Minimizing Decomposition of Vaporized Hydrogen Peroxide for Biological Decontamination of Galvanized Steel Ducting

Abstract

The behavior of vaporous hydrogen peroxide (VHP) was examined in clean, room-scale galvanized steel (GS) and polyvinylchloride-coated steel air ducts, to understand how it might be used to decontaminate larger ventilation systems. VHP injected into the GS duct decreased in concentration along the length of the duct, whereas VHP concentrations in the polyvinylchloride coated duct remained essentially constant, suggesting that VHP decomposed at the GS surface. However, decomposition was reduced at lower temperatures (approximately 22 degrees C) and higher flow rates (approximately 80 actual cubic meter per hour). A computational fluid dynamics model incorporating reactive transport was used to estimate surface VHP concentrations where bioaerosol contamination is likelyto reside, and also showed that VHP decomposition was enhanced at bends within the duct, compared to straight sections. Use of G. stearothermophilus indicators, in conjunction with model estimates, indicated that a concentration-contact time of approximately 100 mg/L H2O2(g) x min was required to achieve a 6 log reduction of indicator spores in clean GS duct, at 30 degrees C. When VHP is selected for building decontamination, this work suggests the most efficacious strategy may be to decontaminate GS ducting separately from the rest of the building, as opposed to a single decontamination event in which the ventilation system is used to distribute VHP throughout the entire building.

Decontamination of Bioaerosols within Engineering Tolerances of Aircraft Materials

“…The decomposition can be minimized by increasing temperature, flow rate, and initial concentration; however, lower decomposition will result in a slower killing of the biological (Verce et al, 2008). Additionally, studies have found that the reduction of organisms using hydrogen peroxide gas is impacted by the porous and nonporous nature of the surfaces (Rogers et al, 2005).…”

“…Surface softening was slight and confined to the immediate vicinity of the surface, necessitating further work (Gale et al, 2009). Studies have shown minimal oxidative damage after 100 experiments over one year, but there was a patina on the surfaces area where the VHP was introduced (Verce et al, 2008).…”

“…Hydrogen peroxide in the vapor phase was used with a high degree of success during the 2001 attacks (McVey, 2005) and tests in both the laboratory (Andersen et al, 2006;Oh et al, 2005) and field studies on grounded aircraft (Gale et al, 2008) have shown its efficacy. This method cannot be used on airworthy aircraft because it has detrimental material impacts (Gale et al, 2009;Verce et al, 2008).…”

Hydrogen embrittlement of 4340 steel due to condensation during vaporized hydrogen peroxide treatment

“…Vaporized hydrogen peroxide treatments have been investigated for possible usage in disinfection/decontamination of buildings [6], spacecraft [7], aircraft [8,9] and railcars [10]. The aircraft studies used vaporized hydrogen peroxide concentrations in the range of 150-600 ppm and cycle times of 80-120 min.…”

Large-Scale Inactivation ofBacillus AnthracisAmes, Vollum, and Sterne Spores Using Vaporous Hydrogen Peroxide

“…Hydrogen peroxide is considered less toxic to humans than other fumigants (e.g., formaldehyde, chlorine dioxide); therefore, it has been widely used to treat laboratory and medical equipment, pharmaceutical facilities, hospital rooms, ambulances, animal holding rooms, and air ducts (Anderson et al, 2006;Dryden et al, 2008;Fichet et al, 2004;French et al, 2004;Heckert et al, 1997;Hillman, 2004;Johnston et al, 2005;Klapes & Vesley, 1990;Krause et al, 2001;;Krishna et al, 2000;Verce et al, 2008;Wagenaar & Snijders, 2004). The use of hydrogen peroxide as a fumigant, dry mist, or an aqueous solution promotes decontamination efficacy against a wide range of microorganisms, including bacterial spores, vegetative bacteria, fungi, viruses, and bacteriophages (French et al, 2004;Grare et al, 2008;Hall et al, 2007;Hall et al, 2008;Heckert et al, 1997;Hillman, 2004;Johnston et al, 2005;Klapes & Vesley, 1990;Melley et al, 2002;Otter & Dudde-Niekiel, 2009;Rastogi et al, 2009;Rogers et al, 2005;Rogers et al, 2008b;Rogers & Choi, 2008).…”