average and maximum doses. The Federal Radiation Council suggests the use of the arbitrary .assumotion that the majority of individuals Co not vary from the average by a factor greater than three. Thus, we recommend the use of 0.17 rem for yearly whole-body exposure of average population groups. (It is noted that this guide is also in essential agreement with current recommendations of the NCRP and the ICRP.) It is critical that this guide be applied with reason and judcment. Especially, it is noted that the use of the average figure, as a substitute for evidence concerning the dose to individuals, is permissible only when there is a probability of appreciable homo- geneity concerning the distribution of the dose within the population included in the average. / ot A ee wr Strict adherence to these guidelines implies that the ambient air standard should be zero particles. 89 While a variety of suggestions could be proposed, we recommend a slight deviation from these guidelines and the acceptance ee ee ee of the disproportionate risk implicit in the 0.2 particle standard. This is a workable solution since best estimatcs of lung burdens can be fractional quantities. Thus, we recommend that the MPLPB for members of the public be 0.2 hot particles, and the average lung burden for members of the public be 0.07 hot particles, a factor of 3 less than the maximum. 79/ FRC Report No. 1, Op. cit., p. 27. 80/ Had we based the standard on a 1/10,000 risk per particle (See Table V), the MPLPB would have been one particle and this problem would not exist.