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1.
PLoS One ; 16(11): e0257549, 2021.
Article in English | MEDLINE | ID: covidwho-1793615

ABSTRACT

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 µm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p<0.001). The amount of respiratory droplets significantly increased after LT. The LFVS enabled a significant decrease in respiratory droplets during anaerobic exercise in healthy subjects. This study's findings will aid in exercising safely during this pandemic.


Subject(s)
Air Conditioning/methods , COVID-19/prevention & control , Exercise/physiology , Particulate Matter/chemistry , Adult , Aerosols/chemistry , Air Filters , Anaerobic Threshold/physiology , COVID-19/metabolism , Exercise Test/methods , Exhalation/physiology , Female , Heart Rate/physiology , Humans , Japan , Lactic Acid/metabolism , Male , Oxygen Consumption/physiology , Respiration , Respiratory System/physiopathology , Running/physiology , SARS-CoV-2/pathogenicity , Ventilation/methods
2.
Sci Total Environ ; 833: 155173, 2022 Aug 10.
Article in English | MEDLINE | ID: covidwho-1783747

ABSTRACT

Proper air distribution is crucial for airborne infection risk control of infectious respiratory diseases like COVID-19. Existing studies evaluate and compare the performances of different air distributions for airborne infection risk control, but the mechanisms of air distribution for airborne infection risk control remain unclear. This study investigates the mechanisms of air distribution for both overall and local airborne infection risk controls. The experimentally validated CFD models simulate the contaminant concentration fields in a hospital ward based on which the airborne infection risks of COVID-19 are evaluated with the dilution-based expansion of the Wells-Riley model. Different air distributions, i.e., stratum ventilation, displacement ventilation, and mixing ventilation, with various supply airflow rates are tested. The results show that the variations of the overall and local airborne infection risks under different air distributions and different supply airflow rates are complicated and non-linear. The contaminant removal and the contaminant dispersion are proposed as the mechanisms for the overall and local airborne infection risk controls, respectively, regardless of airflow distributions and supply airflow rates. A large contaminant removal ability benefits the overall airborne infection risk control, with the coefficient of determination of 0.96 between the contaminant removal index and the reciprocal of the overall airborne infection risk. A large contaminant dispersion ability benefits the local airborne infection risk control, with the coefficient of determination of 0.99 between the contaminant dispersion index and the local airborne infection risk.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , Ventilation/methods
3.
J Occup Environ Hyg ; 19(5): 295-301, 2022 05.
Article in English | MEDLINE | ID: covidwho-1740663

ABSTRACT

Ventilation plays an important role in mitigating the risk of airborne virus transmission in university classrooms. During the early phase of the COVID-19 pandemic, methods to assess classrooms for ventilation adequacy were needed. The aim of this paper was to compare the adequacy of classroom ventilation determined through an easily accessible, simple, quantitative measure of air changes per hour (ACH) to that determined through qualitative "expert judgment" and recommendations from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), and the American Conference of Governmental Industrial Hygienists (ACGIH)®. Two experts, ventilation engineers from facilities maintenance, qualitatively ranked buildings with classrooms on campus with regard to having "acceptable classroom ventilation." Twelve lecture classrooms were selected for further testing, including a mix of perceived adequate/inadequate ventilation. Total air change per hour (ACH) was measured to quantitatively assess ventilation through the decay of carbon dioxide in the front and rear of these classrooms. The outdoor ACH was calculated by multiplying the total ACH by the outdoor air fraction. The classrooms in a building designed to the highest ASHRAE standards (62.1 2004) did not meet ACGIH COVID-19 recommendations. Four of the classrooms met the ASHRAE criteria. However, a classroom that was anticipated to fail based on expert knowledge met the ASHRAE and ACGIH criteria. Only two classrooms passed stringent ACGIH recommendations (outdoor ACH > 6). None of the classrooms that passed ACGIH criteria were originally expected to pass. There was no significant difference in ACH measured in the front and back of classrooms, suggesting that all classrooms were well mixed with no dead zones. From these results, schools should assess classroom ventilation considering a combination of classroom design criteria, expert knowledge, and ACH measurements.


