STRONTIUM-90, STRONTIUM-89, PLUTONIUM-239, AND PLUTONIUM-238 CONCENTRATIONS IN GROUND LEVEL AIR FROM 1964 to 1969 INTRODUCTION The radionuclides strontium-90, strontium-89, plutonium-239%, and plutonium-—23& are present in the atmosphere as the result of nuclear weapons tests. In the case of plutonium-238, in addition to the above source, an injection of this radionuclide into the atmosphere took place in April 1964 when 17 kilocuries of plutonium-238, contained in a SNAP-9A power source, burned up south of the — Information on airborne strontium and equator off the coast of Africa.(1) plutonium isotopes is of interest in evaluating the potential health hazards of these matertals and in investigating the transport processes involved. Analysis of ground. level airborne particulate samples for the radionuclides of strontium has been performed at the Northeastern Radiological Health For the plutonium isotopes, radioLaboratory (NERHL) since October 1963, chemical and alpha spectroscopic analysis has been done since May 1965. Results of these analyses to April 1966 (for strontium-90) and to February 1967 (for the plutonium isotopes) have been previously reported, (7? Extensive measurements of these radionuclides in air particulates and precipitation have been performed by the Health and Safety Laboratory (HASL) of the Atomic Energy Commission for several years (455) In addition, the Joint Nuclear Research Center, ISPRA Establishment, Italy, has published data on SNAP-9A plutonium-238, (6) This paper presents results on ground level airborne concentrations of the above radionuclides from the inception of the sampling and analysis program at NERHL to March 1969, A recent assessment of doses from these radio- nuclides, based on the concentrations presented in this paper, indicates that only an infinitesimal portion of the total strontium-90 dose to bone is due to inhalation of airborne material. On the other hand, the dose from plutoniun-239 to the tracheobronchial lymph nodes was reported to be 160 millirem in 50 years, second in magnitude only to the dose from strontium-90 (from ingestion)to the bone. The dose from plutondym-238 to this lymphatic tissue was about one-quarter of that from plutonium-239. In this publication attention will be given to the origin of these radionuclides and to the contribution of various atmospheric nuclear tests and the burnup of the SNAP-9A satellite to the total quantity of the radionuclides present in ground level air. A summary of reported atmospheric detonations or vents which occurred during the period of this study is given in Table l. 8) METHODOLOGY | Monthly composite particulate samples, representing 12,000 mof air, are collected - on 8' X 10' membrane filters (pore size 0.8 micron at a height of one meter above F the ground. The samples are wet ashed with a mixture of nitric and perchloric acids. The sample is split into two parts for radiochemical analysis. + } The energies of the alpha particles from plutonium-239 and plutonium-240 are hot sufficiently different to be separated by alpha spectroscopy. Therefore, when plutonium-239 is referred to in this report, it is meant to represent the Sum of the activities of plutonium-239 and plutonium-240. l.