Development of a rapid, multi-organisational, multi-modal assessment of a newly available disposable respirator.

BACKGROUND: A rapid large-scale evaluation of a newly available duckbill style P2/N95 respirator, the Care Essentials (CE) MSK-003, was required to determine its suitability for deployment into the Victorian healthcare service. The aims of this study were to assess the feasibility of establishing a rapid, multi-organisational and multi-modal evaluation of the respirator, and to investigate whether this respirator would meet the needs of healthcare workers. METHODS: The evaluation was a collaboration among three healthcare organisations - two tertiary hospitals in metropolitan Melbourne and a rural-based hospital. Participants were healthcare workers undertaking their routine fit tests. They were required to complete quantitative fit testing and a usability assessment survey on the CE MSK-003 respirator. The a priori performance criteria were set as fit test pass rate of >70%, plus satisfactory subjective overall comfort and performance assessments, defined as a rating of adequate, good, or very good in >90% of the cohort. RESULTS: A total of 1070 participants completed the multi-modal assessment within a month. Seventy-eight percent of participants passed their quantitative fit test. Over 90% of survey respondents reported that the CE MSK-003 was adequate, good or very good in terms of its overall comfort and performance assessments. CONCLUSION: We demonstrated that a multi-modal evaluation of a new respirator can be rapidly conducted with a high level of participation in a controlled, consistent manner across multiple organisations. The evaluation results of the CE MSK-003 respirator exceeded our predetermined (a priori) minimal criteria, making it suitable for broad distribution to healthcare organisations.

Development of Korean Representative Headforms for the Total Inward Leakage Testing on Filtering Facepiece Respirators.

Background: The lack of headforms that accurately reflect the head characteristics of Koreans and the demographic composition of the Korean population can lead to inadequate FFR testing and reduced effectiveness of FFRs. Method: Direct measurements of 5,110 individuals and 3D measurements of 2,044 individuals, aged between 9 and 69 years, were sampled from the data pool of Size Korea surveys based on the age and gender ratios of the Korean resident demographics. Seven head dimensions were selected based on the ISO 16976-2, availability of Size Korea measurements, and their relevance to the fit performance of FFRs. A principal component analysis (PCA) was performed using the direct measurements to extract the main factors explaining the head characteristics and then the main factors were standardized and remapped to 3D measurements, creating five size categories representing Korean head shapes. Lastly, representative 3D headforms were constructed by averaging five head shapes for each size category. Results: The study identified two main factors explaining Korean head characteristics by the PCA procedure specified in ISO 16976-2 and developed five representative headforms reflecting the anthropometric features of Korean heads: medium, small, large, short & wide, and long & narrow. Conclusion: This study developed representative headforms tailored to the Korean population for conducting total inward leakage (TIL) tests on filtering facepiece respirators (FFRs). The representative headforms can be used for TIL testing by employing robotic headforms to enhance the performance of FFRs for the Korean target population.

Respiratory Protection: Lessons Learned from a Global Pandemic.

The COVID-19 pandemic exposed the limitations of global health systems' abilities to manage the rapid spread of a novel infectious disease, which was exacerbated by shortages of respiratory protective devices and other critical personal protective equipment (PPE). An advisory panel of experienced health-care professionals with backgrounds in Occupational and Environmental Health and Safety (OEHS), Infection Prevention, Nursing, and Clinical Application Specialists convened to discuss challenges and strategies associated with the selection and use of respiratory protective devices as experienced during the first year of the COVID-19 pandemic. This discussion led to the following recommendations: 1) the need for clear communication of alternative respiratory protection selection and use recommendations in accordance with US regulatory and agency guidance; 2) the need for collaboration between Infection Prevention, OEHS, clinical staff, supply chain/materials management, emergency preparedness, executive leadership, and finance; 3) the need for adequate stockpiling, inventory rotation, and diverse respiratory protection options to accommodate the majority of health-care workers; 4) the need for efficient and innovative strategies to communicate evolving regulatory, agency, and facility recommendations and to deliver appropriate training on respiratory protection; and 5) the need for additional research on respiratory protection use - involving filtering facepiece respirators (FFRs) as well as other respirator types designed to be reused - to balance infection prevention best practices with a sustainable process. In conclusion, these considerations may offer guidance and identify areas for research on preparedness, communication, education, and training to enhance the preparation of health-care facilities including community-based health-care organizations for unexpected public health events.

