Respiratory protective devices are widely used to reduce occupational exposure to hazardous airborne particles. However, the protective performance of respirators can deteriorate during real-world use due to poor fit, even if they were initially well-fitted. The Exposure Protection Integrated Communicator (EPIC) is a recently developed portable system that is equipped with dual optical particle counters (OPCs) to measure aerosol concentrations inside and outside a respirator, enabling real-time fit monitoring in a real-world workplace. Since OPC performance is sensitive to humidity, this study evaluated two drying methods, Nafion tubing and a desiccant membrane (DM) dryer, for their effectiveness in reducing relative humidity and minimizing particle loss within the EPIC device. Experiments were conducted to characterize the efficiency of relative humidity (RH) reduction and particle transmission across a range of particle sizes (0.3-10 µm). Nafion tubing showed ~25% desiccant efficiency at ambient RH ≤ 40%, whereas the DM dryer achieved >50% efficiency at higher RH levels. However, both dryer units exhibited particle losses, particularly of larger micron-sized particles, with the DM dryer exhibiting >90% loss for particles >5 µm. These findings highlight the trade-offs between RH control and particle preservation in a field-deployable aerosol monitoring system. Nafion tubing has the potential for applications requiring real-time respirator monitoring under moderate RH environmental conditions. This study provides critical design insights for optimizing OPC-based systems like EPIC, where maintaining both sensor accuracy and particle transmission is essential.
ABSTRACT Introduction: Respirator fit is significantly impacted by facial features, which can differ greatly due to the diversity of race and ethnicity. In our previous study, we reported on a “Specified PCA panel for Japanese” that better represented the Japanese facial features, along with five corresponding digital headforms. Objective: This report describes the construction of digital headforms into “soft headforms” with softness and elasticity parameters similar to a human face, and evaluates their respirator fit. Methods: Using a skin softness and elasticity meter, the skin deformation curves at 10 facial points on each subject were measured to obtain softness and elasticity parameters. Subsequently, based on the information obtained from the subject test, five soft headforms were developed using an elastic material. Finally, the fit factors of the soft headforms for the six respirator models were compared with those of hard headforms (plastic) with identical shapes. Results: In the subject test, the softness parameter values varied across various points, including the cheek and chin, whereas the elasticity parameter values were almost constant, regardless of the points. The softness and elasticity parameters of the five soft headforms were also measured, and confirmed that both parameters were close to the target value ranges based on the subject test. For the fit factor evaluation, while the fit factors of all respirator models on hard headforms were below 100, soft headforms could achieve 100 or more, depending on the combination of headform type and respirator model. Conclusion: The soft headforms showed higher fit factors, confirming the efficacy of elastic material for respirator fit. However, further research is required to assess the effect of headform type and respirator model on fit factors by comparing subject groups in the corresponding facial category in the Specified PCA panel for Japanese.
Introduction: A National Academies of Science study details the need for respiratory protection for the public. However, assistance with facepiece selection, fit, and use, is rarely available in the community resulting in suboptimal use of facepieces. This study evaluated filtering facepiece respirators (FFR) and a barrier face covering in unassisted conditions. Objective: This study compares the effectiveness of diverse facepieces in blocking aerosols during unassisted use, by employing the ASTM F3502 Leakage Assessment, which adopts the ASTM F3407 fit capability test method with modifications designed to model unassisted donning. Methods: An ASTM F3502-2021 Standard Specification for Barrier Face Coverings Leakage Assessment was conducted with a TSI Portacount 8048, for facepiece models worn by participants given no coaching or assistance. The F3502 method follows ASTM F3407 Standard Test Method for Respirator Fit Capability but with modifications to account for unassisted facepiece use outside of a respiratory protection program. The performance target, a leakage ratio of 10, would reflect 90% blocking of particles. Two FFR models and a reusable Barrier Face Covering were studied on 59 participants. Results: The facepieces performed above the target performance level, indicating, on average, more than 90% protection, with one FFR achieving 94% and the reusable barrier face covering achieving 93%. Conclusion: Disposable respirators and reusable face coverings can be compared quantitatively using the Leakage Assessment test method in ASTM F3502, which provides a critical tool for understanding and improving unassisted use of facepieces by the public.
