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Measurement and control of airborne microorganisms using electrostatic methods.
Mainelis-G; Gorny-R; Willeke-K; Grinshpun-S; Reponen-T; Baron-P
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana. Fairfax, VA: American Industrial Hygiene Association, 2001 Jun; :1
Most of the widely used bioaerosol sampling devices employ collection techniques that are known to reduce viability of sampled microorganisms. An electrostatic collection method, where airborne particles are electrically charged and then removed from the air by electrostatic forces, has the potential for being a "gentle" collection technique. Our tests with an Electrostatic Aerosol Sampler showed that charged microorganisms could be effectively removed from the airstream. However, charging by a conventional corona discharge inactivated sensitive airborne cells. The goal of this study was to determine how the bacterial recovery and injury depended on the amount of electric charge imparted on bacteria. In our tests, the charging of airborne microorganisms was achieved not by the traditionally used corona discharge, but by applying induction charging. In this setting, bacteria were aerosolized and then imparted a charge ranging from -10,000 to + 10,000 elementary charges. The bacteria carrying a desired electric charge were selected using a parallel plate mobility analyzer and collected with a BioSampler (SKC Inc., Eighty Four, PA) for a subsequent analysis of their relative recovery and injury. The results showed that the relative recovery of Pseudomonas fluorescens bacterial cells carrying from -4,100 to +30 electrical charges ranged from 40 to 60%, while the recovery of the same cells carrying about -9,000 charges was below 20%. The relative recovery of P. fluorescens cells carrying more than 2,700 positive charges was less than 1.5%. In contrast, the relative recovery of Bacillus subtilis var niger did not depend on the amount of imparted electric charge. The extent of metabolic and structural injury of P. fluorescells cells also did not depend on the amount of electric charge carried by airborne bacteria. The study showed that polarity and magnitude of imparted electric charge is very important when developing microorganism collection methods employing electrostatics.
Sampling-equipment; Microorganisms; Electrostatic-fields; Electrical-charge; Force; Aerosols; Aerosol-particles; Bacteria; Bacterial-dusts; Injuries; Airborne-dusts; Airborne-particles; Cell-biology; Cell-cultures; Cellular-function; Cellular-reactions
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana