Aims: To develop test methods and evaluate the survival of Bacillus anthracis ΔSterne and Bacillus thuringiensis Al Hakam spores after exposure to hot, humid air. Methods and Results: Spores (>7 logs) of both strains were dried on six different test materials. Response surface methodology was employed to identify the limits of spore survival at optimal test combinations of temperature (60, 68, 77°C), relative humidity (60, 75, 90%) and time (1, 4, 7 days). No spores survived the harshest test run (77°C, 90% r.h., 7 days), while > 6Á5 logs of spores survived the mildest test run (60°C, 60% r.h., 1 day). Spores of both strains inoculated on nylon webbing and polypropylene had greater survival rates at 68°C, 75% r.h., 4 days than spores on other materials. Electron microscopy showed no obvious physical damage to spores using hot, humid air, which contrasted with pH-adjusted bleach decontamination. Conclusions: Test methods were developed to show that hot, humid air effectively inactivates B. anthracis ΔSterne and B. thuringiensis Al Hakam spores with similar kinetics. Significance and Impact of the Study: Hot, humid air is a potential alternative to conventional chemical decontamination.

Response surface models of hot, humid air decontamination were developed which may be used to select decontamination parameters for contamination scenarios including aircraft.

Aims: To develop test methods and evaluate survival of Bacillus anthracis Ames, B. anthracis ΔSterne and B. thuringiensis Al Hakam spores after exposure to PES-Solid (a solid source of peracetic acid), including PES-Solid formulations with bacteriostatic surfactants. Methods and Results: Spores (≥7 logs) were dried on seven different test materials and treated with three different PES-Solid formulations (or preneutralized controls) at room temperature for 15 min. There was either no spore survival or less than 1 log (<10 spores) of spore survival in 56 of 63 test combinations (strain, formulation and substrate). Less than 2Á7 logs (<180 spores) survived in the remaining seven test combinations. The highest spore survival rates were seen on water-dispersible chemical agent resistant coating (CARC-W) and Naval ship topcoat (NTC). Electron microscopy and Coulter analysis showed that all spore structures were intact after spore inactivation with PES-Solid. Conclusions: Three PES-Solid formulations inactivated Bacillus spores that were dried on seven different materials. Significance and Impact of the Study: A test method was developed to show that PES-Solid formulations effectively inactivate Bacillus spores on different materials.

Aims: To develop infectious (live/dead) enveloped virus test indicators and response surface methodology (RSM) models that evaluate survival of an enveloped ribonucleic acid (RNA) virus on contaminated aircraft materials after exposure to hot, humid air (HHA). Methods and Results: Enveloped RNA bacteriophage Phi6 (6) was dried on wiring insulation, aircraft performance coating (APC), polypropylene, and nylon at ≥ 8 log 10 plaque-forming units (PFU) test coupon −1. Only 2.4 log 10 inactivation was measured on APC at 70 • Celsius (• C), 5% relative humidity (RH) after 24 h. In contrast, HHA RSM models showed a 90% probability of a 7 log 10 inactivation at ≥63 • C, 90% RH after 1 h, and decontamination kinetics were similar across different materials. HHA decontamination of C-130 and C-17 aircraft showed >7 log 10 and ≥5.9 log 10 inactivation of enveloped virus on 100 and 110 test indicators, respectively, with a 1-h treatment, excluding ramp-up and ramp-down times. Conclusions: Enveloped RNA virus test indicators were successfully developed, lab tested for HHA decontamination, analyzed for RSM, and field-tested in aircraft demonstrations. Significance and Impact of the Study: The utility of HHA decontamination was demonstrated after inactivating enveloped RNA virus on aircraft with a 1-h HHA treatment within aircraft temperature and RH limits.

Transition of a new technology from research and development to acquisition at a Technology Readiness Level 7 is unprecedented.