This grant funds work by Paul Ziemann, professor of chemistry at the University of Colorado, to investigate the sources and processes that influence the composition of organic chemicals in indoor environments and to improve predictions of the chemistry of indoor air. Ziemann and his team will conduct field studies in several locations on and around the University of Colorado campus. Study sites have been chosen to reflect the diversity of indoor environments: a carpeted meeting room in the Sustainability, Energy, and Environment Community building; the Chapel Theatre in Old Main, which is the oldest building on campus and which contains extensive wooden paneling; and the swimming pool at the universityХs recreation center. State-of-the-art instruments and methods will be used to measure organic chemicals and other reactive species at each site. Measurements will include gas (volatile organic compounds and other trace gases), aerosols, surface composition (functional groups and single compounds), and air exchange. Laboratory studies will be conducted to investigate the fundamental interactions of organic chemicals with surfaces composed of common indoor materials, including bare plastics, bare wood, varnished wood, and carpet polymers. Results of the field and laboratory studies will be used to develop models to describe and quantify indoor chemical emissions, deposition, and reactions; and to determine the effects of chemical and physical variables such as organic gases, oxidants, surfaces, humidity, acids, light and temperature, and human occupancy on the composition of indoor air.