Poor Performance of Masks Secured Using Ear Loops

To the Editor The Original Investigation by Sickbert-Bennett and colleagues¹ provides much-needed data to help ensure that health care professionals caring for patients with respiratory viral illness are provided with an effective mask for respiratory protection.^2,3 Importantly, their results may also provide insights that could guide future design of masks, especially in terms of how they are held in place on the user’s face. They also highlight the need to expand mask approval criteria beyond mask filter performance.

When comparing a surgical mask with head ties vs a procedure mask with ear loops, there was a large difference in fitted filtration efficiencies (FFEs) (71.5% v 38.1%, respectively).¹ Even more worrying, there was also a similar trend of poor FFE performance for N95 respirators designed with ear loops vs those with head straps. The bottom 6 FFE-performing N95 respirators in their Table 1¹ results used ear loops to hold the mask in place on the user’s face, and they all had less than 90% FFE.¹ The FFE performance of surgical masks secured with head ties within 1 SD would have a range of 66% to 77%. This would overlap with the FFE performance of 4 out of the 6 bottom N95 respirators secured using ear loops (within 1 SD).¹ Currently, N95 respirators are usually prioritized for high-risk exposures, including when performing aerosol-generating procedures, and these findings show that health care workers using N95 respirators secured with ear loops may not have better protection than those using a surgical mask secured with head ties.

Data on the actual mask filter performance were not reported, and only 1 surgical/procedure mask with head ties/ear loop was included in the study. The former’s potential bias is important to exclude, as actual mask filter performance can vary significantly from manufacturer-reported filtration efficiencies.⁴ However, if these findings can be confirmed to be consistent, future design and manufacture of N95 respirators may need to exclude ear loops altogether. The current approval process with a focus on mask filter performance may also need to be updated, to consider how they are held in place. From a physics perspective, the forces generated by elastic ear loops are unlikely to be stronger than head ties or straps, which are needed to ensure better fit on the user’s face, especially for N95 respirators.

Corresponding Author: Chee Fu Yung, MBChB, MSt, 100 Bukit Timah Rd, Infectious Disease Service, KK Women’s and Children’s Hospital, Singapore 229899 (yung.chee.fu@singhealth.com.sg).

Published Online: November 23, 2020. doi:10.1001/jamainternmed.2020.6393

Conflict of Interest Disclosures: None reported.

Editorial Note: This letter was shown to the corresponding author of the original article, who declined to reply on behalf of the authors.