DCHAS-L Discussion List Archive
From: Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Subject: Re: [DCHAS-L] ASHRAE guidance on Reopening Schools and Universities
Date: Tue, 7 Jul 2020 14:07:36 +0000
Reply-To: Monona Rossol <actsnyc**At_Symbol_Here**cs.com>
Message-ID: 2119826668.2976700.1594130856983**At_Symbol_Here**mail.yahoo.com
In-Reply-To
All good advice except the MERV 13 filter recommendation. A study now shows the bug goes through a properly installed MERV15. So we are up to the full HEPA MERV 17 in our plans. And that makes for a system upgrade in most facilities. In a few cases, a shop with industrial dilution ventilation can be used -- which is even better..
We also, FYI, are finding that employers, if they really want to reopen, can find a way to test employees up to 3 times a week for COVID-19 (not antibodies, etc.) And we now require level A personnel (those who can't distance or wear a mask due to the nature of their work) be tested three times a week.
Others get tested once a week. And we are making it stick, Oh ye of little faith.
Monona
-----Original Message-----
From: Stuart, Ralph <Ralph.Stuart**At_Symbol_Here**KEENE.EDU>
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Tue, Jul 7, 2020 8:28 am
Subject: [DCHAS-L] ASHRAE guidance on Reopening Schools and Universities
CHAS readers many be interested in the link to the ASHRAE guidance on reopening schools and universities at
It's a good review of basic concepts and best practices related to institutional ventilation systems, which many people are suddenly interested in.
The challenge I see in using this document is that the design basis for this document is to dilution of (chemical) pollutants to negligible levels. I'm not sure that dilution is a good approach for biohazards such as virus which can survive on surfaces for hours after it is introduced into a space. In the BSL-3 labs I have helped evaluate, direction of air flow was more important than number of air changes per hour.
- Ralph
Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859
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