Bactericidal effects of negative air ions on airborne and surface Salmonella enteritidis from an artificially generated aerosol

The bactericidal effect of high levels of negative ions was studied using a custom-built electrostatic space charge device. To investigate whether the ion-enriched air exerted a bactericidal effect, an aerosol containing Salm onella Enteritidis (SE) was pumped into a sealed plastic chamber. Plates of XLT4 agar were attached to the walls, top, and bottom of the chamber and e xposed to the aerosol for 3 h with and without the ionizer treatment. The p lates were then removed from the chamber, incubated at 37 degreesC for 24 h , and colonies were counted. An average of greater than 10(3) CFU/plate wer e observed on plates exposed to the aerosol without the ionizer treatment ( control) compared with an average of less than 53 CFU/plate on the ionizer- treated plates. in another series of experiments, the SE aerosol was pumped for 3 h into an empty chamber containing only the ionizer and allowed to c ollect on the internal surfaces. The inside surfaces of the chamber were th en rinsed with 100 mi phosphate-buffered saline that was then plated onto X LT4 plates. While the rinse from the control chamber contained colony count s greater than 400 CFU/ml of wash, no colonies were found in the rinse from the ionizer-treatment chamber. These results indicate that high levels of negative air ions can have a significant impact on the airborne microbial l oad, and that most of this effect is through direct killing of the organism s. This technology, which also causes significant reduction in airborne dus t, has already been successfully applied for poultry hatching cabinets and caged layer rooms. Other potential applications include any enclosed space such as food processing areas, medical institutions, the workplace, and the home, where reduction of airborne and surface pathogens is desired.