Dealing with decontamination
April 30, 2008
Can your workers be cleanly and safely extricated from a contaminated protective ensemble? Are you willing to risk that your workers are proficient or merely trained to perform decontamination activities?
U.S. manufacturing standards governing protective device performance don’t ensure protection against toxic material exposures during post-mission decontamination and doffing procedures. Employers are responsible to certify worker competency with personal protective equipment (PPE). Improper decontamination and doffing of contaminated protective ensembles can result in exposures to the wearer and others in proximity. If you’re the slightest bit uncertain, then here’s some insight based on our experience with protective ensemble testing and training.
A systems viewIn general terms, decontamination is performed in a system of four basic elements: people, procedures, equipment and environment. Each element introduces variables that impact the outcome of worker or responder decontamination efforts:
1. People. This includes workers, responders and/or bystanders. Each represents a large source of individual variability according to the nature of their occupation, personal habits, level of training and proximity to toxic materials.
2. Procedures. The documents that govern or guide decontamination operations can vary widely due to intrinsic material characteristics, e.g., toxicity and/or physical hazards, material phase, solubility, etc. Document quality can vary according to the skill of the preparer, the level of worker understanding, and implementation by those performing the decontamination activities.
3. Equipment. This includes all of the physical materials, supplies and tools needed to perform the required actions. It includes the protective ensembles (garment, gloves, respirator, etc.), work or response tools, and decon supplies and equipment, as well as the associated operating instructions.
4. Environment. Broadly, this includes such considerations as whether conditions are normal or abnormal, indoor (fixed) or outdoor (mobile/portable), extremely hot or cold, dry or humid, and the effect of terrain or location, e.g., flat, open, urban, suburban, etc.
Definitions, goals & practiceDecontamination is addressed frequently within the regulatory framework of OSHA. For instance, 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.” Decontamination also appears extensively in OSHA standards 1910, 1915, 1926, as well as standards for mineral dusts, asbestos, carcinogens, inorganic arsenic and methylenedianaline.
One of the broadest discussions on decontamination is contained in Chapter 10, Decontamination, NIOSH Publication No. 85-115, “Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities.”
Decontamination processes must eliminate or minimize the possibility of employee exposure during the doffing process. Practical approaches to decontamination are generally limited to one or more of the following: 1) remove the contaminant from protective ensemble surfaces; 2) inactivate protective ensemble surface contaminants; or 3) immobilize the contaminants on the protective ensemble surfaces. Commonly accepted practices, especially wet decontamination methods, tend to employ a combination of these approaches.
Employee education is a key element in controlling post-mission exposures for employees who use PPE in potentially contaminated working environments. The effectiveness of the selected decontamination processes is complicated by a variety of factors, including:
1. Protective ensemble characteristics, e.g., “open” or “closed,” disposable or limited-use, and ensemble “nooks and crannies”;
2. Worker skill levels in achieving “clean suits” as opposed to “clean workers”;
3. Decontamination processing time versus “in-suit” time, prescribed work-rest cycles, or equipment limitations, such as SCBA breathing air capacity;
4. Routine working conditions versus emergency circumstances;
5. Extreme circumstances, such as mass casualties, “walking wounded,” worker or responder injury or illness, and in-suit emergencies.
Doffing a contaminated ensembleDecontamination is required by law during emergency events. For emergency responders, decon is a technician-level competency; most are taught how to set up a line, which hoses and brushes to use, and basic cleaning techniques. High-hazard occupations involving toxic industrial chemicals often use engineered decontamination facilities in conjunction with protective ensembles. However, as trainers know, individual skills vary depending upon many factors including the quality of instruction. Here are some tips for improving your ability to get out of a contaminated ensemble as cleanly as possible:
1. Make certain that the selected PPE will keep decontamination solutions and contaminants away from contact with workers during the planned decontamination procedure. Encapsulating ensembles are more effective in this regard than open-design garments, but their protective barrier can still be breached with poor technique.
2. When time is of the essence, such as emergency response, focus on removing the contaminated protective ensemble as cleanly and safely as possible; contaminated ensembles and equipment can be dealt with after people are safely extricated.
3. Minimize decontamination solution ingress through non-encapsulating suit openings by keeping delivery pressures low. Tape doesn’t effectively seal wrist and neck openings.
4. Minimize exposure to decontamination solutions by removing excess fluids from suit openings before doffing.
5. Disciplined technique with step-off lines limits the spread of contamination and improves contamination control effectiveness.
6. SCBA masks, frame-packs and cylinders can harbor contaminants even after decontamination has been completed. Keep these items away from the worker or responder during doffing by providing appropriate work surfaces, such as tables or benches.
7. Respirators and mask assemblies can harbor contaminants after decontamination; particulate materials can be dislodged through mechanical means. Minimize potential airborne exposures by keeping the mask-MMR assembly together and holding the breath while it is removed as a unit.
8. Workers and responders should immediately move away from the emergency response contamination reduction corridors (CRC) after doffing the respirator.
9. Regularly verify decontamination procedure effectiveness and individual skills.