Subject(s)
Air Pollution, Indoor , COVID-19 , Air Pollution, Indoor/prevention & control , COVID-19/epidemiology , Humans , Pandemics , Schools , Universities , Ventilation/methods
5.
PLoS One ; 16(11): e0257549, 2021.
Article in English | MEDLINE | ID: covidwho-1511814

ABSTRACT

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 µm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p<0.001). The amount of respiratory droplets significantly increased after LT. The LFVS enabled a significant decrease in respiratory droplets during anaerobic exercise in healthy subjects. This study's findings will aid in exercising safely during this pandemic.


Subject(s)
Air Conditioning/methods , COVID-19/prevention & control , Exercise/physiology , Particulate Matter/chemistry , Adult , Aerosols/chemistry , Air Filters , Anaerobic Threshold/physiology , COVID-19/metabolism , Exercise Test/methods , Exhalation/physiology , Female , Heart Rate/physiology , Humans , Japan , Lactic Acid/metabolism , Male , Oxygen Consumption/physiology , Respiration , Respiratory System/physiopathology , Running/physiology , SARS-CoV-2/pathogenicity , Ventilation/methods
7.
Virol J ; 18(1): 109, 2021 06 02.
Article in English | MEDLINE | ID: covidwho-1388777

ABSTRACT

BACKGROUND: The ongoing SARS-CoV-2 pandemic has spread rapidly worldwide and disease prevention is more important than ever. In the absence of a vaccine, knowledge of the transmission routes and risk areas of infection remain the most important existing tools to prevent further spread. METHODS: Here we investigated the presence of the SARS-CoV-2 virus in the hospital environment at the Uppsala University Hospital Infectious Disease ward by RT-qPCR and determined the infectivity of the detected virus in vitro on Vero E6 cells. RESULTS: SARS-CoV-2 RNA was detected in several areas, although attempts to infect Vero E6 cells with positive samples were unsuccessful. However, RNase A treatment of positive samples prior to RNA extraction did not degrade viral RNA, indicating the presence of SARS-CoV-2 nucleocapsids or complete virus particles protecting the RNA as opposed to free viral RNA. CONCLUSION: Our results show that even in places where a moderate concentration (Ct values between 30 and 38) of SARS-CoV-2 RNA was found; no infectious virus could be detected. This suggests that the SARS-CoV-2 virus in the hospital environment subsides in two states; as infectious and as non-infectious. Future work should investigate the reasons for the non-infectivity of SARS-CoV-2 virions.


Subject(s)
COVID-19/transmission , Cross Infection/epidemiology , Disease Transmission, Infectious/statistics & numerical data , Environmental Monitoring/methods , Animals , Cell Line , Chlorocebus aethiops , Confined Spaces , Cross Infection/virology , Hospitals , Humans , Risk , SARS-CoV-2/growth & development , Ventilation/methods , Vero Cells
8.
Psychosomatics ; 61(6): 662-671, 2020.
Article in English | MEDLINE | ID: covidwho-1386490

ABSTRACT

BACKGROUND: Patients with psychiatric illnesses are particularly vulnerable to highly contagious, droplet-spread organisms such as SARS-CoV-2. Patients with mental illnesses may not be able to consistently follow up behavioral prescriptions to avoid contagion, and they are frequently found in settings with close contact and inadequate infection control, such as group homes, homeless shelters, residential rehabilitation centers, and correctional facilities. Furthermore, inpatient psychiatry settings are generally designed as communal spaces, with heavy emphasis on group and milieu therapies. As such, inpatient psychiatry services are vulnerable to rampant spread of contagion. OBJECTIVE: With this in mind, the authors outline the decision process and ultimate design and implementation of a regional inpatient psychiatry unit for patients infected with asymptomatic SARS-CoV-2 and share key points for consideration in implementing future units elsewhere. CONCLUSION: A major takeaway point of the analysis is the particular expertise of trained experts in psychosomatic medicine for treating patients infected with SARS-CoV-2.


Subject(s)
Asymptomatic Infections , Coronavirus Infections/complications , Hospital Design and Construction/methods , Hospital Units , Hospitalization , Infection Control/methods , Mental Disorders/therapy , Personnel Staffing and Scheduling/organization & administration , Pneumonia, Viral/complications , Betacoronavirus , COVID-19 , Humans , Involuntary Commitment , Mental Disorders/complications , Pandemics , Personal Protective Equipment , Psychiatric Department, Hospital , Psychotherapy, Group/methods , Recreation , SARS-CoV-2 , Ventilation/methods , Visitors to Patients
9.
Nat Commun ; 12(1): 5096, 2021 08 19.
Article in English | MEDLINE | ID: covidwho-1366815

