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1.
Environ Health Perspect ; 129(4): 47002, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33793301

RESUMO

BACKGROUND: Evidence for indoor airborne transmission of SARS-CoV-2 is accumulating. OBJECTIVES: We assessed of the risk of illness due to airborne SARS-CoV-2 particles from breathing, speaking, singing, coughing, and sneezing in indoor environments. METHODS: A risk assessment model, AirCoV2, for exposure to SARS-CoV-2 particles in aerosol droplets was developed. Previously published data on droplets expelled by breathing, speaking, singing, coughing, and sneezing by an infected person were used as inputs. Scenarios encompassed virus concentration, exposure time, and ventilation. Newly collected data of virus RNA copies in mucus from patients are presented. RESULTS: The expelled volume of aerosols was highest for a sneeze, followed by a cough, singing, speaking, and breathing. After 20 min of exposure, at 107 RNA copies/mL in mucus, all mean illness risks were largely estimated to be below 0.001, except for the "high" sneeze scenario. At virus concentrations above 108 RNA copies/mL, and after 2 h of exposure, in the high and "low" sneeze scenarios, the high cough scenario and the singing scenario, risks exceeded 0.01 and may become very high, whereas the low coughing scenario, the high and low speaking scenarios and the breathing scenario remained below 0.1. After 2 h of exposure, singing became the second highest risk scenario. One air exchange per hour reduced risk of illness by about a factor of 2. Six air exchanges per hour reduced risks of illness by a factor of 8-13 for the sneeze and cough scenarios and by a factor of 4-9 for the other scenarios. DISCUSSION: The large variation in the volume of expelled aerosols is discussed. The model calculations indicated that SARS-CoV-2 transmission via aerosols outside of the 1.5-m social distancing norm can occur. Virus concentrations in aerosols and/or the amount of expelled aerosol droplets need to be high for substantial transmission via this route. AirCoV2 is made available as interactive computational tool. https://doi.org/10.1289/EHP7886.


Assuntos
Aerossóis , Pandemias/prevenção & controle , Medição de Risco/métodos , Microbiologia do Ar , Tosse , Transmissão de Doença Infecciosa , Humanos , Canto , Espirro
2.
Huan Jing Ke Xue ; 42(4): 1668-1678, 2021 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-33742802

RESUMO

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.


Assuntos
Microbiologia do Ar , Poluentes Atmosféricos , Aerossóis/análise , Poluentes Atmosféricos/análise , China , Cidades , Monitoramento Ambiental , Fungos , Humanos , Tamanho da Partícula
3.
Nat Commun ; 12(1): 1653, 2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33712573

RESUMO

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.


Assuntos
Microbiologia do Ar , Furões/virologia , Vírus da SARS , Síndrome Respiratória Aguda Grave/transmissão , Aerossóis , Substituição de Aminoácidos , Pelo Animal/virologia , Animais , Modelos Animais de Doenças , Feminino , Fômites/virologia , Vírus da Influenza A Subtipo H1N1 , Modelos Biológicos , Infecções por Orthomyxoviridae/transmissão , Polimorfismo de Nucleotídeo Único , Síndrome Respiratória Aguda Grave/virologia , Fatores de Tempo , Carga Viral , /virologia , Eliminação de Partículas Virais
4.
J R Soc Interface ; 18(176): 20200967, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33757291

RESUMO

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.


Assuntos
Aerossóis , Microbiologia do Ar , Instrumentos Odontológicos , Terapia por Ultrassom , /prevenção & controle , Humanos
6.
Infez Med ; 29(1): 10-19, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33664169

RESUMO

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.


Assuntos
Microbiologia do Ar , /transmissão , Número Básico de Reprodução/estatística & dados numéricos , Tosse/virologia , Exposição Ambiental , Humanos , Máscaras , Espirro
7.
Infez Med ; 29(1): 20-36, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33664170

RESUMO

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.


Assuntos
Saúde Global/estatística & dados numéricos , Pandemias , /patogenicidade , Corticosteroides/uso terapêutico , Microbiologia do Ar , Antivirais/uso terapêutico , /diagnóstico , /terapia , /uso terapêutico , Transmissão de Doença Infecciosa , Hospitalização , Humanos , Hipóxia/etiologia , Hipóxia/terapia , Imunização Passiva , Fatores Imunológicos/uso terapêutico , Período de Incubação de Doenças Infecciosas , Prevenção Primária/métodos , Respiração Artificial , /genética , Esteroides/uso terapêutico , Avaliação de Sintomas/métodos
8.
Ecotoxicol Environ Saf ; 212: 112006, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33556810

RESUMO

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.


Assuntos
Microbiologia do Ar/normas , Poluentes Atmosféricos/análise , Bactérias/isolamento & purificação , Monitoramento Ambiental/métodos , Material Particulado/análise , Sistema Respiratório/microbiologia , Aerossóis , Animais , China , Poeira , Humanos , RNA Ribossômico 16S , Estações do Ano , Suínos , Temperatura
9.
Phys Rev Lett ; 126(3): 034502, 2021 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-33543958

RESUMO

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.


Assuntos
Líquidos Corporais/química , Líquidos Corporais/virologia , Modelos Biológicos , Aerossóis/química , Microbiologia do Ar , Movimentos do Ar , Simulação por Computador , Transmissão de Doença Infecciosa , Expiração , Humanos , Pandemias , /isolamento & purificação
10.
IEEE Pulse ; 12(1): 28-30, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33606621

RESUMO

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.


Assuntos
Filtros de Ar , Microbiologia do Ar , Pandemias , Engenharia Biomédica , /virologia , Desenho de Equipamento , Expiração , Grafite , Humanos
11.
Sci Rep ; 11(1): 4617, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33633316

RESUMO

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.


Assuntos
Microbiologia do Ar , Tosse/virologia , /fisiologia , Humanos , Hidrodinâmica , Máscaras , Modelos Biológicos , Tamanho da Partícula , Medição de Risco
12.
J Med Microbiol ; 70(3)2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33629949

RESUMO

This study tests the release of SARS-CoV-2 RNA into the air during normal breathing, without any sign of possible risk of contagion such as coughing, sneezing or talking. Five patients underwent oropharyngeal, nasopharyngeal and salivary swabs for real-time reverse transcriptase PCR (RT-PCR) detection of SARS-CoV-2 RNA. Direct SARS-CoV-2 release during normal breathing was also investigated by RT-PCR in air samples collected using a microbiological sampler. Viral RNA was detected in air at 1 cm from the mouth of patients whose oropharyngeal, nasopharyngeal and salivary swabs tested positive for SARS-CoV-2 RNA. In contrast, the viral RNA was not identified in the exhaled air from patients with oropharyngeal, nasopharyngeal and salivary swabs that tested negative. Contagion of SARS-CoV-2 is possible by being very close to the mouth of someone who is infected, asymptomatic and simply breathing.


Assuntos
Microbiologia do Ar , /isolamento & purificação , Aerossóis/análise , Idoso , Infecção Hospitalar/diagnóstico , Infecção Hospitalar/virologia , Hospitais , Humanos , Itália/epidemiologia , Nasofaringe/virologia , Orofaringe/virologia , Isoladores de Pacientes , Saliva/virologia
13.
PLoS One ; 16(1): e0244983, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33400714

RESUMO

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.


Assuntos
/transmissão , Transmissão de Doença Infecciosa/prevenção & controle , Aerossóis/análise , Microbiologia do Ar , Poluição do Ar em Ambientes Fechados/análise , /virologia , Tosse , Transmissão de Doença Infecciosa/estatística & dados numéricos , Poeira , Humanos , Modelos Teóricos , Espirro/fisiologia , Viroses/prevenção & controle
14.
J Otolaryngol Head Neck Surg ; 50(1): 3, 2021 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-33461626

RESUMO

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).


Assuntos
Microbiologia do Ar , Contaminação de Equipamentos , Unidades de Terapia Intensiva , Traqueostomia , Eliminação de Partículas Virais , Aerossóis , Idoso , Feminino , Humanos , Intubação Intratraqueal , Masculino , Pessoa de Meia-Idade
15.
Nano Lett ; 21(2): 1017-1024, 2021 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-33444028

RESUMO

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.


Assuntos
Aerossóis , Bactérias/isolamento & purificação , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Microbiologia do Ar , Biomassa , Limite de Detecção , Luminescência , Nanopartículas , Tamanho da Partícula , Saúde Pública , Propriedades de Superfície , Temperatura
16.
Sci Rep ; 11(1): 2508, 2021 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-33510270

RESUMO

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.


Assuntos
/transmissão , Monitoramento Ambiental/métodos , /química , Aerossóis/análise , Aerossóis/química , Microbiologia do Ar , Poluição do Ar em Ambientes Fechados , /metabolismo , Fômites/microbiologia , Fômites/estatística & dados numéricos , Hospitais , Humanos , Malásia/epidemiologia , Pandemias , Material Particulado/análise , RNA Viral
17.
Artigo em Inglês | MEDLINE | ID: mdl-33419142

RESUMO

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.


Assuntos
Microbiologia do Ar , /transmissão , Ar Condicionado , Desinfecção , Humanos , Máscaras , Ventilação
18.
Environ Monit Assess ; 193(1): 47, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33415530

RESUMO

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.


Assuntos
Poluição do Ar em Ambientes Fechados , Ar Condicionado , Microbiologia do Ar , Poluição do Ar em Ambientes Fechados/análise , Bactérias/genética , Monitoramento Ambiental , Humanos , Filogenia , Saúde Pública , Universidades , Ventilação
20.
Sci Total Environ ; 753: 141852, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32891995

RESUMO

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.


Assuntos
Microbiologia do Ar , Esgotos , Aerossóis , Humanos
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