DCHAS-L Archives, Jun 26 2020 - Re: [DCHAS-L] Innovative face shields

? By that logic, there is no point in wearing a face covering. Yet the data suggests otherwise. Face coverings and procedural mask generally have some gaps, but they also clearly do some filtering of exhaled air and trapping of droplets. Suggesting that molecules as small as CO2 and O2 would face any real impedance in crossing a cloth barrier, especially in the presence of convective forces produced by breathing, is rather implausible.

Sent from my iPad

On Jun 26, 2020, at 4:51 PM, Monona Rossol <actsnyc**At_Symbol_Here**cs.com> wrote:

?
Look at the picture and see the gaps between the neck and the cloth. Air won't go through the air-resistant cloth as long as there is a path with no resistance at all right next to it.

But lets entertain the idea that they find a way to make the cloth seal to the neck and that the air is forced to filter through the cloth. There still will be a problem because of the volume of air in the enclosed shield. The person in the shield will never get a breath of air that does not contain a significant percentage of the expired air from the previous breath which contains 4-5% CO2. To calculate more precisely, you just need the volume of air inside the shield and the volume of air/breath. But however you calculate it, the person in the shield breathing air that is high in CO2.

Monona

-----Original Message-----
From: Kristi Ohr <kohr**At_Symbol_Here**umass.edu>
To: Monona Rossol <actsnyc**At_Symbol_Here**CS.COM>; DCHAS-L**At_Symbol_Here**Princeton.EDU <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Sent: Fri, Jun 26, 2020 4:13 pm
Subject: RE: [DCHAS-L] Innovative face shields

The fabric around the edges is cloth, so I really don't think it would be any harder than breathing through a cloth face covering. I think it's an interesting hybrid between face coverings and face shields that might be used to address a variety of situations that have been discussed here recently.

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Monona Rossol
Sent: Friday, June 26, 2020 10:38 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Innovative face shields

Gee that would be perfect if we didn't need oxygen. Each time you exhale in that thing your breath fills the space and some leaks out round the edges. When you inhale, you breathe in mostly what you just exhaled plus a little that leaks in from the sides. The CO2 level is going to rise and I give that patient about 4 minutes before there is some heavy breathing and a complaint made familiar by activists.

Note the video says it is just for moving patients from one place to another. Wouldn't work in a NYC hospital where you typically are grown over by moss while you wait in the hall on gurney.

Monona

-----Original Message-----
From: Kristi Ohr <kohr**At_Symbol_Here**UMASS.EDU>
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Fri, Jun 26, 2020 8:10 am
Subject: [DCHAS-L] Innovative face shields

This was posted on the ABSA listserv, and I thought there might be some interest in this community as well given recent discussions.

https://youtu.be/YGWkRW8nejA

All the best,

Kristi

Sent from my iPad

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