> >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 â??wasteâ?? 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**At_Symbol_Here**rstuartcih.org
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