scholarly journals Evaluation of N95 Respirator Ultraviolet Decontamination and Clinical Reuse with Quantitative Fit Testing

2021 ◽  
pp. 1-10
Author(s):  
Gregory K. Wanner ◽  
Douglas Ader ◽  
Richard Caplan ◽  
Amit S. Padaki ◽  
Debra Ravert ◽  
...  
Keyword(s):  
Failure Rate ◽  
Probability Of Failure ◽  
Fit Testing ◽  
The Mean ◽  
N95 Respirators ◽  
Test Failure

Abstract The supply of N95 respirators has been severely strained by COVID-19. We used quantitative fit-testing to evaluate sixteen participants and forty-five respirators through up to four rounds of ultraviolet decontamination and clinical reuse. The mean fit-test failure rate was 29.7% and probability of failure increased through N95 reuse.

scholarly journals Comparative analysis of N95 respirators fit testing with commercially available and in house reagent

2021 ◽  
pp. 100116
Author(s):  
Erum Khan ◽  
Joveria Farooqi ◽  
Humaira Shafaq ◽  
Kaleem Ullah Khushik ◽  
Syed Shamim Raza ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Fit Testing ◽  
N95 Respirators

scholarly journals Evaluation of Bearing Capacity of Strip Footing Using Random Layers Concept

2015 ◽  
Vol 37 (3) ◽  
pp. 31-39 ◽  
Author(s):  
Marek Kawa ◽  
Dariusz Łydżba
Keyword(s):  
Monte Carlo ◽  
Bearing Capacity ◽  
Failure Mechanism ◽  
Design Theory ◽  
Cohesive Soil ◽  
Probability Of Failure ◽  
Mean Value ◽  
Strip Footing ◽  
Random Field Theory ◽  
The Mean

Abstract The paper deals with evaluation of bearing capacity of strip foundation on random purely cohesive soil. The approach proposed combines random field theory in the form of random layers with classical limit analysis and Monte Carlo simulation. For given realization of random the bearing capacity of strip footing is evaluated by employing the kinematic approach of yield design theory. The results in the form of histograms for both bearing capacity of footing as well as optimal depth of failure mechanism are obtained for different thickness of random layers. For zero and infinite thickness of random layer the values of depth of failure mechanism as well as bearing capacity assessment are derived in a closed form. Finally based on a sequence of Monte Carlo simulations the bearing capacity of strip footing corresponding to a certain probability of failure is estimated. While the mean value of the foundation bearing capacity increases with the thickness of the random layers, the ultimate load corresponding to a certain probability of failure appears to be a decreasing function of random layers thickness.

Respirator-Fit Testing: Does It Ensure the Protection of Healthcare Workers Against Respirable Particles Carrying Pathogens?

2008 ◽  
Vol 29 (12) ◽  
pp. 1149-1156 ◽  
Author(s):  
M. C. Lee ◽  
S. Takaya ◽  
R. Long ◽  
A. M. Joffe
Keyword(s):  
Healthcare Workers ◽  
Respiratory Protection ◽  
Pass Rates ◽  
Test Protocol ◽  
Term Efficacy ◽  
Fit Testing ◽  
Observational Cohort ◽  
Short And Long Term ◽  
N95 Respirators

Objective.Respiratory protection programs, including fit testing of respirators, have been inconsistently implemented; evidence of their long-term efficacy is lacking. We undertook a study to determine the short- and long-term efficacy of training for fit testing of N95 respirators in both untrained and trained healthcare workers (HCWs).Design.Prospective observational cohort study.Methods.A group of at-risk, consenting HCWs not previously fit-tested for a respirator were provided with a standard fit-test protocol. Participants were evaluated after each of 3 phases, and 3 and 14 months afterward. A second group of previously fit-tested nurses was studied to assess the impact of regular respirator use on performance.Results.Of 43 untrained fit-tested HCWs followed for 14 months, 19 (44.2%) passed the initial fit test without having any specific instruction on respirator donning technique. After the initial test, subsequent instruction led to a pass for another 13 (30.2%) of the 43 HCWs, using their original respirators. The remainder required trying other types of respirators to acheive a proper fit. At 3 and 14 months' follow-up, failure rates of 53.5% (23 of 43 HCWs) and 34.9% (15 of 43 HCWs), respectively, were observed. Pass rates of 87.5%-100.0% were observed among regular users.Conclusions.Without any instruction, nearly 50% of the HCWs achieved an adequate facial seal with the most commonly used N95 respirator. Formal fit testing does not predict future adequacy of fit, unless frequent, routine use is made of the respirator. The utility of fit testing among infrequent users of N95 respirators is questionable.

