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Rad Resilient City Initiative

Fallout Preparedness Education Campaign

Suggested Topics for a Fallout Preparedness Education Campaign

Below is information on topics that communities may wish to address when designing their own pre-incident public education campaigns around fallout preparedness. Professional associations, the federal government, and others have also provided guidance on information the public would need to prepare and respond to a nuclear detonation.1-3 These resources can help to inform a fallout preparedness campaign tailored to a specific community.

How will I know that a nuclear detonation has occurred? It is important to recognize the cues or physical signs of a nuclear detonation promptly on your own, because damaged or disrupted communication lines may make it impossible for authorities to warn you to protect yourself. Detonation of a 10-kiloton nuclear weapon will cause a brilliant flash of light. At a distance of 1 mile from ground zero, the flash would be as bright as 1,000 midday suns. A mushroom-shaped cloud rising miles into the air may also indicate a nuclear detonation, but the weather can interfere with the cloud shape being formed or being seen. The mushroom cloud may not be seen at night. Conventional explosives can also produce a mushroom cloud, which could be confused with a nuclear incident, especially for smaller bombs. Sudden disruption of electronic equipment may also signal the explosion of a nuclear device, as might the sudden appearance of burn victims distant from the explosion.

What is fallout? Fallout is created when soil and debris combine with radioactive material from the nuclear explosion as they are drawn miles upward into the air by the heat of the blast. As this cloud cools, the mixture of radioactive materials falls onto the ground and roofs where it looks like sand or dust.

How can fallout hurt me? Some types of radioactivity work like x-rays in that their energy (penetrating radiation) can pass through solid objects. Fallout that has settled on the ground and building roofs can release this penetrating radiation, and it can then damage cells and tissues in the human body. Exposure to high levels of radiation over a short period of time causes people to become very ill or to die, within minutes to months. This injury is known as acute radiation syndrome (ARS). After a nuclear explosion, people can avoid ARS by immediately finding a safe place to shelter. Another health effect—having a higher chance of developing cancer later in life—comes from long-term exposure to low doses of radiation. Your first concern following a nuclear detonation is avoiding ARS. After the crisis period is over, officials will provide you with additional information on how to lower the chances of developing cancer over time.

How can I avoid dangerous amounts of fallout radiation? The single most important thing to do is to immediately go inside a sound and stable building before fallout arrives, picking a shelter that provides the most protection as possible. The goal is to put as much dense, solid material and distance as possible between you and the radioactive dust. Some types of buildings protect people better than others. Dense materials such as brick, cement, and earth stop radiation better than wood, drywall, and thin sheet metal. Similarly, areas within a building, such as restrooms and stairwell cores, which are farther away from where the fallout has settled, protect better than those close to roofs, windows, and exterior walls. Multistory brick or concrete structures, cores of large office buildings, multistory shopping malls, and basements, tunnels, subways, and other underground areas are examples of good shelters. Poor shelters include outdoor areas, cars and other vehicles, mobile homes, single-story wood-frame houses, strip malls, and other single-story light structures.

How long do I need to stay in my shelter before it’s safe to come out? In general, to reduce total radiation exposure, the longer you can wait in safety, the lower the amount of radiation you will receive. Everyone needs to be inside a shelter during the first hour following the detonation, when the levels of radiation are at their most dangerous. Then:

  • If you are in a poor shelter and there’s a better one nearby, wait at least 1 hour before moving. Potential radiation exposure decreases by 55% in the first hour following a detonation. If you move to a different shelter, minimize the time outside.

  • If you are in a good shelter, stay inside a minimum of 1 day and then wait for instructions from authorities about when to come out. In the first day following a nuclear detonation, potential radiation exposure decreases by 80%.

It may take officials a day or more to determine where there are dangerous levels of fallout as well as which roads are passable. Once they know this, officials can inform people when and where it’s safe to leave their shelters. Officials will help move people whose lives are most in danger first; others will be asked to wait their turn and keep the roads clear. Evacuating early may endanger your life and others’ lives. This means that you may be sheltering for several days. TV, phone, and internet access may be difficult due to power outages or high demand. Therefore, turning on a battery-powered or hand-crank radio may be the best option for finding out what is happening and learning about what you should do next.

Should I go get my children from school after a nuclear detonation? No. It’s safest for your children immediately to go deep inside their school and stay there to avoid fallout radiation. You put both your children’s and your own safety at risk by being outdoors or in cars during the time when radiation levels are at their highest. Your kids need you healthy. Take time now to find out the school’s plans for a nuclear detonation. Where will they keep the children? Do they have enough food and water for several days? Do they have an alternative site chosen for moving students? How will you be reunited with your children? Making sure that the school has a good plan to keep your children safe should reduce some of the pressure you may feel to pick them up from school immediately following a nuclear detonation. Having a family emergency plan on how you will stay in touch and reunite can also provide some peace of mind while you wait until it’s safe.

