If the Mask Doesn’t Fit, COVID-19 Will Hit


The most poorly fitting mask can almost double the risk of infection for the wearers and even those around them.

When the United States and rest of the world struggled against the first waves of COVID-19 last year, it quickly became apparent that health care professionals were outgunned. There was just not enough personal protective equipment (PPE) on hand, especially masks. The health care system responded by relaxing infection prevention guidelines for PPE and mask use, allowing them to be reused, and hospitals also turned to just-in-time fit testing to help mitigate the problem, as Infection Control Today® (ICT®) reported.

A mask that doesn’t fit properly doesn’t offer much protection.

In fact, masks that don’t fit properly might actually increase a health care worker’s chances of contracting COVID-19. That’s the conclusion reached by investigators at the University of Cincinnati’s College of Engineering and Applied Sciences, in collaboration with the FDA’s Division of Applied Mechanics.

Results from their study were published in the journal Scientific Reports.

“Many people do not realize that the fit of face masks can vary. There are different face shapes and different sizes of masks,” Rupak Banerjee, a professor in UC’s Department of Mechanical and Materials Engineering said. “If you do not match them well, you can lead to greater leaks and higher risks of infection.”

In an interview with ICT® in March, Beau Wangtrakuldee, PhD, the CEO and founder of a company called AmorSui, pointed out that “in the health care industry in general, small sizes are typically based on Caucasian males, so once you get to women who truly have smaller frames there are no products available for them.”

Wangtrakuldee also spoke about a hospital ward in the United Kingdom in which 80% of the staff were women and how “they developed ulcers from having to tie N95 masks too tightly in order to feel protected or have them fit properly.”

In the Scientific Reports study, investigators employed computerized tomography (CT) scans of 3 different sized face masks which were attached to 3 different sized dummy heads to measure the gaps between the face and the fabric.

They then created a 3D computer-aided design model using the CT scans that showed the gaps between the mask and the dummy head and calculated the rate of airflow through them to identify the relative risk of infection for each mask.

Findings from the study demonstrated that the aerosol transport due to the gaps between the mask and the dummy heads varied from 30% to 95%. Leaks were seen to be largest around the nose.

The most poorly fitting mask can almost double the risk of infection for the wearers and even those around them.

The investigators hope that the results from this research will help to educate consumers and aid manufacturers in developing masks.

“The set of computational models presented are useful for predicting the relative infection risk for different types of protection, facial profile types, pathogen characteristics, and level of compliance,” the authors wrote. “The leakage and the risk-assessment models can be helpful in developing protection strategy, establishing PPE guidelines, and promoting awareness for the general public during a pandemic.”

This article originally appeared inContagion®.

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