Well...you had to know I'd open my yap.
You seem to be forgetting that the cloth mask is not meant for protection of the person wearing it. It is very little help to the wearer because it can only catch the larger droplets such as those from someone coughing, sneezing, or talking nearby. However, this makes the cloth mask very helpful in catching the large droplets that the wearer emits keeping them from entering the room. And the wearer is the generation point at which a large portion of their emissions are droplets that are still big enough to be captured by the cloth.
If everyone in the room wears a cloth face mask, they are all reducing the risk for each other. If one infected person is not wearing a mask, their droplets go out when they cough or talk and a portion dehydrate into the small aerosol particulates that float on the air perhaps for hours. Now the 6 foot rule doesn't work. Those tiny particles put everyone around at risk since these are not stopped by any of the cloth masks.
Wear a shield, and you inhale the room air along with what ever is in it. Exhale and you release your particles freely to the air around you for others to breathe. Your breath many not go straight out in front of you, but who ever is standing along side is going to get a dose. Dumb, my friends and disrespectful. I'm paying a professional cartoonist to illustrate a sneeze behind the shield for my ppt.
As for studies to determine how effective a shield might be, there's none. And I think anyone who reflects for a moment on this wouldn't waste their time doing it. While the protection factor for a cloth mask is really low, imagine what it is for a shield!
Monona
-----Original Message-----
From: Zack Mansdorf <mansdorfz**At_Symbol_Here**BELLSOUTH.NET>
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Sent: Thu, Jun 4, 2020 3:07 pm
Subject: Re: [DCHAS-L] cloth face masks
This has become an incredible circular discussion that I believe will be never ending.
If you are doing lab work that requires a respirator, use the correct respirator. If you are doing lab work that does not require a respirator (e.g., in a hood), then use common sense. If a face covering is more of a risk than not wearing a face covering (e.g., flammability, corrosivity, vision, etc.) than do not use a face covering and just maintain a 6 foot separation from other persons. If you cannot and the face covering will not work, use a face shield. Before my colleague and friend, Monna, admonishes me--..if you have access to an N-95 or better, use that. It has become pretty clear that the vast majority of cases are from person to person contact and the likelihood of a younger person suffering severe consequences is very small. Consider the overall risk of wearing a face covering versus not wearing a face covering given the lab work. I do not think there is a universal solution for all circumstances nor a universal material that can be used in all circumstances.
That's my non-CDC sanctioned opinion.
Zack
S.Z. Mansdorf, PhD, CIH, CSP, QEP
Consultant in EHS and Sustainability
7184 Via Palomar
Boca Raton, FL 33433
561-212-7288
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Patricia Redden
Sent: Thursday, June 4, 2020 2:13 PM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: [DCHAS-L] cloth face masks
CDC is recommending the use of cloth face mask in academic institutions, but the question is what is the best fabric for them. Lab coats in academic labs are supposed to be chemical- and fire-resistant. Does this apply to face masks as well? If so, is there a source for them?
Professor, Chemistry Department
Fellow, American Chemical Society
Fellow, ACS Division of Chemical Health and Safety
SAINT PETER'S UNIVERSITY
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