usly, from the
first hour after the bombing. It is apparent therefore that insofar as
could be determined at Hiroshima and Nagasaki, the residual radiation
alone could not have been detrimental to the health of persons entering
and living in the bombed areas after the explosion.

The second approach to this question was to determine if any persons
not in the city at the time of the explosion, but coming in immediately
afterwards exhibited any symptoms or findings which might have been due
to persistence induced radioactivity. By the time of the arrival of
the Manhattan Engineer District group, several Japanese studies had
been done on such persons. None of the persons examined in any of
these studies showed any symptoms which could be attributed to
radiation, and their actual blood cell counts were consistently within
the normal range. Throughout the period of the Manhattan Engineer
District investigation, Japanese doctors and patients were repeatedly
requested to bring to them any patients who they thought might be
examples of persons harmed from persistent radioactivity. No such
subjects were found.

It was concluded therefore as a result of these findings and lack of
findings, that although a measurable quantity of induced radioactivity
was found, it had not been sufficient to cause any harm to persons
living in the two cities after the bombings.

SHIELDING FROM RADIATION

Exact figures on the thicknesses of various substances to provide
complete or partial protection from the effects of radiation in
relation to the distance from the center of explosion, cannot be
released at this time. Studies of collected data are still under way.
It can be stated, however, that at a reasonable distance, say about 1/2
mile from the center of explosion, protection to persons from radiation
injury can be afforded by a layer of concrete or other material whose
thickness does not preclude reasonable construction.

Radiation ultimately caused the death of the few persons not killed by
other effects and who were fully exposed to the bombs up to a distance
of about 1/2 mile from X. The British Mission has estimated that
people in the open had a 50% chance of surviving the effects of
radiation at 3/4 of a mile from X.

EFFECTS OF THE ATOMIC BOMBINGS ON THE INHABITANTS OF THE BOMBED CITIES

In both Hiroshima and Nagasaki the tremendous scale of the disaster
largely destroyed the cities as entities. Even the worst of