Total outward leakage of half-mask respirators and surgical masks used for source control.

Both respirators and surgical masks (SM) are used as source control devices. During the COVID-19 pandemic, there was much interest in understanding the extent of particle total outward leakage (TOL) from these devices. The objective of this study was to quantify the TOL for five categories of devices: SMs, National Institute for Occupational Safety and Health (NIOSH) Approved N95 filtering facepiece respirators (FFRs) without exhalation valves, NIOSH Approved N95 FFRs with exhalation valves (N95 FFRV), NIOSH Approved elastomeric half-mask respirators (EHMRs) with exhalation valves, and NIOSH Approved EHMRs with an SM covering the exhalation valve (EHMRSM). A benchtop test system was designed to test two models of each device category. Each device was mounted on a headform at three faceseal levels (0% faceseal, 50% faceseal, and 100% faceseal). At each faceseal level, the TOL was assessed at three flow rates of minute ventilations of 17, 28, and 39 L/min. The experimental design was a split-split-plot configuration. Device type, faceseal level, flow rate, and the interaction of device type and faceseal level were found to have a significant effect (p-value < 0.05) on the TOL. This study found that the N95 FFRs without exhalation valves had the lowest mean TOL. The SMs had about three times higher TOL than the N95 FFRs without exhalation valves. The TOL of the N95 FFRV was comparable to that of the SM at 0% and 50% faceseal on average overall conditions, but the N95 FFRV had a significantly higher TOL than the SM at a 100% faceseal. The EHMRs had the highest TOL because of the exhalation valve. Using an SM to cover the exhalation valve did not improve the EHMRs' efficiency in mitigating the TOL. Caution should be exercised when using N95 FFRVs as a source control measure against respiratory activities with heavy work rates, such as performing CPR. Results of this study showed that reduced faceseal leakage for N95 FFRs and SMs improves source control.

Evaluation of properties of elastomeric head straps of filtering facepiece respirators.

Frequent donning and doffing of filtering facepiece respirators (FFRs) can reduce their effectiveness due to the residual deformation of their elastic head straps. This study investigates the loss of elasticity of head straps during repeated use. Five elastomeric tapes were tested as FFR head straps, and their tensile strength was measured using a DU-100 dynamometer after repeated donning and doffing cycles. After eight consecutive uses, the protection factor drops significantly, requiring strap length adjustments to guarantee the specified level of user protection. The maximum tensile force of the elastomeric head straps causes residual elongation, which remains consistent after eight cycles. The study also establishes how strap elongation depends on the force and number of donning and doffing cycles. This knowledge is vital for designing better FFRs. Additionally, the research explores alternative materials for FFR construction to address strap elongation and its effects on performance and comfort.

Health effects of filtering facepiece respirators: Research and clinical implications of comfort, thermal, skin, psychologic, and workplace effects.

Filtering facepiece respirators (FFR's) such as N95s have become widely used in appropriate settings for personal respiratory protection and are increasingly used beyond workplace settings. Concerns about possible adverse effects have appeared in many publications, particularly since the COVID-19 pandemic led to much more widespread use. This paper synthesizes known effects based upon review of publications in PubMed since 1995, addressing effects other than pulmonary and cardiovascular (reviewed elsewhere). Findings: (1) Subjective discomfort is very frequently reported; this includes general discomfort or organ-system-specific complaints such as respiratory, headache, dermatologic, and heat. Research methods are widely divergent, and we propose a taxonomy to classify such studies by methodology, study population (subjects, experimental vs. observational methodology, comparator, specificity, and timeframe) to facilitate synthesis. (2) Objective measures of increased heat and humidity within the mask are well documented. (3) Frequency and characteristics of dermatologic effects have been insufficiently evaluated. (4) Physical mask designs are varied, making generalizations challenging. (5) More studies of impact on work performance and communication are needed. (6) Studies of effect of FFR design and accompanying training materials on ease and consistency of use are needed.

