26 February 1993
materials such as infectious agents, radioisotopes, toxins or
units are suited for sanitizing water bottles, small cages, and a
carcinogens from escaping to the outside (Biohazard Suite).
variety of other small equipment items. In those cases where a
Species housed in such areas are typically rodents.
tunnel washer is selected, a pass through bottle washer is usually
not needed.
Barrier Suites are used for protection of specific pathogen
The cage and rack style washer is provided in facilities up to
free (SPF) or viral antibody free (VAF) rodents, immunodeficient
14,000 NSF. Facilities exceeding 14,000 NSF are equipped with
animals, or for particularly valuable animals such as transgenics.
both a cage and rack washer and a tunnel style washer.
These suites require restricted personnel access, dress codes
Regardless of the washer style, cages should move in a single
and means of decontaminating (autoclaving) supplies entering
direction, entering through the soiled side of the cage wash room
the area. Air pressure within a Barrier Suite should be positive
and exiting through the clean side.
relative to the corridor and separated from the corridor by an air
lock.
Cubicles
Prevention of contamination by radioisotopes and hazardous
Cubicles are essentially rooms within a room. Typically,
chemicals and infectious agents of low pathogenicity may be
supply air delivered through ceiling diffusers located in the center
attained by controlled access, protective clothing, and
of the room passes to the floor and under the cubicle door and is
performance of procedures under a properly designed biological
then exhausted through registers in the ceiling of the cubicle.
safety cabinet or fume hood. Work with microbial agents
The direction of air flow may be reversed in some systems. A
classified by the Center for Disease Control (CDC) as Biosafety
higher level of protection is attained through the provision of
Level 3 (BSL 3) or higher requires special engineering features
individual supply and exhaust in each cubicle. The air may pass
that protect the laboratory worker, the community, and the
through a HEPA (High Efficiency Particle Arrester) filter at the
environment. The unique features that distinguish the BSL 3
supply end, the exhaust end, or both. Cubicles offer the
facility or Infectious Disease Suite from a basic laboratory are the
advantage of isolating small segments of the animal population
provisions for access control and a specialized ventilation
within a room permitting the housing of multiple species in a
system. The CDC handbook Biosafety in Microbiological and
single room, thereby providing more efficient use of space. They
Biomedical Laboratories should be consulted in planning a BSL 3
are particularly useful for quarantine of incoming animals.
facility. Air pressure in an Infectious Disease Suite should be
Cubicles may preclude the need for a separate quarantine room
negative relative to the corridor. Requirements for a maximum
for small animals. Cubicles may also promote the containment of
containment laboratory (Biosafety Level 4) are extremely unlikely
hazardous substances used in animal studies, provide an added
at a VA medical center. Means of containment using cubicles,
degree of security against mix-ups for the user, and reduce odors
ventilated cages or cage racks and microisolator units are
and allergens. Cubicle installation can be of the prefabricated
described below.
type that precludes masonry structures and can be readily
With conventional housing, animals are maintained in
disassembled to convert the room to other uses.
primary enclosures (cages, pens) that do not provide protection
from contaminants that may be present in the room environment.
Barriers and Containment Areas
Some racks and caging systems are designed to reduce airborne
Specialized areas may be required to keep infectious agents
contaminants in the animals' environment. Systems used for this
away from animals (Barrier Suite) or for preventing hazardous
purpose include microisolator cages, ventilated racks, individually
VA Design Guide -- Veterinary Medical Unit
Page 2-8
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