Types of Contamination
Contaminants can be located either on the surface of personal protective equipment or permeated into the PPE material.
The longer a contaminant is in contact with an object, the greater the probability and extent of permeation.
Surface contaminants may be easy to detect and remove; however, contaminants that have permeated a material are difficult or impossible to detect and remove.
If contaminants that have permeated a material are not removed by decontamination, they may continue to permeate to surfaces of the material where they can cause an unexpected exposure.
Five major factors affect the extent of permeation:
- Contact time: The longer a contaminant is in contact with an object, the greater the probability and extent of permeation. For this reason, minimizing contact time is one of the most important objectives of a decontamination program.
- Concentration: Molecules flow from areas of high concentration to areas of low concentration. As concentrations of wastes increase, the potential for permeation of personal protective clothing increases.
- Temperature: An increase in temperature generally increases the permeation rate of contaminants.
- Size of contaminant molecules and pore space: Permeation increases as the contaminant molecule becomes smaller, and as the pore space of the material to be permeated increases.
- Physical state of wastes: As a rule, gases, vapors, and low-viscosity liquids tend to permeate more readily than high-viscosity liquids or solids.
Knowledge Check Choose the best answer for the question.
3-4. Which of the five major permeation factors is one of the most important objectives of a decontamination program?
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