Several methods are available for exposing laboratory animal models to aerosols, each having its advantages and disadvantages (Table 2.1). Whole-body exposure systems (chambers) have a long history in inhalation toxicology, mainly due to their animal loading capacity and adaptability to several species. Chambers are often unsuitable for use with radioactive, infectious, and other potentially hazardous exposure materials, due to the need for large amounts of exposure material, inefficient delivery of aerosols to animals, multiple routes of exposure (e.g., oral, skin, and eyes), and the external contamination of exposed subjects. Also, chambers are costly, require considerable laboratory space, require expensive air supplies, and are difficult to decontaminate.