Evaluation of particle penetration and breathing resistance of N95 filtering face-piece respirators and uncertified dust masks

Ramirez, Joel Amilcar

doi:10.17077/etd.wfvehzie

Cited by 6 publications

(6 citation statements)

References 55 publications

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“…This is the first reported human subject validation of a locally manufactured reusable respirator using standardized quantitative fit testing (per CSA Z94. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Within the same collaborative, a 2 nd N95 respirator derivative has been developed that contains valves that prolong filter life, decrease subjective work of breathing, and improve acoustics [14].…”

Section: Discussionmentioning

confidence: 99%

“…That means 84 L/min flow for single filter cartridge, with option to split up to a maximum of three cartridges, using aerosolized NaCl 0.075 ± 0.020 micrometer at density not exceeding 200 mg/m 2 , at chamber temperature 38 ± 2.5˚C and 85 ± 5% relative humidity; see reference for full details on testing conditions. The respirator filtration efficiency of aerosolized NaCl at 0.3 um diameter should be 95% or greater, with 0.3um being the largest penetrating [18]. This is a costly commercial test and we are currently seeking a certified laboratory and funding to complete this process.…”

Section: Plos Onementioning

confidence: 99%

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Subject validation of reusable N95 stop-gap filtering facepiece respirators in COVID-19 pandemic

Hondjeu

Syrett

et al. 2020

PLoS ONE

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Introduction The COVID-19 pandemic has unveiled widespread shortages of personal protective equipment including N95 respirators. Several centers are developing reusable stop-gap respirators as alternatives to disposable N95 respirators during public health emergencies, using techniques such as 3D-printing, silicone moulding and plastic extrusion. Effective sealing of the mask, combined with respiratory filters should achieve 95% or greater filtration of particles less than 1um. Quantitative fit-testing (QNFT) data from these stop-gap devices has not been published to date. Our team developed one such device, the “SSM”, and evaluated it using QNFT. Methods Device prototypes were iteratively evaluated for comfort, breathability and communication, by team members wearing them for 15-30min. The fit and seal were assessed by positive and negative pressure user seal checks. The final design was then formally tested by QNFT, according to CSA standard Z94.4–18 in 40 volunteer healthcare providers. An overall fit-factor >100 is the passing threshold. Volunteers were also tested by QNFT on disposable N95 masks which had passed qualitative fit testing (QLFT) by institutional Occupational Health and Safety Department. Results The SSM scored 3.5/5 and 4/5 for comfort and breathability. The median overall harmonic mean fit-factors of disposable N95 and SSM were 137.9 and 6316.7 respectively. SSM scored significantly higher than disposable respirators in fit-test runs and overall fit-factors (p <0.0001). Overall passing rates in disposable and SSM respirators on QNFT were 65% and 100%. During dynamic runs, passing rates in disposable and SSM respirators were 68.1% and 99.4%; harmonic means were 73.7 and 1643. Conclusions We present the design and validation of a reusable N95 stop-gap filtering facepiece respirator that can match existent commercial respirators. This sets a precedence for adoption of novel stop-gap N95 respirators in emergency situations.

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Section: Discussionmentioning

confidence: 99%

Section: Plos Onementioning

confidence: 99%

Subject validation of reusable N95 stop-gap filtering facepiece respirators in COVID-19 pandemic

Hondjeu

Syrett

et al. 2020

PLoS ONE

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“…In addition to the NaCl aerosol test, N95 respirators must meet other specifications according to 42 CFR Part 84 (1995) and NIOSH standards, such as inhalation and exhalation resistance to airflow (≤ 343 Pa and ≤ 245 Pa, respectively) for both N95 types, synthetic blood penetration (ASTM F1862/F1862M-17 2017) and biological filtration efficiency for the surgical N95 type, and exhalation valve leakage (leak rate 30 mL/min) and force applied (-245 Pa) for the standard N95 type. Other tests can also be performed, such as surface wetting resistance, microorganism index (bioburden) (Davison 2012), CO2 clearance, and total inward leakage (TIL), which quantifies the respirator's ability to fit individual facial dimensions to ensure that the respirator fits properly (not a requirement for respirator approval testing) (He et al 2013(He et al , 2014Ramirez 2015).…”

