key: cord-0695022-d38nk1x3
authors: Juang, Pascal S.C.; Tsai, Peter
title: “N95 Respirator Cleaning and Re-Use Methods Proposed by the Inventor of the N95 Mask”
date: 2020-04-16
journal: J Emerg Med
DOI: 10.1016/j.jemermed.2020.04.036
sha: 9bef7e8d22ce05d29ac629a633b62925d6a1dab1
doc_id: 695022
cord_uid: d38nk1x3

nan

The N95 mask can be ROTATED, one mask every 3-4 days. Use 3-4 masks, numbered on the outside 1-4, for each day. They can be used each day in numbered sequence. All viruses on the mask will be dead in 2-3 days. 2 There is no change in the mask's properties.

The N95 mask can be HEATED at 70° C (158° F) for 30 minutes. The mask will retain FE 98.5% after heating for 24 hours. Therefore, masks may be heated multiple times without loss of FE. Hang the mask in an oven or using plastic or wooden clips. If the mask contacts or is <6" from hot metal, there may be severe material compromise and charge loss. Damaged elastic bands: equivalent elastic may be re-stapled onto the mask. Alternatively, blanket warmers commonly found in hospitals may be used. Masks may be hung using a wooden dowel.

The N95 mask can be BOILED for 5 minutes. The mask will retain FE 92.4% after boiling.

The elastic band should not be immersed in the water. Do not stir while boiling (physical structure of the mask may be disturbed 

Medical grade alcohol erases charges and may decrease FE by 10x. Gamma radiation is not recommended.

The NEJM article "Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1" 2 provides evidence that the virus will not survive on plastic for more than 3 days. Since T½ is 6.8 hours it is unlikely there is a clinically significant amount of viable virus on the mask, well before the full 3-day period. It is reasonable that the masks can be rotated every 3 days.

There is strong evidence that indicates SARS-CoV-2 will not survive the cleaning methods resources. Therefore, these may not be available in all places that are in need.

Currently, the methods recommended by Dr. Tsai are not approved by any regulatory agency and short and long term effects of N95 respirator reuse after cleaning is unknown. It is possible the edge contour of the mask may change slightly during heating, steaming and boiling methods.

The contour may change by simply re-using the masks, without using these methods. During this COVID19 pandemic, many HCWs around the world have limited options and desperately need N95 respirators. These HCWs may not be able to wait for regulatory agency approval of these methods. The clinician in the field may determine if they will use this research data to clean and reuse N95 respirators. As an Emergency Physician on the front lines of this pandemic, I am acutely aware that the alternative of using no mask or ineffective masks will have grim repercussions.

I present these methods and suggest, where there are N95 respirator shortages around the world, clinicians consider using one or more of these methods as a BRIDGE until sufficient N95 masks are available. I also call upon the FDA and CDC to grant EUA for these methods that are supported by evidence and science.

Good luck to us all.

Information and FAQs on the Performance, Protection, and Sterilization of Face Mask Materials Published

NEJM: Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1

CDC: Decontamination and Reuse of Filtering Facepiece Respirators

A pandemic influenza preparedness study: use of energetic methods to decontaminate filtering facepiece respirators contaminated with H1N1 aerosols and droplets

Stability of SARS-CoV-2 in different environmental conditions

Hospital Blanket WarmerHeat Setting 70° C (158° F) Wooden Dowel with End Caps