What is the Best Cleaning Method the Public Can Use to Remove Bacillus Spores from Indoor Surfaces?

JONATHAN THORNBURG, John Archer, Andrew Dart, Marshall Gray, M. Worth Calfee, RTI International

     Abstract Number: 253
     Working Group: Bioaerosols

Abstract
An outdoor, wide area release of a biological agent will significantly disrupt society. An unexplored aspect of consequence management and public health guidance is the need to minimize the risk from immediate and delayed exposure to Ba spores within the indoor environment. The possibility that “low technology” or “self-help” surface cleaning methods for the disinfection, removal, and resuspension of Ba spores with materials and chemicals readily available to the public could minimize risk requires research. We tested different combinations of cleaning materials, cleaning solutions, application methods, and cleaning force to cover a broad range of exposure and hazard risks. Experiments were conducted on laminate flooring loaded with dry Bacillus thuringiensis kurstaki (Btk) spores inside a sealed glove box. Spores resuspended, removed by the cleaning material, and remaining on the surface were extracted from the sample, plated, and incubated and counted. Comparison of spore resuspension, collection, and residuals within and between experimental conditions were inconclusive. We noted, however, that the spore counts on the cleaning material were 10 to 100 times higher than the number of spores resuspended or remaining on the surface. This observation led us to develop a risk minimization ratio, defined as the sum of the spores resuspended and remaining on the surface divided by the number collected by the cleaning material. This analysis determined a wet wipe with any type of cleaning liquid performed best, a paper towel with bleach or dry was in the middle, and a sponge dipped in bleach solution or dry was worst.