This UVC box is designed to irradiate fifteen (15) N95 masks placed onto the tray in 30 minutes with at least 1,000 mJ/cm2 of 254 nm UVC light. Studies show that a dose of 1,000 mJ/cm2 of UVC destroys the RNA in SARS-CoV-2 virus on N95 masks, rendering the virus inactive. These same studies show that, with good practices of donning and doffing N95 masks, the masks retain their function and fit over several cycles. This box uses four (2 top and 2 bottom), low ozone-germicidal UVC lamps to generate the required UV energy. The interior of the box and the tray have several reflectors that ensure every surface of every masks receive the required dosage. Fifty-four of these UVC decontamination boxes have been manufactured and distributed to the first responder community in King County, Washington (Nov. 2020).
Below we provide a document describing the operation and maintenance and a second document detailing the validation of the 1000 mJ/CM2 UVC dosage on every surface of each mask as well as the development of a process control dosimetry tool. We also provide several videos detailing the operation, maintenance, and usage of the process control dosimetry tool.
Please contact Jonathan Posner with any questions or feedback.
Jonathan Posner
Richard and Victoria Harrington Professor for Engineering Innovation in Health
Mechanical Engineering, Chemical Engineering, Family Medicine
University of Washington
email: jposner@uw.edu
phone: 206.543.9834
Documents
Operation and Maintainence Manual
Dose Verification and Process Control Dosimetry
King County Fire Departments Ultraviolet Germicidal Irradiation (UVGI) – N95 Decontamination Guideline
Videos
Introduction
Operation
Routine Cleaning
Replacing the Fuse
Replacing the UV Lamps
Validation of UVC Exposure
Acknowledgments
We thank King County Public Health, Medic One Foundation, UW's Population Health Initiative, Medtronic Foundation, and many private donors for financial support fo this project. This project would not have been possible without the generous in-kind technical and design contributions from Paul Leondard, RC Leondard (Facebook), Bob Powell (Meadow Creature, Vashon Island), Ben Sullivan (UW), Paul Means (Burn Design Labs, Vashon Island, WA), Dan Casey (Burn Design Labs, Vashon Island, WA), Jeremy Su (Burn Design Labs, Vashon Island, WA), Michael Chiu, Kyle Johnstone, and Dave Szakelyhidi. We thank Tom Rhea (King County EMS, UW Medicine) for his leadership in obtaining financial support for this project as well as serving as a bridge between engineering and public health, medicine, EMS, and fire. DC Dennis (Chris) Dahline (Seattle Fire Department) lead the development of the King County Fire operating procedure. DC Dave Van Valkenburg (Kirkland Fire Department) managed the UVC box requests and distribution. We also thank Fluke Corporation for use of their electrical safety analyzer.