nam weapons = v f fis Carbon-14 (Table 2) 4 / Natural carbon-14 is also produced by cosmic ray bombardment in the atmosphere. The production rate is about 2 atoms/sec per om*, which is equivalent to an annual The worldwide inventory has been estimated as 270 meza= et production of 50 pci/m®. sti euries which is distributed with 1.5% in the atmosphere, 3.5% in biological ma- 1 terial and 95% in the oceans. fhe 2% above the thermocline. EAR Living organic matter is generally fairly close to equilibrium with the rune natural C-14 in the atmosphere. of of carbon. sine ing Potassium (Table 3) Rubidium (Table 4) pit Most of the latter is in the deep oceans with only This results in a specific activity of 6.5 pCi/g Uranium Series (Tables 5-10) At least six members of the uranium series are sufficiently important to require measurement in man and his environment. The actual uranium isotopes are atc not of great dosimetric significance and most attention has been paid tec radium-2°6 ath and later members of the chain. ern some of which escapes from soil at an annual rate of about 10" pCi/mé and decays Radium-226 has a gaseous daughter, radon-222, to solid descendants which are important contributors to radioactivity in the ran environment. ve selves to aerosols which have an average life in the troposphere of about one ve month or less before being deposited on the ground. tt The daughters formed from the radon which does escape attach them- The deposited material along with daughters formed from the radon which does not escape are significant contributors to the external terrestrial gamma dose rate. The airborne material contributes to the internal lung dose and to the external dose from the air. The short-lived daughters are of greater significance indoors than out, with their concentrations being a function of the building material. For the