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1.
Huan Jing Ke Xue ; 42(4): 1668-1678, 2021 Apr 08.
Artículo en Chino | MEDLINE | ID: mdl-33742802

RESUMEN

The aim of this study was to analyze the differences in the concentration, particle size, and bacterial community structure of microbial aerosols and further investigated the effects of meteorological conditions and air pollutants on microbial aerosol distribution at different periods during spring in Lanzhou. The results showed that the average aerosol concentrations of total microbes, bacteria, fungi, and actinomycetes in the air environment of Lanzhou were (2730±376), (2243±354), (349±38), and (138±22) CFU·m-3, respectively. The contribution rate of bacteria was 82.16%, which was significantly higher than that of fungi and actinomycetes (P<0.05). The concentrations of total microorganisms, bacteria, and actinomycetes during 08:00-09:00 were significantly higher than those sampled during 18:00-19:00, indicating that meteorological conditions and air pollutants have a remarkable influence on the concentration of microbial aerosols. Aerosol particles of bacteria and fungi were primarily distributed at the first four levels (>2.1 µm), accounting for 85.13% and 83.26%, respectively, while 73.15% of the actinomycetes aerosol particles focused largely on the latter four stages (<4.7 µm). Illumina MiSeq sequencing results indicated that there was no significant difference in the composition of the bacterial community (P>0.05) during the periods of 08:00-09:00 and 18:00-19:00. Lactococcus and Bacillus were the dominant bacteria genus. Enterococcus, Staphylococcus, Pseudomonas, Acinetobacter, Klebsiella, Erwinia, Bacillus cereus, Streptococcus agalactiae, and Clostridium perfringens were potential pathogens detected in the air environment of Lanzhou in the spring. The results could provide fundamental data for further revealing the contamination status of microbial aerosols and the potential harm of the related pathogenic bacteria to human health during the spring in Lanzhou.


Asunto(s)
Microbiología del Aire , Contaminantes Atmosféricos , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , China , Ciudades , Monitoreo del Ambiente , Hongos , Humanos , Tamaño de la Partícula
2.
Infez Med ; 29(1): 10-19, 2021 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-33664169

RESUMEN

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a pandemic worldwide. On a daily basis the number of deaths associated with COVID-19 is rapidly increasing. The main transmission route of SARS-CoV-2 is through the air (airborne transmission). This review details the airborne transmission of SARS-CoV-2, the aerodynamics, and different modes of transmission (e.g. droplets, droplet nuclei, and aerosol particles). SARS-CoV-2 can be transmitted by an infected person during activities such as expiration, coughing, sneezing, and talking. During such activities and some medical procedures, aerosols and droplets contaminated with SARS-CoV-2 particles are formed. Depending on their sizes and the environmental conditions, such particles stay viable in the air for varying time periods and can cause infection in a susceptible host. Very few studies have been conducted to establish the mechanism or the aerodynamics of virus-loaded particles and droplets in causing infection. In this review we discuss the various forms in which SARS-CoV-2 virus particles can be transmitted in air and cause infections.


Asunto(s)
Microbiología del Aire , /transmisión , Número Básico de Reproducción/estadística & datos numéricos , Tos/virología , Exposición a Riesgos Ambientales , Humanos , Máscaras , Estornudo
3.
Infez Med ; 29(1): 20-36, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33664170

RESUMEN

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), the causative pathogen for the COVID-19, first emerged in Wuhan, China, in December 2019 and by March 2020, it was declared a pandemic. COVID-19 pandemic has overburdened healthcare systems in most countries and has led to massive economic losses. SARS-CoV-2 transmission typically occurs by respiratory droplets. The average incubation period is 6.4 days and presenting symptoms typically include fever, cough, dyspnea, myalgia or fatigue. While the majority of patients tend to have a mild illness, a minority of patients develop severe hypoxia requiring hospitalization and mechanical ventilation. Management is mostly supportive. However, several direct anti-viral agents, and immunomodulatory therapy with steroids and various cytokine blockers seem promising in early results. However, an effective vaccine has been established, which will help curb the pandemic.


