damage may be anticipated. Therefore, most sur-
viving casualties will not have the severe injuries
that result from the direct compressive effects of
the blast wave.
Secondary blast injuries are caused by collaps-
ing buildings and by timber and other debris flung
about by the blast. Persons may also be hurled
against stationary objects or thrown to the ground
by the high winds accompanying the explosions.
The injuries sustained are thus similar to those
due to a mechanical accident: bruises, concus-
sions, cuts, fractures, and internal injuries.
At sea, the shock wave accompanying an
underwater burst will produce various mechan-
ical injuries. These injuries will resemble those
caused aboard ship by more conventional under-
water weapons, such as noncontact mines and
depth charges, but instead of being localized, they
will extend over the entire vessel.
Equipment, furniture, gas cylinders, boxes,
and similar gear, when not well secured, can act
as missiles and cause many injuries.
A weapon detonated as an air burst may pro-
duce more burn casualties than blast or ionizing
radiation casualties. Burns due to a nuclear ex-
plosion can also be divided into two classes: direct
and indirect burns. Direct burns (usually called
flash burns) are the result of thermal (infrared)
radiation emanating from a nuclear explosion,
while indirect burns result from fires caused by
the explosion. Biologically, they are similar to any
other burn and are treated in the same manner.
Since all radiation travels in a straight line
from its source, flash burns are sharply limited
to those areas of the skin facing the center of the
explosion. Furthermore, clothing will protect the
skin to some degree unless the individual is so
close to the center of the explosion that the cloth
is ignited spontaneously by heat. Although light
colors will absorb heat to a lesser degree than dark
colors, the thickness, air layers, and types of
clothing (wool is better than cotton) are far more
important for protection than the color of the
In addition to injuries to the skin, the eyes may
also be affected by thermal radiation. If people
are looking in the general direction of a nuclear
detonation, they may be flash blinded. This blind-
ness may persist for 20 to 30 minutes.
A second and very serious type of eye injury
may also occur. If people are looking directly at
the fireball of a nuclear explosion, they may
receive a retinal flash burn similar to the burn that
occurs on exposed skin. Unfortunately, when the
burn heals, the destroyed retinal tissue is replaced
by scar tissue that has no light perception capa-
bility, and the victims will have scotomas, blind
or partially blind areas in the visual field. In severe
cases, the net result may be permanent blindness.
The effective range for eye injuries from the flash
may extend for many miles when a weapon is
detonated as an air burst. This effective range is
far greater at night when the pupils are dilated,
thereby permitting a greater amount of light to
enter the eye.
Radioactivity may be defined as the spon-
taneous and instantaneous decomposition of the
nucleus of an unstable atom with the accompa-
nying emission of a particle, a gamma ray, or
both. The actual particles and rays involved in the
production of radiation injuries are the alpha and
beta particles, the neutron, and the gamma ray.
These particles and rays produce their effect by
ionizing the chemical compounds that make up
the living cell. If enough of these particles or rays
disrupt a sufficient number of molecules within
the cell, the cell will not be able to carry on its
normal functions and will die.
Alpha particles are emitted from the nucleus
of some radioactive elements. Alpha particles are
helium nuclei of nuclear origin having an atomic
mass number of four and an electrical charge of
two positive. Because of this charge, alpha par-
ticles produce a high degree of ionization when
passing through air or tissue. Also, due to their
large size and electrical charge, they are rapidly
stopped or absorbed by a few inches of air, a sheet
of paper, or the superficial layers of skin.
Therefore, alpha particles do not constitute a ma-
jor external radiation hazard. However, because
of their great ionization power, they constitute a
serious hazard when taken into the body through
ingestion, inhalation, or an open wound.
Beta particles are electrons of nuclear origin.
They have a mass of approximately 1/2,000 of
a hydrogen atom and an electrical charge of minus
one. The penetration ability of a beta particle is
greater than an alpha particle, but it will only pen-
etrate a few millimeters of tissue and will most
probably be shielded out by clothing. Therefore,
beta particles, like alpha particles, do not