ISRP Journal Public Abstracts

1 | Development and Evaluation of Soft Headforms Representing Japanese Facial Features for Improved Respirator Fit Testing; Hiroki Haruta, Hisashi Yuasa

15 | Performance Evaluation of a New Respirator Fit Testing Apparatus (Sibata MT-11D) against the Established PortaCount Fit Tester (TSI 8048); Xinyi Niu, Michael Yermakov, Sergey A. Grinshpun 

22 | Performance of different classes of Filtering Facepiece Respirators toward nanoparticles; C. Brochot and A. Bahloul

35 | Low-cost FFP2 face masks from the COVID-19 pandemic era – what size range do one size products actually cover?; Ikram Abdellaoui, David Schnura, Tobias Kalisch

50 | Informing the Public’s Unassisted Use of Diverse Facepieces Designed to Form a Seal: Quantitative, Comparative Testing Using the ASTM F3502 Leakage Assessment Test Method;  Chris Baglin, Paul Baglin, Axel Bawor, Fiona Henriquez, William Mackay

73 |  Developing Regulatory Framework and Performance Criteria for Children’s Respiratory Protective Devices – a White Paper; Jonathan Szalajda, Jessica Tredinnick-Higgins, Margaret Sietsema, Claire J. Horwell, Stephanie Holm, Stephanie Lynch, Simon Smith, Caroline Johnson 

101 | Instructions for Authors

Developing Regulatory Framework and Performance Criteria for Children’s Respiratory Protective Devices – a White Paper

Jonathan Szalajda1 , Jessica Tredinnick-Higgins2 , Margaret Sietsema2 , Claire J. Horwell3 , Stephanie Holm4 , Stephanie Lynch5 , Simon Smith6 , Caroline Johnson2

1. JVS Respiratory Protection Consulting, LLC, Pittsburgh PA
2. Personal Safety Division, 3M Center, St. Paul, MN, US
3. Institute of Hazard, Risk & Resilience, Department of Earth Sciences, Durham University, UK
4. Stephanie Holm Consulting, Vancouver, BC, Canada
5. OHD, Birmingham, AL, US and current President, International Society for Respiratory Protection (ISRP)
6. Retired, currently chair ISO and CSA Working Groups

Corresponding author: Jonathan Szalajda, JVS Respiratory Protection Consulting, LLC, 605 Moreland Drive, Pittsburgh, PA 15243: szalajda@verizon.net

ABSTRACT

This White Paper is a call to action for the development of a regulatory framework and performance criteria for children’s respiratory protective devices. 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[1]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 cultures 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 Vol. 42, No. 2, 2025 Journal of the International Society for Respiratory Protection 74 performance standards, manufacturers can create effective solutions tailored to children’s respiratory protection needs. Additionally, there is a need for comprehensive regulatory frameworks, 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.

Keywords: pediatric respiratory protection; global consensus standards; respirator design and performance; air pollution exposure; child health vulnerability; filtration efficiency and fit; respirator regulatory frameworks

Informing the Public’s Unassisted Use of Diverse Facepieces Designed to Form a Seal: Quantitative, Comparative Testing Using the ASTM F3502 Leakage Assessment Test Method

Chris Baglin1*, Paul Baglin1 , Axel Bawor1 , Fiona Henriquez2 , William Mackay3 .

1 tensARC, Ltd. Unit 122, Stirling Enterprise Park, FK7 7RP, United Kingdom +44 (0)7960 897809, 2 University of Strathclyde, 3 University of the West of Scotland

* Corresponding author email: Chris Baglin, chris.baglin@tensarc.com

ABSTRACT

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 a setting where neither professional guidance nor assistance were available.

Objective: This study compares the effectiveness of various facepieces at blocking aerosols during unassisted use, using the ASTM F3502 Leakage Assessment—a modified version of the ASTM F3407 fit capability test.

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 ASTM 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 (LR) of 10, would reflect 90% blocking of particles. Two FFR models and a reusable barrier face covering in a tubular form were studied. There were 59 participants.

