Comparing the Fit of N95, KN95, Surgical, and Cloth Face Masks and Assessing the Accuracy of Fit Checking

Abstract

Introduction: The COVID-19 pandemic has made well-fitting face masks a critical piece of protective equipment for healthcare workers and civilians. While the importance of wearing face masks has been acknowledged, there remains a lack of understanding about the role of good fit in rendering protective equipment useful. In addition, supply chain constraints have caused some organizations to abandon traditional quantitative or qualitative fit testing, and instead, have implemented subjective fit checking. Our study seeks to quantitatively evaluate the level of fit offered by various types of masks, and most importantly, assess the accuracy of implementing fit checks by comparing fit check results to quantitative fit testing results. Methods: Seven participants first evaluated N95 and KN95 masks by performing a fit check. Participants then underwent quantitative fit testing wearing five N95 masks, a KN95 mask, a surgical mask, and fabric masks. Results: N95 masks offered higher degrees of protection than the other categories of masks tested; however, it should be noted that most N95 masks failed to fit the participants adequately. Fit check responses had poor correlation with quantitative fit scores. All non-N95 masks achieved low fit scores. Conclusion: Fit is critical to the level of protection offered by masks. For an N95 mask to provide the promised protection, it must fit the participant. Performing a fit check was an unreliable way of determining fit.

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