Design Sensitivity Method for Sampling-Based RBDO With Varying Standard Deviation

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Hyunkyoo Cho ◽  
K. K. Choi ◽  
Ikjin Lee ◽  
David Lamb
Keyword(s):  
Standard Deviation ◽  
Design Variable ◽  
Score Function ◽  
Random Variable ◽  
Probability Of Failure ◽  
Design Sensitivity ◽  
Mean Value ◽  
Reliability Based Design ◽  
The Mean ◽  
Sensitivity Method

Conventional reliability-based design optimization (RBDO) uses the mean of input random variable as its design variable; and the standard deviation (STD) of the random variable is a fixed constant. However, the constant STD may not correctly represent certain RBDO problems well, especially when a specified tolerance of the input random variable is present as a percentage of the mean value. For this kind of design problem, the STD of the input random variable should vary as the corresponding design variable changes. In this paper, a method to calculate the design sensitivity of the probability of failure for RBDO with varying STD is developed. For sampling-based RBDO, which uses Monte Carlo simulation (MCS) for reliability analysis, the design sensitivity of the probability of failure is derived using a first-order score function. The score function contains the effect of the change in the STD in addition to the change in the mean. As copulas are used for the design sensitivity, correlated input random variables also can be used for RBDO with varying STD. Moreover, the design sensitivity can be calculated efficiently during the evaluation of the probability of failure. Using a mathematical example, the accuracy and efficiency of the developed design sensitivity method are verified. The RBDO result for mathematical and physical problems indicates that the developed method provides accurate design sensitivity in the optimization process.

Respiratory Protection by Respirators: The Predictive Value of User Seal Check for the Fit Determination in Healthcare Settings

2011 ◽  
Vol 32 (4) ◽  
pp. 402-403 ◽  
Author(s):  
Simon Ching Lam ◽  
Joseph Kok Long Lee ◽  
Linda Yin King Lee ◽  
Ka Fai Wong ◽  
Cathy Nga Yan Lee
Keyword(s):  
Electronic Device ◽  
World Health ◽  
Respiratory Pathogens ◽  
Respiratory Protection ◽  
Healthcare Settings ◽  
The World ◽  
Fit Testing ◽  
Control And Prevention ◽  
Health Organization ◽  
N95 Respirators

The N95 respirator is one type that is recommended by the World Health Organization and the Centers for Disease Control and Prevention (CDC) to prevent inhalation of droplets that may act to transmit respiratory pathogens. However, the reliability of this respirator to prevent transmission is dependent on how well it is fitted to the wearer. For ill-fitting respirators, the average penetration by ambient aerosol was found to be 33%, compared with 4% for well-fitting respirators. Such penetration or leakage may be caused by the gap between the respirator and the wearer's face. Therefore, formal fit testing should be carried out prior to the use of N95 respirators. Quantitative fit testing measures “the adequacy of respirator fit by numerically measuring the amount of leakage into the respirator” using an electronic device.

Mechanical properties of a dissimilar aluminum alloy joint welded by hybrid laser–MIG welding

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744037 ◽  
Author(s):  
Qiuying Wang ◽  
Hui Chen ◽  
Zongtao Zhu ◽  
Yunlong Cui
Keyword(s):  
Mechanical Properties ◽  
Fatigue Strength ◽  
Welded Joint ◽  
Probability Of Failure ◽  
Dissimilar Joint ◽  
Mig Welding ◽  
Welded Structure ◽  
Fatigue Data ◽  
Service Conditions ◽  
The Mean