Effect of N95 Filtering Facepiece Respirator on Venous Blood Carbon Dioxide Levels and Hemodynamic Changes in Health Care Workers.

Background: N95 filtering facepiece respirators (FFR) are used by health care workers for prevention of airborne infection, and its use has increased manifolds during COVID-19 pandemic. Prolonged use may result in carbon dioxide (CO2) accumulation, affect hemodynamics, and blood gas values. Although arterial blood gas values accurately measure the blood CO2 levels, venous blood gas values also show acceptable correlation. Aim: To evaluate the physiological impact of N95 FFRs on health care workers, including hemodynamic changes and venous blood levels of CO2 during a period of 6 h. Settings and Design: Prospective observational study in a tertiary care hospital. Methods: The study was conducted on 30 health care workers who performed routine duties while wearing N95 FFR. Venous blood gas values (CO2, pH, and bicarbonate) and vitals (respiratory rate, heart rate, blood pressure, and saturation) were noted at baseline, 2 (T2), and 6 h (T6) after wearing the mask. Discomfort level was also measured on a Visual Analogue Scale (VAS) of 1-10. Statistical Analysis: Repeated measures analysis was done using repeated measures ANOVA or Friedman's test. Group comparisons for continuously distributed data were made using independent sample "t" test or Wilcoxon test. Results and Conclusion: Hemodynamic and blood gas values did not change over time. The VAS for discomfort because of respirator use was 1.33 (1.42) at T2 and 2.77 (1.91) at T6. This was a significant increase in discomfort over time (P = 0.001). About 80% of participants experienced discomfort during this period. N95 FFR did not lead to significant alteration in hemodynamics or change in blood gas values after 6 h of continuous usage. However, discomfort significantly increased over time.

Fit evaluation of NIOSH approved N95 filtering facepiece respirators with various skin protectants: A pilot study.

Widespread disease outbreaks can result in prolonged wear times of National Institute for Occupational Safety and Health Approved N95 filtering facepiece respirators by healthcare personnel. Prolonged wear times of these devices can cause the development of various adverse facial skin conditions. Healthcare personnel have been reported to apply "skin protectants" to the face to reduce the pressure and friction of respirators. Because tight-fitting respirators rely on a good face seal to protect the wearer, it is important to understand if the fit is affected when skin protectants are used. This laboratory pilot study included 10 volunteers who performed quantitative fit tests to evaluate respirator fit while wearing skin protectants. Three N95 filtering facepiece respirator models and three skin protectants were evaluated. Three replicate fit tests were performed for each combination of subject, skin protectant (including a control condition of no protectant), and respirator model. Fit Factor (FF) was affected differently by the combination of the protectant type and respirator model. The main effects of the protectant type and respirator model were both significant (p < 0.001); additionally, their interaction was significant (p = 0.02), indicating FF is affected by the combined effects of the protectant type and respirator model. Compared to the control condition, using a bandage-type or surgical tape skin protectant decreased the odds of passing the fit test. Using a barrier cream skin protectant also decreased the odds of passing the fit test across all models compared to the control condition; however, the probability of passing a fit test was not statistically significantly different from the control condition (p = 0.174). These results imply that all three skin protectants reduced mean fit factors for all N95 filtering facepiece respirator models tested. The bandage-type and surgical tape skin protectants both reduced fit factors and passing rates to a greater degree than the barrier cream. Respirator users should follow respirator manufacturers' guidance on the use of skin protectants. If a skin protectant is to be worn with a tight-fitting respirator, the fit of the respirator should be evaluated with the skin protectant applied before use in the workplace.