ABSTRACT

Nearly all mass gathering events worldwide were banned at the beginning of the COVID-19 pandemic, as they were suspected of presenting a considerable risk for the transmission of SARS-CoV-2. We investigated the risk of transmitting SARS-CoV-2 by droplets and aerosols during an experimental indoor mass gathering event under three different hygiene practices, and used the data in a simulation study to estimate the resulting burden of disease under conditions of controlled epidemics. Our results show that the mean number of measured direct contacts per visitor was nine persons and this can be reduced substantially by appropriate hygiene practices. A comparison of two versions of ventilation with different air exchange rates and different airflows found that the system which performed worst allowed a ten-fold increase in the number of individuals exposed to infectious aerosols. The overall burden of infections resulting from indoor mass gatherings depends largely on the quality of the ventilation system and the hygiene practices. Presuming an effective ventilation system, indoor mass gathering events with suitable hygiene practices have a very small, if any, effect on epidemic spread.


Subject(s)
Air Pollution, Indoor/prevention & control , COVID-19/transmission , Hygiene/standards , SARS-CoV-2/pathogenicity , Ventilation/methods , Aerosols , COVID-19/diagnosis , COVID-19/virology , Computer Simulation , Disease Transmission, Infectious/prevention & control , Humans , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification
10.
J Breath Res ; 15(4)2021 07 30.
Article in English | MEDLINE | ID: covidwho-1320288

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic has imposed a considerable burden on hospitals and healthcare workers (HCWs) worldwide, increasing the risk of outbreaks and nosocomial transmission to 'non-COVID-19' patients, who represent the highest-risk population in terms of mortality, and HCWs. Since HCWs are at the interface between hospitals on the one hand and the community on the other, they are potential reservoirs, carriers, or victims of severe acute respiratory syndrome coronavirus 2 cross-transmission. In addition, there has been a paradigm shift in the management of viral respiratory outbreaks, such as the widespread testing of patients and HCWs, including asymptomatic individuals. In hospitals, there is a risk of aerosol transmission in poorly ventilated spaces, and when performing aerosol-producing procedures, it is imperative to take measures against aerosol transmission. In particular, spatial separation of the inpatient ward for non-COVID-19 patients from that designated for patients with suspected or confirmed COVID-19 as well as negative-pressure isolation on the floor of the ward, using an airborne infection isolation device could help prevent nosocomial infection.


Subject(s)
COVID-19/prevention & control , Cross Infection/prevention & control , Health Personnel/statistics & numerical data , Hospitals , Infection Control , Physical Distancing , Ventilation , Aerosols , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/transmission , COVID-19 Testing , Cross Infection/diagnosis , Cross Infection/epidemiology , Cross Infection/transmission , Humans , Infection Control/methods , Infection Control/statistics & numerical data , SARS-CoV-2 , Ventilation/methods , Ventilation/statistics & numerical data
11.
Asian J Endosc Surg ; 14(3): 620-623, 2021 Jul.
Article in English | MEDLINE | ID: covidwho-1294946

ABSTRACT

The pandemic of COVID-19 has been a game changer in many aspects of medical care, including laparoscopic surgery service. Uncertainty in the early pandemic has led to the fear of doing laparoscopic surgery with regard to the possibility of SARS-COV-2 transmission through surgical smoke. We carried out laparoscopic surgery during the COVID-19 pandemic with intention to test our local adaptation of a laparoscopic smoke evacuator. Twenty-five laparoscopic cases for digestive surgery were performed with uneventful results. In summary, a low cost local adaptation of laparoscopic smoke and safe surgical behavior should be the standard of care when delivering laparoscopic surgery service in the pandemic era and forward.


Subject(s)
COVID-19 , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Laparoscopy/methods , Laparotomy/methods , Smoke/adverse effects , Ventilation/methods , Humans , Infection Control/methods , Pandemics , SARS-CoV-2
12.
Sci Rep ; 11(1): 11778, 2021 06 03.
Article in English | MEDLINE | ID: covidwho-1258598

ABSTRACT

The COVID-19 pandemic has generated many concerns about cross-contamination risks, particularly in hospital settings and Intensive Care Units (ICU). Virus-laden aerosols produced by infected patients can propagate throughout ventilated rooms and put medical personnel entering them at risk. Experimental results found with a schlieren optical method have shown that the air flows generated by a cough and normal breathing were modified by the oxygenation technique used, especially when using High Flow Nasal Canulae, increasing the shedding of potentially infectious airborne particles. This study also uses a 3D Computational Fluid Dynamics model based on a Lattice Boltzmann Method to simulate the air flows as well as the movement of numerous airborne particles produced by a patient's cough within an ICU room under negative pressure. The effects of different mitigation scenarii on the amount of aerosols potentially containing SARS-CoV-2 that are extracted through the ventilation system are investigated. Numerical results indicate that adequate bed orientation and additional air treatment unit positioning can increase by 40% the number of particles extracted and decrease by 25% the amount of particles deposited on surfaces 45s after shedding. This approach could help lay the grounds for a more comprehensive way to tackle contamination risks in hospitals, as the model can be seen as a proof of concept and be adapted to any room configuration.


Subject(s)
Air Microbiology , COVID-19/transmission , Cough/virology , Respiratory Distress Syndrome/virology , Aerosols , Humans , Intensive Care Units , Models, Theoretical , Optical Imaging , Ventilation/methods
15.
Int J Hyg Environ Health ; 234: 113746, 2021 05.
Article in English | MEDLINE | ID: covidwho-1163860

ABSTRACT

Natural window ventilation is frequently employed in schools in Europe and often leads to inadequate levels of human bioeffluents. However, intervention studies that verify whether recommended ventilation targets can be achieved in practice with reasonable ventilation regimes and that are also suitable for countries with cold winters are practically non-existent. To explore the initial situation in Switzerland we carried out carbon dioxide (CO2) measurements during the winter in 100 classrooms, most of which (94%) had natural window ventilation. In more than two thirds of those, the hygienic limit value of 2000 ppm specified for CO2 in the Swiss Standard SN 520180 (2014) was exceeded. To improve ventilation behavior, an intervention was implemented in 23 classrooms during the heating season. Ventilation was performed exclusively during breaks (to avoid discomfort from cold and drafts), efficiently, and only for as long as was necessary to achieve the ventilation objective of compliance with the hygienic limit value (strategic ventilation). The intervention included verbal and written instructions, awareness-raising via a school lesson and an interactive tool for students, which was also used to estimate the required duration of ventilation. CO2 exposure was significantly reduced in pilot classes (Wilcoxon signed-rank test, p = 3.815e-06). Median CO2 levels decreased from 1600 ppm (control group) to 1097 ppm (intervention group), and the average proportion of teaching time at 400-1400 ppm CO2 increased from 40% to 70%. The duration of ventilation was similar to spontaneous natural window ventilation (+5.8%). Stricter ventilation targets are possible. The concept of the intervention is suitable for immediate adoption in schools with natural window ventilation for a limited period, pending the installation of a mechanical ventilation system. The easy integration of this intervention into everyday school life promotes compliance, which is particularly important during the COVID-19 pandemic.


Subject(s)
Air Pollution, Indoor/prevention & control , COVID-19/prevention & control , Environmental Monitoring/methods , Inhalation Exposure/prevention & control , Ventilation/methods , Adolescent , Air Pollution, Indoor/analysis , COVID-19/epidemiology , COVID-19/transmission , Carbon Dioxide/analysis , Child , Disease Transmission, Infectious/prevention & control , Female , Humans , Male , SARS-CoV-2 , Schools , Seasons , Switzerland/epidemiology
16.
Ann R Coll Surg Engl ; 103(3): 151-154, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-1110067

ABSTRACT

INTRODUCTION: Owing to the COVID-19 pandemic, there has been significant disruption to all surgical specialties. In the UK, units have cancelled elective surgery and a decrease in aerosol generating procedures (AGPs) was favoured. Centres around the world advocate the use of negative pressure environments for AGPs in reducing the spread of infectious airborne particles. We present an overview of operating theatre ventilation systems and the respective evidence with relation to surgical site infection (SSI) and airborne pathogen transmission in light of COVID-19. METHODS: A literature search was conducted using the PubMed, Cochrane Library and MEDLINE databases. Search terms included "COVID-19", "theatre ventilation", "laminar", "turbulent" and "negative pressure". FINDINGS: Evidence for laminar flow ventilation in reducing the rate of SSI in orthopaedic surgery is widely documented. There is little evidence to support its use in general surgery. Following previous viral outbreaks, some centres have introduced negative pressure ventilation in an attempt to decrease exposure of airborne pathogens to staff and surrounding areas. This has again been suggested during the COVID-19 pandemic. A limited number of studies show some positive results for the use of negative pressure ventilation systems and reduction in spread of pathogens; however, cost, accessibility and duration of conversion remain an unexplored issue. Overall, there is insufficient evidence to advocate large scale conversion at this time. Nevertheless, it may be useful for each centre to have its own negative pressure room available for AGPs and high risk patients.