Efficiency of respiratory protective equipment (RPE), which is essential for protecting workers and the general public from various airborne hazards, largely relies on the quality of the face seal. The latter is typically assessed using a US OSHA-accepted eight-exercise quantitative fit testing (QNFT). This study aimed at evaluating the performance of a newly developed respirator fit testing apparatus, the Sibata MT-11D, by comparing it with the reference PortaCount® 8048 across three respirator types: N95 filtering facepiece respirators (FFRs), P100 FFRs, and half-face elastomeric respirators. Twenty-six adult participants, representing a diverse range of facial dimensions, were recruited and trained in proper donning and doffing procedures to ensure standardized use of the respirators. Overall fit factors (FFs) were determined using the MT-11D and PortaCount® operating in parallel. The collected data were analyzed in accordance with American National Standards Institute (ANSI) guidelines to ensure statistical validity, including the application of exclusion zones and evaluation of test sensitivity, specificity, predictive values, and Kappa coefficients. Strong correlations were observed between the MT-11D and PortaCount® across all respirator types, with R² values of 0.93, 0.99, and 0.94 for N95 FFR, P100 FFR, and half-face elastomeric respirators, respectively. The test statistics met or exceeded ANSI thresholds, demonstrating the accuracy, reliability, and reproducibility of the MT-11D. These findings demonstrate that the MT-11D is a suitable alternative to other quantitative fit testers, capable of providing robust fit assessment for a variety of respirators in occupational and public health applications, thereby contributing to improved respiratory protection.
The unique physiological and developmental characteristics of children make them very susceptible to inhalation hazards. Almost all respiratory protective devices (RPDs) are designed for adult occupational use and rarely address the needs of pediatric populations. Studies in National Academies of Sciences, Engineering, and Medicine (NASEM) proceedings indicate that, while respirators can reduce children’s exposures, they are generally less effective than when designed for, and properly used by, adults (NASEM, 2022). Challenges such as lower inspiratory and expiratory pressures, discomfort due to filtration (breathing) resistance, and cognitive limitations in younger children make respirator usage more complex. In addition, the facial dimensions vary greatly. These factors highlight the necessity for specialized design frameworks that ensure safety, usability, and accessibility (NASEM, 2022). The International Society for Respiratory Protection (ISRP) has been a collaborating partner with the FACE-UP (Factors Affecting Childhood Exposures to Urban Particulates) project, which aimed to establish the efficacy of children’s use of respiratory protection to reduce their exposure to particulate air pollution. As part of this effort, ISRP and FACE-UP conducted two workshops in 2024 to give an overview of existing information and identify knowledge gaps surrounding respiratory protection for children. The intent of the workshops was to address priorities for the development of regulatory frameworks, including recommendations for design and performance criteria, the design of a global consensus standard, manufacturing and distribution considerations, product registration requirements, selection and use guidance, education and training, ethical considerations, and recommended next steps. This White Paper lays out these recommendations. A worldwide standard for pediatric respirators should be established under the leadership of a global consensus standard development organization, such as the International Organization for Standardization (ISO) or ASTM International, ensuring adaptability to diverse populations and regional needs. This requires standardized testing protocols that incorporate child-specific physiological and ergonomic considerations; regional flexibility within global standards to account for variable demographics and environmental exposures, and alignment with existing national regulatory frameworks to streamline certification and adoption. Developing pediatric RPDs necessitates a nuanced approach which integrates filtration, breathability, fit, comfort, and accessibility. By leveraging insights from recent research and establishing age-appropriate performance standards, manufacturers can create effective solutions tailored to children’s respiratory protection needs. Additionally, comprehensive regulatory frameworks should be developed, which include guidance for families on when, where, and how respirators should be used by children, including references to the worldwide consensus standard as part of clear selection guidance. Continued interdisciplinary collaboration will refine these guidelines and enhance protection for pediatric populations amid evolving health and safety challenges.
