int ; 2021: 8963168, 2021.
Article in English | MEDLINE | ID: covidwho-1553725

ABSTRACT

Background: The risk of acquiring COVID-19 during a pandemic is a major concern among health care workers. Dental professionals being in close proximity to the patients had been exposed more than other health care workers. Hence, all the standard operating procedures (SOPs) are strictly advised to be followed. Methods: A detailed relevant literature search was conducted in international databases such as PubMed, Web of Science, and Science Direct, from January 2020 to November 2020. All the studies that provided recommendations regarding endodontic procedures during the COVID-19 pandemic were included, and those that were not in the English language, case reports, book chapters, and short communications were excluded in this review. In the end, only 6 articles were selected for the systematic review considering that complete information regarding the provision of dental care in the time of COVID-19 with diagnostic accuracy (STARD) was provided. Results: Endodontic treatments were restricted to only emergency dental procedures, and all other patients have advised medications and catered through teledentistry. Endodontic emergencies were advised to be carried out with minimal aerosol production procedures. Conclusion: Provision of endodontic care during COVID-19 restricted to only emergency dental procedures by strictly following standard operating procedures. A protocol for COVID-19 prevention was followed by all the dentists and the dental staff in the dental clinics.


Subject(s)
COVID-19/drug therapy , Aerosols/therapeutic use , Dental Care/methods , Health Personnel , Humans , Pandemics/prevention & control
11.
Can J Anaesth ; 67(9): 1217-1248, 2020 09.
Article in English | MEDLINE | ID: covidwho-1536371

ABSTRACT

PURPOSE: We conducted two World Health Organization-commissioned reviews to inform use of high-flow nasal cannula (HFNC) in patients with coronavirus disease (COVID-19). We synthesized the evidence regarding efficacy and safety (review 1), as well as risks of droplet dispersion, aerosol generation, and associated transmission (review 2) of viral products. SOURCE: Literature searches were performed in Ovid MEDLINE, Embase, Web of Science, Chinese databases, and medRxiv. Review 1: we synthesized results from randomized-controlled trials (RCTs) comparing HFNC to conventional oxygen therapy (COT) in critically ill patients with acute hypoxemic respiratory failure. Review 2: we narratively summarized findings from studies evaluating droplet dispersion, aerosol generation, or infection transmission associated with HFNC. For both reviews, paired reviewers independently conducted screening, data extraction, and risk of bias assessment. We evaluated certainty of evidence using GRADE methodology. PRINCIPAL FINDINGS: No eligible studies included COVID-19 patients. Review 1: 12 RCTs (n = 1,989 patients) provided low-certainty evidence that HFNC may reduce invasive ventilation (relative risk [RR], 0.85; 95% confidence interval [CI], 0.74 to 0.99) and escalation of oxygen therapy (RR, 0.71; 95% CI, 0.51 to 0.98) in patients with respiratory failure. Results provided no support for differences in mortality (moderate certainty), or in-hospital or intensive care length of stay (moderate and low certainty, respectively). Review 2: four studies evaluating droplet dispersion and three evaluating aerosol generation and dispersion provided very low certainty evidence. Two simulation studies and a crossover study showed mixed findings regarding the effect of HFNC on droplet dispersion. Although two simulation studies reported no associated increase in aerosol dispersion, one reported that higher flow rates were associated with increased regions of aerosol density. CONCLUSIONS: High-flow nasal cannula may reduce the need for invasive ventilation and escalation of therapy compared with COT in COVID-19 patients with acute hypoxemic respiratory failure. This benefit must be balanced against the unknown risk of airborne transmission.


Subject(s)
Coronavirus Infections/therapy , Oxygen Inhalation Therapy/methods , Pneumonia, Viral/therapy , Respiratory Insufficiency/therapy , Aerosols , COVID-19 , Cannula , Coronavirus Infections/complications , Coronavirus Infections/mortality , Humans , Pandemics , Pneumonia, Viral/complications , Pneumonia, Viral/mortality , Randomized Controlled Trials as Topic , Respiratory Insufficiency/physiopathology , Respiratory Insufficiency/virology
12.
J Indian Soc Pedod Prev Dent ; 39(3): 316-320, 2021.
Article in English | MEDLINE | ID: covidwho-1528960

