J Korean Med Sci.  2021 Jul;36(28):e209. 10.3346/jkms.2021.36.e209.

Respiratory Protection Effect of Earloop-type KF94 Masks according to the Wearing Method in COVID-19 Pandemic: a Randomized, Open-label Study

• Yang HJ
• Yoon H
• Kang SY
• Lee G
• Park JE
• Kim T
• Lee SU
• Hwang SY
• Cha WC
• Shin TG
• Jo IJ

• KMID: 2518527
• DOI: http://doi.org/10.3346/jkms.2021.36.e209

Abstract

Background
Ear-loop-type Korean Filter 94 masks (KF94 masks, equivalent to the N95 and FFP2) are broadly used in health care settings in Korea for the coronavirus disease 2019 pandemic.
Methods
A prospective randomized open-label study was designed to identify differences in the fitting performance between mask wearing methods in three different types of KF94 mask with ear loops between January to March 2021. General-fitting involved wearing an earloop-type KF94 mask, and tight-fitting involved wearing a mask aided by a clip connecting the ear loops. Each of the 30 participants wore three types of masks according to a randomly assigned order in both methods and performed a total of six quantitative fit tests (QNFTs) according to the occupational safety and health administration protocol.
Results
All fit factors (FFs) measured by the QNFT were significantly higher for tight-fitting method with the clip in all KF94 masks (P < 0.001). However, the total FFs were very low, with a median (interquartile range) of 6 (3–23) and 29 (9–116) for general-fitting and tight-fitting, respectively. When wearing tightly, the horizontal 3-fold type mask with adjustable ear-loop length had the highest FF, with a median of 125, and the QNFT pass rate (FF ≥ 100) increased significantly from 4 (13%) to 18 (60%).
Conclusion
Even with sufficient filter efficiency, ear-loop-type-KF94 masks do not provide adequate protection. However, in relatively low-risk environments, wearing a face-seal adjustable KF94 mask and tight wearing with a clip can improve respiratory protection for healthcare workers.

Keyword

Respiratory Protective Devices; Quantitative Fit Test; COVID-19; N95 Filtering Facepiece Respirators; Infection Control; KF94 Mask

Figure

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  Fig. 1 KF94 mask types and clip.(A) horizontal 3-fold mask, (B) horizontal 3-fold mask with adjustable ear loops length, (C) vertical 2-fold mask, (D) clip.

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  Fig. 2 Study flow.A: horizontal 3-fold mask, B: horizontal 3-fold mask with adjustable ear-loops length, C: vertical 2-fold mask.FF = fit factor, OSHA = occupational safety and health administration.

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  Fig. 3 Total fit factors of general fitting (A) and of tight fitting (B) for the 3 KF94 masks.A: horizontal 3-fold mask, B: horizontal 3-fold mask with adjustable ear loops length, C: vertical 2-fold mask.

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