Introduction: In the case of exposure to harmful substances and the use of a filtering facepiece respirator (FFR) to protect workers, it is important to know the performance of commercial FFR. In previous studies, the authors investigated a series of parameters on the effectiveness of a standard N95 FFR: particle diameter, airflow rate intensity, breathing simulation, time of use, relative humidity. It remains uncertain whether previous results can be extrapolated to all commercial FFRs. Objective: To determine whether previous conclusions apply to other FFRs, different models were selected for evaluation. The initial penetrations are then measured in order to compare the penetrations according to the differences between the FFRs. Methods: To do so, an experimental setup generates NaCl nanoparticles before introducing them into a test chamber containing the FFR and filtered at a constant flow of 85 L/min. It allows to obtain the penetration as a function of the particle diameter from 10 to 200 nm, as well as the pressure drop. Results: The benchmark established in this study confirms that penetration measurements align with previously reported values. All tested FFRs exhibit comparable trends: the most penetrating particle size (MPPS) remains between 30 and 50 nanometers, with penetration decreasing for particles smaller or larger than this range. Conclusion: The results obtained thus indicate that the outcome achieved previously for the standard N95 FFRs and can be extrapolated to the other FFRs presented here.
Introduction: The poor fit of respiratory face masks was a contributing factor to infec-tion during the COVID-19 pandemic. As there is no sizing system for FFP2 face masks according to the relevant European standard, product sizes can vary unpre-dictably. This circumstance has made it difficult to select tight-fitting face masks, par-ticularly for people with smaller, narrower faces. Objective: To investigate the actual size range of low-cost vertical flat-fold face masks that dominated the market during the COVID-19 pandemic and beyond. Methods: Fifty-two one size products and 19 products with generic sizes (XS-XL) from 58 manufacturers were scanned in two dimensions and digitally measured. Results: The one size products showed a rather narrow size distribution, since they only covered the upper third of the total size range found, thereby corresponding to size L (large). Although the average dimensions of products in generic sizes showed a systematic increase from size XS to XL, the variations observed within each size cat-egory call into question any kind of common database. Conclusion: Given the results presented, it seems unlikely that low-cost one size face masks can effectively cover a wider range of facial dimensions. To improve the selec-tion of tight-fitting FFP2 face masks, either specific sizes should be defined by the relevant standardization bodies or manufacturers should describe the facial dimen-sions of the target group for which their products are intended. At the very least, siz-ing metrics should be provided so that consumers can identify appropriate face masks through repeated testing. Premium products with complex designs and additional seals usually provide the required tight fit over a wide range of facial dimensions, but recent experience has shown that these products are difficult to obtain in times of market shortages.
Some respiratory protective devices (RPDs) such as filtering facepiece respirators (FFRs) are manufactured in discrete sizes, with some models being limited in accommodating the fit of some gender and race combinations. This study presents the development of a custom-fit RPD which conforms to a user’s facial features and flexes and moves with facial movements during use. Our design also integrates a pressure-sensing network, which continuously monitors fit and will alert the user when the fit is compromised. In this final part of the three-part series, we transform the digital prototypes of the custom-fit RPD presented in Parts I and II to physical prototypes through 3D printing (additive manufacturing) using silicone-based elastomers. We identify the key material properties required for creating the physical prototypes. Based on a comparative analysis of commercially available materials, we select two of them and create prototypes of the RPD using two different commercial 3D printers. We then demonstrate the responsiveness of the custom-fit RPD to changes in facial profile during use from natural (neutral facial expression with mouth closed) to talking, to smiling, and to yawning, and the quantification of the changes in pressure at the faceseal by the continuous fit monitoring system through an App running on an Android tablet. With the realization of the successful custom-fit RPDs using the developed methodology, we lay the foundation for providing respiratory protection, and improved source control, to the full spectrum of individuals in the United States public including children, for whom FFRs options are currently limited.
