The 2019 Novel Coronavirus (COVID-19) has caused an acute reduction in world supplies of personal protective equipment (PPE) due to increased demand. To combat the impending shortage of equipment including N95 masks, the George Washington University Hospital (GWUH) developed a 3D printed reusable N95 comparable respirator that can be used with multiple filtration units. We evaluated several candidate prototype respirator models, 3D printer filaments, and filtration units detailed here. Our most recent working model was based on a respirator found on an open source maker website and was developed with PLA (printer filament), a removable cap, a removable filtration unit consisting of two layers of MERV 16 sandwiched between MERV 13, and removable elastic bands to secure the mask. Our candidate mask passed our own suction test protocol to evaluate leakage and passed a qualitative Bitrix N95 fit test at employee health at GWUH. Further efforts are directed at improving the current model for seal against face, comfort, and sizing. The 3D model is available upon request and in the supplement of this paper. We welcome collaboration with other institutions and suggest other facilities consider mask fit for their own population when exploring this concept.

The 2019 Novel Coronavirus has caused an acute shortage of personal protective equipment (PPE) globally as well as shortage in the ability to test PPE such as respirator fit testing. This limits not only the ability to fit PPE to medical practitioners, but also the ability to rapidly prototype and produce alternative sources of PPE as it is difficult to validate fit. At the George Washington University, we evaluated an easily sourced method of qualitative fit testing using a nebulizer or "atomizer" and a sodium saccharin solution in water. If aerosolized saccharin entered candidate masks due to poor fit or inadequate filtration, then a sweet taste was detected in the mouth of the user. This method was tested against previously fit tested Milwaukee N95 and 3D Printed Reusable N95 Respirator as a positive control. A Chinese sourced KN95, cotton cloth material, and surgical mask were tested as other masks of interest. Sensitivity testing was done with no mask prior to fit test. A sweet taste was detected for both the surgical mask and cotton cloth, demonstrating a lack of seal. However, there was no sweet taste detected for the Milwaukee N95, 3D Printed Reusable N95 Respirator, or Chinese KN95. These results demonstrate this could be a valuable methodology for rapid prototyping, evaluation, and validation of fit in a non-clinical environment for use in creation of PPE. This method should be not be used without confirmation in a formal qualitative or quantitative fit test but can be used to preserve those resources until developers are confident that potential new N95 comparable respirators will pass. We strongly suggest validation of masks and respirators with Occupational Safety and Health Administration (OSHA) approved fit testing prior to use in a clinical environment.