Asunto(s)
Salud Global/estadística & datos numéricos , Pandemias , /patogenicidad , Corticoesteroides/uso terapéutico , Microbiología del Aire , Antivirales/uso terapéutico , /diagnóstico , /terapia , /uso terapéutico , Transmisión de Enfermedad Infecciosa , Hospitalización , Humanos , Hipoxia/etiología , Hipoxia/terapia , Inmunización Pasiva , Factores Inmunológicos/uso terapéutico , Periodo de Incubación de Enfermedades Infecciosas , Prevención Primaria/métodos , Respiración Artificial , /genética , Esteroides/uso terapéutico , Evaluación de Síntomas/métodos
4.
Nat Commun ; 12(1): 1653, 2021 03 12.
Artículo en Inglés | MEDLINE | ID: mdl-33712573

RESUMEN

SARS-CoV-2 emerged in late 2019 and caused a pandemic, whereas the closely related SARS-CoV was contained rapidly in 2003. Here, an experimental set-up is used to study transmission of SARS-CoV and SARS-CoV-2 through the air between ferrets over more than a meter distance. Both viruses cause a robust productive respiratory tract infection resulting in transmission of SARS-CoV-2 to two of four indirect recipient ferrets and SARS-CoV to all four. A control pandemic A/H1N1 influenza virus also transmits efficiently. Serological assays confirm all virus transmission events. Although the experiments do not discriminate between transmission via small aerosols, large droplets and fomites, these results demonstrate that SARS-CoV and SARS-CoV-2 can remain infectious while traveling through the air. Efficient virus transmission between ferrets is in agreement with frequent SARS-CoV-2 outbreaks in mink farms. Although the evidence for virus transmission via the air between humans under natural conditions is absent or weak for SARS-CoV and SARS-CoV-2, ferrets may represent a sensitive model to study interventions aimed at preventing virus transmission.


Asunto(s)
Microbiología del Aire , Hurones/virología , Virus del SRAS , Síndrome Respiratorio Agudo Grave/transmisión , Aerosoles , Sustitución de Aminoácidos , Pelaje de Animal/virología , Animales , Modelos Animales de Enfermedad , Femenino , Fómites/virología , Subtipo H1N1 del Virus de la Influenza A , Modelos Biológicos , Infecciones por Orthomyxoviridae/transmisión , Polimorfismo de Nucleótido Simple , Síndrome Respiratorio Agudo Grave/virología , Factores de Tiempo , Carga Viral , /virología , Esparcimiento de Virus
5.
J R Soc Interface ; 18(176): 20200967, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33757291

RESUMEN

As a result of the outbreak and diffusion of SARS-CoV-2, there has been a directive to advance medical working conditions. In dentistry, airborne particles are produced through aerosolization facilitated by dental instruments. To develop methods for reducing the risks of infection in a confined environment, understanding the nature and dynamics of these droplets is imperative and timely. This study provides the first evidence of aerosol droplet formation from an ultrasonic scalar under simulated oral conditions. State-of-the-art optical flow tracking velocimetry and shadowgraphy measurements are employed to quantitatively measure the flow velocity, trajectories and size distribution of droplets produced during a dental scaling process. The droplet sizes are found to vary from 5 µm to 300 µm; these correspond to droplet nuclei that could carry viruses. The droplet velocities also vary between 1.3 m s-1 and 2.6 m s-1. These observations confirm the critical role of aerosols in the transmission of disease during dental procedures, and provide invaluable knowledge for developing protocols and procedures to ensure the safety of both dentists and patients.