Filtering facepiece respirators (FFRs) are manufactured in discrete sizes, with some models being limited in accommodating the fit of some sex and race combinations. This study presents the development of a custom-fit respiratory protective device (RPD) which conforms to a user's facial features and flexes and moves with facial movements during use. Our design also integrates a pressure-sensing network, which continuously monitors fit and will alert the user when the fit is compromised. In this Part II of the three-part series, we design and incorporate a continuous fit monitoring system in the RPD designed in Part I to enhance its role in protecting users from inhalation hazards in an effective manner during its use. The fit monitoring system comprises a fabric-based sensor network integrated into the RPD and an Android-based App designed to alert the user when the pressure at the faceseal falls below a given threshold established during the initial configuration of the RPD for the user. We also develop algorithms for the incorporation of the sensor slots and data buses into the custom-fit RPD using the Taxonomy of Landmarks defined in Part I. We enhance the structure developed in Part I to secure the sensor network during the use of the RPD. We develop algorithms for customizing a fastening hub to suit the head profiles of individuals to enable them to don the RPD quickly, easily, effectively, and in a repeatable manner. We demonstrate the successful application of the total design methodology by creating digital prototypes for three individuals with different facial profiles and make further advances to our goal of ensuring equitable respiratory protection for all including children, for whom RPDs are currently limited.
Few studies have been done to investigate the ability of tight-fitting Powered Air Purifying Respirators (PAPRs) to compensate for face seal leaks, and this project developed an innovative approach to evaluating the protection level of PAPRs when the face seal is compromised. For this study, a cross sectional area of seal leaks versus a reduction in protection factor was used to evaluate the potential effect of a simulated leak on PAPRs during over breathing whilst exercising on a bicycle. It was found that the ability of PAPRs to maintain positive pressure cannot be assessed by constant-flow measurement or by the sinusoidal profile of a breathing machine, however it can be assessed by collecting pressure data from inside the mask during TIL human exercise and analysing the cumulative “weight” of the negative-pressure events. Furthermore, the pressure fluctuation representing Work of Breathing does not show as much variation as the variation of the mask leakage, and some PAPRs have even larger pressure variation in comparison to the negative-pressure masks. It was concluded that the PAPRs tested are not so much breathing-assisting respirators as they are mask-leak compensation devices. PAPRs can provide additional face seal protection to the wearer in the event of mask leakage. Some PAPRs significantly outperformed the Air Purifying Respirators (APRs) (by 1900 times) whilst others minimally exceeded the protection of APRs (by 2 times) with a greater pressure variation (caused by the breathing resistance due to motor/impeller inertia) during the breathing cycles at high workloads.
Annual fit testing, as mandated by the Occupational Safety and Health Administration (OSHA), is required for every employee in the United States who wears a tight-fitting respirator. Considering the volume of fit tests performed annually, a reduced test duration would prove advantageous. This study evaluated two shortened fit test protocols for full-facepiece respirators using Controlled Negative Pressure (CNP) technology. This study is a continuation of a previous study that evaluated the effectiveness and accuracy of the same shortened protocols for elastomeric half-mask respirators. The new protocols are a modification of the OSHA-accepted CNP REDON protocol, titled modified-REDON and brief-REDON, and would reduce the test duration to 1.9 and 1.2 minutes, respectively. The overall fit factor measured using the new methods was compared to that of a reference method following the “Criteria for Evaluating New Fit Test Methods” outlined in American National Standards Institute (ANSI) publication Z88.10-2010, Annex A2. Sequential paired fit tests were performed on human test participants during the same respirator donning. Fit factors were measured using the Quantifit® CNP instrument. The exercise set for the reference method was the standard OSHA 8-exercise protocol for CNP-based instruments. The exercise set for the modified-REDON method included facing forward, facing parallel to the floor, head shaking, and two redon exercises. The results demonstrated that the sensitivity of the modified-REDON method (1.00) was greater than the requirement (>0.95) defined in ANSI Z88.10-2010. The modified- REDON method also met the test specificity, predictive value of a pass, predictive value of a fail, and kappa statistic recommended by ANSI. The brief-REDON method evaluated the effect of reducing the number of redon exercises from two to one. The results demonstrated the sensitivity (0.99) remained essentially unchanged indicating removal of the second redon step would not negatively impact the ability of the new method to effectively identify poorly fitting respirators.
