LETTER OF PROMULGATION This report, Evaluation of Radioactive Fall-out, is published in order to present the facts to the extent that they are known, about the radiological situation following the detonation of nuclear weapons; and the facts and opinions relating to the biological hazards likely to be encountered from radioactive fall-out. The discussion given in the report, the evaluation presented and the conclusions drawn are those for both the close-in fall-out and the world-wide contamination problems and the interrelationship of the two. General concepts are developed from available data. Detailed treatment of several aspects of the fall-out problem may be found in the references listed in the report. It is planned to keep the problem under continuous active study and it is expected that, as more information becomes available, supplementary reports will be presented. ORLisle A. R. LUEDECKE Major General, USAF Chief, AFSWP THIS DOCUMENT consists oF..72©.PAGEIS| no._/Mor3DOCOPIES, SERIES.