but frequent exposure to radiation may cause radiation sickness.
3.
Persistency of Contamination.
The term persistency, with reference to a chemical or biological agent, refers to the duration of
effectiveness under conditions after its dispersal. The length of time a hazard remains depends on the
persistency of the contamination.
In the following paragraphs you will find some general guidance on the impact and results of
persistency. A full discussion of detection and hazard prediction for all types on contamination is
presented in FM 3-3.
a. Chemical.
For planning purposes, consider any contamination nonpersistent, if it remains less than 10 minutes.
Nonpersistent contamination, usually gases and some liquids, generally requires no decon.
Contamination remaining 10 minutes or longer is persistent and usually requires some decon. Any
contamination found on your skin must be decontaminated immediately, regardless of persistency.
Some contamination hazards can affect you within minutes after touching your skin. Once you
complete skin decon, use detection equipment to determine the type of contamination and persistency to
decide whether any additional decontamination will be required.
Factors affecting persistency are:
■ Type of contamination
■ Concentration and droplet size
■ Temperature
■ Wind speed
■ Sunlight
■ Humidity and rain
■ Composition of the contaminated surface
b. Biological.
The variables involved in predicting the persistency of biological hazards are so numerous that each
incident of contamination must be considered separately. You must refer to specially trained medical
personnel at division level and higher for information on biological agents. Even these personnel can
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CM 2506
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