Face Mask Fit Hacks: Improving the Fit of KN95 Masks and Surgical Masks with Fit Alteration Techniques

O’Kelly, Eugenia; Arora, Amit; Pirog, Sophia; Pearson, Charlotte; Ward, James; Clarkson, P. John

doi:10.1101/2020.10.28.20221895

Cited by 9 publications

(26 citation statements)

References 4 publications

(5 reference statements)

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“…54−57 While not the focus of this study, mask bracing has also been shown to improve the performance of surgical masks. 37,38,40,58 This is consistent with the previous result that peripheral leakage contributes to the total leakage from flat surgical masks in addition to that associated with filter penetration. 59−63 While the wide availability of low-cost plastic 3D printers and associated materials is also an important advantage of 3Dprinted mask technology for pandemic management applications, access to widely available low-cost engineering controls remains an occupational health and safety challenge in developing regions, particularly associated with the inhalation of airborne pathogens or contaminants in construction-based operations.…”

Section: ■ Results and Discussionsupporting

confidence: 89%

“…A comparison of the dimensional error among the data in Figures b and S3 supports the experimentally observed gaps that arose upon application of the rigid frame to the test manikin (which exhibits a headform similar to that of a child). While these results suggest that 3D-printed mask frames can be potentially useful for improving the performance of a low-cost cloth mask and that additive manufacturing processes can be utilized for mask frame prototyping, additional studies that examine testing on diverse head shapes with realistic flesh and skin can be utilized to understand the mechanisms by which the mask performance is altered on a mask-by-mask basis. − While not the focus of this study, mask bracing has also been shown to improve the performance of surgical masks. ,,, This is consistent with the previous result that peripheral leakage contributes to the total leakage from flat surgical masks in addition to that associated with filter penetration. − …”

Section: Resultssupporting

confidence: 82%

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3D Printed Mask Frames Improve the Inward Protection Efficiency of a Cloth Mask

et al. 2021

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Here, we show that improving the fit of a cloth mask using a low-cost 3D-printed frame significantly improves its inward protection efficiency for airborne particles known to transmit SARS-CoV-2. We found that a 3D-printed flexible frame (i.e., brace) increased the inward protection efficiency of a cottonbased cloth mask by 13−43% for particles ranging in size from 0.5−2 μm relative to the efficiency obtained in the absence of the frame. For example, the use of a flexible form-fitting frame increased the inward protection efficiency for 0.5 and 1 μm particles by 31 and 40%, respectively. Rapid prototyping of the mask frame geometry and material properties was also highlighted for optimization of the facial contact area and mechanical matching. This work demonstrates the opportunity for leveraging additive manufacturing processes for rapid prototyping of personalized and form-fitting personal protective equipment components at home and at point-of-care settings, such as mask frames.

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Section: ■ Results and Discussionsupporting

confidence: 89%

Section: Resultssupporting

confidence: 82%

3D Printed Mask Frames Improve the Inward Protection Efficiency of a Cloth Mask

et al. 2021

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“…Unlike N95 Filtering Facepiece Respirators (FFRs), it is challenging to wear sealed surgical masks due to the difficulty of exporting exhaled gas, resulting in an accumulation of exhaust gas in the surgical mask and subsequently causing difficulty breathing (Huang & Huang, 2007;Skaria & Smaldone, 2014). Nevertheless, we have studied the FE of sealed surgical masks as healthcare frontliners have used them in case of a significant shortage of FFRs during the COVID-19 pandemic (Ekpreechakul et al, 2020;O'Kelly et al, 2020;Ekpreechakul et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

Al-Hadyan

Al-Harbi²,

Judia³

et al. 2021

KJS publishes peer-review articles in Mathematics, Computer Sci

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Wearing face masks have been implemented as a public and personal health control measure against the spread of coronavirus disease (COVID-19). However, the protection level of nonmedical face masks, such as women face veils, is still uncertain. This study aimed to assess the filtration efficiency (FE; percentage of particles retained by a mask) of different types of medical masks (either as sealed or unsealed, single or doubled), non-medical masks (cloth masks) and face veils. FE of face masks was evaluated using an in-house 3D-printed air duct connected to the Aerotrak particle counter with a capability of counting particle sizes of 0.3, 0.5, 0.7, 1, 2 and 5 μm. A set of 10 earloop surgical masks,10 tie-on surgical masks, 3 triple-layers reusable cloth masks and 3 types (short, medium and long) of traditional face veils were included in the study. The unsealed surgical masks showed intermediate FE (36.54-80.58%), with no observed differences between tie-on and earloop or single and doubled masks. For each mask type, the mean FE values of sealed surgical masks (FE≥99.16%) was significantly higher (P<0.001) than the unsealed ones (FE≤80.58%). No significant difference was observed in the mean FE values between unsealed surgical masks and either cloth masks (FE=23.19-75.35%, P=0.26) or face veils (FE=19.10- 70.68%, P=0.14). However, a mockup experiment showed that wearing a surgical mask under the face veil significantly improve the FE (33.73-79.18%; P<0.001). We conclude that besides sealed surgical masks that ensure optimal filtration under the experimental conditions, the unsealed surgical and cloth masks and face veils showed comparable performance and acceptable protection at 5 μm particle size, which is the most relevant particle size associated with COVID-19 infectious droplets. Wearing a surgical mask under the face veil significantly improves the FE compared to wearing a face veil alone.

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“…Whilst it has been noted that improved fit of surgical masks and fabric face coverings augments their performance, the fit of these masks is typically poor and so they are not included in this study. 18 As we were not measuring the impact of facial dimensions on fit, our study was limited to a small pool of participants.…”

Section: Limitationsmentioning

confidence: 99%

Experimental Measurement of the Size of Gaps Required to Compromise Fit of an N95 Respirator

O’Kelly

Arora

Pirog

et al. 2022

Disaster med. public health prep.

Self Cite

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Objectives: The effectiveness of filtering facepiece respirators such as N95 respirators is heavily dependent on the fit. However, there have been limited efforts to discover the size of the gaps in the seal required to compromise filtering facepiece respirator performance, with prior studies estimating this size based on in vitro models. In this study, we measure the size of leak necessary to compromise the fit of N95 respirators. Methods: Two methods were used to create a gap of specific dimensions. A set of 3D-printed resin spacers and hollow steel rods were used to generate gaps in N95 respirators while worn on two participants. Occupational Safety and Health Administration (OSHA) quantitative fit testing methods were used to quantify mask performance with gaps between 0.4 and 2.9mm diameters. Results: Gap size was regressed against fit factor, showing that overall the minimum gap size to compromise N95 performance was between 1.5mm2 and 3mm2. Conclusions: These findings suggest the fit of a N95 respirator is compromised by gaps that may be difficult to visually detect. The study also adds to the body of evidence supporting the routine use of quantitative fit testing to ensure that masks are well-fitting.

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Face Mask Fit Hacks: Improving the Fit of KN95 Masks and Surgical Masks with Fit Alteration Techniques

Cited by 9 publications

References 4 publications

3D Printed Mask Frames Improve the Inward Protection Efficiency of a Cloth Mask

3D Printed Mask Frames Improve the Inward Protection Efficiency of a Cloth Mask

Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

Experimental Measurement of the Size of Gaps Required to Compromise Fit of an N95 Respirator

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