From: Ray Cook <raycook**At_Symbol_Here**APEXHSE.COM>
Subject: Re: [DCHAS-L] NIOSH Technical Report P/N 2021-107: Filtering Facepiece Respirators with an Exhalation Valve: Measurements of Filtration Efficiency to Evaluate Their Potential for Source Control
Date: Sat, 12 Dec 2020 06:50:48 -0600
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: B03F4986-8E08-4EFC-A893-F75D99821E71**At_Symbol_Here**

I find this paragraph very interesting.

If I read it correctly and avoid confirmation bias, it sounds as though wearing a valved N95 can be as or more effective at source control than the current masks & other items worn by the public, all while actually protecting the wearer to a much higher degree. 

"Even without mitigation, FFRs with exhalation valves can reduce 0.35-=CE=BCm MMAD particle emissions more consistently than surgical masks, procedure masks, cloth face coverings, or fabric from cotton t-shirts; however, the 0.35-=CE=BCm MMAD particle emissions are not expected to be lower for every model."

So in my opinion, there should be no restrictions against wearing these, such as those being applied by various companies & govt entities. I'll be curious to see if they are lifted, but somehow I an not optimistic.

Confirmation bias creates a strong motive for dismissing information inconsistent with popular opinions.


Ray Cook, MS, CIH 2000-2016
CSP ret.
I Cor 1:18
In omnia paratus
Sent from my iPhone

On Dec 12, 2020, at 4:46 AM, John Callen <jbcallen**At_Symbol_Here**> wrote:


The subject study is "hot-off-the-press" and is worthy of your consideration.

This summary has PDF Link so you can read the entire report (attached below).

The Bottom Line : "These finds have important implications for guidance on source control and mitigation."

It maybe possible that this will open up a blocked avenue of RPE.

After review, I certainly welcome your comments.

Be Safe and Stay Healthy!

All My Best and Happy Holidays,

John B. Callen, Ph.D.
3M Personal Safety Division - Retired
ACS/DCHAS Founding Member
(312) 632-0195
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