Shelter in place or evacuate after a nuclear emergency?

Short answer. In most nuclear or radiological emergencies, the first official instruction is to shelter, not to flee: "get inside, stay inside and stay tuned" ¹. U.S. agencies advise staying in the most protective place, a basement or the centre of a large building, for at least 24 hours ¹². Evacuate only when local authorities order it, and follow the routes they give ¹⁴⁷.

Why do agencies tell you to stay inside first?

Two reasons recur in the official guidance.

First, buildings shield you. Ready.gov says that "putting material between you and the radiation provides protection while you tune in for instructions from responders", and that the safest buildings have brick or concrete walls ¹. The CDC adds that radiation settles on the outside of buildings, which is why it recommends the basement or the middle of the building ².

Second, the danger drops quickly. Ready.gov says that "radiation levels decrease rapidly, becoming significantly less dangerous, during the first 24 hours" ¹. The CDC says that "staying inside for at least 24 hours can protect you and your family until it is safe to leave the area" ².

Germany's Federal Office for Radiation Protection (BfS) makes the comparison directly: while a radioactive cloud passes, staying in a building "is safer than being unprotected in a car or outdoors during an evacuation" ⁷. A car offers little shielding, and its ventilation can draw particles inside ⁷.

What does "get inside, stay inside, stay tuned" mean in practice?

Get inside. Move indoors as fast as you can. If you are in a car, the CDC says to get inside a building right away ². After a nuclear detonation, Ready.gov advises reaching a multi-storey building or a basement if you can do so within a few minutes; underground parking garages and subways can also provide good shelter ¹.

Stay inside. Go to the basement or the middle of the building ² and put as many walls as possible between you and the outside, away from windows ¹. Canada's guidance adds: close all doors, windows and fireplace dampers; turn off fans, air conditioners and forced-air heating that bring in outside air; stay away from windows and outside walls until advised otherwise ⁴. Germany's BfS gives the same steps and points to interior rooms and basements without windows ⁶.

If you came in from outside, remove your outer layer of clothing: Ready.gov says this "can remove up to 90% of radioactive material" ¹. Wash with soap and water if you can; hand sanitizer does not protect against radioactive material ¹.

Do not go out to collect family. The CDC is explicit: "Going outside to get loved ones could expose you and them to dangerous levels of radiation" ². The CDC notes that schools, daycares, hospitals, nursing homes and other places have emergency plans to keep people safe there ².

Stay tuned. Ready.gov recommends a battery-powered or hand-crank radio and following instructions from emergency response officials. Remain sheltered for the first 24 hours unless an immediate hazard such as fire, a gas leak, building collapse or serious injury forces you out, or officials say it is safe to leave ¹.

When do authorities order an evacuation instead?

Evacuation is a targeted decision, not a general reflex. Around U.S. nuclear power plants, the plume exposure emergency planning zone extends about 10 miles (16 km) in radius, and the ingestion pathway zone about 50 miles (80 km) ³. In a General Emergency, the NRC describes a minimum response in which a two-mile ring around the plant is evacuated, along with people living in the 5-mile zone directly downwind; people in the rest of the 10-mile zone will most likely be advised to go indoors, and evacuation beyond 5 miles is assessed as the accident progresses ³.

Who decides matters. In the United States, "the state or local government agencies are responsible for making decisions necessary to protect the public" ³. In Germany, state disaster protection authorities define evacuation areas and routes, and the BfS says to evacuate only when the authorities ask you to ⁷. Its sheltering page "most strongly" advises against self-evacuation until the affected fallout areas are identified and safe evacuation routes designated ⁶. Canada's regulator says to avoid rushing to evacuate and not to leave unless authorities tell you to ⁵.

When an evacuation is ordered:

• Take your emergency kit ⁴ and everyday necessities: clothing, medication, important papers and hygiene items ⁷.
• Follow official information on routes, shelters and procedures ¹⁴.
• Do not return until authorities say it is safe ¹⁴.

How do I follow local alerts?

Each country has its own channels. Know yours before you need it.

In Sweden, the outdoor warning is a 7-second tone alternating with 14 seconds of silence for at least 2 minutes; the all-clear is a continuous tone of 30 to 40 seconds ⁸. Canada asks residents to check that their wireless phone can receive Alert Ready messages ⁴.

