Hazards: Nuclear (CBRN)


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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.

During a nuclear incident, it is important to avoid radioactive material, if possible. While experts may predict at this time that a nuclear attack is less likely than other types, terrorism by its nature is unpredictable.

More information on Chemical, Biological, Radiation and Nuclear (CBRN) hazards.

What to Do

If there is advanced warning of an attack:

Take cover immediately, as far below ground as possible, though any shield or shelter will help protect you from the immediate effects of the blast and the pressure wave.

If there is no warning:

  1. Quickly assess the situation.
  2. Consider if you can get out of the area or if it would be better to go inside a building to limit the amount of radioactive material you are exposed to.
  3. If you take shelter go as far below ground as possible, close windows and doors, turn off air conditioners, heaters or other ventilation systems. Stay where you are, watch TV, listen to the radio, or check the Internet for official news as it becomes available.
  4. To limit the amount of radiation you are exposed to, think about shielding, distance and time.

o    Shielding: If you have a thick shield between yourself and the radioactive materials more of the radiation will be absorbed, and you will be exposed to less.

o    Distance: The farther away you are away from the blast and the fallout the lower your exposure.

o    Time: Minimizing time spent exposed will also reduce your risk.

Use available information to assess the situation. If there is a significant radiation threat, health care authorities may or may not advise you to take potassium iodide. Potassium iodide is the same stuff added to your table salt to make it iodized. It may or may not protect your thyroid gland, which is particularly vulnerable, from radioactive iodine exposure.

Nuclear Power Plant Emergency Terms

Familiarize yourself with these terms to help identify a nuclear power plant emergency:

  • Notification of Unusual Event - A small problem has occurred at the plant. No radiation leak is expected. No action on your part will be necessary.
  • Alert - A small problem has occurred, and small amounts of radiation could leak inside the plant. This will not affect you and no action is required.
  • Site Area Emergency - A more serious problem has occurred at the plant, and small amounts of radiation might have or could leak into the environment. Area sirens might sound, and state and local officials will act to ensure public safety.
  • General Emergency - A very serious problem has occurred at the plant, and radiation could leak outside the plant and off the plant site. Area sirens will sound. Listen to local radio or television stations for information. State and local officials will act to ensure public safety. Be prepared to follow instructions promptly.

Electromagnetic Pulse (EMP)

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.

Radioactive Fallout

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 also are drawn into the cloud. As the heat diminishes, radioactive materials that have vaporized condense on the particles and fall back to Earth. The phenomenon is called radioactive fallout. 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 exist. Effects from even a small portable device exploded at ground level can be potentially deadly.

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, such as floods or hurricanes. 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.

Related Information




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