Evaluation of ventilation rates through four types of rat cages

Laboratory animal ventilation systems should provide a healthy and pleasant environment for both animals and animal caretakers. Microenvironment (cage) conditions that animals experience may be markedly different from the macroenvironment (room) conditions experienced by their caretakers. Specifying laboratory animal ventilation rates in terms of room air exchange rates often does not guarantee even minimally acceptable environments for the laboratory animals. Quantification of the cage ventilation rates is important understand microenvironmental conditions and is needed by laboratory animal facility designers and operators. Cage ventilation rates at four room air velocities - 0, 12, 50, and 100 fpm (0, 0.06, 0.25, and 0.5 m/s); five room airflow directions - 0°, 45°, 90°, 135°, and 180° from the front cage surface; and four caging systems - micro-isolator, shoebox, wire-mesh multiple, and wire-mesh single - were measurement using a thermal equilibrium calorimetry method.