Asunto(s)
Aerosoles , Microbiología del Aire , Instrumentos Dentales , Terapia por Ultrasonido , /prevención & control , Humanos
6.
Sci Rep ; 11(1): 4617, 2021 02 25.
Artículo en Inglés | MEDLINE | ID: mdl-33633316

RESUMEN

The Covid-19 pandemic has focused attention on airborne transmission of viruses. Using realistic air flow simulation, we model droplet dispersion from coughing and study the transmission risk related to SARS-CoV-2. Although this model defines most airborne droplets as 8-16 µm in diameter, we infer that larger droplets of 32-40 µm in diameter may potentially be more infectious due to higher viral content. Use of face masks is therefore recommended for both personal and social protection. We found social distancing effective at reducing transmission potential across all droplet sizes. However, the presence of a human body 1 m away modifies the aerodynamics so that downstream droplet dispersion is enhanced, which has implications on safe distancing in queues. At 1 m distance, we found that an average of 0.55 viral copies is inhaled for a cough at median loading, scalable up to 340 copies at peak loading. Droplet evaporation results in significant reduction in droplet counts, but airborne transmission remains possible even under low humidity conditions.


Asunto(s)
Microbiología del Aire , Tos/virología , /fisiología , Humanos , Hidrodinámica , Máscaras , Modelos Biológicos , Tamaño de la Partícula , Medición de Riesgo
7.
Ecotoxicol Environ Saf ; 212: 112006, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33556810

RESUMEN

Particulate matter (PM) is a carrier of many substances. Microorganisms are vital constituents contained in PM, and their varieties and concentrations are closely connected to human health and animal production. This study aimed to investigate the distribution characteristics of bioaerosols inside a pig house and in the respiratory tract of pigs. Environmental indices inside a nursery pig house were monitored in winter, including temperature, relative humidity, total suspended particulate (TSP), PM10, PM2.5, NH3, CO2, CO and NO. The concentrations of airborne culturable bacteria, fungi and Escherichia coli were detected. Then, 16S rRNA sequencing technology was applied to identify different-sized bioaerosols and bacteria in the respiratory tract of piglets. The results showed that the concentration of airborne culturable bacteria inside the pig house was significantly higher than that outside, and no significant difference was found among culturable fungi and Escherichia coli. The 16S rRNA results showed that the bacterial aerosols presented high similarity to the bacteria in the respiratory tract of piglets. The airborne bacterial aerosols within the size range of 1.1-3.3 µm showed high similarity to the bacteria in the lower respiratory tract (bronchus and lung) of piglets. In addition, four potential pathogenic bacterial genera (Escherichia-Shigella, Streptococcus, Acinetobacter, Pseudomonas) were identified both in the bacterial aerosols and the respiratory tract of piglets. These results will provide a significant scientific basis for exploring the potential risk of aerosols from animal houses to human and animal health.


Asunto(s)
Microbiología del Aire/normas , Contaminantes Atmosféricos/análisis , Bacterias/aislamiento & purificación , Monitoreo del Ambiente/métodos , Material Particulado/análisis , Sistema Respiratorio/microbiología , Aerosoles , Animales , China , Polvo , Humanos , ARN Ribosómico 16S , Estaciones del Año , Porcinos , Temperatura
8.
IEEE Pulse ; 12(1): 28-30, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33606621

RESUMEN

Researchers have developed new ways to use the extremely versatile material graphene, and a company is now building on that work to manufacture an air-filtration device that kills bacteria and viruses-including the virus responsible for coronavirus disease 2019 (COVID-19)-on contact.


Asunto(s)
Filtros de Aire , Microbiología del Aire , Pandemias , Ingeniería Biomédica , /virología , Diseño de Equipo , Espiración , Grafito , Humanos
9.
Phys Rev Lett ; 126(3): 034502, 2021 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-33543958

RESUMEN

To quantify the fate of respiratory droplets under different ambient relative humidities, direct numerical simulations of a typical respiratory event are performed. We found that, because small droplets (with initial diameter of 10 µm) are swept by turbulent eddies in the expelled humid puff, their lifetime gets extended by a factor of more than 30 times as compared to what is suggested by the classical picture by Wells, for 50% relative humidity. With increasing ambient relative humidity the extension of the lifetimes of the small droplets further increases and goes up to around 150 times for 90% relative humidity, implying more than 2 m advection range of the respiratory droplets within 1 sec. Employing Lagrangian statistics, we demonstrate that the turbulent humid respiratory puff engulfs the small droplets, leading to many orders of magnitude increase in their lifetimes, implying that they can be transported much further during the respiratory events than the large ones. Our findings provide the starting points for larger parameter studies and may be instructive for developing strategies on optimizing ventilation and indoor humidity control. Such strategies are key in mitigating the COVID-19 pandemic in the present autumn and upcoming winter.


