~4~- the inhalation route to man is more hazardous than the soil- root pathway for ingestion of plants by man. 1. These assumptions are: Plutonium in soil is resuspended at rates similar to the soil material, e.g., tne specific activity of soil equals the specific activity of air particulates. 2. All particles in air originate from local soil. 3. Plutonium in air is allin the respirable range of particle size and is soluble in lung fluids. The average mean value for airborne particulate concentration for fre 30 locations, is 38 micrograms per p cubic meter (microgram/m? ). * Assuming, to be conservative, that the average airborne particulate concentration level at Eniwetok is 150 microgram/m”, and further assuming that all of this particulate matter consists of local soil (i.e., no salt spray from the ocean), one obtains a value of 400 pCi/gm as an average surface soil concentration which corresponds to the ICRP guide for maximum permissible average airborne concentration of plutonium. In the evaluation of the radiological condition of Eniwetok, we will apply the criteria that areas in which any soil samples show concentrations greater than 400 pCi/gm should receive corrective action, areas which show soil concentrations between 40 and 400 pCi/gm may receive corrective action, depending on other conditions present, and areas showing less than 40 pCi/gm do not require corrective action because of the presence of plutonium alone. *Air Quality Data, 1966 Edition, APTD 68-9, published by the U.S. Department of Health, Education, and Welfare. Sdpe PM al wears 7 . ? wor. . toate ? so re oye . wae Jif , RTee i he rea teen: 3Hwee a IMETee tees ey Ne Lf A - . se ea a a4 . tt a, Roe Gg ee, ,oee tt Te seo} , tS "in ae . . a mo pop Re tg EB tg ye sey tt ky OR oa , tbe eat