What official agencies recommend

The agencies agree on the order of actions: shelter immediately, cut outside air, wait for official instructions, and evacuate only on order. They differ on details.

• Duration. The U.S. CDC and Ready.gov say at least 24 hours ¹²; Canada says be prepared for at least 24 hours ⁴. Germany's BfS cites the first 24 to 48 hours as a recommended measure after a nuclear weapon explosion, and otherwise says to stay inside until you receive other instructions ⁶.
• Where to shelter. U.S. agencies point to the basement or the centre of a large building ¹². Germany specifies interior rooms and basements without windows ⁶. Canada emphasises staying away from windows and outside walls ⁴.
• Planning distances. The U.S. uses about 10-mile and 50-mile zones around power plants ³. Other countries set their own zones, published by regional authorities; Germany's BfS refers residents to the information brochures for each plant's planning zones ⁷.
• Who gives the order. Always local or regional authorities: state and local governments in the U.S. ³, provinces in Canada ⁵, state disaster authorities in Germany ⁷.

These are general rules. Your local emergency plan, and the instructions issued on the day, take priority.

Frequently asked questions

Should I drive away as soon as I hear about a nuclear emergency?

No, unless authorities order it. Canada's regulator advises against rushing to evacuate ⁵, and Germany's BfS says being in a building during plume passage is safer than being unprotected in a car ⁷. Shelter first and listen for instructions ¹.

How long should I stay sheltered?

U.S. and Canadian guidance says at least 24 hours ¹²⁴. Germany cites 24 to 48 hours after a nuclear explosion and otherwise until authorities give new instructions ⁶. Leave earlier only for an immediate hazard such as fire, a gas leak, building collapse or serious injury ¹.

Can I go and pick up my children from school?

The CDC advises against it: going outside to get loved ones could expose both you and them to dangerous radiation levels ². Stay where you are and follow official updates.

What should I do if I was outside when it happened?

Get inside a building right away ², remove your outer layer of clothing, which can remove up to 90% of radioactive material, and wash with soap and water ¹.

Which room in my home is best?

The basement, or a room in the middle of the building away from windows and outside walls ¹²⁴. Germany's BfS points to interior rooms and basements without windows ⁶.

Make your plan before you need it

Choose your shelter room, check how alerts reach you and learn the evacuation information your local authorities publish before an emergency. Your local emergency plan, and the instructions issued on the day, take priority.

Sources

1. Ready.gov (U.S. DHS / FEMA) — Radiation Emergencies — https://www.ready.gov/radiation (accessed 2026-10-20)
2. U.S. Centers for Disease Control and Prevention — What to Do: Get Inside — https://www.cdc.gov/radiation-emergencies/response/get-inside.html (accessed 2026-10-20)
3. U.S. Nuclear Regulatory Commission — Backgrounder on Emergency Preparedness at Nuclear Power Plants — https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/emerg-plan-prep-nuc-power (accessed 2026-10-20)
4. Government of Canada — Radiological and nuclear emergencies – Get prepared — https://www.canada.ca/en/services/policing/emergencies/preparedness/get-prepared/hazards-emergencies/radiological/how-prepare.html (accessed 2026-10-20)
5. Canadian Nuclear Safety Commission — Protecting your family in a nuclear emergency — https://www.cnsc-ccsn.gc.ca/eng/resources/emergency-management-and-safety/protecting-your-family-during-a-nuclear-emergency/ (accessed 2026-10-20)
6. Bundesamt für Strahlenschutz (Germany) — Gebäude schützen im Notfall vor Strahlung — https://www.bfs.de/DE/themen/ion/notfallschutz/verhalten/aufenthalt-haus/aufenthalt-haus.html (accessed 2026-10-20)
7. Bundesamt für Strahlenschutz (Germany) — Evakuierung als Schutzmaßnahme in einem radiologischen Notfall — https://www.bfs.de/DE/themen/ion/notfallschutz/verhalten/evakuierung/evakuierung_node.html (accessed 2026-10-20)
8. Länsstyrelsen Halland (Sweden) — Viktigt meddelande till allmänheten — https://www.lansstyrelsen.se/halland/samhalle/sakerhet-och-beredskap/eget-ansvar-vid-kris-eller-krig/viktigt-meddelande-till-allmanheten.html (accessed 2026-10-20)