Laboratory evaluation of large-scale decontamination approaches.

AIMS

To evaluate the effectiveness of two spray-based decontamination methods for surface contamination reduction and to determine the potential for contamination spread by these methods.

METHODS AND RESULTS

Material coupons (treated plywood and concrete) were contaminated with c. 1 × 10(7) spores of Bacillus atrophaeus by aerosol deposition. Decontaminants (pH-adjusted bleach or Spor-Klenz(®) RTU) were applied to coupons by either backpack sprayer or gas-powered sprayer. Contact time, reapplication frequency and rinse method were also varied. In addition to surface removal efficacy, partitioning of contamination between the rinsate and aerosol fractions was determined. Results indicated that pH-adjusted bleach was effective (≥6 logs reduction) when two applications and a 30 min contact time were administered, regardless of the decontaminant application method or material. Spor-Klenz(®) RTU was effective on wood, but achieved ≤3 logs reduction on concrete. A shortened application procedure with pH-adjusted bleach resulted in lower efficacy on wood, and a greater apparent potential for contamination spread.

CONCLUSIONS

Consideration of material surface type is important when selecting a decontaminant. Also, achieving conditions that effectively inactivate surface biological contamination are critical to preventing the spread of contamination.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results presented here are intended to help development of remediation plans following a biological contamination incident.