A randomised crossover trial of two flat-fold cup respirators: BYD DE2322 N95 versus Care Essentials MSK-002 P2.

BACKGROUND: The use of respiratory protection remains important in protecting health care workers from airborne pathogens such as viruses. Respirator supply is constantly changing with new models regularly becoming available. Health services should consider a broad range of factors when procuring respirators, including the results of quantitative fit testing in a representative sample of the workforce. Subjective comfort factors and compatibility with a variety of workplace tasks, such as suitability for staff use near magnetic resonance imaging (MRI) environments where relevant, should also be considered. This article compares the quantitative fit factors and user assessments for two styles of flat-fold cup respirators, Care Essentials (CE) MSK-002 P2 and BYD DE2322 N95. METHODS: Quantitative fit tests (QNFT) were performed on 300 participants on each model of respirator in this randomised crossover trial. Participants then completed a questionnaire on their assessments of each respirator. RESULTS: The Care Essentials MSK-002 had a significantly higher quantitative fit test pass rate than the BYD DE2322 (57% vs 18%, p < 0.001). There was no concordance between fit test pass rates for each model. Additionally, the Care Essentials MSK-002 achieved significantly higher scores on each of the responses in the subjective usability survey. CONCLUSION: It is recommended that the Care Essentials MSK-002 be made available for health care use due to higher QNFT pass rates, higher subjective usability assessment scores, plus its potential for use in MRI environments when compared to the BYD DE2322.

Health effects of filtering facepiece respirators: Systematic review of pulmonary and cardiovascular effects.

Filtering facepiece respirators (FFRs) were introduced to protect the wearer by removing small particles from inspired air. FFRs are now also used to reduce the spread of transmissible agents from the wearer and are worn outside traditional healthcare and other workplaces. The COVID-19 pandemic increased concerns about potential adverse effects on wearers. A PUBMED query retrieved articles through June 2022. Abstracts and selected full-text articles were systematically reviewed by the authors. This article focuses upon cardiopulmonary physiologic effects (e.g., ventilation, CO2 elimination, oxygen uptake, and respiratory control) with emphasis upon current and potential research methods as well as summarizing results. 1985 records were identified, of which only 26% were published before 2020. FFR effects on CO2 elimination appear more likely to be significant than effects on oxygenation or cardiovascular function. While FFRs appear well tolerated by healthy persons, more research is needed for those with pulmonary or cardiac disorders, and for children. Many traditional pulmonary exercise study methods require special care when applied to filtering facepiece respirators. Studying additional parameters may explain the paradox of many subjective discomfort reports despite very limited physiologic effects.

A Medical Nebulizer as a Substitute for the OSHA-Approved Nebulizer for Qualitative Fit Testing of Respirators During the Respiratory Infectious Pandemics: An Experimental Feasibility Study.

OBJECTIVE: The qualitative fit testing procedure would be challenging due to severe shortages, high cost, and unavailability of commercial fit test kits in the marketplaces during pandemics of respiratory infectious diseases. Assessment of alternatives for commercial fit test kits to be prepared for emergencies is critically required. This study aimed to investigate the feasibility of an alternative of the Accumed NF60 nebulizer for the Occupational Safety and Health Administration (OSHA)-approved Allegro nebulizer. METHODS: Thirty-two participants were randomly allocated to 6 filtering facepiece respirators (FFRs). They were qualitatively fit tested by both manual Allegro and automated Accumed NF60 nebulizers. RESULTS: There was no statistically significant difference between the Allegro and Accumed NF60 nebulizers by passing rates. The odds for passing fit testing using the Accumed NF60 nebulizer was similar to that of the Allegro one (odds ratio=1.0, 95% confidence interval [0.58-1.74]). CONCLUSIONS: The Accumed NF60 nebulizer could be used as a cost-benefit substitute for the standard fit test nebulizers in the pandemic situation where there is a shortage and difficulty of access. It is more convenient, decreases the time investment, and reduces the contact stress in the operators' hands as it does not require squeezing the nebulizer bulb frequently. The test solutions' preparation and fit testing procedures on many personnel are more straightforward, efficient, and hygienic than the Allegro one.

