"The National Council on Radiation Protection and Measurements (NCRP), successor to the National Committee on Radiation Protection and Measurements, has embarked on a program to examine and evaluate the many private studies and government programs related to sources of ionizing radiation that may contribute to the overall exposure of the population. An assessment of the radiation doses will be made in several broad categories, such as exposure from consumer products, occupational exposure, etc. To the extent possible, the results will be expressed in meaningful quantities and units so as to facilitate comparisons of sources and exposures. This report, the first in a series of reports envisioned under this program, is concerned with the assessment of the radiation dose to the population from natural background radiation. Included in this report are the absorbed doses to the population due to radiation from cosmic sources, radionuclides in the earth, internally deposited radionuclides, inhaled radioactivity and fallout from nuclear weapons tests."--Preface, page iii.