What should I do if I get radioactive dust on me? What about dust on my pet? Radioactive dust that settles on clothing, skin, and hair is known as external contamination. Some very easy steps can help remove radioactive dust that may be on you or your clothes or on your pets. Simply removing the outer layer of clothing can eliminate the vast majority of fallout;4 more dust, however, is taken off when removing a winter coat and boots than when taking off shorts and a t-shirt. Place the removed clothing in a plastic bag and leave outdoors. When possible, take a shower and use soap and water to eliminate any remaining radioactive material. If it is not possible to shower, use a wet cloth to wipe off skin not covered by clothing, especially hands and faces to prevent accidental ingestion of radioactive materials. Pets that have been outdoors following the detonation can also be washed to remove fallout.

What can I do to help others? Can I open my doors to people covered in fallout dust? In the event of a nuclear detonation, you can help people in a variety of ways, whether you are in the dangerous fallout zone, in nearby affected areas, or in other parts of the country. It is safe to take in others using precautions to limit the spread of radioactive dust as described above. Letting others into your building could save their lives and not endanger yours. If you are in a community adjacent to an affected area, you can temporarily house evacuees or help organize reception shelters. People who live in major cities outside the stricken region can begin to make plans to accept longer-term evacuees and to provide support to people and their families who come for medical treatment.

What about breathing in fallout? Should I wear a mask? Actually, inhaling fallout is not a major source of radiation exposure. During the first 24 hours, when fallout radiation levels are highest, the particles settling to the ground tend to be big enough that the nose filters them out, preventing them from going into the lungs.5 Once fallout has settled on the ground, you are much more likely to get it on lower parts of your body while walking through it. Generally, the dust won’t be kicked up high enough to breathe in. That said, if you have a mask or want to cover your face with a cloth, it is a sensible thing to do. However, make sure the mask is definitely free of radioactive dust, otherwise you are increasing your chance of breathing in fallout.

Is it safe to eat and drink after a nuclear explosion, or will I get radiation inside me? You can avoid ingesting fallout by consuming only things that were protected from fallout dust (eg, food that is wrapped or inside of containers or refrigerators) and/or that can be washed off. Also, make sure that your hands and face are clean of fallout dust so that you don’t accidentally get it in what you are eating and drinking. Once the immediate crisis is over, officials will identify the places where food and water contain too high a level of radiation, and they will prevent people from eating and drinking items from these areas.

What are the 3 most important things I can do now to be prepared for a nuclear detonation?

  1. Have a family emergency plan and kit.
    1. Knowing what steps your loved ones plan to take after a nuclear detonation and how you will find one another after 24 to 72 hours reduces worry. In turn, this increases the likelihood that you will all stay inside buildings rather than exposing yourselves to radiation while trying to find one another.
    2. Set aside emergency supplies of medications, food, and water in your home and workplace. Emergency professionals recommend that if you have not yet set aside anything, begin with a 3-days’ supply and work your way up to 1 week and then 2 weeks as you adopt a preparedness lifestyle. Larger stockpiles provide you more flexibility for unpredictable events. For more details on gathering supplies to support sheltering-in-place, consult the and American Red Cross websites.
  2. Determine which buildings give the best fallout protection near and en route to where you live, work, or attend school.
  3. Buy a hand-crank or battery-powered radio to get information in the event other means don’t work.


  1. Just-in-Time: Nuclear Detonation—10 Rules for the Public and Citizen Responders. Homeland Security Committee of the Health Physics Society. Accessed August 5, 2011.

  2. National Council on Radiation Protection and Measurements (NCRP). Responding to a Radiological or Nuclear Terrorism Incident: A Guide for Decision Makers. NCRP report no. 165. Bethesda, MD: NCRP; 2010.

  3. Domestic Resilience Group, IND Response Sub-IPC, Nuclear Detonation Response Communications Working Group. Nuclear Detonation Preparedness: Communicating in the Immediate Aftermath. Approved for Interim Use, Department of Homeland Security, September 2010.

  4. Ferlic KP. Fallout: Its Characteristics and Management. Armed Forces Radiobiology Research Institute Technical Report AFRRI TR83-5. Bethesda, MD; December 1983. Accessed August 6, 2011.

  5. Glasstone S, Dolan PJ. The Effects of Nuclear Weapons, 3rd ed. Washington, DC: U.S. Department of Defense and the Energy Research and Development Administration; 1977.



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