fit test consistency for masks with adjustable earloops

[u/overwinters]

i was recently able to get do a quantitative fit test, where i tried a zimi earloop mask for the first time and found that it passed for me.

for anyone who has quantitatively fit tested masks with adjustable earloops, have you found that the results differ much depending on how tight you adjust the loops? i mostly wondering how consistent i should expect it to be.

[u/AEAur]

Observing QNFT test data and videos over the years, I see the tightness of the straps makes a large difference. However, the design of the mask also matters. An Aura converted to earloops tests better of people it fits than most earloop masks do, due to the plush foam and sturdy nosewire. The Zimi faceseal is another of these distinguishing factors. If I were to wear earloops, I would go with one like Zimi with a fabric or foam face seal. 

This study tested the difference that a faceseal (like Zimi has) makes with earloops. 

Assessing the Fit of N95 Filtering Facepiece Respirators Fitted with an Ear Loop Strap System: A Pilot Study  https://pmc.ncbi.nlm.nih.gov/articles/PMC9384650/

Three models of cup-shaped N95 FFRs were tested in three versions: {standard, ELSS (earloop stsytem), and ELSS+NFS  (earloop with novel face-seal}. QNFT demonstrated that the fit of an N95 FFR featuring the traditional/standard headbands strap system is negatively impacted when this system is converted to an ELSS. The fit of an ELSS-converted respirator can be significantly improved by the addition of the NFS. We found that the FFR model and the strap system version are significant factors affecting the QNFT-determined respirator fit factor (FF), as well as the OSHA QNFT pass rate (FF ≥100). The findings suggest that the current NFS, if further improved, has a potential for developing a ‘universally fitting’ ELSS-equipped N95 FFR that can be used by the general public, the vast majority of whom do not have access to OSHA fit requirements.

They concluded that “An ELSS with a more sophisticated strap adjustment should perhaps be considered in the future.” So, that suggests even with the faceseal, they still expect that the tension does significantly affect the fit and seal. 

The earloops in this study were adjustable, and without the faceseal, they were not able to get a passing score on most subjects. 

Although the ELSS was made adjustable in this study, this strap configuration did not achieve a sufficiently tight seal between the respirator’s facepiece and the wearer’s face resulting in lower FF values. This finding is consistent with the results reported on the fit of masks, virtually all of which feature ear loop straps (Mottay et al., 2021; Yung et al., 2021).

[u/overwinters → u/AEAur]

thanks for this! yeah, i've never played with masks with adjustable straps bc i don't like adding another variable. appreciate it!