by the house and gravel. In addition, if the housing were located near lagoon roads, the average external gamma exposure will be much less than in the interior of the island, so selection of the housing site can also make a significant difference.° INHALATION Airborne concentrations of respirable 239+240, u and 241 Am are estimated from data developed in resuspension experiments conducted at Bikini Atoll in May 1978. We briefly describe the resuspension methodology here; further details can be found in a paper summarizing the studies at Enewetak and Bikini Atolls. 12 The study conducted on Bikini Island in May 1978 provided a more complete set of data than our preliminary studies on Enjebi (Janet) Island of Enewetak Atoll! in February 1977. (Subsequent studies were conducted on Eneu Island at Bikini Atoll.) The Bikini Island study used extensive soil sampling and in situ gamma spectroscopy to determine isotope concentrations in soil and vegetation, various air-sampling devices to determine particle size distribution and radioactivity, and micrometeorological techniques to determine aerosol fluxes. Four simultaneous experiments were conducted: (1) a characterization of the normal (background) suspended aerosols and the contributions from sea spray off the windward beach leeward across the island, (2) a study of resuspension of radionuclides from a field purposely laid bare by bulldozers as a worst-case condition, (3) a study of resuspension of radioactive particles by vehicular and foot traffic, and (4) a study of personal inhalation exposure using small dosimeters carried by volunteers during daily routines. Less complete studies similar to (1) and (2) had been performed previously on Enjebi (Janet) and background studies similar to (1) were later performed on Eneu. The normal or background mass loading measured by gravimetric methods for both atolls is approximately 55 ug/m?. The Bikini Island experiments show that 34 ve/m? of this total is from sea salt, which is present across the entire island as a result of ocean, reef, and wind action. 2) ve /m?. The mass loading from terrestrial origins is therefore about The highest terrestrial mass loading observed was 136 we/m? immediately after bulldozing. Concentrations o f 2394240), have been determined for (1) collected aerosols for normal ground cover and conditions, that is, normal conditions in coconut groves; (2) areas being cleared by bulldozers and being tilled, that is, high-activity conditions; and 12