ABSTRACT
Modern inhalation studies must conform to rigorous criteria with respect to generation and control of the exposure environment. Pure air, having precisely adjusted temperature and relative humidity, is intentionally polluted with substances having known and stable characteristics. In most well-designed studies, a matched control population of subjects is exposed either simultaneously (preferred) or serially to pure air. One requirement of such studies is the ability to clean and condition quantities of ambient air. To meet this challenge, a suitable air purification and conditioning system must be installed, tested, and successfully operated. Additionally, equipment for generating pollutants must be carefully designed or selected, tested, and then operated successfully during exposures. Furthermore, experience has shown that the manner in which pollutants are combined and mixed with clean throughput air, and the ability to suppress unwanted, animal-generated contaminants, are important to achieving a high-quality exposure.
