From: Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Subject: Re: [DCHAS-L] Sars-CoV2 infectivity
Date: Sat, 27 Jun 2020 20:05:41 +0000
Reply-To: Monona Rossol <actsnyc**At_Symbol_Here**cs.com>
Message-ID: 28203572.181308.1593288341436**At_Symbol_Here**mail.yahoo.com
In-Reply-To




Thinking out loud: I wonder if anyone has thought about what measurements might be appropriate to make to assess whether the occupancy loads for labs or classrooms are appropriate after groups have started to gather in them. For example, OSHA's 1000 ppm target for CO2 includes a safety element to reduce transmissions of colds, etc. That's something that is relatively easy to monitor over time.
It would tell you if the exchange in the breathing zone is enough to meet the standard.  But It won't tell you if there is also a MERV 15 or 16 filter that will capture the aerosol or will just end up dumping it back into the room.  So CO2 monitoring, plus an engineers report on the the efficacy of the system and the choice of the right filter might be really helpful.  

The caveat here also is where the diffusers and returns are located.  Some rooms have really dead areas where the exchange is relatively poor.    Monona


-----Original Message-----
From: Boitumelo Kgarebe <bkgarebe**At_Symbol_Here**GMAIL.COM>
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Sat, Jun 27, 2020 11:56 am
Subject: Re: [DCHAS-L] Sars-CoV2 infectivity

Very interesting, though scary preliminary findings. This could be the reasons why for us in South Africa, where living conditions are far from ideal and social distancing is utterly impossible, we are experiencing the types of inexplicable spreading patterns of the virus.
BVK (PhD) FAAS 

On Thu, Jun 25, 2020 at 7:11 PM Stuart, Ralph <Ralph.Stuart**At_Symbol_Here**keene.edu> wrote:
> >For the aerosol discussion this is out of the CDC. Preliminary results but noteworthy

"our findings suggest retained infectivity and virion integrity for up to 16 hours in respirable-sized aerosols."

Thanks for pointing this out.

<speculation> Their finding above could explain the rapid spread of infection in specific settings. Potentially related, someone pointed out to me today that the areas with recent increases in spread are areas where people are likely to stay inside for air conditioning purposes this time of year. And those areas are potentially recirculating indoor air more than in the spring.</speculation>

Thinking out loud: I wonder if anyone has thought about what measurements might be appropriate to make to assess whether the occupancy loads for labs or classrooms are appropriate after groups have started to gather in them. For example, OSHA's 1000 ppm target for CO2 includes a safety element to reduce transmissions of colds, etc. That's something that is relatively easy to monitor over time.

- Ralph

Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859

ralph.stuart**At_Symbol_Here**keene.edu

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Regards
BVK
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