Transmission of respiratory pathogens occurs primarily in indoor settings. Engineering interventions that are known to reduce the risk of transmission of respiratory pathogens include increases in outdoor air introduction, filtration and inactivation by technologies including ultraviolet germicidal irradiation (UVGI). However, testing and validation of these interventions are challenging, particularly in actual applications. This study introduces an aerosol tracer system utilizing DNA as the tracer molecule, aimed at quantitative characterization of the performance of indoor air cleaning systems. Two DNA tracers, one designed to be relatively UV-resistant and another designed to be relatively UV-sensitive, were employed to assess air quality changes related to filtration and ventilation systems and the unique contributions of UVGI fixtures in various built environments. Read More