Chemical Protective Clothing Penetration v. Permeation

Chemical protective clothing includes body suits, boots and gloves. The clothing comes in multiple different materials that offer a range of protection depending on how hazardous the environment is. “These materials include cotton and synthetic fibers, natural and synthetic rubber, various plastic films and coatings and leather.”  OSHA provides criteria and regulations as to what protective clothing that individuals are required to wear based on the hazards that may be encountered.  

“Penetration in the context of Personal Protective Equipment is the leaking of a contaminant through seams, zippers, pinholes, and other seemingly visible openings in protective clothing or gloves.” Penetrations are best suited for determining particle barrier in fabrics. Factors that can influence particle penetration include the size of the particle and the size of the pores or openings in the fabrics structure. The larger the opening in the fabric structure, it is more likely a particle will be able to penetrate the fabric.

“Permeation is the process by which a chemical dissolves in or moves through a barrier material, in this case, protective clothing or gloves.” Permeation tests are better suited for testing hazardous vapors and liquids. “There are many critical factors that influence permeation: the challenge chemical, the makeup of the barrier material, the exposure time, and several physical factors like ambient temperature and pressure.”  Permeation rate in the context of Personal Protective Equipment is the speed at which the chemical passes through the barrier material per minute; it is usually measured using a standardized testing method. “This test can provide information about the barriers materials ability to withstand exposure to the chemical.” It is measured from the point of initial contact of the challenge chemical with the outside surface of the test fabric to the time the challenge chemical is detected on the inside of the fabric. “The standardized breakthrough time is a measure of the elapsed time from initial contact with the challenge chemical until the chemical permeates the fabric.”

 Basics of Industrial Hygiene by Debra Nims

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