Basic Documentation

Ventilation Systems
Siemens Industry, Inc. 97
Topic Requirement(s) Commentary
Ventilation
Rates for
Animal
Rooms
Institute of Laboratory Animal Research, Commission on Life Sciences, National
Research Council, Guide for the Care and Use of Laboratory Animals, Eight
Edition, 2011:
Page 45: The primary purpose of ventilation is to provide appropriate air quality and a
stable environment. Specifically, ventilation provides an adequate oxygen supply;
removes thermal loads caused by the animals, personnel, lights, and equipment;
dilutes gaseous and particulate contaminants including allergens and airborne
pathogens; adjusts the moisture content and temperature of room air; and, where
appropriate, creates air pressure differentials (directional air flow) between adjoining
spaces. Importantly, ventilating the room (i.e., the macroenvironment) does not
necessarily ensure adequate ventilation of an animal’s primary enclosure (i.e., the
microenvironment), that is, the air to which the animal is actually exposed. The type
of primary enclosure may considerably influence the differences between these two
environments - for example, differences may be negligible when animals are housed
in open caging or pens, whereas they can be significant when static isolator cages
are used.
The volume and physical characteristics of the air supplied to a room and its diffusion
pattern influence the ventilation of an animal’s primary enclosure and are important
determinants of the animal’s microenvironment. The type and location of supply air
diffusers and exhaust registers in relation to the number, arrangement, location, and
type of primary and secondary enclosures affect how well the microenvironments are
ventilated and should therefore be considered. The use of computer modeling for
assessing those factors in relation to heat loading, air diffusion patterns, and
particulate movement may be helpful in optimizing ventilation of micro- and
macroenvironments.
Direct exposure of animals to air moving at high velocity (drafts) should be avoided as
the speed of air to which animals are exposed affects the rate at which heat and
moisture are removed from an animal. For example, air at 20°C moving at 60 linear
feet per minute (18.3 m/min) has a cooling effect of approximately 7°C. Drafts can be
particularly problematic for neonatal homeotherms (which may be hairless and have
poorly developed mechanisms for thermoregulatory control), for mutants lacking fur,
and for semiaquatic amphibians that can desiccate.
Provision of 10 to 15 fresh air changes per hour in animal housing rooms is an
acceptable guideline to maintain macroenvironmental air quality by constant volume
systems and may also ensure microenvironmental air quality. Although this range is
effective in many animal housing settings, it does not take into account the range of
possible heat loads; the species, size, and number of animals involved; the type of
primary enclosure and bedding; the frequency of cage changing; the room
dimensions; or the efficiency of air distribution both in the macroenvironment and
between the macro- and microenvironments.
(Continued on Next Page)
To ensure a proper ventilation rate is in effect,
a means of measuring and continuously
monitoring room exhaust airflow is necessary.
Animal room exhaust airflow sensors should
be located after adequate filtering to prevent
clogging from airborne matter (that is, dust,
hair, bedding material, etc.).
A means for automatically monitoring and
recording room ambient parameters is
recommended to substantiate that the
research was conducted in accord with proper
practices. Automatic and systematic
monitoring and documentation for animal room
ambient parameters is recommended to
substantiate that research was conducted in
accord with proper practices. This is typically
necessary for accreditation of research
programs.
Animal laboratories must generally be
accredited by the American Association for
Accreditation of Laboratory Animal Care
(AAALAC) in accordance with the “Guide for
the Care and Use of Laboratory Animals
”. The
“Guide” is the standard used by AAALAC to
accredit more than 650 animal care and use
programs worldwide.
Compliance with the “Guide” is also mandated
by the Public Health Service as a prerequisite
for receiving support from the NIH. The
recommendations of the “Guide” carry the
force of law based on the Health Research
Extension Act passed by Congress in 1985.