MAIN CONCLUSIONS

MAIN CONCLUSIONS

The following are the main conclusions which were reached
after thorough examination of the effects of the bombs
dropped on Hiroshima and Nagasaki:
1. No harmful amounts of persistent radioactivity were
present after the explosions as determined by:
A. Measurements of the intensity of radioactivity at the
time of the investigation; and
B. Failure to find any clinical evidence of persons harmed
by persistent radioactivity.
The effects of the atomic bombs on human beings were
of three main types:
A. Burns, remarkable for (1) the great ground area over
which they were inflicted and (2) the prevalence of “flash”
burns caused by the instantaneous heat radiation.

B. Mechanical injuries, also remarkable for the wide area
in which suffered.
C. Effects resulting from penetrating gamma radiation. The
effects from radiation were due to instantaneous discharge
of radiation at the moment of explosion and not to persistent
radioactivity (of either fission products or other substances
whose radioactivity might have been induced by
proximity to the explosions).
The effects of the atomic bombs on structures and installations
were of two types:
A. Destruction caused by the great pressure from the blast;
and
B. Destruction caused by the fires, either started directly
by the great heat radiation, or indirectly through the collapse
of buildings, wiring, etc.
4. The actual tonnage of T.N.T. which would have caused
the same blast damage was approximately of the order of
20,000 tons.
5. In respect to their height of burst, the bombs performed
exactly according to design.
6. The bombs were placed in such positions that they could
not have done more damage from any alternative bursting
point in either city.
7. The heights of burst were correctly chosen having regard
to the type of destruction it was desired to cause.
8. The information collected would enable a reasonably
accurate prediction to be made of the blast damage likely
to be caused in any city where an atomic explosion could
be effected.