ABSTRACT

Background: Restrictions on routine dental procedures involving aerosols during COVID-19 have resulted in a significant increase in the suffering of pediatric patients. Aim: The study reported the alternative measures followed in our department using SDF during the COVID era when routine elective dental procedures were prohibited. Materials and Methods: The retrospective data of patients aged 2-13 years with carious molar teeth who were treated with silver diamine fluoride without (Group 1) or with (Group 2) caries excavation were collected. Results: One thousand and seventy-two patients (646 males and 426 females) with 2459 carious molar were treated. On follow-up assessment at 3 months, 28 teeth in Group 1 and 21 teeth in Group 2 showed progression of carious lesion using International Caries Detection and Assessment System (ICDAS II criteria). Out of these failure cases, 32 (1.8%) teeth were primary and 17 (2.5%) were permanent. Complete relief in sensitivity/pain on stimulation was reported in 2381 teeth (96.83%), whereas in 78 (3.17%) teeth, mild sensitivity/pain on stimulation was reported. The average time consumed during treatment per tooth in Group 1 was 5.04 min and in Group 2 was 5.78 min. Conclusion: SDF application can be carried out as a nonaerosol-generating procedure and is a simple technique for children and clinicians.


Subject(s)
COVID-19 , Dental Caries , Aerosols , Cariostatic Agents , Child , Dental Caries/drug therapy , Dentistry , Female , Fluorides, Topical , Humans , Male , Quaternary Ammonium Compounds , Retrospective Studies , SARS-CoV-2 , Silver Compounds
13.
Emerg Infect Dis ; 27(12): 3052-3062, 2021 12.
Article in English | MEDLINE | ID: covidwho-1528794

ABSTRACT

Middle East respiratory syndrome coronavirus (MERS-CoV) infects humans and dromedary camels and is responsible for an ongoing outbreak of severe respiratory illness in humans in the Middle East. Although some mutations found in camel-derived MERS-CoV strains have been characterized, most natural variation found across MERS-CoV isolates remains unstudied. We report on the environmental stability, replication kinetics, and pathogenicity of several diverse isolates of MERS-CoV, as well as isolates of severe acute respiratory syndrome coronavirus 2, to serve as a basis of comparison with other stability studies. Although most MERS-CoV isolates had similar stability and pathogenicity in our experiments, the camel-derived isolate C/KSA/13 had reduced surface stability, and another camel isolate, C/BF/15, had reduced pathogenicity in a small animal model. These results suggest that although betacoronaviruses might have similar environmental stability profiles, individual variation can influence this phenotype, underscoring the need for continual global viral surveillance.


Subject(s)
COVID-19 , Middle East Respiratory Syndrome Coronavirus , Aerosols , Animals , Camelus , Humans , Middle East Respiratory Syndrome Coronavirus/genetics , SARS-CoV-2 , Virulence , Zoonoses
14.
Clin Infect Dis ; 73(10): 1924-1926, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1522131

ABSTRACT

We examine airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) potential using a source-to-dose framework beginning with generation of virus-containing droplets and aerosols and ending with virus deposition in the respiratory tract of susceptible individuals. By addressing 4 critical questions, we identify both gaps in addressing 4 critical questions with answers having policy implications.


Subject(s)
COVID-19 , Viruses , Aerosols , Humans , Respiratory System , SARS-CoV-2
15.
Eur Rev Med Pharmacol Sci ; 25(21): 6745-6766, 2021 11.
Article in English | MEDLINE | ID: covidwho-1524863

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has created the current pandemic, has caused a worldwide worry. Different countries have since enforced varying levels of lockdowns and guidelines for their populations to follow in a serious effort to mitigate the spread. Up until recently, the majority of these regulations and policies were established on the assumption that the dominant routes of transmission of this virus are through droplets and fomite contact. However, there is now a substantial amount of research pointing towards the strong possibility that SARS-CoV-2 can spread through airborne means. The World Health Organization (WHO) and the Center for Disease Control and Prevention (CDC) have recently recognized this, which poses the question of whether our collective methods of lessening transmission risk and keeping people safe have been sufficient. This paper is a comprehensive review of the evidence on SARS-CoV-2 being an airborne disease, through different epidemiological, experimental, and animal-model based published research. Studies opposing this evidence have also been discussed. The majority of these studies are favoring the high plausibility of SARS-CoV-2 aerosol transmission, and therefore the many implications of aerosol transmission have been discussed in this paper to suggest effective mitigation and control strategies.


