Richard LL. Williams -2- The following is an update of progress since last March: 1. A map has been prepared showinr terrestrial external radiation levels for a number of locations in the U.S. This use of the term terrestrial means that this source of radiation exposure for the U.S. population includes the naturally occurring radioactivity contained in soil and rocks, plus fallout, but excludes cosmic radiation. This information will permit comparison of external radiation levels from fallout for the survey islands and atolls presented in March with external radiation levels in the United States. 2. Summary information is being prepared piving average xternal radiation levels contributed by fallout from nuclear testing for each island surveyed. This data will be available in August 1975. A summary sheet of these data is being prepared for each of the 13 islands and atolls surveyed. 3. The specific radionuclides contributing to external 4. Graphic material is being produced that shows the location and narie of each survey island keyed to the data on island extermal radiation levels in item 2 radiation levels have now been identified for each island surveyed. above. The following schedule is provided to indicate when results of the analysis of data are expected to be completed, and when formal reports of the survey are anticipated: 1. Status information - March '79 (already provided). 2, Status information update - July ‘79 (this letter). Qo External Radiation Summary report - January-March 4. Finel report with all graphics - July-September ‘80. se. 9011 Got ‘80.