Shortages in personal protective equipment (PPE) for health care workers and recommendations made by the Centers for Disease Control and Prevention to wear face masks during essential outings have left many wondering what safe alternatives can protect them from the coronavirus disease 2019 (COVID-19).

In response to a request made by the Washington State Department of Labor & Industries (L&I), researchers from the University of Washington School of Public Health tested the performance of different materials to use for possible handmade face masks.

The team of environmental and occupational health sciences faculty, which included Principal Lecturer Martin Cohen, Professor and Chair Michael Yost, and Professors Christopher Simpson and Scott Meschke, examined fabrics from L&I’s Safety & Health Assessment & Research for Prevention (SHARP) program for filtration and breathability. Based on this criteria, they tested cotton, muslin, fleece, lycra, surgical wrap and polyurethane foams sent from SHARP, as well as rayon and Thinsulate.

In order for a face mask to be effective, users must be able to breath in it easily and particles need to filter through it properly. Unfortunately, these two qualities can work in opposition. A good filter can impede breathing or make a wearer more likely to breathe in unfiltered air from around the edges of the mask. In contrast, some fabrics are very breathable but not effective at filtering for particles.

“You’re looking for something in between,” Cohen said.

To test these metrics quickly, Cohen developed a make-shift approach in his lab that approximates methods used by the Food and Drug Administration (FDA) for testing surgical masks. Cohen found that surgical wrap – a polypropylene fabric used in hospitals to prevent dust from settling on instruments after they are sterilized – and Thinsulate insulation performed best for filtration and breathability. 

The results are exploratory, and none of the materials was tested for safety, Cohen noted. Cohen hopes the last-resort use of handmade masks for health care workers and others won’t last long.

“After this outbreak, hopefully we will learn that we need to have good supplies of PPE,” he said.

Read the full story from the Department of Environmental & Occupational Health Sciences.