Optical Monitor for Non-invasive, Chemical & Size-differentiated Characterization of Airborne Aerosols

Atmospheric aerosol plays an important role in climate and climate change, reduced visibility in urban areas, heterogeneous atmospheric reactions, and acid rain production. Fine aerosol from combustion sources is believed to be an important risk factor for cardiopulmonary disease and mortality. The Phase I objective is to examine the feasibility of producing an inexpensive, compact, robust laser-based system for continuous monitoring of anthropogenic aerosol emissions. Air Instruments & Measurements, Inc.'s proposed automated technique is expected to yield particulate matter (PM) mass concentrations, as well as bulk size and chemical properties, in real time. This novel optical approach to PM continuous monitoring uses diode laser sources in combination with solid-state, dispersive spectrometers and fiberoptics. The Phase I project includes design and assembly of a prototype instrument, laboratory optimization studies, and performance evaluation. Synthetic aerosol mixtures will be generated in the laboratory and analyzed. Based on these experiments, the feasibility of the proposed technique will be evaluated in terms of observed detection limits and the instrument's ability to differentiate between various bulk aerosol sizes and chemical compositions. Currently, no analogous technology is commercially available, nor has it been described in the open literature. The proposed optical PM analyzer will have the flexibility to be used in an in situ (i.e., across-stack) configuration for stationary source monitoring and in a remote sensing configuration for noninvasive sensing of vehicle exhaust emissions and open path monitoring. Consequently, numerous commercial opportunities for this technology exist in a wide range of industries.