Subject(s)
Air Filters , COVID-19/prevention & control , Environment, Controlled , Operating Rooms , Patient Isolators , Surgical Procedures, Operative/methods , Ventilation/methods , COVID-19/transmission , Humans , Orthopedic Procedures , SARS-CoV-2 , Surgical Wound Infection/prevention & control
18.
Enferm Clin (Engl Ed) ; 31: S68-S72, 2021 Feb.
Article in Spanish | MEDLINE | ID: covidwho-1061834

ABSTRACT

OBJECTIVE: This review aims to map scientific evidence in nursing care aimed at controlling coronavirus infections. METHOD: A bibliographic search was conducted in the Medline, CINAHL, Scopus and WOS main databases, with no date limit and using the keywords «transmission¼, «infection¼, «contagious¼, «spreads¼, «coronavirinae¼, «coronavirus¼, «covid 19¼, «sars cov 2¼, «nurses¼ and «nursing¼. Initially, 154 studies were identified and, after selecting them according to eligibility criteria, 16 were included. RESULTS: Among the main recommendations according to the available evidence are air exchange in rooms as a measure to reduce the risk of infection among patients; reinforcement of measures in intensive care units; follow-up of positive case contacts; and adequate training of professionals. DISCUSSION AND CONCLUSIONS: The studies included in the review addressed infection prevention and control practices by analyzing risks associated with exposure and listing actions to avoid complications in critically ill patients. Patterns of case transmission, contacts and associated factors were identified. Professional knowledge and attitudes were also studied, showing the importance of good infection control training, and of sufficient equipment and adequate infrastructure.Nurses are important vectors of spread. Although there is little evidence available on the effectiveness of care to prevent the spread of SARS-CoV-2, published studies on the prevention and control of previous outbreaks of coronavirus are of considerable value.


Subject(s)
COVID-19/nursing , COVID-19/prevention & control , SARS-CoV-2 , Attitude of Health Personnel , COVID-19/transmission , Contact Tracing , Cross Infection/prevention & control , Health Knowledge, Attitudes, Practice , Health Personnel/education , Humans , Intensive Care Units , Patients' Rooms , Ventilation/methods
19.
Air Med J ; 40(1): 54-59, 2021.
Article in English | MEDLINE | ID: covidwho-1060089

ABSTRACT

OBJECTIVE: The aeromedical transport of coronavirus patients presents risks to clinicians and aircrew. Patient positioning and physical barriers may provide additional protection during flight. This paper describes airflow testing undertaken on fixed wing and rotary wing aeromedical aircraft. METHODS: Airflow testing was undertaken on a stationary Hawker Beechcraft B200C and Leonardo Augusta Westland 139. Airflow was simulated using a Trainer 101 (MSS Professional A/S, Odense Sø, Syddanmark, Denmark) Smoke machine. Different cabin configurations were used along with variations in heating, cooling, and ventilation systems. RESULTS: For the Hawker Beechcraft B200C, smoke generated within the forward section of the cabin was observed to fill the cabin to a fluid boundary located in-line with the forward edge of the cargo door. With the curtain closed, smoke was only observed to enter the cockpit in very small quantities. For the Leonardo AW139, smoke generated within the cabin was observed to expand to fill the cabin evenly before dissipating. With the curtain closed, smoke was observed to enter the cockpit only in small quantities CONCLUSION: The use of physical barriers in fixed wing and rotary wing aeromedical aircraft provides some protection to aircrew. Optimal positioning of the patient is on the aft stretcher on the Beechcraft B200C and on a laterally orientated stretcher on the AW139. The results provide a baseline for further investigation into methods to protect aircrew during the coronavirus pandemic.


Subject(s)
Air Ambulances , Air Conditioning/methods , Air Movements , COVID-19/prevention & control , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Ventilation/methods , Air Conditioning/instrumentation , COVID-19/transmission , Humans , Ventilation/instrumentation
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