Asunto(s)
Líquidos Corporales/química , Líquidos Corporales/virología , Modelos Biológicos , Aerosoles/química , Microbiología del Aire , Movimientos del Aire , Simulación por Computador , Transmisión de Enfermedad Infecciosa , Espiración , Humanos , Pandemias , /aislamiento & purificación
10.
Sci Rep ; 11(1): 2508, 2021 01 28.
Artículo en Inglés | MEDLINE | ID: mdl-33510270

RESUMEN

The rapid spread of the SARS-CoV-2 in the COVID-19 pandemic had raised questions on the route of transmission of this disease. Initial understanding was that transmission originated from respiratory droplets from an infected host to a susceptible host. However, indirect contact transmission of viable virus by fomites and through aerosols has also been suggested. Herein, we report the involvement of fine indoor air particulates with a diameter of ≤ 2.5 µm (PM2.5) as the virus's transport agent. PM2.5 was collected over four weeks during 48-h measurement intervals in four separate hospital wards containing different infected clusters in a teaching hospital in Kuala Lumpur, Malaysia. Our results indicated the highest SARS-CoV-2 RNA on PM2.5 in the ward with number of occupants. We suggest a link between the virus-laden PM2.5 and the ward's design. Patients' symptoms and numbers influence the number of airborne SARS-CoV-2 RNA with PM2.5 in an enclosed environment.


Asunto(s)
/transmisión , Monitoreo del Ambiente/métodos , /química , Aerosoles/análisis , Aerosoles/química , Microbiología del Aire , Contaminación del Aire Interior , /metabolismo , Fómites/microbiología , Fómites/estadística & datos numéricos , Hospitales , Humanos , Malasia/epidemiología , Pandemias , Material Particulado/análisis , ARN Viral
11.
Nano Lett ; 21(2): 1017-1024, 2021 01 27.
Artículo en Inglés | MEDLINE | ID: mdl-33444028

RESUMEN

Bioaerosols, including infectious diseases such as COVID-19, are a continuous threat to global public safety. Despite their importance, the development of a practical, real-time means of monitoring bioaerosols has remained elusive. Here, we present a novel, simple, and highly efficient means of obtaining enriched bioaerosol samples. Aerosols are collected into a thin and stable liquid film by the unique interaction of a superhydrophilic surface and a continuous two-phase centrifugal flow. We demonstrate that this method can provide a concentration enhancement ratio of ∼2.4 × 106 with a collection efficiency of ∼99.9% and an aerosol-into-liquid transfer rate of ∼95.9% at 500 nm particle size (smaller than a single bacterium). This transfer is effective in both laboratory and external ambient environments. The system has a low limit of detection of <50 CFU/m3air using a straightforward bioluminescence-based technique and shows significant potential for air monitoring in occupational and public-health applications.


Asunto(s)
Aerosoles , Bacterias/aislamiento & purificación , Monitoreo del Ambiente/instrumentación , Monitoreo del Ambiente/métodos , Microbiología del Aire , Biomasa , Límite de Detección , Luminiscencia , Nanopartículas , Tamaño de la Partícula , Salud Pública , Propiedades de Superficie , Temperatura
12.
PLoS One ; 16(1): e0244983, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33400714

RESUMEN

Here we look into the spread of aerosols indoors that may potentially carry viruses. Many viruses, including the novel SARS-CoV-2, are known to spread via airborne and air-dust pathways. From the literature data and our research on the propagation of fine aerosols, we simulate herein the carryover of viral aerosols in indoor air. We demonstrate that a lot of fine droplets released from an infected person's coughing, sneezing, or talking propagate very fast and for large distances indoors, as well as bend around obstacles, lift up and down over staircases, and so on. This study suggests equations to evaluate the concentration of those droplets, depending on time and distance from the source of infection. Estimates are given for the safe distance to the source of infection, and available methods for neutralizing viral aerosols indoors are considered.


