results of the measurements in the Olympic Peninsula area and also by the generally lower fallout levels observed in the San Francisco Bay area (1-2 ur/hr). In addition to providing information about the natural and fallout gamma dose rate levels in particular areas covered by these surveys, these data, when combined with the data ob- tained from surveys conducted in New England® and New York State,* permit certain conclusions to be drawn regarding natural environmental radiation levels in the United States in the years 1962-1963.° It was found that most of the inferred natural dose rates were in the range 5-9 ur/hr and that the dose rates from K40 and the Th232 series were generally comparable, usu- ally amounting to approximately 80% of the total natural gamma dose rate, while the uranium series seldom contributed more than 25% of the total natural gamma dose rate. Dose rates from the uranium series ranged between 0.5 and 2.0 ur/hr at almost 90% of the survey locations; K4O contributions were in the range 1.5-3.5 ur/hr at over 75% of the locations and two-thirds of the thorium series contributions were between 1.5 and 4.0 wr/hr. The average natural gamma dose rate for the more than 200 locations surveyed in 1962 and 1963 was 7.0 ur/hr. -ll1-