ELECTROSTATIC SAMPLING OF AIRBORNE MICROORGANISMS

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DESCRIPTION: (Adapted from the Investigator's Abstract) Exposure to airborne microorganisms in agricultural, industrial, indoor and health-care environments causes over 100 million episodes per year of respiratory infections in the US. Side-by-side monitoring by different commercially available bioaerosols samplers does not result in the same data for a given exposure level because the viability of the organisms is affected by the stresses they are exposed to during the process of collection from the air environment. The overall objective of this research is to use electrostatic mechanisms to collect the airborne microorganisms, thus collecting the organisms more gently than is currently achievable by the inertial forces in conventional impactors and impingers. The collection medium will be a moving fluid that surrounds the collected organisms and moves them out of the electric field, thus minimizing losses in viability due to the electric field and avoiding desiccation during the sampling period. To find the optimal conditions for high efficiency collection with the least amount of viability loss, a bioaerosol generator with induction charging and no ozone production will be designed, built and used to study the effect of different charge levels on the organisms during collection. The electric field in the electrostatic precipitation unit will be varied from a high positive kilovolt/cm level to its equivalent negative value. The results will be evaluated relative to the naturally present charge levels embedded in the organisms. The electrostatic precipitation plates will be at an angle to the horizontal, and a continuous flow of fluid over the lower plate will remove the organisms from the electric field into a liquid pool where the organisms are filtered out while remaining in the liquid. The new sampler will be tested in the laboratory and in an agricultural environment with high concentrations of bioaerosols present. Comparison sampling will be performed against a conventional impactor and a conventional impinger. Analysis will be made on how to use the new collection method in indoor and health-care environments where the bioaerosol concentration is low.