Subject(s)
Aerosols , COVID-19/transmission , SARS-CoV-2/physiology , Animals , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19/virology , Cricetinae , Disease Models, Animal , Equipment and Supplies, Hospital/virology , Feces/virology , Humans , Masks , Pandemics , Particulate Matter , RNA, Viral/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Ventilation/standards , Virus Inactivation
16.
Respir Care ; 66(12): 1858-1865, 2021 12.
Article in English | MEDLINE | ID: covidwho-1524338

ABSTRACT

BACKGROUND: Methacholine bronchoprovocation or challenge testing (MCT) is commonly performed to assess airway hyper-responsiveness in the setting of suspected asthma. Nebulization is an aerosol-generating procedure, but little is known about the risks of MCT in the context of the ongoing coronavirus disease 2019 (COVID-19) pandemic. We aimed to quantify and characterize aerosol generation during MCT by using different delivery methods and to assess the impact of adding a viral filter. METHODS: Seven healthy subjects performed simulated MCT in a near particle-free laboratory space with 4 different nebulizers and with a dosimeter. Two devices continuously sampled the ambient air during the procedure, which detected ultrafine particles, from 0.02-1 µm, and particles of sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10 µm, respectively. Particle generation was compared among all the devices, with and without viral filter placement. RESULTS: Ultrafine-particle generation during simulated MCT was significant across all the devices. Ultrafine-particle (0.02-1 µm) concentrations decreased 77%-91% with the addition of a viral filter and varied significantly between unfiltered (P < .001) and filtered devices (P < .001). Ultrafine-particle generation was lowest when using the dosimeter with filtered Hudson nebulizer (1,258 ± 1,644 particle/mL). Ultrafine-particle concentrations with the filtered nebulizer devices using a compressor were higher than particle concentrations detected when using the dosimeter: Monaghan (3,472 ± 1,794 particles/mL), PARI (4,403 ± 2,948), Hudson (6,320 ± 1,787) and AirLife (9,523 ± 5,098). CONCLUSIONS: The high particle concentrations generated during MCT pose significant infection control concerns during the COVID-19 pandemic. Particle generation during MCT was significantly reduced by using breath-actuated delivery and a viral filter, which offers an effective mitigation strategy.


Subject(s)
COVID-19 , Pandemics , Aerosols , Humans , Infection Control , Methacholine Chloride , Nebulizers and Vaporizers , Particle Size , SARS-CoV-2
17.
Environ Pollut ; 292(Pt A): 118299, 2022 Jan 01.
Article in English | MEDLINE | ID: covidwho-1525784

ABSTRACT

Microplastics (MPs) have been reported in the outdoor/indoor air of urban centres, raising health concerns due to the potential for human exposure. Since aerosols are considered one of the routes of Coronavirus disease 2019 (COVID-19) transmission and may bind to the surface of airborne MPs, we hypothesize that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could be associated with the levels of MPs in the air. Our goal was to quantify the SARS-CoV-2 RNA and MPs present in the total suspended particles (TSP) collected in the area surrounding the largest medical centre in Latin America and to elucidate a possible association among weather variables, MPs, and SARS-CoV-2 in the air. TSP were sampled from three outdoor locations in the areas surrounding a medical centre. MPs were quantified and measured under a fluorescence microscope, and their polymeric composition was characterized by Fourier transform infrared (FT-IR) microspectroscopy coupled with attenuated total reflectance (ATR). The viral load of SARS-CoV-2 was quantified by an in-house real-time PCR assay. A generalized linear model (GzLM) was employed to evaluate the effect of the SARS-CoV-2 quantification on MPs and weather variables. TSP samples tested positive for SARS-CoV-2 in 22 out of 38 samples at the three sites. Polyester was the most frequent polymer (80%) found in the samples. The total amount of MPs was positively associated with the quantification of SARS-CoV-2 envelope genes and negatively associated with weather variables (temperature and relative humidity). Our findings show that SARS-CoV-2 aerosols may bind to TSP, such as MPs, and facilitate virus entry into the human body.


