scholarly journals A numerical study of ventilation strategies for infection risk mitigation in general inpatient wards

2020 ◽  
Vol 13 (4) ◽  
pp. 887-896 ◽  
Author(s):  
Manoj Kumar Satheesan ◽  
Kwok Wai Mui ◽  
Ling Tim Wong
Keyword(s):  
Risk Mitigation ◽  
Numerical Study ◽  
Infection Risk ◽  
Ventilation Strategies

scholarly journals Numerical Study of Variable Lung Ventilation Strategies

2015 ◽  
pp. 299-306
Author(s):  
Reena Yadav ◽  
Mayur Ghatge ◽  
Kirankumar Hiremath ◽  
Ganesh Bagler
Keyword(s):  
Numerical Study ◽  
Lung Ventilation ◽  
Ventilation Strategies

Numerical study of the effects of ventilated cavities outlet location on thermal comfort and air quality

2019 ◽  
Vol 29 (11) ◽  
pp. 4462-4483
Author(s):  
Zohir Younsi ◽  
Lounes Koufi ◽  
Hassane Naji
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Numerical Study ◽  
Vertical Wall ◽  
Heat Removal ◽  
Fluid Temperature ◽  
Position Effects ◽  
Content Type ◽  
Mixed Regime ◽  
Ventilation Strategies

Purpose A comprehensive investigation on the outlet air position effects on the thermal comfort and air quality has been achieved. In addition, airflow and temperature distributions in ventilated cavities filled with an air-CO2 mixture with mixed convection are predicted. The airflow enters from the cavity through an opening in the lower side of the left vertical wall and exits through the opening in one wall of the cavity. This paper aims to investigate the outlet location effect, four different placement configurations of output ports are considered. Three of them are placed on the upper side and the fourth on top of the opposite side of the inlet opening. A uniform heat and CO2 contaminant source are applied on the left vertical wall, while the remaining walls are impermeable and adiabatic to heat and solute. The cooling efficiency inside the enclosure and the average fluid temperature are computed for different Reynolds and Rayleigh numbers to find the most suitable fluid outlet position that ensures indoor comfortable conditions while effectively removing heat and the contaminant. This is demonstrated by three relevant indices, namely, the effectiveness for heat removal, the contaminant removal and the index of indoor air quality. Design/methodology/approach The simulations were performed via the finite-volume scSTREAM CFD solver V11. Three different values of CO2 amount are considered, namely, 103, 2 × 103 and 3 × 103 ppm, the Reynolds number being in the range 100 ≤ Re ≤ 800. Findings Based on the findings obtained, it is the configuration whose air outlet is placed near the heat source and the contaminant, which provides a better air distribution and a ventilation efficiency compared to the others ventilation strategies. Originality/value The studies on heat and mass transfers by natural and forced convection in ventilated cavities remain a fruitful research topic. Thereby, such a study deals with different ventilation strategies through cavities containing an air-CO2 mixture subjected to a mixed regime. In particular, the air inlet velocity and contaminant sources’ effects on thermal comfort and air quality have been investigated.

scholarly journals Analysis and forecast of extreme new-snow avalanches: a numerical study of the avalanche cycles of February 1999 in France

2010 ◽  
Vol 56 (199) ◽  
pp. 758-770 ◽  
Author(s):  
Marie Rousselot ◽  
Yves Durand ◽  
Gérald Giraud ◽  
Laurent Merindol ◽  
Luc Daniel
Keyword(s):  
Risk Mitigation ◽  
Numerical Study ◽  
Weather Conditions ◽  
Local Scale ◽  
Civil Protection ◽  
Snow Avalanches ◽  
Sensitivity Tests ◽  
Fresh Snow ◽  
Key Factor ◽  
Northern Alps

AbstractSnow and weather conditions typical of exceptional cycles of fresh-snow avalanches in the northern Alps are investigated using the numerical avalanche-hazard forecasting procedure of Météo-France. Sensitivity tests are performed on the events of February 1999 in the Chamonix France region, and resulting snowpack instability modeled at the massif scale is compared using adapted new indices and maps. Our results complete conclusions of earlier observation-based studies by providing new insights into the snow and weather conditions of February 1999. The large avalanches mainly resulted from large and very unstable fresh-snow accumulations. Moreover, the snowpack instability was increased locally by wind transport of light and fresh snow in February. The mechanical weaknesses resulting from the weather conditions prior to February were a key factor in explaining the unusual volumes of these avalanches. This study suggests that the operational numerical SAFRAN/Crocus/ MÉPRA (SCM) chain provides reliable forecasts of extreme new-snow avalanche situations at the massif scale, but that local-scale simulations are still needed to improve the efficiency of risk mitigation and civil protection policies.