Review and demonstration of equations applied to models of filtering facepiece respirator particle capture efficiency.

The use of filtering facepiece respirators (FFRs) of various types increased dramatically by both workers and the public during the ongoing COVID-19 pandemic. This increased use has, likewise, instigated a proliferation of research on the qualities of FFRs. An aspect of FFR development and optimization involves the use of mathematical models that predict filter efficiency based on various filter characteristics while also considering a number of particle capture forces. An evaluation of current literature failed to identify a publication that provides a comprehensive assessment of the models developed to predict filter efficiency. The purpose of this review was, therefore, to describe models developed to include the forces associated with diffusion, interception, impaction, and electrostatic attraction as they contribute to the efficiency of an entire filter. The literature review was augmented with figures created with the use of many of the models discussed to compare different models of the same force as well as to illustrate the influence of electrostatic forces on overall filter efficiency.

Effect of UV-C germicidal irradiation (UVGI) on the structural integrity of N95 and KN95 respirators.

This study focuses on reprocessing a group of filtering facepiece respirators (FFR) using ultraviolet germicidal irradiation (UVGI). The aim is to explore the possibility of disinfecting selected KN95 FFRs, in comparison with the N95 FFRs, and assess their viability for reusage. For this purpose, five models of unused N95 and KN95 FFR models obtained from the hospital were exposed to UV-C light using a customized UVGI chamber. The material integrity of treated FFRs was examined in terms of particle penetration and strap tension. The surface morphology of all models is inspected to determine the visible changes of each FFR upon exposure to 1-100 cycles (1 cycle is equivalent to 1 J/cm2 UV dose). The penetration test results indicate that the physical properties of the KN95 and N95 FFRs remain within permissible limits despite being reprocessed by up to 100 cycles (100 J/cm2). Using a microscope, the physical observations also reveal that no visible damage can be seen even after 100 J/cm2 exposure. Apart from the filter bodies, the tension of each strap was also found to not be significantly affected by UV radiation by at least 10 disinfection cycles (10 J/cm2). This confirms that KN95, as well as N95 FFRs, can be subjected to UV treatment as a means of disinfection.

Testing of a mobile heating facility to sanitize N-95 respirators against an enveloped respiratory virus.

In the spring of 2020, the Alaska Native Tribal Health Consortium (ANTHC) designed and built a sanitizing treatment system to address shortages of filtering facepiece respirators (FFRs). The design criteria included sanitizing large numbers of FFRs, repeatedly achieving FFR fit test requirements, and deactivating enveloped respiratory viruses, such as SARS-CoV-2. The outcome was the Mobile Sanitizing Trailer (MST), a 20 by 8-foot modified trailer designed to process up to 1,000 FFRs during a standard heat cycle. This paper reports on the MST's ability to: (1) sustain a target temperature, (2) produce tolerable conditions for FFRs as measured by fit factor and (3) successfully deactivate an infectious model virus. We found that the MST reliably and uniformly produced 75 degrees Celsius in the treatment chamber for the prescribed periods. Quantitative analysis showed that the FFRs achieved acceptable post-treatment fit factor even after 18, 60-minute heat cycles. Finally, the treated FFR materials had at least a log 3.0 reduction in viral RNA and no viable virus after 30, 60 or 90 minutes of heat treatment. As a sanitizing treatment during supply shortages, we found the MST a viable option for deactivation of virus and extending the usable life of FFRs.

