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, etc. have been provided ~, to which the general public has access, " The primary ambient air standards define "levels which... are necessary, with an adequate margin of safety, to protect the- An arithmetic mean would be more desirable for predictive purposes. Data from 1966°° 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 of a pollutant,” These standards for particu- Representative Calculations late matter are given below: Because one of the primary objects is National ambient air quality standards for particulate matter, ug/m”. Annual geometric mean Max, 24-hr carentration not to bé exceeded more than once a vear Primary: 75 Table 151. Enewetak Islands, the approaches developed above were used to derive such levels for both soluble and insoluble 239 bu, The derived values are given in Table 151, 260 Secondary: 60 to derive an acceptable soil level for the The two methods agree within . afactor of two, at least for soil distributions like those found at the Nevada Test 150 ais eur, _~ Acceptable soil levels of 239 Pu Te ns ey Ce adel atliniCin ait v4 9? ft aasté ivadiny wii 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, pCi/ cm? Soluble 10712 6 x 10744 10°? 10° 20 10°? 60 1 107 10 10° 0.6 Resuspension-factor approach , , -1 Assumed resuspension factor, m Acceptable soil deposition®, uCi/m? Acceptable soil concentration?, nCi/g Mass-loading approach Assumed mass loading, ug/m°> Acceptable soil concentration, nCi/g “Equivalent to approximately 104 pg of insoluble Passumes same distribution of 239 Pu the Nevada Test Site. 239 m2, with depth and soil density as measured at 14-26 tf