In recent years, there has been an increasing emphasis on air cleaning and treatment technologies that could be used to reduce infectious aerosol concentrations in occupied spaces, including traditional (e.g., filtration, 254 nm ultraviolet) and emerging (far-UVC, chemical treatments) methods. Although there has been a recent push to develop standardized test methods to evaluate the efficacy of these technologies against bioaerosols, they have largely been evaluated using disparate methods, making it difficult to compare results across studies. To address this challenge, the U.S. Environmental Protection Agency has been conducting systematic bioaerosol testing with a wide variety of technologies to understand how changes to test methodology impact performance against bioaerosols. Experiments have been conducted in chambers up to 85 m3 using surrogates for airborne pathogens, primarily the bacteriophage MS2. Results have demonstrated that relatively simple changes to test methodology, including changing the aerosolization media (or even simulated saliva recipe used) can have a significant impact on efficacy results. Similarly, changing the chamber size or material composition can influence performance. These findings are not only critical for facilitating comparisons across technologies but are key to developing and optimizing reliable and repeatable efficacy test methods. As new public-health based indoor air quality standards and targets for reducing disease transmission emerge (e.g., ASHRAE Standard 241), improving the applicability of these test methods to real-world applications and settings is increasingly important. This presentation will also highlight fundamental knowledge gaps that remain in this field and bridge several disciplines.