Reusability of P3 Facial Filter in a Pandemic Emergency: A 3D Analysis of Filter Microstructure with X-ray Microtomography Images after Dry Heat and UV Sterilization Procedures.

OBJECTIVE: Our goal is to evaluate the effects of heat and ultraviolet (UV) irradiation on P3 facial respirator microstructure. INTERVENTION: P3 facial filters were exposed to dry heat and UV sterilization procedures. METHODS: P3 facial filter samples underwent a standardized sterilization process based on dry heat and UV irradiation techniques. We analyzed critical parameters of internal microstructure, such as fiber thickness and porosity, before and after sterilization, using 3D data obtained with synchrotron radiation-based X-ray computed microtomography (micro-CT). The analyzed filter has two inner layers called the "finer" and "coarser" layers. The "finer" layer consists of a dense fiber network, while the "coarser" layer has a less compact fiber network. RESULTS: Analysis of 3D images showed no statistically significant differences between the P3 filter of the controls and the dry heat/UV sterilized samples. In particular, averages fiber thickness in the finer layer of the control and the 60° dry heated and UV-irradiated sample groups was almost identical. Average fiber thickness for the coarser layer of the control and the 60° dry heated and UV-irradiated sample groups was very similar, measuring 19.33 µm (±0.47), 18.33 µm (±0.47), and 18.66 µm (±0.47), respectively. There was no substantial difference in maximum fiber thickness in the finer layers and coarser layers. For the control group samples, maximum thickness was on average 11.43 µm (±1.24) in the finer layer and 59.33 µm (±6.79) in the coarser layer. Similarly, the 60° dry heated group samples were thickened 12.2 µm (±0.21) in the finer layer and 57.33 µm (±1.24) in the coarser layer, while for the UV-irradiated group, the mean max thickness was 12.23 µm (±0.90) in the finer layer and 58.00 µm (±6.68) in the coarser layer. Theoretical porosity analysis resulted in 74% and 88% for the finer and coarser layers. The finer layers' theoretical porosity tended to decrease in dry heat and UV-irradiated samples compared with the respective control samples. CONCLUSIONS: Dry heat and UV sterilization processes do not substantially alter the morphometry of the P3 filter samples' internal microstructure, as studied with micro-CT. The current study suggests that safe P3 filter facepiece reusability is theoretically feasible and should be further investigated.

Review of the Effect of Continuous Use and Limited Reuse of N95 Respirators on Respirator Fit.

Background: Coronavirus disease 2019 (COVID-19) has led to severe shortages of filtering facepiece respirators (FFRs). As a result, extended use, limited reuse, and FFR decontamination have been utilized to extend the life of single-use FFRs. Although some studies have raised concerns that reuse could affect the FFR's ability to form a seal, no comprehensive literature review of the effect of extended use or limited reuse on FFR seal exists. Objective: The goal of this review was to assess the effect of extended use and reuse on respirator fit, with and without decontamination. Methods: Searches of PubMed and Medrxiv yielded 24 papers that included assessment of fit after extended use or limited reuse on a human. One additional handpicked paper was added. Results: Studies report a wide variation in the number of donnings and doffings before fit failure between different models of respirators. Additionally, while seal checks lack sufficient sensitivity to reliably detect fit failures, individuals who failed fit testing were often able to pass subsequent tests by re-positioning the respirator. Even with failure, respirators often maintained a substantially higher level of fit than a surgical mask, so they may still provide a level of protection in crisis settings. Conclusion: Based on currently available data, this literature review was unable to establish a consensus regarding the amount of time a respirator can be worn or the number of uses before fit failure will occur. Furthermore, variations in reuses before fit failure between different models of N95 respirators limit the ability to offer a comprehensive recommendation of greater than one reuse or a specific amount of wear time.

Randomized crossover study comparing quantitative fit tests between Trident™ and 3M™ Aura™ N95/P2 respirators.