Section: N95 Respiratorsmentioning

confidence: 99%

Cellulose, nanocellulose, and antimicrobial materials for the manufacture of disposable face masks: A review

Garcia

Stevanović

Berthier

et al. 2021

BioRes

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Cellulose is among the most promising renewable and biodegradable materials that can help meet the challenge of replacing synthetic fibers currently used in disposable N95 respirators and medical face masks. Cellulose also offers key functionalities that can be valued in filtration applications using approaches such as nanofiltration, membrane technologies, and composite structures, either through the use of nanocellulose or the design of functional composite filters. This paper presents a review of the structures and compositions of N95 respirators and medical face masks, their properties, and regulatory standards. It also reviews the use of cellulose and nanocellulose materials for mask manufacturing, along with other (nano)materials and composites that can add antimicrobial functionality to the material. A discussion of the most recent technologies providing antimicrobial properties to protective masks (by the introduction of natural bioactive compounds, metal-containing materials, metal-organic frameworks, inorganic salts, synthetic polymers, and carbon-based 2D nanomaterials) is presented. This review demonstrates that cellulose can be a solution for producing biodegradable masks from local resources in response to the high demand due to the COVID-19 pandemic and for producing antimicrobial filters to provide greater protection to the wearer and the environment, reducing cross-contamination risks during use and handling, and environmental concerns regarding disposal after use.

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Section: Introductionmentioning

confidence: 99%

“…Mask performance can be evaluated by measuring particle removal efficiency (or filtration efficiency) and breathing resistance (Newnum et al, 2010;Ramirez et al, 2015). Particle removal efficiency is mainly dependent on particle size and velocity, and the removal mechanism is related to impaction, diffusion, settling, and electrostatic attraction (Ramirez et al, 2015;Yang et al, 2015). Breathing resistance is associated with a pressure drop as the air passes through the mask, and can be affected by air velocity, particle loading, particle type (hygroscopic or non-hygroscopic), and RH (Miguel et al, 2003;Newnum et al, 2010;Mostofi et al, 2011;Ramires et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

A Study on Performance and Reusability of Certified and Uncertified Face Masks

Lee

Kim

Joo

et al. 2022

Aerosol Air Qual. Res.

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In this study, the performance (particle removal efficiency and breathing resistance) of several commercially available face masks (KF80-certified electrostatic and nanofiber filter masks, and an uncertified mask) was evaluated, along with their filter structure and composition. Also, the effects of the relative humidity (RH) of incoming air, of water and alcohol exposure, and of reuse, on the performance of face masks were examined. Monodisperse and polydisperse sodium chloride particles were used as test aerosols. Except for the uncertified mask filter, PM2.5 removal efficiency was > 90%. The nanofiber filter mask had the highest quality factor due to its low pressure drop and high removal efficiency, and densely packed nanofiber pore structure, and significant amounts of fluorine, carbon and oxygen. The removal efficiency of the KF80-certified mask was barely affected by the higher RH of incoming air. When the mask filters were soaked in water, their removal efficiency decreased. The uncertified mask filter showed the largest decrease in removal efficiency (26%). When the mask was soaked in alcohol, the removal efficiency decreased to a greater degree than when soaked in water. The nanofiber mask filter showed the strongest resistance to alcohol among the tested mask filters. During evaluation of mask reusability, the removal efficiency of certified mask filters decreased by 4% over 5 consecutive days (2 hours per day), and that for the uncertified mask filter decreased significantly, by 30% after 5 days.

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Evaluation of particle penetration and breathing resistance of N95 filtering face-piece respirators and uncertified dust masks

Cited by 6 publications

References 55 publications

Subject validation of reusable N95 stop-gap filtering facepiece respirators in COVID-19 pandemic

Subject validation of reusable N95 stop-gap filtering facepiece respirators in COVID-19 pandemic

Cellulose, nanocellulose, and antimicrobial materials for the manufacture of disposable face masks: A review

A Study on Performance and Reusability of Certified and Uncertified Face Masks

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