Asunto(s)
/transmisión , Transmisión de Enfermedad Infecciosa/prevención & control , Aerosoles/análisis , Microbiología del Aire , Contaminación del Aire Interior/análisis , /virología , Tos , Transmisión de Enfermedad Infecciosa/estadística & datos numéricos , Polvo , Humanos , Modelos Teóricos , Estornudo/fisiología , Virosis/prevención & control
13.
Environ Monit Assess ; 193(1): 47, 2021 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-33415530

RESUMEN

The installation of HVAC systems in building is meant to enhance indoor air quality as well as increase comfort to occupants. However, HVAC systems have also become a vehicle of contamination of indoor air with potentially pathogenic microorganisms. DNA was extracted from ten HVAC filter dust samples collected from two buildings and subjected to high throughput sequencing analysis to determine the bacterial community structure. Further, the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2) software was used to predict the potential functional capabilities of the bacterial communities. Sequencing analysis led to the identification of five major bacterial phyla, including Proteobacteria, Cyanobacteria, Actinobacteria, Firmicutes and Bacteroidetes. At genus level, Mycobacterium, Bacillus, Cupriavidus, Hyphomicrobium and Mesorhizobium were the most dominant. With the exception of the later two bacterial genera, the first three are potential pathogens whose presence in HVAC systems poses a significant public health risk, especially among immunocompromised individuals. Nine pathways associated with antibiotics resistance and bacterial pathogenicity were identified, including polymyxin resistance and peptidoglycan biosynthesis pathways. Further, investigation of the relationship between the detected bacterial meta-communities and predicted potential virulence factors (antibiotic resistance and pathogenic genes) led to the detection of 350 positive associations among 43 core bacteria, 2 pathogenic genes (sitA and uidA) and 14 resistance genes. Overall, the heterogeneous nature of microorganisms found in HVAC systems observed in this study shows that HVAC systems are the origin of airborne infections in indoor environments, and must be periodically cleaned and disinfected to avoid the build-up of pathogens, and the subsequent exposure of human occupants of these pathogens.


Asunto(s)
Contaminación del Aire Interior , Aire Acondicionado , Microbiología del Aire , Contaminación del Aire Interior/análisis , Bacterias/genética , Monitoreo del Ambiente , Humanos , Filogenia , Salud Pública , Universidades , Ventilación
14.
Artículo en Inglés | MEDLINE | ID: mdl-33419142

RESUMEN

The multiple modes of SARS-CoV-2 transmission including airborne, droplet, contact, and fecal-oral transmissions that cause coronavirus disease 2019 (COVID-19) contribute to a public threat to the lives of people worldwide. Herein, different databases are reviewed to evaluate modes of transmission of SARS-CoV-2 and study the effects of negative pressure ventilation, air conditioning system, and related protection approaches of this virus. Droplet transmission was commonly reported to occur in particles with diameter >5 µm that can quickly settle gravitationally on surfaces (1-2 m). Instead, fine and ultrafine particles (airborne transmission) can stay suspended for an extended period of time (≥2 h) and be transported further, e.g., up to 8 m through simple diffusion and convection mechanisms. Droplet and airborne transmission of SARS-CoV-2 can be limited indoors with adequate ventilation of rooms, by routine disinfection of toilets, using negative pressure rooms, using face masks, and maintaining social distancing. Other preventive measures recommended include increasing the number of screening tests of suspected carriers of SARS-CoV-2, reducing the number of persons in a room to minimize sharing indoor air, and monitoring people's temperature before accessing a building. The work reviews a body of literature supporting the transmission of SARS-CoV-2 through air, causing COVID-19 disease, which requires coordinated worldwide strategies.