scholarly journals SARS-CoV-2 infection risk during delivery of childhood vaccination campaigns: a modelling study

2021 ◽  
Author(s):  
Simon R Procter ◽  
Kaja R Abbas ◽  
Stefan Flasche ◽  
Ulla Griffiths ◽  
Brittany Hagedorn ◽  
...  
Keyword(s):  
Risk Mitigation ◽  
Infection Risk ◽  
Childhood Vaccination ◽  
World Health ◽  
Mitigation Measures ◽  
Transmission Model ◽  
Contact Patterns ◽  
Health Organization ◽  
Vaccination Campaigns ◽  
N95 Respirators

Background The COVID-19 pandemic has disrupted delivery of immunisation services globally. Many countries have postponed vaccination campaigns out of concern about infection risks to staff delivering vaccination, the children being vaccinated and their families. The World Health Organization recommends considering both the benefit of preventive campaigns and the risk of SARS-CoV-2 transmission when making decisions about campaigns during COVID-19 outbreaks, but there has been little quantification of the risks. Methods We modelled excess SARS-CoV-2 infection risk to vaccinators, vaccinees and their caregivers resulting from vaccination campaigns delivered during a COVID-19 epidemic. Our model used population age-structure and contact patterns from three exemplar countries (Burkina Faso, Ethiopia, and Chile). It combined an existing compartmental transmission model of an underlying COVID-19 epidemic with a Reed-Frost model of SARS-CoV-2 infection risk to vaccinators and vaccinees. We explored how excess risk depends on key parameters governing SARS-CoV-2 transmissibility, and aspects of campaign delivery such as campaign duration, number of vaccinations, and effectiveness of personal protective equipment (PPE) and symptomatic screening. Results Infection risks differ considerably depending on the circumstances in which vaccination campaigns are conducted. A campaign conducted at the peak of a SARS-CoV-2 epidemic with high prevalence and without special infection mitigation measures could increase absolute infection risk by 32% to 58% for vaccinators, and 0.3% to 0.9% for vaccinees and caregivers. However, these risks could be reduced to 3.6% to 8.0% and 0.1% to 0.4% respectively by use of PPE that reduces transmission by 90% (as might be achieved with N95 respirators or high-quality surgical masks) and symptomatic screening. Conclusions SARS-CoV-2 infection risks to vaccinators, vaccinees and caregivers during vaccination campaigns can be greatly reduced by adequate PPE, symptomatic screening, and appropriate campaign timing. Our results support the use of adequate risk mitigation measures for vaccination campaigns held during SARS-CoV-2 epidemics, rather than cancelling them entirely.

scholarly journals The Facility Infection Risk Estimator™: A web application tool for comparing indoor risk mitigation strategies by estimating airborne transmission risk

2021 ◽  
pp. 1420326X2110395
Author(s):  
Marcel Harmon ◽  
Josephine Lau
Keyword(s):  
Web Application ◽  
Risk Mitigation ◽  
Infection Risk ◽  
Mitigation Strategies ◽  
Transmission Risk ◽  
Physical Parameters ◽  
Airborne Transmission ◽  
Risk Mitigation Strategies ◽  
Risk Estimator ◽  
Number Of Individuals

The COVID-19 pandemic created needs for (a) estimating the existing airborne risk of infection from SARS-CoV-2 in existing facilities and new designs and (b) estimating and comparing the impacts of engineering and behavioural strategies for contextually reducing that risk. This paper presents the development of a web application to meet these needs, the Facility Infection Risk Estimator™, and its underlying Wells–Riley based model. The model specifically estimates (a) the removal efficiencies of various settling, ventilation, filtration and virus inactivation strategies and (b) the associated probability of infection, given the room physical parameters and number of individuals infected present with either influenza or SARS-CoV-2. A review of the underlying calculations and associated literature is provided, along with the model's validation against two documented spreading events. The error between modelled and actual number of additional people infected, normalized by the number of uninfected people present, ranged from roughly –18.4% to +9.7%. The more certain one can be regarding the input parameters (such as for new designs or existing buildings with adequate field verification), the smaller these normalized errors will be, likely less than ±15%, making it useful for comparing the impacts of different risk mitigation strategies focused on airborne transmission.