Results: The facepieces performed above the target performance level, indicating, on average, more than 90% protection. One FFR achieved 93% protection with a LR of 15.0 (SD=5.5%), another FFR achieved 92% protection with a LR of 12.2 (SD=12.6%), and the reusable tubular facepiece achieved 93% protection with a LR of 14.2 (SD=4.3%) after 110 laundering cycles.

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.

KEYWORDS: Unassisted, Leakage, Fit Capability; Product Test, Fit Test, Filtering Facepiece Respirator, Barrier Face Covering, Source Control, Reusable, Gaiter, Tubular

Low-cost FFP2 respirators from the COVID-19 pandemic era – what size range do one size products actually cover?

Ikram Abdellaoui1 , David Schnura1 , Tobias Kalisch1*

1. Products and Work Systems, Federal Institute for Occupational Safety and Health

* Corresponding author e-mail: kalisch.tobias@baua.bund.de

ABSTRACT

Introduction: The poor fit of filtering face piece respirators was a contributing factor to infection during the COVID-19 pandemic. As there is no sizing system for FFP2 respirators according to the relevant European standard, product sizes can vary unpredictably. This circumstance has made it difficult to select tight-fitting respirators, particularly for people with smaller, narrower faces.

Objective: To investigate the actual size range of low-cost vertical flat-fold respirators 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 category call into question any kind of common database.

Conclusion: Given the results presented, it seems unlikely that low-cost one size respirators can effectively cover a wider range of facial dimensions. To improve the selection of tight-fitting FFP2 respirators, either specific sizes should be defined by the relevant standardization bodies or manufacturers should describe the facial dimensions of the target group for which their products are intended. At the very least, sizing metrics should be provided so that consumers can identify appropriate respirators 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.

Keywords: COVID-19 pandemic; FFP2 respirator; one size; generic size; size range

Performance of different classes of Filtering Facepiece Respirators toward nanoparticles

C. Brochot1* and A. Bahloul1

1 Research Department, Institut de recherche Robert-Sauvé en santé et en sécurité du travail, Montréal, Canada.

* Corresponding author E-mail: Clothilde.brochot@irsst.qc.ca

ABSTRACT

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, an expanded selection of models was evaluated in this study. The initial penetrations are then measured in order to compare the penetrations amongst the different FFRs.

Methods: To do so, an experimental setup generates NaCl nanoparticles before introducing them into a test chamber containing the FFR. A constant flow of 85 L/min is drawn through the FFR and particle concentration is measured upstream and downstream of the FFR with a Scanning Mobility Particle Sizer. This setup allows penetration to be measured as a function of the particle diameter from 10 to 200 nm. Pressure drop was also measured across the FFR.

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 can be extrapolated to the other FFRs presented here.

Keywords: Filtering facepiece respirators, electret, NaCl, classification, efficiency, penetration.

Performance Evaluation of a New Respirator Fit Testing Apparatus (Sibata MT-11D) against the Established PortaCount Fit Tester (TSI 8048)

Xinyi Niua,b , Michael Yermakova , Sergey A. Grinshpuna*

aDepartment of Environmental and Public Health Sciences, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267-0056, USA;

bDepartment of Environmental & Occupational Health Sciences, UTHealth Houston School of Public Health, Houston, Texas, 77030, USA.

*Corresponding author GRINSHS@UCMAIL.UC.EDU

ABSTRACT

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 faceseal. The faceseal is typically assessed using a US OSHA-accepted 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 TSI 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 but not specially to match the NIOSH bivariate fit test panel, 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 simultaneously. 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 device 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.

Keywords: Respiratory protective equipment, Quantitative fit testing, Filtering facepiece respirator, Half-face elastomeric respirator.

Development and Evaluation of Soft Headforms Representing Japanese Facial Features for Improved Respirator Fit Testing

Hiroki Haruta*, Hisashi Yuasa

Koken LTD., Basic Laboratory, 3-10-1 Akanedai, Hanno, Saitama, 357-0044, Japan.

