A nuclear incident could happen because of an accident or natural disaster, or through an intentional act like terrorism or warfare.
If there is an incident at a nuclear power plant, radioactive material can be released into the environment, carried by the wind, and settle on the ground and buildings.
If a nuclear weapon is detonated, radioactive dust and debris will be released into the air. It will take more than 10 minutes to arrive back at ground, and then cause widespread contamination.
Find out how to prepare for a nuclear incident on our Get ready to travel page
If you were in range of a nuclear incident, you should get inside a building immediately. If the incident is a nuclear explosion, you will have at least 10 minutes to find shelter before fallout arrives.
Buildings with brick or concrete walls, like underground parking garages and subway stations, provide the best shelter. Find the room or space that is most protected from ventilation or the outdoors.
Close off the building from the outdoors by:
If you are in a vehicle and aren’t near a protective building, pull over and consider moving under an overpass or behind an embankment.
Remove clothing that you have worn outside since the incident and put it in a plastic bag outside. Decontaminate your body by having a shower or wiping exposed skin and hair. Pets that may have been contaminated can be taken to a separate room and then brushed and washed.
Find something to cover your mouth and nose, like a mask, scarf, handkerchief or cloth. Avoid touching your eyes, nose and mouth until you can wash with soap and water.
Packaged food, drinks or medicines should still be safe to consume.
Immediate actions to take when a nuclear detonation occurs from the United States Centers for Disease Control and Prevention (CDC)
Protective actions for radiation emergencies video from the CDC
Potassium iodide can have harmful health effects so it’s important you don’t self-medicate. You should only take potassium iodide if directed by a public health or emergency response official.
Potassium iodide can be used in a nuclear emergency to protect the thyroid from potential exposure to radioactive iodine. However, it must be taken immediately before or within 24 hours of exposure to be effective and is less effective for certain population groups. In addition, it does not protect other parts of the body against other types of radiation.
Unless there is a threat to the building you’re sheltering in, you should stay inside until local authorities say you can go outside. Do not attempt to self-evacuate until hazardous areas have been identified and safe evacuation routes have been established.
If you are evacuating by car, keep the windows closed and the ventilation system turned off.
