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NOTE: This document is provided for historical purposes only.
The authors ask you:
Decontamination is addressed frequently within the regulatory framework of OSHA.1 The HAZWOPER rule defines decontamination as "... the removal of hazardous substances from employees and their equipment to the extent necessary to preclude the occurrence of foreseeable adverse health effects." The topic also appears extensively in OSHA standards 1910, 1915, 1926, as well as standards for mineral dusts, asbestos, carcinogens, inorganic arsenic, and methylenedianaline. A broad discussion is contained in NIOSH Publication No. 85-1152,2 which states: "The effectiveness of any decontamination method should be assessed at the beginning of a program and periodically throughout the lifetime of the program. If contaminated materials are not being removed or are penetrating protective clothing, the decontamination program must be revised." To date, there is no recognized standard for responder/worker decontamination, which addresses the effectiveness of a decontamination process to safely and cleanly extricate people from contaminated protective ensembles; instead, it is up to the employer to certify worker competency. Dirty doffing evaluation provides a means to both judge and improve the effectiveness of responder/worker decontamination processes.
The techniques used for Dirty Doffing Evaluation grew out of Contaminated Doffing Research performed at Los Alamos National Laboratory in support of the Departments of Energy and Defense. The basic method was originally developed to assess the performance of encapsulating protective suits used in tritium-contaminated areas. Since then, the technique has been improved and applied to the study of military protective ensembles to determine whether contaminated garments could be doffed "without endangering the wearer." A field evaluation application, Decontamination Proficiency Training, was developed in 2003, and has since been used with emergency responders and receivers, including hazmat and civil support teams as well as hospital workers.
The approach is intended to challenge the decontamination process consisting of people, procedures, and equipment. One or more workers are dressed out in the desired/prescribed protective ensemble (garment, respirator, and ancillary equipment, such as boots and gloves, etc.). A suitable non-toxic contamination simulant is then applied to the protective ensemble surface, and the workers are then decontaminated and doffed in accordance with established procedures and equipment. On completion of this process, the workers are evaluated for the presence of simulants on unprotected skin or duty uniforms beneath the protective ensemble barrier; a disposable garment is used for evaluation purposes. A post-process critique using observer feedback and/or videotape review provides an opportunity to identify potential vulnerabilities in decontamination and doffing actions. The collected information can be used as the basis for suggesting equipment design modifications or changes, identifying component interface issues, or improving the procedures and practices employed by workers engaged in the decontamination and doffing process.
Figure1 illustrates dirty doffing evaluation results of the performance of similarly constructed protective ensembles.3 These results suggest performance differences among similar garment design during well-controlled decontamination and doffing procedures. The red and blue color-coded areas indicate body locations where dry and wetted surface contaminants, respectively, were judged to cross the protective ensemble barrier to unprotected skin or duty uniform surfaces. The authors have observed other phenomenon during dirty doffing evaluation, including evidence of skin or duty uniform contamination attributable to inward leakage during simulated work motions, and re-suspension of particulates from poorly decontaminated equipment, such as respirators.
Figure 2 illustrates two specific results, which have been observed in fixed-facility or field evaluation conditions. The blue streak is representative of a common failure of un-encapsulating garments, in which surface contaminants on the head and/or shoulders are washed into the garment neck opening during the decontamination process; when performed with relatively high volume and pressure delivery rates, "decon water" can come into contact with unprotected surfaces extending to the groin and beyond. The red mark above the right knee represents contact with a gloved and inadequately decontaminated hand, which occurred well into the process of doffing the contaminated protective garment.
Results of work performed with hospital-based emergency receivers4 are illustrated in Figures 3 and 4. Figure 3 shows a map of six body locations to which water-soluble non-toxic simulants were applied; Figure 4 displays an analysis of cleaning results before and after providing feedback to the hospital workers. These results indicated that contamination on the palm, axilla, and shin were more persistent through cleaning efforts than contamination applied to other body locations. The authors observed anecdotal evidence of other details that impact the ability to cleanly and efficiently extricate people from contaminated articles.
Manufacturing standards alone are insufficient to ensure continuity of protection through decontamination and doffing of contaminated protective ensembles. Dirty doffing evaluation provides an opportunity to improve continuity of protection by identifying potential vulnerabilities as a matter of routine preparedness for operational events involving significant contamination of protective ensemble surfaces.
These include: establishing performance baselines for emergency responders and receivers; working out a standard evaluation methodology for competency certification; and application to affected occupational groups, such as environmental restoration workers and workers engaged in the processing of highly toxic chemicals and industrial materials.
The findings and conclusions in this poster are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these Web sites.
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