Why Prepare?

Basic Preparedness
Getting Informed
Planning and Checklists
Special Needs
Disaster Supplies Kit

Natural Hazards
Thunderstorms and lightning
Winter storms and extreme cold
Extreme heat
Landslides and debris flow

Technological Hazards
Hazardous materials incidents
Household chemical emergencies
Nuclear power plant emergencies

Biological threats
Chemical threats
Nuclear blasts
Radiological dispersion device events

Recovering from Disaster
Health and safety guidelines
Returning home
Seeking disaster assistance
Coping with disaster
Helping others

Radiological Dispersion Device
Terrorist use of an RDD—often called “dirty nuke” or “dirty bomb”—is considered far more likely than use of a nuclear explosive device. An RDD combines a conventional explosive device with radioactive material. It is designed to scatter dangerous and sub-lethal amounts of radioactive material over a general area.
The primary purpose of terrorist use of an RDD is to cause psychological fear and economic disruption. Some devices could cause fatalities from exposure to radioactive materials. Depending on the speed at which the area of the 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.
The size of the affected area and the level of destruction caused by an RDD would depend on the sophistication and size of the conventional bomb, the type of radioactive material used, the quality and quantity of the radioactive material and the local meteorological conditions—primarily wind and precipitation. The area affected could be placed off-limits to the public for several months during cleanup efforts.

Take Protective Measures
What can I do before a RDD Event occurs?

There is no way of knowing how much warning time there will be before an attack by terrorists using an RDD, so being prepared in advance and knowing what to do and when is important. Take the same protective measures you would for fallout resulting from a nuclear blast.

What do I do During a RDD Event?

While the explosive blast will be immediately obvious, the presence of radiation will not be known until trained personnel with specialized equipment are on the scene. 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, try to avoid the area as breathing and proximity to it could cause exposure.
If the explosion or radiological release occurs inside, get out immediately and seek safe shelter. Otherwise, if you are:
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 or from blast effects of a nearby explosion.

Listen for official instructions and follow directions.


Seek shelter indoors immediately in the nearest undamaged building.

If appropriate shelter is not available, move as rapidly as is safe upwind and away from the location of the explosive blast.

Then, seek appropriate shelter as soon as possible.

Listen for official instructions and follow directions.

What do I do After a RDD Event?

After finding safe shelter, those who may have been exposed to radioactive material should decontaminate themselves. To do this, remove and bag your clothing, isolate the bag away from other inhabitants and shower thoroughly with soap and water. Seek medical attention after officials indicate it is safe to leave shelter.
Contamination from a 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 a 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
Follow the instructions for recovering from a disaster in Part 5.

Homeland Security Advisory System
The Homeland Security Advisory System was designed to provide a national framework and comprehensive means to broadcast information regarding the risk of terrorist acts to the following:
Federal, state, and local authorities

The private sector

The American people
This system provides warnings in the form of a set of graduated threat conditions that increase as the risk of the threat increases. Risk includes both the probability of an attack occurring and its potential gravity. Threat conditions may be assigned for the entire nation, or they may be set for a particular geographic area or industrial sector. At each threat condition, government entities and the private sector, including businesses and schools, would implement a corresponding set of protective measures to further reduce vulnerability or increase response capability during a period of heightened alert.
There are five threat conditions, each identified by a description and corresponding color. Assigned threat conditions will be reviewed at regular intervals to determine whether adjustments are warranted.

Threat Conditions and Associated Protective Measures
There is always a risk of a terrorist threat. Each threat condition assigns a level of alert appropriate to the increasing risk of terrorist attacks. Each threat condition contains suggested protective measures that the government, the private sector and the public can take.
In each case, as threat conditions escalate, protective measures are cumulative to those already taken in lower threat conditions.

Citizen Guidance on the Homeland Security Advisory System
Low Risk

Develop a family emergency plan
Create an Emergency Supply Kit for your household
Know where to shelter and how to turn off utilities (power, gas, and water) to your home
Examine volunteer opportunities in your community and donate your time
Consider completing an American Red Cross first aid, CPR course or Community Emergency Response Team (CERT) course.

Guarded Risk
Complete recommended steps at level green
Review stored disaster supplies and replace items that are outdated
Be alert to suspicious activity and report it to proper authorities

Elevated Risk
Complete recommended steps at levels green and blue
Ensure disaster supplies are stocked and ready
Check telephone numbers in family emergency plan and update as necessary
Develop alternate routes to/from work or school and practice them
Continue to be alert for suspicious activity and report it to authorities

High Risk
Complete recommended steps at green, blue and yellow levels
Exercise caution when traveling
Pay attention to travel advisories
Review your family emergency plan and make sure all family members know what to do
Be patient
Expect delays
Check on neighbors or others that might need assistance in an emergency

Severe Risk
Complete all recommended actions at green, blue, yellow and orange levels
Listen to local emergency management officials
Stay tuned to TV or radio for current information
Be prepared to shelter or evacuate, as instructed
Expect traffic delays, restrictions and searches
Provide volunteer services only as requested
Contact your school and business to determine status of work day

*Developed with input from the American Red Cross.
To determine the current threat level visit Homeland Security. Keep your family informed when changes in the threat level occur and go over the personal actions you need to take.