The proposed project will develop and demonstrate a miniaturized, portable aerosol sampler that will collect a series of time- and location-resolved personal exposure samples for conducting research into the relationships among environmental exposure, genetics and health. It will also develop a bench-top assay unit that will perform colorimetric assays for endotoxin on the collected samples. The sampler will employ an array of novel micro-channel collectors, and, when combined with a position-monitor (GPS) and activity monitor (accelerometer), will collect a time-series of exposure samples that will be time- and location- stamped to allow researchers to fully characterize the exposure history of subjects as they travel through their environment. The sampling unit will be extremely small, light-weight and battery operated to allow it to be carried in a back-pack even by a 10-year old child. This device will significantly improve the ability to localize exposure events in space and time and will provide a critical tool for use in resolving uncertainties about the relationships between exposure and human health impacts. Each sampling unit will contain a carousel holding an array of micro-channel collectors which will collect samples at 30 minute (or shorter) intervals. The carousel will hold up to 48 collectors allowing samples to be collected over a 24 hour period. Once all the samples have been collected, the carousel will be transferred to the bench-top assay unit which will perform assays on all of the collected samples, greatly reducing the workload associated with the analysis of the numerous samples collected during a typical epidemiological study. This aerosol sampling and detection apparatus will be integrated with automation technology developed by the Pacific Northwest National Laboratory (PNNL) to produce a self-contained portable personal exposure sampling unit and a bench-top assay unit. Enertechnix will be responsible for the aerosol sampling and microfluidic components and for system integration. PNNL will adapt its automation, power management, and position- and motion- sensing technologies for use in the PEM. The University of Washington (UW) will assist in the implementation of an endotoxin assay employing a miniature colorimetric readout unit developed by FAR Sciences. Prototypes will be developed and, in collaboration with the UW, will be field tested in a variety of environments to demonstrate the performance of the sampler and bench-top assay unit. This system will be the first to provide a highly efficient aerosol to microfluidics interface and the first to provide automated, time- and space-resolved sampling in a portable package.