This is an award to support research the focus of which is on organic air pollutants, with particular emphasis on the sources, chemical reactivity, and ultimate fates of organic aerosols. The goal of the research program to be initiated with this award by this Presidential Young Investigator is to characterize the origins and behavior of organic aerosols well enough to allow the development of accurate organic source-receptor models for use in engineering design of air pollution control processes and systems. This award provides initial base-level support for this Presidential Young Investigator. Results are expected to advance the understanding we now have of chemical mechanisms that influence the fate of air pollutants associated with aerosols in outdoor and indoor air. This in turn is expected to be applied to formulation of mathematical models that can serve as the basis for engineering design of processes and systems for dealing with this environmental threat.