Volume I - Section I - Introduction 
Page 1-13 
Ventilation of 20 air changes per hour was balanced so that pressure differences allowed 
air to flow from the corridor and ceiling supply vent (130 CFM) over the entry door 
through the room into the far wall exhaust ceiling vent (270 CFM). A 12/12-hour 
light/dark cycle with no twilight was used. Room temperatures averaged 22.8 ± 1.7 °C 
(range 18.4 to 26.9 °C) in the trials where nationally accepted standard macro 
environment RHs were used and averaged 24.1 ± 0.7 °C (range 22.2 to 25.2 °C) during 
below normal macroenvironmental RH trials. The average range in room temperature per 
trial was ± 1.35 °C. Room humidity in the standard RH group was 51.5 ± 8.2 percent 
(range 38.5 to 66.5 percent RH). Room humidity in the below normal RH group was 22.7 
± 7.7 percent (range 11.4 to 35.1 percent RH). The range in room humidity per trial 
averaged 1 1 .7 percent RH. At macroenvironmental room humidities of 40 to 70 percent, 
the relative humidity (RH) levels in the microisolation cages with four animals per cage 
averaged 27.1 percent RH above room RH levels. With two animals per cage, the RH 
levels in the microisolation cages averaged 16.1 percent RH above the room RH levels. 
At macroenvironmental room humidities of <40 percent, the RH levels in microisolation 
cages with four animals averaged 35.4 percent RH above the room RH levels. At two 
animals per cage the RH levels in the microisolation cages averaged 22.6 percent above 
room levels. 
• Study I (BALB/c mice): Population density of four animals per cage (Trials 1 and 2): 
Temperature: There was no significant temperature variation between microisolator 
caging systems. 
Relative humidity: Microenvironmental RH in the type microisolator cages averaged 
28 percent higher than the room RH levels. 
Ammonia: All cages accumulated less than 5 ppm ammonia at day 9. 
• Study I (BALB/c mice): Population density of two animals per cage (Trials 3 and 4): 
Relative humidity: Micro environmental RH in microisolator cages averaged 9 
percent higher than the room RH levels. 
Ammonia: All cages contained less than 3 ppm ammonia at day 9. 
• Study II (CD-I mice): Population density of four animals per cage (Trials 1 and 2): 
Relative humidity: Micro environmental RH in microisolator cages averaged 36 
percent higher than the room RH levels. 
Ammonia: In trial 1, 8-day trial averages were, 50.6 ppm, in microisolator cages. In 
trial 2, 8-day trial averages were 8.7 ppm, in microisolator. 
