ambient air is defined as ",,..that portion Data to support these standards in terms of the atmosphere, external to buildings, of health effects, visibility restrictions, to which the general public has access." etc, have been provided”, An arithmetic mean would be more The primary ambient air standards define Data "levels which... are necessary, with an desirable for predictive purposes. adequate margin of safety, to protect the from 19667" for nonurban locations indi- public health, " The secondary standards define “levels which... (are)... necessary cate that the annual arithmetic mean is to protect the public welfare from any geometric mean, (on the average} 120% of the annual known or anticipated adverse effects ofa pollutant. " Representative Calculations These standards for particu- Because one of the primary objects is late matter are given below: to derive an acceptable soil level for the Nationai ambient air quality standards for particulate matter, ug/m?’. Annual geometric mean Enewetak Islands, the approaches developed above were used to derive such Max. 24-hr carentration not to be exceeded more levels for both soluble and inscluble than once a vear 239 Primary: 75 60 Table 151. Table 151, 260 Secondary: The derived values are given in The two methods agree within a factor of two, at least for soil distributions like those found at the Nevada Test 150 Site, The ambient air mags loading at 239 Acceptable soil levels of Pu for a source which has weathered for several years, Values are approximate and are subject to uncertainty. Permissible Concentration in Air for 168-hr occupational exposure (MPC,)25. Insoluble Acceptable air concentration, uCi/em? . Soluble 19714 6 x107!4 Resuspension-factor approach 4 1079 107? Acceptable soil deposition®, uCi/m™” 10° 60 Acceptable soil concentration”, nCi/g 20 Assumed resuspension factor, m My o) p2 Feb {hf nn 1 rs —— c ' 9 1 anoreach 9 Assumed mass loading, ug/m°> 107 Acceptable soil concentration, nCi/g 10 a . ; 2: 239 2 Equivalent to approximately 107 ue of insoluble 3 Pu/m”, 9 Ds ssumes same distribution of 23 the Nevada Test Site. 9 , . 10° 0.6 Pu with depth and soil density as measured at Hi—2]