Background: Throughout the COVID-19 pandemic, respirators and masks have been recommended, and in many instances mandated, across the globe. The National Institute for Occupational Safety and Health (NIOSH) is the main regulatory agency for respirators in the United States. Currently, the TSI 8130A and the ATI 100Xs machines are utilized for respirator filtration and resistance testing, but both are costly and valued upwards of U.S. $100,000. Objective: The goal of this study was to develop a low-cost respirator evaluation mechanism (LREM) to evaluate respirators as well as masks and other materials for filtration efficiency (FE), inhalation resistance (IR), and exhalation resistance (ER). The aim of this mechanism is to support the development of innovative and alternative respirator and mask designs and materials with an inexpensive and more accessible testing device. Methods: The methods and design for the LREM were based on U.S. 42 CFR Part 84 Subpart K and the corresponding standard testing procedures for air-purifying respirators published by NIOSH. The LREM itself is constructed from available components and functions to deliver sodium chloride (NaCl) aerosols in a stream of airflow to challenge a respirator or mask sample. A variety of respirators, masks, and materials were tested on both the LREM and an ATI 100Xs to assess how the LREM compares to one of the current evaluation devices. Results: Overall, the LREM offers promise as an accessible and low-cost testing option. The LREM can accurately determine the pass/fail status of the N95 filtering facepiece respirators (FFRs) samples tested for both IR and FE based on NIOSH criteria. For all respirators, masks, and materials tested, the LREM and ATI 100Xs both show similar performance trends as seen by rankings of sample performance. Conclusions: The LREM was constructed for approximately 6% the cost of current respirator testing gold standards. The LREM could serve as a first pass testing method done before official respirator testing (e.g. per NIOSH mandated testing) and can be particularly useful in the development of innovative respirators and masks or in testing alternative materials for each.
A manikin fit test method developed by the Center for Disease Control and Prevention's (CDC) National Institute of Occupational Safety and Health (NIOSH) has been proposed as an alternative to fit testing with human subjects. The advantages of a manikin fit test method over actual fit testing are that it does not require human subjects which can be resource intensive, and hence easier to implement. At the beginning of coronavirus 2019 (COVID-19) pandemic, although early studies showed that manikin fit can be maintained after several decontamination cycles, real world evidence obtained using human subjects revealed that the N95 respirators failed only after a few decontamination cycles. The goal of this article was to make modifications to the NIOSH's manikin fit-test method so it can mimic real world performance of N95 respirators better. After making modifications to this method, we then investigated the effect of long-term wear after donning of the respirators, repeated donning and doffing, as well as decontamination methods (i.e. autoclaving and microwave generated steam) on the fit factor. Averaging the overall manikin fit factor across all scenarios, our modified method overpredicted overall fit factor by only 7 % and 14 % compared to adult human subjects using a breathing routine that included simulated heavy breathing rates of 85, and 70 Liters/minute, respectively. In addition, a constant flow produced similar results as cyclic flow using a breathing simulator. The modified test method also offered the following additional insights into reuse of respirators during future pandemics - when reused within a single work shift, more than 5 donnings should be avoided; and microwave generated steam may be a more viable option for decontaminating N95 respirators compared to autoclaving for a single decontamination cycle.
