By Kyle Nicholson B.S., Biomedical Engineering, 2020
McKelvey School of Engineering, Washington University in St. Louis
Global Health Student Advisory Committee Co-Chair, Global Health Center
Recently, Jacaranda van Rheenen, PhD, manager of the Global Health Center connected me with Hiram Gay, MD, a radiation oncologist interested in developing emergency protective equipment for his team of radiation therapists. Dr. Gay had come up with the idea to use commonly available air filters to turn a recreational full-face snorkeling mask into protective equipment that is better than the N95 masks currently in short supply. The snorkel mask could serve as a reusable face shield and we knew that commercially available filters exist that exceed 95 % efficiency. I immediately connected him to people that I knew in the McKelvey School of Engineering who were already working on producing emergency PPE (personal protective equipment).
Meanwhile, I reached out to Alexxai Kravitz, PhD in the Department of Psychiatry at the School of Medicine who had helped me with 3D printing projects for another lab in the department. We were quickly able to design and print an adaptor (using designs by the snorkeling manufacturer, Ocean Reef) made available online that connected into the port on the mask where a snorkel is usually fitted. With a few modifications, this port now led to a 3D printed housing for a vacuum filter. After we were satisfied with the design and successfully printed it with Dr. Kravitz’s 3D printer, Dr. Gay was able to test the design by having a participant wear the mask in a hood with a bitter smelling but harmless gas. Our design passed the initial qualitative fit test, as the respiratory therapist wearing the mask was unable to smell the gas. Dr. Gay found a group at the medical campus quantitatively testing PPE solutions. Unfortunately, the initial design did not pass the stringent quantitative testing as the filter and adapter were not airtight enough.
Our initial failure helped us to focus our attention on creating an adapter that can use commercial P100 filters that will block 99.9% of particles .3 microns or larger. I was able to quickly adapt open source designs online for 3M P100 filters and the snorkel mask connection from Ocean Reef so that we could connect the filters to the mask. Dr. Kravitz was able to modify the initial design to be easier and more efficient to print, and Dr. Gay was able to rent testing equipment so we could conduct quantitative testing of the mask at home. We discovered that our design was sufficiently airtight and filtered out a vast majority of the particles in the air with a fit factor greatly exceeding the OSHA passing fit factor for a full-face respirator of 500 or higher. In comparison, the N95 mask OHSA passing fit factor is 100 or higher. The filters provided by 3M filter out 99.97% of particulates while N95 masks filter out 95% of particulates. Users of the converted snorkel mask appreciated how it combined eye and face protection with a respirator for enhanced comfort.
Examples of similar projects can be found across the world and point toward the ingenuity and creativity of healthcare professionals. Although our project is not unique, I hope that our process shows how important it is to ask for help and come together to overcome the obstacles we face in this unprecedented time. We all bring unique skills and resources to the table, and can use them to help one another.
Ocean Reef offered adapter usage for this project through a not-for-profit release.