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.

Human Errors in Qualitative Respiratory Protective Equipment Fit Testing: A Study of Real-World Fit Testers

Karen M. Long1,*, Nathalie Mai1, Michael Williams1

1. Cranfield University, Cranfield Defence and Security, Bedford UK.

* Corresponding author email: karen.long@face-fit.co.uk

ABSTRACT

Background. Fit testing is an essential part of any respiratory protective device program and provides a method for assessing the effectiveness of the face-to-facepiece seal of a tight-fitting facepiece which helps to assure wearer protection. Although qualitative fit test methods are assumed to be simple and easy to use, it remains critical that the methodology is applied in accordance with the protocols set out in guidance to ensure that a correct ‘pass’ or ‘fail’ result is assigned. An incorrectly assigned pass result increases the risk to the wearer of exposure to hazardous respiratory substances in the workplace, putting their health or life in danger. Fit testing stakeholders, manufacturers and regulatory bodies have raised concerns about the quality of fit testing conducted in the UK workplace, but there have been no published research studies in this area to date.

Methods. This article presents results from a study into the errors made by real-world qualitative fit testers, using the data gathered during Fit2Fit practical assessments conducted in the UK over a ten-year period from 2009 to 2019.

Results. When application of the qualitative fit test method was measured against the HSE INDG479 protocol, assessment records indicate that fit testers made a median of 4 errors, and a high of 29 errors. Fit2Fit accredited fit testers appear to make half as many errors as non-accredited fit testers, yet the scheme remains voluntary in the UK. The sources of errors were analysed in detail and revealed that the most common errors were made in instructing the wearer, donning and fit checking RPE, verifying the nebuliser function, and assuring the wearer’s taste detection.

Conclusion. Results from this study suggest that errors made by real-world fit testers are common, and steps to mitigate the assignment of false pass fit test results arising from these errors are needed if wearer health is to be better protected.

Keywords: Qualitative fit test, QLFT, FFP3 respirator, half mask respirator, Fit2Fit, competency.

Minimum oxygen concentration in breathing gas:

Effects of altitude

Dan Warkander1,2,*, Richard Arnold1, Alberto Spasciani3

1. Naval Medical Research Unit Dayton, Dayton, OH, USA,
2. Leidos, Reston, VA, USA,
3. Spasciani Spa, Origgio, Italy.

* Corresponding author email: dan.warkander.1.ctr@us.af.mil, dwarkand@buffalo.edu

ABSTRACT

Background. Oxygen is essential for life and a minimum safe level shall be determined before using air purifying respiratory protective devices. However, no consensus among regulatory standards exists on what is a safe low limit of oxygen concentration (O2%) – the values range from 17% to 19.5%. A person’s fundamental need is the partial pressure of oxygen, not the O2%. The partial pressure of O2 is proportional to the number of molecules of O2 in the air. Since the barometric pressure decreases with altitude, the number of O2 molecules in a breath of air also decreases. Therefore, it makes little sense to express a safe low limit as a concentration, unless the altitude of use is specified. For instance, if an altitude of 2,400 m (8,000 feet) is considered safe when breathing air, the equivalent partial pressure of O2% would be provided at sea level from a gas containing 15.3% O2.

Objective. To highlight the different levels of O2% or altitude that are considered safe in various situations and provide means to determine how the necessary O2% level changes with altitude.

Methods. The alveolar gas equation was used to determine the equivalence between O2% and altitude for a given partial pressure of O2.

Results. The equivalences between O2% and altitude are shown in graphs for easy interpretation. For instance, if it is deemed acceptable to breathe air at 2,400 m, then the equivalent O2% is 19.3% at 1,800 m or 17.3% at 1,000 m. Breathing gas containing 23.5% O2 at an altitude of 3,300 m is equivalent to breathing air at 2,400 m.

Conclusion. The step-by-step approach described will allow a Safety Officer or user of respiratory protective devices to determine equivalent O2% based upon a generally accepted safe condition from a known altitude.

Keywords: partial pressure of oxygen, partial pressure of carbon dioxide, O2, CO2, hypoxia, hyperoxia, alveolar gases.

Desmitificando los FPAs para EPR: intentando lo imposible

(This is a Spanish language translation of a commentary originally published in English language by the ISRP)

Samantha Connell¹*, CIH^[1], Stephanie Lynch, PhD, CSP²

¹Directora de Programas de Salud Global, Indorama Ventures PCL y presidente de la Asociación Internacional de Higiene Ocupacional

²Gerente senior de tecnología e investigación en OHD LLLP y vicepresidente de la Sociedad Internacional de Protección Respiratoria

* Autor correspondiente y correo electrónico:samantha.connell.cih@outlook.com

^[1] Certified Industrial Hygienist (Higienista Industrial Certificada)

RESUMEN

Este comentario tiene como objetivo compartir perspectivas internacionales sobre los equipos de protección respiratoria (EPR) y el concepto de factores de protección asignados (FPA)^[1]. FPA es un valor numérico establecido por una organización que indica el nivel de protección que se debe esperar para la mayoría de la población que utiliza ese equipo de protección respiratoria (EPR), cuando se usa correctamente. Diferentes países y organizaciones tienen diferentes enfoques para establecer los FPA, lo que puede llevar a que exactamente el mismo EPR tenga diferentes valores de FPA en diferentes países. Después de años de navegar por múltiples reglas específicas de cada país (o la falta de ellas), los autores buscaron establecer qué FPA debería aplicarse a empresas como las suyas, que operan a nivel mundial. En este comentario, los autores no llegan a una conclusión específica, sino que comparten la información que obtuvieron a lo largo de su viaje y brindan una discusión sobre la situación global. Los autores se educaron en los Estados Unidos y tienen experiencia laboral internacional, pero no pretenden representar las perspectivas de todos los países con respecto a las FPA.

Palabras clave: equipo de protección respiratoria, factor de protección asignado, factor de protección nominal, normas internacionales

^[1] En ingles APF por “assigned protection factors”. Al traducir se prefirió respetar las designaciones en español.

Demystifying APFs for RPE: Attempting the impossible

Samantha Connell¹*, CIH, Stephanie Lynch, PhD, CSP²

¹Global Health Programs Director, Indorama Ventures PCL, and President, International Occupational Hygiene Association

²Senior Technology and Research Manager at OHD LLLP, and Vice President, International Society of Respiratory Protection

* Corresponding author and email: samantha.connell.cih@outlook.com

ABSTRACT

This commentary aims to share international perspectives on respiratory protective equipment (RPE) and the concept of assigned protection factors (APFs). APF is a numerical value established by an organization indicating the level of protection that should be expected for a majority of the population using that respiratory protective equipment (RPE), when used correctly. Different countries and organizations have different approaches to setting AFPs, which can lead to the same exact RPE having different APF values in different countries. After years of navigating multiple country specific rules (or lack thereof), the authors sought to establish which APFs should be applied for companies like theirs that operate globally. In this commentary, the authors do not come to a specific conclusion, rather they share the information they obtained along their journey and provide some discussion of the global situation. The authors are educated in the United States and have international work experience but do not claim to represent all countries’ perspectives regarding APFs.

Keywords: respiratory protective equipment, assigned protection factor, nominal protection factor, international standards