* Corresponding author email: haruta@koken-ltd.co.jp

ABSTRACT

Introduction: Respirator fit is significantly impacted by facial features, which can differ greatly due to the diversity in race and ethnicity. In our previous study, we reported on a PCA panel for Japanese workers (Haruta et al., 2023) 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. 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 dimensions.

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, confirming that most values fell within the target ranges determined from the subject test. For the fit factor evaluation, while the geometric mean 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.

Conclusions: The soft headforms had higher fit factors, confirming the efficacy of elastic material in improving 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 workers.

Keywords: respiratory protection, respirator fit, headform, elastic material, facial features, skin deformation

Accelerated Aging of Surgical N95 filtering facepiece respirator (FFR) Straps: Pressure Reactor vs. Oven Aging Methods:

Supplemental Materials

K Zin Htut and Tanmay Jain*Division of Biology, Chemistry, and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration (FDA), Silver Spring, MD. * Corresponding Author: Tanmay.jain@fda.hhs.gov

CONTENTS:S1. Scanning Electron Microscope AnalysisS2. Tensile TestsS3. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) Analysis

Do child-size respirators sold in Indonesia and Nepal meet standard adult performance requirements for filtration and air resistance, and requirements as modified for children?

Eva F. Gudgin Dickson1 , Jessica L. Tredinnick-Higgins2 , Claire J. Horwell3 , Karen S. Galea4 , Miranda Loh5

1. Assoc. Professor, Dept. of Chemistry & Chemical Engineering, Royal Military College of Canada (RMC), Kingston ON Canada
2. Global Regulatory Engagement Leader, Personal Safety Division, 3M Center, St. Paul MN, United States.
3. Professor, Institute of Hazard Risk & Resilience, Department of Earth Sciences, Durham University, UK
4. Institute of Occupational Medicine, UK
5. Director of Scientific Growth, Engagement and Innovation, Institute of Occupational Medicine, UK

* Corresponding author and E-mail: Dr. Eva F. Gudgin Dickson, eva.dickson@rmc.ca.

ABSTRACT

Background: The FACE-UP project (Factors Affecting Childhood Exposures to Urban Particulates) aims to establish ways to reduce the lifetime vulnerability of children in the urban environment to noncommunicable diseases by reducing childhood exposure to particulate air pollution. The project focuses on achieving exposure reduction through context-appropriate interventions that can be accomplished personally by individuals and their caregivers, in Nepal and Indonesia. One part of the project, discussed in this paper, involves measuring the efficacy of child-sized respirators marketed as respiratory protection certified to other countries’ regulatory respirator standards (KN95, FFP2, and/or KF94). Those respirators meeting acceptable criteria would be put forward for fit-testing on children in a subsequent part of the project.

Methods: Eight children’s respirators, selected as being potentially appropriate for respiratory protection, and available in Nepal or Indonesia, were inspected for appropriate features or defects and measured using adapted standard US National Institute for Occupational Safety and Health (NIOSH) methods for pressure drop (breathing resistance) and particulate filtration efficiency of adult respirators. Two certified N95 models, designed for adults, were also measured as reference. The corresponding requirements that might be appropriate for children’s respiratory protection were discussed.

Results: Of the eight candidate respirators investigated, six met the particulate penetration requirements from the NIOSH N95 filtering facepiece respirator (FFR) standard, with two others having particulate penetration substantially higher than the maximum threshold specified by the NIOSH standard and by the standards claimed by the supplier, even at the reduced flow rate more appropriate for a children’s respirator. All of the tested respirators met the pressure drop requirements specified by the adult FFR standards. One (Purvigor) had a quality control problem (missing nose clips).

Conclusions: The results confirm that there are respirators available in both Nepal and Indonesia that meet the performance requirements of both adult respirator standards and also values adjusted for child physiology. However, since 25% of the models of respirators tested did not meet standard requirements, the results also emphasized the need for a technical evaluation of products claiming respiratory protection before they are recommended as a potential intervention. When considering the potential for future recommendations for the use of respirators for children in countries such as Indonesia and Nepal, where there is no regulation of the performance or certification claims made by respirator manufacturers, it is apparent that a quality assurance program would be an important component of implementation in order to prevent the use of products that do not perform to an acceptable minimum standard. Due to the physiological and anthropometric differences between children and adults, as well as potential differences in concept of use compared with adults in the workplace, further work is warranted to help define requirements and standards appropriate specifically for children’s respiratory protection.

