This report describes the experiments and modeling conducted to determine the effectiveness of commercially available in-room air cleaners (i.e., particulate matter (PM) filtration devices) in mitigating the impact of an aerosolized biological threat agent attack on a building. In one set of experiments, two air cleaners were evaluated for their single-pass filtration efficiency as a function of airflow rate, particle diameter (ranging from 0.03 im to 10 im), and type of particle (an inert aerosol and a bioaerosol). One of the air cleaners tested was a high-efficiency particulate air (HEPA) filtration device, and the other was an electrostatic precipitator (ESP) air cleaner. Following the single-pass experiments, the HEPA filter was further evaluated to verify its effectiveness in reducing in-room PM levels.