This grant provides renewed support to the Berkeley Indoor Microbial Ecology Consortium (BIMERC), a multidisciplinary group of mycologists, microbiologists, chemists, architects, and engineers who are working together to better understand the sources, factors, and processes involved in the assembly of microbial communities indoors. Grant funds support a number of planned scientific studies by the BIMERC team, including an investigation into which microbial volatile organic compounds are indicators of microbial population growth;, a study of how environment, building characteristics, and human behavior affect airborn microbes; a project to measure and model living particles using a laser-based ultraviolet spectrometer; and an analysis of microbial reproduction using gene transcripts. Additional funds support the purchase of a state-of-the-art mass spectrometer, a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS), which will permit the team to conduct real-time chemical analysis.  The team will share their findings through peer-reviewed scientific publications, presentations at meetings and workshops, and through web-based blogs.