From: Richard Palluzi <000006c59248530b-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Subject: Re: [DCHAS-L] Fume hood article of interest
Date: Tue, 31 Aug 2021 16:03:08 -0400
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: a30b4456-431d-43c0-8086-1924dd447e10**At_Symbol_Here**email.android.com
In-Reply-To


The committee's position in my opinion is that 4 ACH is a minimum exhaust rate if you have hazardous chemicals in the lab regardless of if they are in use. Less than that I think you will have smells and even some potential for exposure. Granted if all you have total in the entire lab is that one waste container in one good you are probably ok but you have to admit that would be rather rare.

On Aug 31, 2021 2:26 PM, Ralph Stuart <ralph@RSTUARTCIH.ORG> wrote:

> >Remember though that NFPA 45 recommends you never let it go below 4 ACH even when unoccupied off hours.

Many teaching labs have a single “waste” hood which are kept on 24/7 to maintain some airflow through the room. They may not achieve 4 ACH that way, but teaching labs do have good control over when there is active chemical use in the lab. I suppose why this is an NFPA recommendation rather than a requirement.

- Ralph

Ralph Stuart, CIH, CCHO
ralph@rstuartcih.org

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