Developing a Full-Body Methodology for Decontamination Visualization

1662 

Student Poster 

E Titus¹, J Slagley²

¹Centauri, in support of AFIT, Dayton, OH, ²Air Force Institute of Technology (AFIT/ENWL), Wright-Patterson AFB, OH

Emily Titus  
Centauri, in support of AFIT

Jeremy Slagley, CIH  
Air Force Institute of Technology (AFIT/ENWL)

Full and effective decontamination is highly important in HAZMAT or WMD situations. Decontamination aims to prevent adverse health outcomes that can be experienced by both first responders and victims after contact with hazardous materials. This work aims to develop a full-body methodology by which contamination and the extent of decontamination can be quantified quickly and easily using image analysis. A UV fluorescent tracer was used as a surrogate contaminant. Images were taken before and after each step of testing and compared using ImageJ. This allowed quantification of the extent of contamination.

This research was aimed towards evaluating the claims of 90% contamination reduction from disrobing. This statistic is often cited in both civilian and military disaster planning guides and states that after a HAZMAT or WMD situation, simply disrobing will remove 90% of contamination. Despite being a main tenet of planning guidelines, this claim has not been thoroughly investigated. While this does appear to be a reasonable assumption for certain populations, no data has been found to support the claim. This work aimed to create a method for visualizing and quantifying contamination and decontamination by using a UV fluorescent tracer as a chemical warfare agent surrogate and image analysis to quantify the spread of contamination.

To test the research question, a UV fluorescent dye was aerosolized by a Collison nebulizer inside an aerosol test chamber. Preliminary work analyzed deposition of the dye onto black posterboard to determine the reproducibility of deposition as well as give a straightforward sample for refining imaging and analysis techniques. For decontamination experiments, a mannequin dressed in black clothing was imaged under UV light to obtain a background reading. It was then placed into the test chamber and the nebulizer was run for 70 minutes. The mannequin was again imaged under UV light to see the extent of contamination. The mannequin was disrobed by cutting the clothing off (similar to non-ambulatory patients) and imaged again. Images were taken in triplicate and averaged at each step to minimize the effects of outlier pixels. A Stouffer 21-step wedge, fluorescence reference slide, and dilution standard created from the UV tracer were used for calibration of images. These images were analyzed for differences between images using ImageJ. The calibration standards were compared between each image and images were adjusted if necessary to ensure the standards had the same values between images prior to analysis. In addition, an average calibration curve was created which allowed conversion of measurements from gray values to optical density units. This analysis allowed a quantification of contamination and decontamination.

Results are currently preliminary but suggest that using a fluorescent tracer and image analysis may be a reliable way to quantify contamination and decontamination efficacy. Final results hope to demonstrate the accuracy of the 90% statistic. Preliminary results show that delivery method and time between contamination and disrobing have considerable effects on the amount of contamination penetrating the mannequins clothing and thus depositing on the mannequin itself, up to 98% removal for a misted delivery removed immediately. In addition, basic modeling predicts that 89% of the body's surface area should be covered in situations where a person is wearing long sleeves and pants as well as closed shoes. It is important to note however, that coverage does not always equal protection. In other situations, as little as 62% may be covered (assuming shorts, T-shirt, and closed shoes are worn). Both scenarios will be explored during further testing to test the accuracy of these predictions.

Emergency Preparedness & Response

Aerosols

Protective Clothing and Equipment/Respiratory Protection