Depending on the speed, at which the area of the Radiological Dispersion Device (RDD) detonation was evacuated, or how successful people were at sheltering-in-place, the number of deaths and injuries from an RDD might not be substantially greater than from a conventional bomb explosion.
There is no way of knowing how much warning time there will be before an attack by terrorists using a Radiological Dispersion Device (RDD), so being prepared in advance and knowing what to do and when is important. To prepare for an RDD event, you should do the following: 
Actions Before: Determine Risk, Increase Knowledge, Safeguard, Plan
- Determine the disaster risks in your locale.
- Learn warning signs and community alert systems.
- Have a shelter in-place and a mobile disaster supplies kit ready.
- Choose an internal room to shelter, preferably one without windows and on the highest level.
- Create a custom Family Emergency Plan. Make plans for elderly, disabled, and pets.
- Develop an emergency communication plan in case of separation.
- Ask an out-of-state person to serve as the "family contact".
- Choose an internal room to shelter, preferably one without windows.
- 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 tunnels.
- 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.
Taking shelter during an RDD event is absolutely necessary. There are two kinds of shelters - blast and fallout. The following describes the two kinds of shelters:
- Blast shelters are specifically constructed to offer some protection against blast pressure, initial radiation, heat, and fire. But even a blast shelter cannot withstand a direct hit from a nuclear explosion.
- 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.
Actions During: Safety Basics, Evacuation, Shelter in Place
Whether you are indoors or outdoors, home or at work, be extra cautious. It would be safer to assume radiological contamination has occurred - particularly in an urban setting or near other likely terrorist targets - and take the proper precautions. As with any radiation, you want to avoid or limit exposure. This is particularly true of inhaling radioactive dust that results from the explosion.
As you seek shelter from any location (indoors or outdoors) and there is visual dust or other contaminants in the air, breathe though the cloth of your shirt or coat to limit your exposure. If you manage to avoid breathing radioactive dust, your proximity to the radioactive particles may still result in some radiation exposure.
If the explosion or radiological release occurs inside, get out immediately and seek safe shelter. Otherwise, if you are:
- Implementing shielding at the scene of a radiological incident can be accomplished by using physical objects such as buildings and vehicles. The penetration effects of radiation are dependent upon the type of material and the nature of the radiation emitted. As a rule of thumb, keep as much mass as possible between yourself and suspected radiological materials.
- Seek shelter indoors immediately in the nearest undamaged building.
- If appropriate shelter is not available, cover your nose and mouth and move as rapidly as is safe upwind, away from the location of the explosive blast. Then, seek appropriate shelter as soon as possible.
- The U.S. Department of Transportation - Emergency Response Guidebook (ERG) - Radiological Materials Section - recommends to isolate the area for at least 25 to 50 meters (80 to 160 feet) in all directions and to stay upwind.
- Listen for official instructions and follow directions.
- If you have time, turn off ventilation and heating systems, close windows, vents, fireplace dampers, exhaust fans, and clothes dryer vents. Retrieve your disaster supplies kit and a battery-powered radio and take them to your shelter room.
- Seek shelter immediately, preferably underground or in an interior room of a building, placing as much distance and dense shielding as possible between you and the outdoors where the radioactive material may be.
- Seal windows and external doors that do not fit snugly with duct tape to reduce infiltration of radioactive particles. Plastic sheeting will not provide shielding from radioactivity nor from blast effects of a nearby explosion.
- Listen for official instructions and follow directions.
Actions After: Get Disaster Relief, Clean-up, Salvage
After finding safe shelter, those who may have been exposed to radioactive material should decontaminate themselves. To do this, remove and bag your clothing (and isolate the bag away from you and others), and shower thoroughly with soap and water. Seek medical attention after officials indicate it is safe to leave shelter.
Contamination from an RDD event could affect a wide area, depending on the amount of conventional explosives used, the quantity and type of radioactive material released, and meteorological conditions. Thus, radiation dissipation rates vary, but radiation from an RDD will likely take longer to dissipate due to a potentially larger localized concentration of radioactive material.
Follow these additional guidelines after an RDD event:
- Continue listening to your radio or watch the television for instructions from local officials, whether you have evacuated or sheltered-in-place.
- Do not return to or visit an RDD incident location for any reason.
- U.S. Air Force – Be Ready – Terrorism: http://www.beready.af.mil/disasters&emergencies/terrorism.asp
- American Red Cross, CDC – Emergency Preparedness and Response, FEMA – Are You Ready? Guide, Ready.gov, Be a Force of Nature with NOAA’s Weather Ready Nation, National Weather Service Weather Safety
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