Utilization of natural electrical charges on airborne microorganisms for their collection by electrostatic means

Bioaerosol exposure assessment requires effective airborne microorganism collection methods. This research investigates whether the natural electrical charges on airborne microorganisms can be utilized for their collection by electrostatic means. To test this hypothesis, a new sampling device (Electrosampler), which deposits airborne microorganisms onto agar collection medium by electrostatic means, was designed and built. Different from traditional electrostatic precipitators, this device features no charging of incoming particles. The performance of the new sampler when collecting culturable bacteria and fungi in indoor and outdoor environments was compared against a traditional microbial impactor operated in parallel. The testing was performed for three different collection flow rates (1.2, 5, and 10 L/min) at a fixed electrostatic field strength of 5 kV/cm inside the collection chamber. For all testing conditions, the Electrosampler recovered more airborne microorganisms than the impactor with a difference as large as 5-9 times under certain conditions. The obtained data indicate that utilization of natural microorganism charge and electrostatic collection technique may provide a bioaerosol sampling method with higher recovery of culturable airborne microorganisms compared to inertia-based techniques. (C) 2005 Elsevier Ltd. All rights reserved.