Two dissimilar Al alloys, 5083-H111 and 6005A-T6, were joined by hybrid laser–MIG welding method. Mechanical properties of the welded joint were investigated and compared. The results show that the tensile strength of the dissimilar joint is 219.8 MPa, 11.7% higher than that of 6005A-T5 joint. After statistical analysis of the fatigue data, the [Formula: see text]–[Formula: see text]–[Formula: see text] curves of the dissimilar joint were obtained. The mean fatigue strength at [Formula: see text] of the dissimilar joint is 112.5 MPa. The fatigue strength at [Formula: see text] of the dissimilar joint for a given 10% probability of failure, at a confidence level of 95%, is 101.4 MPa. The fatigue strength at [Formula: see text] of the dissimilar joint is almost same as that of the 6005A-T6 joint. In welded structure designing, different [Formula: see text]–[Formula: see text]–[Formula: see text] curves should be chosen according to the different service conditions and reliability requirements.

scholarly journals Comparing the fit of N95, KN95, surgical, and cloth face masks and assessing the accuracy of fit checking

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245688
Author(s):  
Eugenia O’Kelly ◽  
Anmol Arora ◽  
Sophia Pirog ◽  
James Ward ◽  
P. John Clarkson
Keyword(s):  
Poor Correlation ◽  
Protective Equipment ◽  
Respiratory Protection ◽  
Factor Scores ◽  
Self Assessment ◽  
Fit Testing ◽  
Assessment Guidelines ◽  
Facial Differences ◽  
N95 Respirators

Introduction The COVID-19 pandemic has made well-fitting face masks a critical piece of protective equipment for healthcare workers and civilians. While the importance of wearing face masks has been acknowledged, there remains a lack of understanding about the role of good fit in rendering protective equipment useful. In addition, supply chain constraints have caused some organizations to abandon traditional quantitative or/and qualitative fit testing, and instead, have implemented subjective fit checking. Our study seeks to quantitatively evaluate the level of fit offered by various types of masks, and most importantly, assess the accuracy of implementing fit checks by comparing fit check results to quantitative fit testing results. Methods Seven participants first evaluated N95 and KN95 respirators by performing a fit check. Participants then underwent quantitative fit testing wearing five N95 respirators, a KN95 respirator, a surgical mask, and fabric masks. Results N95 respirators offered higher degrees of protection than the other categories of masks tested; however, it should be noted that most N95 respirators failed to fit the participants adequately. Fit check responses had poor correlation with quantitative fit factor scores. KN95, surgical, and fabric masks achieved low fit factor scores, with little protective difference recorded between respiratory protection options. In addition, small facial differences were observed to have a significant impact on quantitative fit. Conclusion Fit is critical to the level of protection offered by respirators. For an N95 respirator to provide the promised protection, it must fit the participant. Performing a fit check via NHS self-assessment guidelines was an unreliable way of determining fit.

scholarly journals Dry Heat as a Decontamination Method for N95 Respirator Reuse

2020 ◽  
Author(s):  
Chamteut Oh ◽  
Elbashir Araud ◽  
Joseph V. Puthussery ◽  
Hezi Bai ◽  
Gemma G. Clark ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Healthcare Providers ◽  
Transmissible Gastroenteritis Virus ◽  
Viable Option ◽  
Dry Heat ◽  
Tulane Virus ◽  
Fit Testing ◽  
Transmissible Gastroenteritis ◽  
Dry Heat Treatment ◽  
N95 Respirators

<div> <div> <p>A pandemic such as COVID-19 can cause a sudden depletion in the worldwide supply of respirators, forcing healthcare providers to reuse them. In this study, we systematically evaluated dry heat treatment as a viable option for the safe decontamination of N95 respirators (1860, 3M) before its reuse. We found that the dry heat generated by an electric cooker (100°C, 5% relative humidity, 50 min) effectively inactivated Tulane virus (>5.2-log<sub>10</sub> reduction), rotavirus (>6.6-log<sub>10</sub> reduction), adenovirus (>4.0-log<sub>10</sub> reduction), and transmissible gastroenteritis virus (>4.7-log<sub>10</sub> reduction). The respirator integrity (determined based on the particle filtration efficiency and quantitative fit testing) was not compromised after 20 cycles of 50-min dry heat treatment. Based on these results, we propose dry heat decontamination generated by an electric cooker (e.g., rice cookers, instant pots, ovens) to be an effective and accessible decontamination method for the safe reuse of N95 respirators.<br></p> </div> </div>

Sign in / Sign up

Export Citation Format

Share Document