From: "Stuart, Ralph" <Ralph.Stuart**At_Symbol_Here**KEENE.EDU>
Subject: Re: [DCHAS-L] Sars-CoV2 infectivity
Date: Thu, 25 Jun 2020 18:40:30 +0000
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: 4B902B12-5548-4AF5-8131-6600FCC774C4**At_Symbol_Here**
In-Reply-To <1442656308.2999568.1593109227242**At_Symbol_Here**>

> >All I know is the PEL at 5000. Where does this reasonable target come from?

The OSHA Technical Manual Chapter 2 on Indoor Air Quality Investigation

They actually got it from a 1987 NIOSH report, back in the good old days when "the outdoor, ambient concentration of C02 is usually 250-350 ppm." It was used a reasonable proxy for air exchange rates and noted that above 1000 ppm, increased complaints could be expected. It's not clear whether they complaints they have in mind include viral infections (the effects they note list "headaches, fatigue and eye and throat irritation are frequently found to be prevalent"). I remember those days when addressing IAQ concerns was as confusing and emotionally fraught as managing Covid issues is today.

Thanks for checking on this.

- Ralph

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


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