which may reasonably be expected to exist in or near the incident area, The information gained will be of especial value to firefighting, reseue and other civil defense groups operating within this vital area, The somcalied “rear areas" include territory extending back from six to eight miles on all sides of the incident area, dere the radiological surveys would be made on the standard parallel-line-basis. They may be expected to crovide facts essential for safety in the directed movements of the civil population, On the basis of information furnished by the Area Survey Units, the police service then would post, and where necessary patrol, the boundaries of all radiologically hazardous areas in order to prohibit entry therein by unauthorized persons, The “immediate down-wind area" extends up to 50 miles from the center of the incident area in the general direction of the winds prevailing at the time of and immediately following the incident, Area survey operations conaucted in these areas would take the form of "spot checks" aimed at detection of any radiological hazards attributable to cloud "fall ont", Down wind surveys at greater distances would be made by Area Survey Units from other local organizations in accordance with directions from the appropriate State Civil Defense Director, acting with the advice of his Radiological Defense Advisor, The go-called “down-water" operations are surface surveys of streems and Tivers aimed at detection of radiological hazards which may be considered Capable of later »roducing hazards at »oints downstream from the incident area, Individuals engaged in area survey operations would record all significant radiation data on standardized grid sheets, Zssential dizests of these data, especially information concerning the nature and location of radiological hazards would be periodically transmitted to the Radiological Situation TO8 ARCHTV se