Keywords: children’s respiratory protection, urban particulate matter, aerosol protection, flow resistance, particulate protection.

Accelerated Aging of Surgical N95 Filtering Facepiece Respirator (FFR) Straps: Pressure Reactor Vs. Oven Aging Methods

K Zin Htut and Tanmay Jain*

Division of Biology, Chemistry, and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration (FDA), Silver Spring, MD, USA.

* Corresponding author email: Tanmay.Jain@fda.hhs.gov

ABSTRACT

Personal Protective Equipment (PPE), such as surgical N95 filtering facepiece respirators (FFR), undergoes oxidative degradation during extended storage, potentially compromising its effectiveness. This study aimed to develop a screening test for oxidative degradation of surgical N95 FFR straps. Straps from three respirator models were aged using traditional oven aging at 70 °C under ambient air or in a pressure reactor at room temperature under oxygen pressures of 20 or 40 bar. Characterization using tensile tests and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy showed that pressure reactor aging significantly accelerated degradation more than traditional oven aging. Straps maintained stability up to a critical oxidative threshold, beyond which significant deterioration occurred. ATR-FTIR analysis underscored the complexity of assessing oxidative degradation due to variable chemical composition across models. This research highlights that mechanical properties, particularly modulus, can serve as reliable indicators of long-term stability and performance, offering a more streamlined and direct approach for future PPE evaluations. The pressure reactor aging at room temperature not only expedites degradation assessment but also potentially more closely mimics real-time aging on the shelf, which could simplify the design of future studies and support the development of standardized oxidative degradation screening tests for various types of PPE.

Keywords: accelerated aging, surgical N95 filtering facepiece respirators (FFR), personal protective equipment (PPE), PPE longevity, respirator straps, degradation screening

Journal of the International Society for Respiratory Protection

1 | Case Study for Verification of the Korean Test Panel Using Fit Testing of Respiratory Protective Equipment (Seo)

10 | Accelerated Aging of Surgical N95 Filtering Facepiece Respirator (FFR) Straps: Pressure Reactor vs. Oven Aging Method (Htut and Jain)

22 | Do child-size respirators sold in Indonesia and Nepal meet standard adult performance requirements for filtration and air resistance, and requirements as modified for children? (Dickson et al.)

44 | Instructions for Authors

Case Study for Verification of the Korean Test Panel Using Fit Testing of Respiratory Protective Equipment

Hyekyung Seo1

1. Department of Health Technology, Shinhan University, Uijeongbu-City, Gyeonggi-Do, Republic of Korea

* Corresponding author email: seohk65@gmail.com

ABSTRACT

Fit tests determine the adequacy of the seal of respiratory protective equipment. Several researchers (Seo et al., 2023; Park et al., 2023) have emphasized the necessity of a South Korean fit test panel. A fit test panel is necessary to assess the fit performance of a respirator and its face seal. This criterion is used to select subjects that can represent the facial characteristics of users. Although anthropometric data has been developed for people in the United States and China it is not yet available for Korea. Therefore, we developed the Korean test panel (Seo et al., 2023). For the 7th and 8th waves of the Size Korea anthropometry data, facial measurements of 11,429 individuals aged 15 to 69 years were utilized for analysis. The y-axis (face length) boundary was 97.87 to 134.59 mm, while the x-axis (face width) boundary ranged from 120.75 to 158.23 mm. A Total of 10,985 people (96.12%) were included in the bivariate panel based on face length and face width. The face types were classified into three categories. The purpose of this study was to validate the Korean test panel classified using the International Organization for Standardization ISO 16976-2 (2022) method. We recruited forty-five participants that fit this panel and compared the pass rates of fit tests. The pass rate in the small face size category was high when wearing medium-sized respirator. The medium face size category exhibited high pass rate (80%) when wearing medium or large-sized respirator. These results were similar for the large face size category (p>0.05). Finally, the test panel was verified by comparing the face size category and fit test pass rate. The fit test demonstrated good reliability and validity for matching face size categories (Intraclass Correlation Coefficient, ICC 0.532; p = 0.043). Therefore, the foundation for a Korean test panel was established. This study conceptualized the standardization of Korean test panels.

