A student-led research team at the Carle Illinois College of Medicine at the University of Illinois Urbana-Champaign is providing new answers on which materials are best for constructing homemade and alternative personal protective equipment.

The team’s research showed that non-mask medical-grade materials and consumer-grade craft fabric could provide the best filtration when creating alternative PPE and masks. The study was cited in a fall publication by the Centers for Disease Control and Prevention on homemade face coverings.

In the early days of the COVID-19 pandemic when N95 respirators and medical-grade surgical masks were in short supply, a multi-disciplinary team from Carle Illinois, UIUC’s College of Medicine, the Grainger College of Engineering, and Carle Health set out to measure the filtration efficiency of various materials that were being used to make face masks. “We thought these mask makers would benefit from a set of filtration data that showed them which materials were better at filtering virus-sized particles,” said Carle Illinois student researcher Valerie Chen.

With the help of a grant from the Carle Illinois Innovation Pathways project and Carle Illinois Health, the team built their own cost-effective testing apparatus using a fit-tester and some basic hardware. “Because official material test sites, such as those which certify N95s, suffered a dramatic back-log, it was necessary to design our own setup to approximate the filtration characteristics of our test materials,” Chen said.

Carle Illinois student Elizabeth Voss Woodburn helped conceptualize and administer the project. Kenneth Long, an MD/PhD student with U of I College of Medicine, and Ian Berg, a PhD candidate in the bioengineering department, provided engineering expertise. Carle Illinois Clinical Associate Professor William Scott of Carle Health supervised the project.

“We then identified materials that were being recommended in online mask-making tutorials and measured their filtration properties through our setup,” said Chen. The team – which tested materials ranging from cotton and paper filters to craft fabric – found a wide range of effectiveness. “For example, a double layer of cotton filtered under 15% of particulates, while a triple layer of the craft cloth Smart-fab® achieved a filtration efficiency of nearly 80%,” Chen said.

The team also tested medical-grade non-mask materials, such as sterilization wrap, to determine their suitability for use in filtering out airborne pathogens. “These often demonstrate superior filtration capabilities compared to consumer materials since they are often pre-selected for their filtration characteristics, albeit for different purposes. Though not available to the average consumer, hospital-grade materials hold the greatest potential for achieving N95-like filtration capabilities in the event of severe respirator shortage in the hospital,” Chen said.

The research team was careful to use testing requirements that approximate those set by government agencies (from the Food and Drug Administration and the National Institutes for Occupational Safety and Health).

The CDC cited the team’s research in the agency’s November 2020 briefing on the use of home-made masks to fight community spread of COVID-19. The research could provide valuable evidence for future efforts to regulate the manufacture of consumer face masks for infection control. “Currently there are no standards for minimum filtration characteristics of face coverings that are sold, but there is talk that this might be changing. If it does, research like ours will be needed to identify mask-making materials that meet these standards,” said Chen.

The team’s research is also being used by a non-technical audience. “We had the opportunity answer email questions from an actual home mask-maker who was trying to understand the technical details of our methodology, which was exactly in line with our overarching project goal: to take very specific NIOSH/FDA testing requirements and bring them to an audience of non-materials engineers,” Woodburn said.

The research is an example of the U of I’s campus-wide response to the COVID-19 pandemic. Preliminary results were published back in April as a ‘practice point’ article, to provide early scientific evidence to mask-makers. “We partnered with students from the School of Engineering and UICOM as well as clinical faculty at Carle Illinois to complete this project within a few short months. This collaboration was made possible by Carle Illinois’ unique mission of fostering partnerships between medicine and engineering. It’s exciting to see what was possible as a result,” said Chen.

The team’s full research study can be found here.