Nuclear Detonation: Get Inside, Stay Inside, Stay Tuned

The single most important thing to know about surviving a nuclear detonation is simple: get inside, stay inside, stay tuned. Most of the radiation danger after the blast comes from fallout, radioactive dust that settles out of the air, and good shelter blocks most of it.

Get inside

• After a detonation, you may have 10 minutes or more before fallout arrives. Use it to get into the nearest substantial building.
• Go to the most protective spot: a basement, or the center of a large building, away from windows. Put as many walls as possible between you and the outside. Brick and concrete are better than wood.
• If you were outdoors when fallout began, remove your outer layer of clothing as soon as you are inside (see decontamination).

Stay inside

• Stay in that protected spot for at least 24 hours, unless there is an immediate danger (such as fire) or authorities tell you otherwise. Fallout radiation is most intense at first and weakens over time.
• Turn off fans, air conditioners and forced-air heating that pull in outside air.
• Bring pets inside.
• Don’t leave to find family members. Shelter where you are; that is also what they should be doing.

Stay tuned

Cell, internet and TV service may be down. A battery-powered or hand-crank radio is the most reliable way to hear official instructions, including when it is safe to leave and which way to go. Follow those instructions over any general rule, including this one.

Prepare now

Keep a radio and spare batteries in your disaster kit, plus a trash bag for contaminated clothing. Know where the most shielded room is in your home, workplace and children’s schools.

Potassium iodide is not a substitute for shelter after a nuclear detonation.