BACKGROUND: Various styles of N95/P2 filtering facepiece respirators (FFRs) have been used by Australian healthcare workers (HCWs) during the COVID-19 pandemic. This is usually driven by the national stockpile availability. Many studies demonstrate three-panel flat-fold N95/P2 FFRs have higher quantitative fit test (QNFT) pass rates than other FFR styles. This prospective randomized crossover study utilized QNFT to evaluate the performance of the new three-panel flat-fold FFR, the Trident™ P2 respirator compared to the previously most effective model, the 3M™ Aura™ 9320A + N95 respirator. METHODS: We recruited 500 participants who completed online training and QNFT on both respirators. The order of the respirator being examined first was randomly allocated. The primary outcome was the QNFT pass rate. Secondary outcomes included the overall fit factor, the individual fit factor for each exercise, and the first-attempt QNFT pass rate. RESULTS: We found that both the overall and first-attempt QNFT pass rates of the Trident P2 respirator were significantly higher than the 3M Aura (99.2% vs 92.6%, p < 0.001; and 92.6% vs 76.4%, p < 0.001 respectively). The overall fit factor and the individual fit factor were also significantly higher for the Trident FFR than the 3M Aura. CONCLUSIONS: This study is the first to report hospital-based QNFT results of the Trident FFR, demonstrating very high first-time and overall pass rates. Our findings are consistent with previous research showing very high QNFT pass rates with three-panel flat-fold FFRs. These findings are important for pandemic preparedness with respect to the stockpiling and safe utilization of N95/P2 respirators.

Review of aerosolized hydrogen peroxide, vaporized hydrogen peroxide, and hydrogen peroxide gas plasma in the decontamination of filtering facepiece respirators.

BACKGROUND: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to over 170?million cases worldwide with over 33.2?million cases and 594,000 deaths in the US alone as of May 31st, 2021. The pandemic has also created severe shortages of personal protective equipment, particularly of filtering facepiece respirators (FFRs). The Centers for Disease Control and Prevention (CDC) has issued recommendations to help conserve FFRs, as well as crisis standards, including four criteria required for decontamination of the traditionally single use respirators. This review is designed to provide an overview of the current literature on vaporized hydrogen peroxide (vHP), hydrogen peroxide gas plasma (HPGP), and aerosolized hydrogen peroxide (aHP) with respect to each of the four CDC decontamination criteria. METHODS: PubMed and Medrxiv were queried for relevant articles. All articles underwent a title and abstract screen as well as subsequent full text screen by two blinded reviewers if indicated. RESULTS: Searches yielded 195 papers, of which, 79 were found to be relevant. Of those, 23 papers presented unique findings and 8 additional articles and technical papers were added to provide a comprehensive review. Overall, while there are potential concerns for all 3 decontamination methods, we found that vHP has the most evidence supporting its use in FFR decontamination consistent with CDC recommendation. CONCLUSIONS: Future research is recommended to evaluate biological inactivation and real world fit failures after FFR reuse.

The effects of face mask specifications on work of breathing and particle filtration efficiency.

The outbreak of the ongoing coronavirus disease 2019 (COVID-19) pandemic has led to the recommended routine use of face masks to reduce exposure risk. In this study, the increase in work of breathing (WOB) imposed by face masks is theoretically studied for both normals and patients with obstructive and restrictive lung diseases at different levels of activity. The results show a significant increase in WOB due to face masks, which is more severe in higher activity levels. The added WOB is considerable during physical activity and may be intolerable for patients with preexisting lung disease and may contribute to inspiratory muscle fatigue and dyspnea. Moreover, in this study, the effects of the physical properties of a fibrous medium, including thickness, porosity, and fiber diameter, are analyzed on the particle filtration efficiency (PFE) and the added WOB. The relations between the physical properties of the fibrous medium and the added WOB and the PFE are shown on some contour plots as a quick and simple tool to select the desired physical properties for a single layer filter to ensure that the added WOB is comfortable while the PFE is sufficiently high.