might call for emergency measures against radiation exposures even in
the face of other possible hazards.
Table 3 shows the approximate
areas encompassed by the three isodose lines.
For areas where the
fallout occurs a few hours or more following detonation, many days
or weeks will be required to accumulate the major portion of effective
biological doses, so that spot decisions involving additional hazards
“3
might not be necessary.
The question is frequently asked as to the time one must
spend within a shelter or remain outside of a contaminated area.
The
answer depends upon a number of parameters, such as the criteria
established for maximum permissible dose, as well as length of stay
within the area of contamination.
With knowledge of the magnitude
of the radiation levels present and an assumed rate of dezay, (t)i-2,
it is possible to plan and execute a short stay even in a highly contaminated area.
tensive analysis.
Planning for continuous occupancy requires more exThe following data may aid in such evaluation.
The fallout map (Idealized Fallout Diagram on page ___) and
Table 3 suggest the degree of radiation exposure received in continuous
occupancy under normal living conditions beginring with the time of
initial fallout.
For those entering the contaminated zone four months
after the first fallout, however, and then Living there indefinitely,
the area encompassed by the 50 r effective biological isodose line
will have shrunk from about 25,000 to 2,500 square miles.
At such
time (four months after fallout), an area of about 1,000 square miles
within the 50 r isodose line might have the highest residual contamination, amounting to about three times the dose rates at the periphery.
+
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