(continued) radioactivity stay in the air. . mom I have here an BRL report which sous of you have already seen published in the Journal of Geophysical Research. The HiL pecple mada studies on the concentration of natural radioactive decay products in the atacaphere, and came to the conclusion after their measurements, and after making certain assumptions about the rate at which they ware produced, that the "mean lifes of each substance dus to nonradioactive loss," that is due to seme sort of scavenging or Temeval process, “was about ten days.* I think that ensvers the question of how long radioactivity, once it got into the lower layera, would last. WEXLER: How low? KELLOGG: Well, theixy chservations wore made at the ground, but presumably on decay products which were produced throughout the atzocophere. VOICE: “Don't these things come from the ground? KELLOGG: This is not a cloud, thene are naturel radioactive... VOICE: Ian't this radon from the ground, going wt KELIONG: (7) Tes. KELLOGG: Radon from the seil and it's decay products. —ESLBSIAN,: (7) Any idea how many readings were taken to ccms up with a statement like that? —_ P3 iin we DUE ARCHIVES