Terrestrial Gamma Dose Rates in the United States with Inferred Sol. Contents K U_. Th Total Dose Rate Range (mrad/y) 1. Populated areas-range (90%) 5 35 10 - 20 15 = 40 30 = 95 Qe 17 13 25 D9 lL - 50 O = 45 5 = 70 15 - 136 " " typical mean 3. All areas-range (90%) Inferred Soil Content 1. Range (90%) (0-4) x 104% ppm 0.5-9 ppm 1.5-30 ppm 2e 1.5 x 104 pom 2e> ppm 9 ppm le pci/g 0.8 pei/g 1 plei/g Typical mean ~ 21 -

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