Disaster Supplies Kit
Thunderstorms and lightning
Winter storms and extreme cold
Landslides and debris flow
Hazardous materials incidents
Household chemical emergencies
Nuclear power plant emergencies
Radiological dispersion device events
Recovering from Disaster
Health and safety guidelines
Seeking disaster assistance
Coping with disaster
A nuclear blast is an explosion with intense light and heat,
a damaging pressure wave and widespread radioactive material
that can contaminate the air, water and ground surfaces for
miles around. All nuclear devices cause deadly effects when
exploded, including blinding light, intense heat (thermal
radiation), initial nuclear radiation, blast, fires started
by the heat pulse and secondary fires caused by the
Hazards of Nuclear Devices
The extent, nature and arrival time of these hazards are
difficult to predict. The geographical dispersion of hazard
effects will be defined by the following:
The size of the device; a more powerful bomb will produce
more distant effects.
Height above the ground the device was detonated. This will
determine the extent of blast effects.
Nature of the surface beneath the explosion; some materials
are more likely to become radioactive and airborne than
others. Flat areas are more susceptible to blast effects.
Existing meteorological conditions; wind speed and direction
will affect arrival time of fallout; precipitation may wash
fallout from the atmosphere.
Even if individuals are not close enough to the nuclear
blast to be affected by the direct impacts, they may be
affected by radioactive fallout. Any nuclear blast results
in some fallout. Blasts that occur near the earth’s surface
create much greater amounts of fallout than blasts that
occur at higher altitudes. This is because the tremendous
heat produced from a nuclear blast causes an up-draft of air
that forms the familiar mushroom cloud. When a blast occurs
near the earth’s surface, millions of vaporized dirt
particles are drawn into the cloud. As the heat diminishes,
radioactive materials that have vaporized condense on the
particles and fall back to Earth. This fallout material
decays over a long period of time, and is the main source of
residual nuclear radiation.
Fallout from a nuclear explosion may be carried by wind
currents for hundreds of miles if the right conditions
Nuclear radiation cannot be seen, smelled or otherwise
detected by normal senses. Radiation can only be detected by
radiation monitoring devices. This makes radiological
emergencies different from other types of emergencies.
Monitoring can project the fallout arrival times, which will
be announced through official warning channels. However, any
increase in surface build-up of gritty dust and dirt should
be a warning for taking protective measures.
In addition to other effects, a nuclear weapon detonated in
or above the earth’s atmosphere can create an
electromagnetic pulse (EMP), a high-density electrical
field. An EMP acts like a stroke of lightning but is
stronger, faster and shorter. An EMP can seriously damage
electronic devices connected to power sources or antennas.
This includes communication systems, computers, electrical
appliances and automobile or aircraft ignition systems. The
damage could range from a minor interruption to actual
burnout of components. Most electronic equipment within
1,000 miles of a high-altitude nuclear detonation could be
affected. Battery-powered radios with short antennas
generally would not be affected. Although an EMP is unlikely
to harm most people, it could harm those with pacemakers or
other implanted electronic devices.
Protection from a Nuclear Blast
The danger of a massive strategic nuclear attack on the
United States is predicted by experts to be less likely
today. However, terrorism, by nature, is unpredictable.
If there were threat of an attack, people living near
potential targets could be advised to evacuate or they could
decide on their own to evacuate to an area not considered a
likely target. Protection from radioactive fallout would
require taking shelter in an underground area or in the
middle of a large building.
In general, potential targets include:
Strategic missile sites and military bases
Centers of government and state capitals
Important transportation and communication centers
Manufacturing, industrial, technology and financial centers
Petroleum refineries, electrical power plants and chemical
Major ports and airfields
The three factors for protecting oneself from radiation and
fallout are distance, shielding and time.
Distance - the more distance between you and the fallout
particles, the better. An underground area such as a home or
office building basement offers more protection than the
first floor of a building. A floor near the middle of a
high-rise may be better, depending on what is nearby at that
level on which significant fallout particles would collect.
Flat roofs collect fallout particles so the top floor is not
a good choice, nor is a floor adjacent to a neighboring flat
Shielding - the heavier and denser the materials between you
and the fallout particles, the better.
Time - fallout radiation loses its intensity fairly rapidly.
In time, you will be able to leave the fallout shelter.
Radioactive fallout poses the greatest threat to people
during the first two weeks, by which time it has declined to
about 1 percent of its initial radiation level.
Remember that any protection, however temporary, is better
than none at all, and the more shielding, distance and time
you can take advantage of the better protection you have.
Take Protective Measures
What can I do Before a Nuclear Blast?
To prepare for a nuclear blast, you should do the following:
Find out from officials if any public buildings in your
community have been designated as fallout shelters. If none
have been designated, make your own list of potential
shelters near your home, workplace and school. These places
would include basements or the windowless center area of
middle floors in high-rise buildings, as well as subways and
If you live in an apartment building or high-rise, talk to
the manager about the safest place in the building for
sheltering and about providing for building occupants until
it is safe to go out
During periods of increased threat increase your disaster
supplies to be adequate for up to two weeks
Taking shelter during a nuclear blast is absolutely
necessary. There are two kinds of shelters - blast and
Blast shelters are specifically constructed to offer some
protection against blast pressure, initial radiation, heat
Fallout shelters do not need to be specially constructed for
protecting against fallout. They can be any protected space,
provided that the walls and roof are thick and dense enough
to absorb the radiation given off by fallout particles
What do I do During a Nuclear Blast?
If an attack warning is issued:
Take cover as quickly as you can, below ground if possible,
and stay there until instructed to do otherwise
Listen for official information and follow instructions
If you are caught outside and unable to get inside
Do not look at the flash or fireball - it can blind you
Take cover behind anything that might offer protection
Lie flat on the ground and cover your head.
If the explosion is some distance away, it could take 3 0
seconds or more for the blast wave to hit
Take shelter as soon as you can, even if you are many miles
from ground zero where the attack occurred - radioactive
fallout can be carried by the winds for hundreds of miles.
Remember the three protective factors: Distance, shielding
What do I do After a Nuclear Blast?
Decay rates of the radioactive fallout are the same for any
size nuclear device. However, the amount of fallout will
vary based on the size of the device and its proximity to
the ground. Therefore, it might be necessary for those in
the areas with highest radiation levels to shelter for up to
The heaviest fallout would be limited to the area at or
downwind from the explosion and 80 percent of the fallout
would occur during the first 24 hours.
People in most of the areas that would be affected could be
allowed to come out of shelter within a few days and, if
necessary, evacuate to unaffected areas.
Returning to Your Home
Remember the following:
Keep listening to the radio and television for news about
what to do, where to go and places to avoid
Stay away from damaged areas.
Stay away from areas marked “radiation hazard” or “HAZMAT”
Follow the instructions for returning home