contaminated areas were established in consideration of the latter. Respiratory protection (respirators) normally was provided for scientific project personnel involved in operations where inhalation of radioactive material was considered a potential problem. Military maneuver troops carried Standard gas masks for use in dusty, possibly radioactive environments. The degree of internal exposure resulting from inhalation or ingestion of radioactive material by DOD test participants was not routinely monitored. Other than a considerable number of urine and blood samples analyzed during Operation CROSSROADS, bioassays were rare among military personnel. To fill this gap in the data base, a methodology has been developed to calculate internal doses from reconstructed exposure scenarios and radiological environments, as noted in chapter 7. Using a comprehensive screening methodology, the dose commitment due to internal emitters has been determined to be less than 0.15 rem to the bone for more than 170,000 test participants. The research and subsequent screening of additional personnel is continuing, and indications are that many more participants will be found to have a bone ddse commitment of less than 0.15 rem. This level is 1 percent of the dose limit recommended by the National Council on Radiation Protection and Measurements. ke*¥kkK* This chapter has discussed general radiation safety only at the nuclear tests. The next chapter considers the U.S. occupation of Hiroshima and Nagasaki, focusing on radiation surveys, patterns of residual radiation, and radiation doses. 149