Asunto(s)
Microbiología del Aire , /transmisión , Aire Acondicionado , Desinfección , Humanos , Máscaras , Ventilación
15.
J Otolaryngol Head Neck Surg ; 50(1): 3, 2021 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-33461626

RESUMEN

BACKGROUND: Tracheostomy, as an aerosol-generating procedure, is considered as a high-risk surgery for health care workers (HCWs) during the coronavirus disease (COVID-19) pandemic. Current recommendations are to perform tracheostomy after a period of intubation of > 14 days, with two consecutive negative throat swab tests, to lower the risk of contamination to HCWs. However, specific data for this recommendation are lacking. Therefore, this study aimed to evaluate viral shedding into the environment, including HCWs, associated with bedside tracheostomy in the intensive care unit. METHODS: Samples obtained from the medical environment immediately after tracheostomy, including those from 19 surfaces, two air samples at 10 and 50 cm from the surgical site, and from the personal protective equipment (PPE) of the surgeon and assistant, were tested for the presence of severe acute respiratory syndrome coronavirus 2 in eight cases of bedside tracheostomy. We evaluated the rate of positive tests from the different samples obtained. RESULTS: Positive samples were identified in only one of the eight cases. These were obtained for the air sample at 10 cm and from the bed handrail and urine bag. There were no positive test results from the PPE samples. The patient with positive samples had undergone early tracheostomy, at 9 days after intubation, due to a comorbidity. CONCLUSIONS: Our preliminary results indicate that delayed tracheostomy, after an extended period of endotracheal intubation, might be a considerably less contagious procedure than early tracheostomy (defined as < 14 days after intubation).


Asunto(s)
Microbiología del Aire , Contaminación de Equipos , Unidades de Cuidados Intensivos , Traqueostomía , Esparcimiento de Virus , Aerosoles , Anciano , Femenino , Humanos , Intubación Intratraqueal , Masculino , Persona de Mediana Edad
16.
Sci Total Environ ; 751: 141811, 2021 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-32882567

RESUMEN

Bioaerosols containing pathogens released from wastewater will pose potential health risks to workers on site. The emission of airborne bacteria from a rural wastewater treatment station and their inactivation by ultraviolet were investigated in this study. High-throughput sequencing technique was utilized to assay airborne bacterial population while the health risks associated with airborne bacteria exposure were estimated based on average daily dose rates. The recorded emission level of airborne bacteria in the air surrounding the multi-point inlet contact oxidation bioreactor (MTB) was 4795 ± 1475 CFU/m3, containing 2233 ± 471 CFU/m3 of intestinal bacteria, and most of them (70.3%) was coarse particles with size over 2.1 µm. Wind disturbance had significant effects on the diffusion and particle size distribution of the bioaerosols emitted from MTB. The identified opportunistic pathogens in bioaerosols were Enterobacter sp., Acinetobacter sp., Pantoea sp., Achromobacter sp., and Curtobacterium sp. They were originated in the water and active sludge in MTB. Inhalation was one of the main ways through which onsite workers were exposed to airborne bacteria. Exposure to ultraviolet radiation caused an apparent decrease in the level of bioaerosols in the air, thereby indicating that it can be utilized as an effective method for the reducing of bioaerosols. This study aims to provide preliminary data for the bioaerosols control in rural wastewater treatment process.


Asunto(s)
Microbiología del Aire , Aguas Residuales , Aerosoles , Bacterias , Humanos , Rayos Ultravioleta
17.
Sci Total Environ ; 753: 141852, 2021 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-32891995

RESUMEN

This article presents a critical review of the peer-reviewed literature related to bioaerosol generation from activated sludge basins. Characterization techniques include a variety of culture- and nonculture-based techniques, each with unique features. Bioaerosols contain a variety of clinical pathogens including Staphylococcus saprophyticus, Clostridium perfringens, and Salmonella enteritidis; exposure to these microorganisms increases human health risks. Release mechanisms involve splashing and bubble burst dynamics. Larger bubbles emit more aerosol particles than smaller ones. Attenuation strategies include covering sources with lids, adjusting the method and intensity of aeration, and using free-floating carrier media. Future studies should combine culture and non-culture based methods, and expand chemical databases and spectral libraries in order to realize the full power of real-time online monitoring.


