Evaluation of Conventional and Electrostatic Sprayers for Decontamination of PPE-Covered Manikins

Following a bioterrorism event, an incident or unified command is established, the impacted area characterized, and response work zones set up based on the extent of indoor/outdoor contamination. The personnel decontamination line, established in the contamination reduction zone, is essential for ensuring potentially biohazardous contamination on worker personal protective equipment (PPE) does not migrate outside of this zone. During personnel decontamination, conventional backpack or portable garden-type sprayers are often used to distribute liquid decontaminant onto PPE surfaces to physically remove and/or inactivate the contaminant. This process can lead to migration of biological contaminants and produces large volumes of liquid waste. A comparison of the performance of electrostatic sprayers and conventional backpack sprayers in personnel biological decontamination revealed that the electrostatic sprayer generated substantially less liquid runoff (∼75X), which would minimize waste generation and disposal costs following an event. Pilot-scale tests using manikins with PPE showed decontamination efficacy greater than 6 log₁₀ reduction (liquid and aerosol inoculation of spores) for the conventional backpack sprayer while decontamination was effective but incomplete with the electrostatic sprayer (<6 log₁₀ reduction) with residual spores detected at "hard-to-reach" areas. Decontamination efficacy of the electrostatic sprayer was improved by increasing the spray time, as greater than 6 log₁₀ reduction was then observed (liquid and aerosol inoculation). Spore reaerosolization was higher during decontamination with the conventional backpack sprayer. The electrostatic sprayer as used in our study presents a viable decontamination option for a personnel decontamination line following biological agent contamination incidents.