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Ventilation Design Handbook on Animal Research Facilities Using Static Microisolators 
relative humidities (40, 55, and 70 percent). Every 24 hours the chamber conditions were 
changed, and cage, bedding, water, filter caps, and food were replaced. Three sensors 
suspended just under the filter cover measured temperature and humidity and transmitted 
the data to a recorder. The first reading was taken after a 3 -hour equilibration period, then 
every three hours until the next day's change. By measuring the average temperature and 
humidity, it was possible to study the differences between cage and ambient conditions. 
At 68 °F and 40 percent relative humidity, the mean conditions in the cage were 72 °F 
and 50 percent relative humidity; at the upper limit of 74 °F, and 70 percent relative 
humidity, the mean cage conditions were 78 °F and 75 percent relative humidity. 
R.S. Runkle: Laboratory Animal Housing , 1964, Amer. Inst. Arch. J., 41:77-80; F.H. Munkelt: 
Air Purification and Deodorization by Use of Activated Carbon , 1948; F.H. Munkelt: Odor 
Control in Animal Laboratories, 1948, Refrig. Engr., 56:222-229. 
Most of the current recommended guidelines for heating, ventiLation, and air conditioning 
systems for the animal research facilities appear to be based on the ventilation criteria 
described by Runkle, which were in turn based on studies done by Munkelt. 
1.3.2 Literature Search on Effects of Ambient Temperature on Growth and 
Behavioral Thermoregulatory Responses in Mice 
Christopher J. Gordon, Peggy Becker, and Joseph S. Ali: Behavioral Thermoregulatory 
Responses of Single- And Group-Housed Mice, 1997, Neurotoxicology Division, National Health 
and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, 
Physiology and Behavior (accepted for publication). 
The ambient temperature (T a ) to house and study laboratory mice is critical for nearly all 
biomedical studies. The ideal T a for housing mice should be based on their 
thermoregulatory requirements. The T a for housing mice should approximate their zone 
of thermoneutrality where neither autonomic nor behavioral thermoeffectors are 
activated. In other words, the T a for housing should not stress the animal’s 
thermoregulatory system. Although laboratory mice are usually housed in groups of five 
or more, most of the information on thermoregulation in mice has been collected in 
individual animals. Overall, individual mice have a thermoneutral zone of approximately 
30 to 32 °C, which is considerably warmer than the standard housing T a of 22 to 24 °C. 
Thus, it is expected that standard housing conditions impart varying amounts of cold 
stress on mice. However, because they frequently huddle and thereby reduce heat loss it 
can been assumed that a standard housing T a of 22 to 24 °C is probably not thermally 
stressful for groups of mice. If huddling behavior alters the thermoneutral zone, then 
groups of mice should prefer markedly cooler T a s compared to individual mice. To 
address this issue, it is necessary to measure the thermoregulatory behavior of individual 
