People spend upwards of 90% of their time inside, yet current air quality regulations only address outdoor air pollution. Indoor environments present distinct air quality challenges, especially for the transmission of respiratory diseases such as the flu, covid, or the common cold. Unfortunately, most of our buildings are not designed to address disease transmission. There is a need for new, accessible strategies to improve the quality of our indoor air. In this talk we will discuss some of the fundamental understanding we have developed about respiratory aerosol production and the role that masks can play in reducing disease transmission.