Biosafety in the laboratory - VIB

Class III safety cabinets
A class III safety cabinet provides maximum protection to the worker and the environment.
The experiment, however, is less protected, because there is no downward air flow
inside the cabinet. A class III cabinet is completely sealed, and arm-length rubber gloves
are attached to ports in the cabinet in a gas-tight manner to allow for manipulation of
the materials isolated inside. Materials are brought into and removed from the cabinet
through a small air-lock or double-ended autoclave.
Room air
Contaminated air
HEPA-filtered air
A
B
C
D
E
glove ports with O-ring
for attaching armlenght
gloves to cabinet
sash
exhaust HEPA filter
supply HEPA filter
double-ended autoclave
or pass-through box
Protection
Safety cabinet worker environment experiment
Class I good good bad
Class II good good good
Class III excellent excellent good
Horizontal laminar air flow cabinets and cross flow cabinets
In laboratories where animal cells or in vitro plant materials are manipulated, use is sometimes
made of a horizontal laminar air flow cabinet or a cross flow cabinet. These are
cabinets in which sterile air is blown into the cabinet, whereas the contaminated air is
blown into the laboratory space. This means that the laboratory worker is sitting in the
contaminated air flow. In other words, these cabinets provide protection neither to the
worker, nor to the environment. They are therefore not considered as real safety cabinets,
and their use should be discouraged in most cases. These cabinets cannot be used for
activities posing a risk to the worker or to the environment. The use of such cabinets may
be permitted exceptionally, when no use is made of open containers holding GMOs, such
as open petri dishes containing modified bacteria or opened Erlenmeyer flasks containing
bacterial cultures.
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Biosafety in the laboratory