There is a growing realisation that more scientific data are needed as a basis for laboratory animal care guidelines and that many design parameters and recommendations are not directly related to the microenvironmental (e.g., cage) conditions that actually affect the health and well-being of the animals. Ventilation recommendations are based on room air exchanges, but the room air diffusing system, cage type, and other room characteristics generally are more important than room air exchanges in their impact on the microenvironment to which the animals are exposed. Data are needed to quantify laboratory animal environmental conditions so as to improve animal well-being, facility design, and energy efficiency. Seven laboratory rat facilities at a US university were surveyed. Temperature, humidity, air velocity, and ammonia levels in rooms and selected cages within the rooms were measured and analysed. It was found that the room air exchange rate had little effect on cage environmental conditions in the surveyed laboratory animal facilities.

KEYWORDS: animals, laboratory animal housing, animal housing, surveys, USA, regulations, designing, microclimate, health, ventilation, air change rate, rooms, temperature, humidity, ammonia, air, speed, properties