scholarly journals Effects of face masks and ventilation on the risk of SARS-CoV-2 respiratory transmission in public toilets: a quantitative microbial risk assessment

2021 ◽  
Author(s):  
Thammanitchpol Denpetkul ◽  
Oranoot Sittipunsakda ◽  
Monchai Pumkaew ◽  
Skorn Mongkolsuk ◽  
Kwanrawee Sirikanchana
Keyword(s):  
Risk Assessment ◽  
Gender Differences ◽  
Risk Mitigation ◽  
Infection Risk ◽  
Virus Concentration ◽  
List Type ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Public Toilets

AbstractPublic toilets could increase the risk of COVID-19 infection via airborne transmission; however, related research is limited. We aimed to estimate SARS-CoV-2 infection risk through respiratory transmission using a quantitative microbial risk assessment framework by retrieving SARS-CoV-2 concentrations from the swab tests of 251 Thai patients. Three virus-generating scenarios were investigated: an infector breathing, breathing with a cough, and breathing with a sneeze. Infection risk (97.5th percentile) was as high as 10−3 with breathing and increased to 10−1 with a cough or sneeze, thus all higher than the risk benchmark of 5 × 10−5 per event. No significant gender differences for toilet users (receptors) were noted. The highest risk scenario of breathing and a sneeze was further evaluated for risk mitigation measures. Risk mitigation to lower than the benchmark succeeded only when the infector and receptor simultaneously wore an N95 respirator or surgical mask and when the receptor wore an N95 respirator and the infector wore a denim fabric mask. Ventilation up to 20 air changes per hour (ACH), beyond the 12-ACH suggested by the WHO, did not mitigate risk. Virus concentration, volume of expelled droplets, and receptor dwell time were identified as the main contributors to transmission risk.Highlights-The use of public toilets poses a risk of SARS-CoV-2 respiratory transmission-Highest risks generated in the order of sneezing, coughing, and breathing-No gender differences in risk by counteracting dwell times and inhalation rates-Ventilation did not reduce risk even at 20 ACH, beyond the WHO-recommended value-N95 and surgical masks offer the most effective risk mitigation to toilet usersGraphical abstract

Infection Risk Mitigation for Biofeedback Providers

Biofeedback ◽  
2014 ◽  
Vol 42 (3) ◽  
pp. 93-95 ◽  
Author(s):  
Dave Hagedorn
Keyword(s):  
Disease Transmission ◽  
Risk Mitigation ◽  
Infection Risk ◽  
Medical Providers ◽  
Aseptic Technique ◽  
Standards Of Practice

Biofeedback providers necessarily make contact with patients or clients using sterile and nonsterile instruments and sensors. Many biofeedback providers lack the aseptic technique training that is common to licensed medical providers. This review familiarizes biofeedback providers with the essential principles and procedures of infection risk mitigation by touching on routes of disease transmission, disinfection, sanitization, and Spaulding classification. Basic suggestions for infection risk mitigation standards of practice are offered.

scholarly journals Maintenance and risk management of rockfall protection net fences through numerical study of deteriorations

2016 ◽  
Author(s):  
Andrea Luciani ◽  
Monica Barbero ◽  
Daniele Martinelli ◽  
Daniele Peila
Keyword(s):  
Risk Management ◽  
Risk Analysis ◽  
Numerical Modelling ◽  
Urban Areas ◽  
Risk Mitigation ◽  
Numerical Study ◽  
Maintenance Planning ◽  
Mountainous Areas ◽  
Protection Systems ◽  
Rockfall Protection

Abstract. Rockfall protection net fences are key protection systems in mountainous areas worldwide to ensure the safety of infrastructures, roads and urban areas against rockfall. Management of the maintenance of rockfall protection net fences is fundamental for public administrations in order to guarantee risk mitigation. This paper deals with the assessment of the installation problems and deterioration of rockfall protection net fences, using numerical modelling in order to evaluate the influence of these issues on their behaviour. A percentage of the residual efficiency is assessed as a useful tool for risk analysis and maintenance planning.

Decision-making analysis of ventilation strategies under complex situations: A numerical study

2021 ◽  
pp. 108217
Author(s):  
Weijia Zhang ◽  
Weirong Zhang ◽  
Kunio Mizutani ◽  
Haotian Zhang
Keyword(s):  
Decision Making ◽  
Numerical Study ◽  
Ventilation Strategies
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