Subject(s)
COVID-19 , SARS-CoV-2 , Aerosols , Humans , Latin America , Microplastics , Plastics , RNA, Viral , Spectroscopy, Fourier Transform Infrared
18.
PLoS One ; 16(11): e0257689, 2021.
Article in English | MEDLINE | ID: covidwho-1518354

ABSTRACT

The worldwide spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has ubiquitously impacted many aspects of life. As vaccines continue to be manufactured and administered, limiting the spread of SARS-CoV-2 will rely more heavily on the early identification of contagious individuals occupying reopened and increasingly populated indoor environments. In this study, we investigated the utility of an impaction-based bioaerosol sampling system with multiple nucleic acid collection media. Heat-inactivated SARS-CoV-2 was utilized to perform bench-scale, short-range aerosol, and room-scale aerosol experiments. Through bench-scale experiments, AerosolSense Capture Media (ACM) and nylon flocked swabs were identified as the highest utility media. In room-scale aerosol experiments, consistent detection of aerosol SARS-CoV-2 was achieved at an estimated aerosol concentration equal to or greater than 0.089 genome copies per liter of room air (gc/L) when air was sampled for eight hours or more at less than one air change per hour (ACH). Shorter sampling periods (75 minutes) yielded consistent detection at ~31.8 gc/L of room air and intermittent detection down to ~0.318 gc/L at (at both 1 and 6 ACH). These results support further exploration in real-world testing scenarios and suggest the utility of indoor aerosol surveillance as an effective risk mitigation strategy in occupied buildings.


Subject(s)
Aerosols/analysis , COVID-19/diagnosis , COVID-19/virology , Environmental Monitoring , SARS-CoV-2/physiology , Genome, Viral , Humans , RNA, Viral/genetics , SARS-CoV-2/genetics
19.
J Craniofac Surg ; 32(3): e309-e311, 2021 May 01.
Article in English | MEDLINE | ID: covidwho-1517954

ABSTRACT

INTRODUCTION: There is urgent need to find a swift and cheap way to safely perform routine endoscopic procedures during the otolaryngological and anesthesiological practice. We want to share our experience of a novel device, inspired by the pediatric head box experience. MATERIALS AND METHODS: Five otolaryngologists and four anesthesiologists were asked to visualize the glottic plane by using the device. A total of 15 attempts was allowed to reach the vocal folds within 60 seconds after entering the box. Student's t-test for unpaired samples was used to compare groups. RESULTS: Transnasal laryngoscopy through our endobox could be successfully performed by all the physicians involved and the mean number of attempts before visualizing and passing the glottis for the first time was 2.8 (range 1-5) in the otolaryngologists' group versus 3.2 (range 1-6) in the anesthesiologists' group (P=0.583). Out of the 15 attempts, the group of otolaryngologists reached the glottis 10.2 times, on average, against 9.7 in the other group (P=0.692). CONCLUSIONS: Our endobox seems a practical and feasible strategy to control droplets diffusion during standard ear, nose, and throat and anesthesiological practice.


Subject(s)
COVID-19 , Pandemics , Aerosols , Child , Glottis , Humans , Laryngoscopy , Otolaryngologists , SARS-CoV-2
20.
Sci Rep ; 11(1): 12110, 2021 06 08.
Article in English | MEDLINE | ID: covidwho-1517640

ABSTRACT

Wearing surgical masks or other similar face coverings can reduce the emission of expiratory particles produced via breathing, talking, coughing, or sneezing. Although it is well established that some fraction of the expiratory airflow leaks around the edges of the mask, it is unclear how these leakage airflows affect the overall efficiency with which masks block emission of expiratory aerosol particles. Here, we show experimentally that the aerosol particle concentrations in the leakage airflows around a surgical mask are reduced compared to no mask wearing, with the magnitude of reduction dependent on the direction of escape (out the top, the sides, or the bottom). Because the actual leakage flowrate in each direction is difficult to measure, we use a Monte Carlo approach to estimate flow-corrected particle emission rates for particles having diameters in the range 0.5-20 µm. in all orientations. From these, we derive a flow-weighted overall number-based particle removal efficiency for the mask. The overall mask efficiency, accounting both for air that passes through the mask and for leakage flows, is reduced compared to the through-mask filtration efficiency, from 93 to 70% for talking, but from only 94-90% for coughing. These results demonstrate that leakage flows due to imperfect sealing do decrease mask efficiencies for reducing emission of expiratory particles, but even with such leakage surgical masks provide substantial control.


Subject(s)
Aerosols , Communicable Disease Control/methods , Cough , Exhalation , Filtration , Masks , Virus Diseases/prevention & control , Adolescent , Adult , COVID-19/prevention & control , Equipment Failure , Female , Humans , Male , Middle Aged , Monte Carlo Method , Particle Size , Probability , Respiration , Sneezing , Young Adult
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