Inactivation of Bacillus subtilis on gypsum board using aerosolized chemical agents

The ability of aerosolized disinfectant agents to reach exterior and interior spaces of walls and other difficult to access areas has potential as a remediation technique for contained biological contamination. Bacillus subtilis were evaluated against aerosolized solutions of distilled water (dH₂O, control), 0.05% chlorine dioxide (ClO₂), and 0.6% sodium hypochlorite (NaOCl). Bacillus subtilis endospores were inoculated onto commercially available gypsum board with paper facing. Aerosols generated from a collison nebulizer were directed into a sterile contact chamber housing the inoculated gypsum board for 4, 8, and 12 hour periods. Independent evaluations were conducted of the gypsum board where the organism B. subtilis were exposed to the aerosolized disinfectant. Treatment effects were evaluated through the collection of surface samples before and after exposures. The aerosolized 0.6% sodium hypochlorite solution was the only treatment successful in reducing the total concentration of B. subtilis. Treatment with sodium hypochlorite solution reduced B. subtilis organisms by 1.55-log after 4 h, 1.92-log after 8 h, and 2.50-log after 12 h of exposure, though the difference in log-reduction between exposure periods were not statistically significant.