meacurenents at a height of three feet. Fast field experience has indicated that the gamma reading from fonisation-type survey meters at ground level is sbout 50% higher than at three feet. Therefore if it be assured that & ground level gamma reading of a survey zoter is equivalent te a surface dose rate, the ratio ef beta dose rate at 7 mg/em~ to gamma doce rate at Sree ie about 200 to 1. Another approach to estinating the ratio of bete dose rate at 7 ng/ex* to gecma dose rate at three feat is as follows. Aseuning a wmiiforn distri- bution of 1.0 megacurie per square zile of gamma aetivity, the dose rate reading from an infinite field is about 4.1 roentgena/hour.” Caleulations given in appendix B indicate that « like concentration of fallout neterial will produes about 430 reps/hour at 7 ag/os®. This suggeste a beta te ganna ratio of about 100 te 1 which ie about a factor of two lower than the first approach. Added support to this latter method of est inating beta doses is found in appendix C. Such considerations may be fraught with pitfalls. above Por exemple, the discussion inplies a uniforz distribution ef felbutaeberted, Ovvicusly, thie is not correct but how far this deviate: from the facts and to what extent this influences the results 4s difficult to assess. indicate that the production of recognisable beta burns particle requires a high specifie activity. Calculations from a single (See Policy III for discussion.) It nay/be,however, that the particles of fallout are eloze enough te have overlapping of radiation fields and thus require signifieantly lover specific activity of the particles to produce beta burns. Weapons", 1950 CLASSIFIED ec *'rffects of Atomica This hypothesis ee Ql