On what basis is the engineer making this recommendation?  Seems to me
there's no justification for change if vapor concentrations are within TLVs.
Exhausting to the outside is best, in my view, but it can be expensive --
depending on the length of the run to the outside.  Outside can be reached
through an opening in a wall or the roof.

Gary Gill

-----Original Message-----
From: Elizabeth Earle [mailto:EEARLE@phxmem.com]
Sent: Tuesday, June 17, 2003 8:03 AM
To: 'Histonet@pathology.swmed.edu'
Subject: fume hoods


OK, Histonet, next question. For years we have been using charcoal filter
fume hoods (the portable ones with the plexiglass or acrylic shrouds) in our
lab, with absolutely no problem.We have always been way below the limits on
our breathing zone testing. Now an engineer is telling me we will need
built-in hoods that exhaust to the outside. I just don't see that it's
necessary in a histology lab where most of the equipment now has fume
control built into the system. The only place we will really need it is in
the area where we change out our processor and stainer fluids. Anybody's
opinions would be appreciated.