ABSTRACT
All inhalation exposures involve the respiratory system as the major portal of entry for the test material. The test material normally is administered in the gaseous/vapor state or as an aerosol. In either case, the test material must be administered in a manner that provides stable, reproducible exposure concentrations. These exposure concentrations must be measured routinely to demonstrate that the actual exposure concentrations are within the desired ranges, or to provide information needed to bring the actual exposure concentrations within the desired ranges.
