This standard prescribes a small-scale laboratory test method for measuring the contaminant removal efficiency of loose granular sorptive media used in gas-phase air-cleaning equipment as installed (in a test apparatus) in an airstream and challenged with test gases under steady-state conditions. This test is conducted at elevated gas challenge concentrations (relative to ventilation applications) and therefore should be used to compare media rather than directly predict performance in any particular application. This standard defines methods of calculating and reporting results obtained from the test data and establishes a results reporting system that can be applied to loose granular media covered by this standard. This standard does not apply to a. bonded carbon panels@ beaded activated carbon@ carbon cloths@ absorbent-loaded nonwovens@ dry-process carbon composites@ or b. particulate removal equipment. PURPOSE The purpose of this standard is to provide a standard laboratory test method for assessing the performance of loose granular media used in gas-phase air-cleaning systems. The results of these tests can provide information to the engineer that is useful in the design and selection of air-cleaning equipment and the design of air-cleaning systems for controlling indoor concentrations of gaseous air contaminants.