Annual fit testing, as mandated by the Occupational Safety and Health Administration (OSHA), is required for every employee in the United States who wears a tight-fitting respirator. Considering the volume of fit tests performed annually, a reduced test duration would prove advantageous. This study evaluated a shortened fit test protocol for elastomeric half-mask respirators using Controlled Negative Pressure (CNP) technology. The new protocol is a modification of the OSHA-accepted CNP REDON protocol and would reduce the test duration to 1.9 minutes. The overall fit factor measured using the new method was compared to that of a reference method following the “Criteria for Evaluating New Fit Test Methods” outlined in American National Standards Institute (ANSI) publication Z88.10-2010, Annex A2. Sequential paired fit tests were performed on human test participants during the same respirator donning. Fit factors were measured using the Quantifit® CNP instrument. The exercise set for the reference method was the standard OSHA 8-exercise protocol for CNP-based instruments. The exercise set for the modified-REDON method included facing forward, facing parallel to the floor, head shaking, and two redon exercises. The results demonstrated that the sensitivity of the shortened method (0.98) was greater than the requirement (>0.95) defined in ANSI Z88.10-2010. The new method also met the test specificity, predictive value of a pass, predictive value of a failure, and kappa statistic recommended by ANSI. This study also evaluated the effect of reducing the number of redon exercises from two to one, further decreasing the test duration to 1.2 minutes. The results demonstrated the sensitivity (0.98) remained unchanged indicating removal of the second redon step would not negatively impact the ability of the new method to effectively identify poorly fitting respirators.
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.
uring the COVID-19 pandemic, many healthcare facilities instituted the continuous use of N95 filtering facepiece respirators to provide respiratory protection from SARS-CoV-2. These disposable, single use respirators soon were in critical shortage. However, due to their high demand and limited availability, healthcare workers were reusing them and, in some cases, had no access to supplies. This created an urgent problem since healthcare workers are continually being exposed to hazardous pathogens. Therefore, it was pertinent to find suitable replacements for N95 FFRs. Powered Air-Purifying Respirators and Elastomeric Half-Mask Respirators were and continue to be recommended by the Centers for Disease Control and Prevention for respiratory protection. These respirators and any respirator used in United States workplace settings, require National Institute for Occupational Safety and Health approval. The objective of this review is to focus on the ergonomics of these respirators in healthcare settings and documented user concerns. To achieve this, databases such as Summon, MEDLINE, Emcare, and CINAHL were used, searching key words to gather information. During this literature study, it was found that while comfort is subjective, there are documented stressors related to breathability and thermal environment that play a major role. Powered Air-Purifying Respirators have little breathing resistance and are generally cool because of the blower device. Elastomeric Half-Mask Respirators are similar to N95 FFRs, in that a hot and humid microclimate can build up inside the respirator and over time, breathing resistance can increase, an issue because they are negative pressure respirators. Powered Air-Purifying Respirators, Elastomeric Half-Mask Respirators, and N95 FFRs can impair senses, negatively affecting communication, as well as diminished field of vision with full-face respirators. Nonetheless, despite these ergonomic barriers, healthcare workers are likely to condone these issues during high-risk conditions for adequate respiratory protection. Even so, there are a considerable number of gaps in the literature on Elastomeric Half-Mask Respirators, more so than for other respirators.
During public health emergencies such as an influenza pandemic, disposable filtering facepiece respirator (FFR) shortages have a significant impact on the national response, affecting many types of workplaces that rely on respiratory protection. During the COVID-19 pandemic, severe FFR shortages led the CDC to publish strategies for optimizing the supply of N95 FFRs. These strategies included the extended use and limited reuse of FFRs, wearing decontaminated FFRs, wearing respirators that meet an international respirator standard, or wearing FFRs that were past their manufacturer-designated shelf life. An additional strategy to mitigate supply shortages that was highlighted during the COVID-19 pandemic was to wear reusable respirators, such as elastomeric half mask respirators (EHMRs), or powered air-purifying respirators, which can be cleaned, disinfected, and reused. A decade of nationwide initiatives to increase the utility of EHMRs in healthcare settings were realized during the COVID-19 pandemic as EHMRs became more well-known and were used in healthcare settings for respiratory protection. This expanded use of EHMRs led to an increase in federal procurement, research, guidance, and private sector research and development of innovative EHMR designs by manufacturers to respond to workers' needs for both respiratory protection and source control. This paper describes the role of reusable EHMRs before and during the COVID-19 pandemic, and reviews past and current research, to inform successful EHMR implementation in healthcare and first responder settings.
