ABSTRACT. The objective of this paper is to describe a test method to determine a Clean Air Delivery Rate-(CADR) type measurement for an air cleaner when challenged with microbiological aerosols. The method is a modi cation of the Association of Home Appliance Manufacturers (AHAM) Standard AC-1, "Standard Method for Measuring Performance of Portable Household Electric Cord-Connected Room Air Cleaner," which determines the CADR for three different particulate matter challenges (smoke, dust, and pollen). The ability to extend the AHAM method to microbial aerosols follows the tradition of the AHAM test of using realistic particle challenges and allows a means to compare and evaluate different brands of room air cleaners regarding characteristics signi cant to product use. This is a useful approach for evaluating a wide range of air cleaning devices.The test procedure requires both a natural decay measurement and a particulate decay measurement. The particulate decay measurement is de ned as the decay while the air cleaner is operating. The aerosol generation and collection optimized the ability of three very different organisms to survive and remain culturable. The results showed that the AHAM test method was successfully adapted to allow testing with actual organisms.