Asunto(s)
Microbiología del Aire , Aguas del Alcantarillado , Aerosoles , Humanos
19.
J Occup Environ Hyg ; 18(2): 72-83, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33315526

RESUMEN

Simple plastic face shields have numerous practical advantages over regular surgical masks. In light of the spreading COVID-19 pandemic, the potential of face shields as a substitution for surgical masks was investigated. In order to determine the efficacy of the protective equipment we used a cough simulator. The protective equipment considered was placed on a manikin head that simulated human breathing. Concentration and size distribution of small particles that reached the manikin respiration pathways during the few tens of seconds following the cough event were monitored. Additionally, water sensitive papers were taped on the tested protective equipment and the manikin face. In the case of frontal exposure, for droplet diameter larger than 3 µm, the shield efficiency in blocking cough droplets was found to be comparable to that of regular surgical masks, with enhanced protection for portions of the face that the mask does not cover. Additionally, for finer particles, down to 0.3 µm diameter, a shield blocked about 10 times more fine particles than the surgical mask. When exposure from the side was considered, the performance of the shield was found to depend dramatically on its geometry. While a narrow shield allowed more droplets and aerosol to penetrate in comparison to a mask under the same configuration, a slightly wider shield significantly improved the performance. The source control potential of shields was also investigated. A shield, and alternatively, a surgical mask, were placed on the cough simulator, while the breathing simulator, situated 60 cm away in the jet direction, remained totally exposed. In both cases, no droplets or particles were found in the vicinity of the breathing simulator. Conducted experiments were limited to short time periods after expiratory events, and do not include longer time ranges associated with exposure to suspended aerosol. Thus, additional evidence regarding the risk posed by floating aerosol is needed to establish practical conclusions regarding actual transmittance reduction potential of face shields and surgical face masks.


Asunto(s)
/prevención & control , Exposición por Inhalación/análisis , Máscaras/normas , Equipo de Protección Personal/normas , /aislamiento & purificación , Aerosoles/análisis , Microbiología del Aire , Tos/virología , Monitoreo del Ambiente , Humanos , Transmisión de Enfermedad Infecciosa de Paciente a Profesional/prevención & control , Exposición por Inhalación/prevención & control , Ensayo de Materiales , Exposición Profesional/análisis , Exposición Profesional/prevención & control
20.
Waste Manag ; 120: 257-268, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33310602

RESUMEN

Bioaerosols emitted in waste sorting plants (WSP) can induce some adverse health effects on the workers such as rhinitis, asthma and hypersensitivity pneumonitis. The composition of these bioaerosols is scarcely known and most of the time assessed using culture-dependent methods. Due to the well-known limitations of cultural methods, these biodiversity measurements underestimate the actual microbial taxon richness. The aim of the study was to assess the airborne microbial biodiversity by using a sequencing method in a French waste sorting plant (WSP) for one year and to investigate the main factors of variability of this biodiversity. Static sampling was performed in five areas in the plant and compared to an indoor reference (IR), using closed-face cassettes (10 L.min-1) with polycarbonate membranes, every month for one year. Environmental data was measured (temperature, relative humidity). After DNA extraction, microbial biodiversity was assessed by means of sequencing. Bacterial genera Staphylococcus, Streptococcus, Prevotella, Lactococcus, Lactobacillus, Pseudomonas and fungal genera Wallemia, Cladosporium, Debaryomyces, Penicillium, Alternaria were the most predominant airborne microorganisms. Microbial biodiversity was different in the plant compared to the IR and seemed to be influenced by the season.


Asunto(s)
Microbiología del Aire , Exposición Profesional , Aerosoles/análisis , Monitoreo del Ambiente , Estudios de Seguimiento , Francia , Hongos , Humanos , Exposición Profesional/análisis
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