Permeation and Degradation
Once the chemicals have been identified, available information sources should be consulted to identify materials resistant to permeation and degradation by the known chemicals.
Penetration vs. Permeation
One excellent reference, the CDC/NIOSH Recommendations for Chemical Protective Clothing Database, provides a detailed description of clothing material recommendations within the NIOSH Pocket Guide to Chemical Hazards.
No material protects against all unique chemicals or combinations of chemicals, and no currently available material is an effective barrier to any prolonged chemical exposure.
Vendor data cannot address the wide variety of uses and challenges to which chemical-protective clothing (CPC) may be subjected. Most vendors strongly emphasize this point in the descriptive text which accompanies their data.
Permeation
The rate of permeation is a function of several factors, including:
- clothing material type and thickness,
- manufacturing method,
- the concentration(s) of the hazardous substance(s),
- temperature, pressure, humidity,
- the solubility of the chemical in the clothing material, and
- the diffusion coefficient of the permeating chemical in the clothing material.
Breakthrough time: The time from initial exposure until hazardous material penetrates the CPC material and is detectable on the inside of the CPC is called breakthrough time and may vary depending on conditions.
Knowledge Check Choose the best answer for the question.
3-2. Which material protects against all unique chemicals or combinations of chemicals?
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