Summary
Highlights
Working safely with hazardous materials relies on four key elements: work practices (e.g., spraying water on dust), engineering controls (e.g., robotic equipment, ventilation fans), personal protective equipment (PPE) like chemical protective clothing (CPC) and respirators, and decontamination. Decontamination is crucial because without it, PPE can become saturated with hazardous chemicals, posing a greater risk than the worksite itself.
OSHA's HAZWOPER (Hazardous Waste Operations and Emergency Response) standard mandates decontamination procedures at all sites with potential exposure to hazardous substances. Access to contaminated areas, known as exclusion zones, is strictly restricted. Determining decontamination procedures involves answering questions about the hazardous materials present, their concentrations, the extent of contamination, the work to be done, required PPE levels, traffic volume, and the most effective decontamination methods. The site safety and health officer designs and implements these procedures.
The Contamination Reduction Zone (CRZ) is the area separating the exclusion zone from the outside world, preventing the spread of contaminants. Within the CRZ is the Contamination Reduction Corridor (CRC), a one-way path through which all workers and equipment must exit the exclusion zone. All decontamination activities take place within the CRC, bottling up contaminants and preventing their spread.
The CRC contains several stations for decontamination. Personnel working in the CRC wear PPE one level below that of exclusion zone workers (e.g., Level B if exclusion zone workers wear Level A). Decontamination equipment often includes wash tubs, brushes, and solutions. A detergent and water solution is commonly used due to its versatility, especially with unknown chemicals. For specific contaminants, special Decon chemicals may be used for neutralization, but contaminants must be identified first to avoid dangerous reactions.
The typical decontamination process for Level A PPE in a CRC involves several stations. First, tools are dropped for later decontamination. Next, the outer suit is washed and scrubbed with detergent and water, then rinsed thoroughly, paying special attention to boots to avoid recontamination. After rinsing, the top of the outer suit is unzipped and peeled away by an assistant to prevent contact with residual contaminants. The respirator hose is detached, air tank removed, and the rest of the suit is removed and placed in a container for decontamination. The respirator face piece and SCBA tank harness are also removed. Finally, the inner suit is removed and bagged for disposal, leaving the worker in their street clothes.
Immediately after exiting the CRC, a medical surveillance examination is required to assess the worker's health, with results added to their permanent medical record. A shower is then necessary to wash off any potential trace contamination and perspiration. In emergencies where someone is injured in a contaminated area, the victim must be decontaminated as thoroughly as possible before receiving medical attention, although specific procedures depend on the injury and contaminant. Supervisors should be consulted for site-specific emergency Decon procedures.
Decontamination is an essential safety measure when working with hazardous materials, complementing work practices, engineering controls, and PPE. Without it, workers can become seriously ill and spread contamination. It ensures hazardous substances remain where they belong, allowing workers and co-workers to go home safely.