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Guidance Curve for Potential Fueling Hazards
Permissible Exposure Time LimitsPartial List

Fire Controlman Volume 02-Fire Control Radar Fundamentals (Revised)
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strength  of  the  field  presents  a  biological  hazard  to personnel located at the point where the measurements were taken. PEL readings are the basis for determining RADHAZ safety boundaries. Permissible  Exposure  Time  (PET)—This  is  the maximum time of exposure to a specific power density for  which  the  PEL  will  not  be  exceeded  when  the exposure is averaged over any 6-minute period. Table 3-1 shows the PET for a variety of radars operated at their normal power levels. If you suspect that you or someone else has been overexposed to EMR, follow the flow chart in figure 3-2.  If  you  confirm  your  suspicions,  the  exposure  is considered   an   incident   and   must   be   reported   as required   by    Protection   of   DOD   Personnel   from Exposure   to   Radio   Frequency   Radiation,   DOD Instruction 6055.11. RFR HAZARDS TO THE SKIN.—The energy impinging on a person in an electromagnetic field may be   scattered,   transmitted,   or   absorbed.   The   energy absorbed into the body depends upon the dimensions of the body, the electrical properties of the tissues, and the wavelength of the RFR. Thus, the wavelength of the   energy   and   its   relationship   to   a   person’s dimensions   are   important   factors   bearing   on   the biological effects produced by RFR. Significant   energy   absorption   will   occur   only when  a  personal  dimension  is  equivalent  to  at  least one-tenth   of   a   wavelength.   As   the   frequency   of radiation increases, the wavelength decreases and the person’s   height   represents   an   increasingly   greater number   of   electrical   wavelengths,   increasing   the danger   from   RFR   exposure.   As   the   frequency   is decreased,  the  wavelength  increases  and  the  person becomes a less significant object in the radiation field. Thus,  the  likelihood  of  biological  damage  increases with  an  increase  in  radiation  frequency.  Also,  as  the radiation   frequency   increases   and   the   wavelength becomes progressively shorter, the dimensions of parts and   appendages   of   the   body   become   increasingly significant   in   terms   of   the   number   of   equivalent electrical wavelengths. When  a  person  stands  erect  in  a  RFR  field,  the body is comparable to a broadband receiving antenna. 3-5 Figure 3-2.—Personnel RFR exposure decision chart.






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