Keywords: fit test, ISO, Korean test panel, Size Korea anthropometry, Intraclass Correlation Coefficient

Journal of the International Society for Respiratory Protection

1 | Next-Generation Custom-Fit Reusable Respiratory Protective Device with Continuous Fit Monitoring – Part III: 3D Printing of Prototypes and Evaluation

13 | Abstracts 21st International Conference of the International Society for Respiratory Protection “Respiratory Protection, Use, and Users”

57 | Instructions for Authors

Next-Generation Custom-Fit Reusable Respiratory Protective Device with Continuous Fit Monitoring – Part III: 3D Printing of Prototypes and Evaluation

Sungmee Park1, Yuanqing Tian2, Michael Bergman3, Jonisha Pollard3, Ziqing Zhuang3, and Sundaresan Jayaraman1*

1 Georgia Institute of Technology, School of Materials Science and Engineering

2 Georgia Institute of Technology, School of Industrial Design

3 National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory

*Corresponding author: Sundaresan Jayaraman, sundaresan.jayaraman@gatech.edu, Phone: 404.894.2461

ABSTRACT

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.

Keywords: Custom-fit respiratory protective device; continuous fit monitoring; 3D printing; additive manufacturing, Shore hardness; protection; comfort; faceseal pressure; pressure injury; data analytics; facial profile

Fit testing of respirators with ear loop straps

Nick Baxter*, Helen Beattie, Gillian Nicholls and Duncan Smith

Health and Safety Executive, Science Division, Buxton, Harpur Hill, SK17 9JN, UK

*Corresponding author and email: Nicholas.baxter@hse.gov.uk

ABSTRACT

Background: Due to large demand for respirators during the COVID-19 pandemic, particularly filtering facepiece respirators (FFP) level 3 (FFP3) in Great Britain (GB), an increasing number of FFPs with ear loop straps were imported into GB from outside of Europe. Many of these FFPs were incorrectly and often dually marked, showing a European “CE” (“Conformité Européenne”) mark which indicates conformance with the European standard BS EN 149 for respiratory protective devices (RPD), and a KN95 marking, which shows conformity to the Chinese standard GB 2626-2006 for respiratory protective equipment (RPE).

There is evidence suggesting FFPs with ear loop straps do not pass a fit test on a significant proportion of the intended population, with many studies throughout the world demonstrating a low fit testing pass rate of FFPs with ear loop straps.

Objective: The aim of this study was to evaluate the fit of KN95 style respirators with ear loop straps on volunteers representative of GB users, using a quantitative fit testing method.

Methods: Eight models of respirators with ear loop straps, with no certification documentation, were selected from different manufacturers. Quantitative fit testing using an ambient particle counting method was conducted on 29 volunteers. The order of the fit testing on each respirator was randomised. The study followed the fit testing protocol as described in Health and Safety Executive (HSE) guidance on RPE fit testing, INDG 479.

Results: From the 232 fit tests completed, only one achieved a fit factor above the pass/fail criteria of 100. The data showed a 95% confidence that the geometric mean of the overall fit factors lies between 3.0 and 4.7, and is significantly lower (P<0.05) than the pass/fail criteria of 100. Volunteer comments on the perceived fit of the respirators with ear loop straps included being loose on the face, and feeling leakage around the edges of the respirator. Discomfort of the straps around the wearers’ ears was also described.

Conclusion: The testing confirmed that there is a very low fit testing pass rate for FFPs with ear loop straps. Comments from volunteers also indicated that the perceived fit was poor.

Keywords: COVID-19 pandemic, healthcare, filtering facepiece respirators, ear loop straps, quantitative fit

test, KN95, discomfort, ears.