Neal et al,

Keep in mind particulate filtering respirators were developed primarily for inert particulate matter (wood dust, silica, etc.). When used in a clinical setting, the particulate matter is no longer inert, but potentially can replicate and infect individuals upon exposure (uptake). For this reason, reuse of an N-95 is not typically recommended for use in biohazard protection, as a general rule.

Having said that we are entering that stage of an emergency where scarcity of the primary protective device is occurring. A number of academic clinical centers are running into the same issues and are doing some testing of methodologies for possible reuse of n-95 particle respirators. The attached is one such report on methodology for disinfection of the masks for possible reuse. Note that gas or vapor is needed to assure complete penetration of the filtrate substrate where infectious particulates may adhere. Work is currently being done by some of the regional academic bio research facilities on this and protocols being developed demonstrating the process and testing using indicator strips of the disinfection. I suggest caution on applying considerations for non-viable particulates to the current situation for N-95s or other respiratory protective equipment.

Larry

Lawrence M. Gibbs, CIH, FAIHA

Associate Vice Provost Emeritus

Stanford University

lgibbs**At_Symbol_Here**stanford.edu

(c) 650-387-1131

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of NEAL LANGERMAN
Sent: Monday, March 23, 2020 10:23 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: [DCHAS-L] COVID-19 Question

All

What do you say to a healthcare provider (assume they are in your core family) who has been told to ration N95 masks. Told to reuse them.

Healthcare provider wants to know about sanitizing them; about effectiveness; about building their own mask.

FYI, here is some NIH published data:

Reduction to exposure by virus-like particulates. Based on article published by NIH

Mask Type % reduction of particulates

N95 99

SURGICAL MASK 74

HOMEMADE TEA CLOTH MASK 58

Also, the Elan Musk companies delivered 50,000 N95 masks to a hospital today.

nl

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