-6-
It is possible that the local fallout has been underestimated
but this is unlikely, he mre reasomble explanation 1s given in
terms of our inability to accurately masure the trues removal of
particles from the atmosphere with simple devices, The estimte
just quoted is based on the measurement of fallout on gunned films
exposed horizontally,
Even if this were 100% efficient (and it
is believed to be about 70% efficient for gross fission products
now under discussion), it fails to detect radioactive particles.
removed by vertical surfaces. The Raval Research Laboratory
has reported an amount of. radioactivity on a vertically-exposed
piece of cheesscloth equal to that deposited on the ground for
the sama time interval and area.
Other experiments confirm the
fact that the particles in the intermdiate range are collected
by other than horizontally-exposed face-up surfeces,
which is still unanswered, however, is eevee? 2
‘The, question
puititeck
this-ronoval_in-comsviihn-with that observed by the gumned Cinta « .
Thus, tke cumulative contribution of the intermediate fallout
and the delayed fallout ovar that portion of the world lying in
the belt surrounding the nuclear proving grounds is still some
what questiongble.
When soil samples are collected, say over ths
U. &., which have integrated all fallout since tha atomic age,
questions may be raised concerning the apportionment of thse fallout.
Although, on the average, the bulk of the radioactivity in
the interzeciete range lies in a belt surrounding the latitude of
the test site, there can bs anoralous situations which will either
spread the ‘debris over a very large north-south range or carry
the entire molear cloud in toto initially to a new and distant
latitude for zonal transport there.