Reusable elastomeric half mask respirators (EHMRs) have been encouraged for use during conventional, contingency, and crisis capacity in healthcare delivery settings as an alternative to disposable N95 filtering facepiece respirators (FFRs). However, standard, operationalized guidelines for implementing EHMRs in healthcare and first responder settings are needed to facilitate such integration. Specifically, research is needed to identify and address specialized concerns in healthcare delivery settings beyond hospitals to understand the widespread barriers to EHMR use and how organizational culture can support or hinder EHMR adoption. The Strategic National Stockpile (SNS) requested support from the National Institute for Occupational Safety and Health (NIOSH) to develop its strategy to purchase and distribute EHMRs to interested health organizations. To support this SNS effort, NIOSH published a Federal Register Notice (FRN) to request formative input from the public on the nationwide distribution of EHMRs and provided the technical analysis of the responses. Twenty-two representatives from first responder organizations, healthcare and dental associations, manufacturers, higher education, medical/nursing societies, and a union provided comments for consideration. This feedback was qualitatively analyzed to identify themes among the comments. This paper discusses patterns that emerged in the feedback provided within the primary topics of perceived advantages and disadvantages of EHMRs and key considerations for a successful national deployment of EHMRs. This paper also discusses how the formative feedback received was critical to informing the SNS's strategy to purchase and deploy EHMRs for longitudinal demonstration projects with the goal to produce updated EHMR implementation guidelines and best practices.
Background:Non-medical face masks, such as face coverings donned by the general population play an important role in reducing transmission of respiratory pathogens. Pressure drop or breathability of such masks is an important attribute especially with the advent of new standards such as ASTM F3502-21 that have specified pressure drop limits for general use of face coverings. Although several standards are available that discuss pressure drop measurement techniques, the methodologies reported are typically complex or are part of more sophisticated and expensive instruments. Thus, the applicability of such methods is often limited to medical device manufacturers. Objective and Methods:This manuscript adapts from the pressure drop measurements proposed in British Standard EN 14683:2019 and describes a methodology to create a simple 3D printed model of a pressure rig for measuring the breathing resistance across non-medical face masks. The method also enables real time pressure drop data acquisition and analysis of multiple samples or batches using Python and MATLAB scripts. Results:We performed a validation study by comparing the pressure drop obtained for one brand of respirators with our set up and compared it with data obtained by traditional means by CDC. An unpaired two-tailed student t-test (n=3) between the two means implied no statistically significant difference. Conclusion:The method we have developed can be easily implemented at community levels for characterizing the breathability of non-medical grade face masks.
The U.S. CDC announced on 04/03/2020 that all citizens should wear face coverings when in public, potentially increasing demand for medical face masks from the public and exacerbating mask shortages for Covid-19 response staff. One solution is reuse after disinfection for the general public. Prior studies have shown that heating for 30 mins at 70°C or above effectively kills SARS, including SARS-CoV-2, and Influenza viruses on masks. Black carbon (BC) particles generated from a kerosene-lamp were used as a proxy for Coronavirus aerosols to test mask performance after disinfection given overlapping size distributions. We determined filtration efficiency (FE) measurements by comparing BC values on both sides of the respirators or masks (Moldex N95 and 3M N95 respirators, HSI surgical masks) placed under vacuum on mannequins. To obtain the maximum FE, each mask type was first measured while taped or modified to tightly fit a mannequin's face when new and after each heating cycle. No reduction in average FE was observed even after 10 disinfection cycles, with FE statistically greater than 95% for N95 respirators and 70% for surgical masks. In sharp contrast, the FE of all medical masks with no additional sealing decreased to ~ 40%, confirming the effectiveness of facial masks relies upon a tight fit. For solving this issue, we designed a method for making individualized custom nose clips to hold a mask tightly to face; FE of 3M N95 respirators and surgical masks remained above 95% and 80%, respectively. Surprisingly, the FE of three homemade thick cloth coverings (in normal use) were 55%. Though more work is still needed, this result supports the public announcements that the public could wear cloth coverings instead of N95 respirators or surgical masks in low-risk environments. When worn with a customized nose clip, N95 respirators and surgical masks have higher FE than the CDC design for cloth coverings.
