OZ FIELD GUIDE / 09 / RADIATION
Nuclear detonation
Get inside, stay inside, and get reliable instructions.
THE QUICK ANSWER
After a nuclear detonation, get inside the nearest sturdy building as quickly as you can. Move to a basement or central interior area, away from walls, windows, and the roof. Stay inside and tune to official updates; the first 24 hours are especially important unless the building is unsafe or authorities direct you elsewhere.
In immediate danger, contact local emergency services. Current instructions for your location take priority.
01 / DO NOW
First moves.
- 01
Get inside
Do not remain outdoors looking at the blast or travel across town for a preferred shelter. A substantial building offers better protection than a vehicle or open space.
- 02
Go deeper inside
Use a basement or the middle of the building with as much material between you and outdoors as possible. Close doors and windows.
- 03
If exposed outdoors, clean up
Once sheltered, remove the outer layer of clothing and set it aside away from people; wash exposed skin with water and soap when available. This reduces contamination brought indoors.
- 04
Stay tuned
Use radio, phone, or other available channels for location-specific instructions. Avoid going out to collect family members who are already sheltered elsewhere.
02 / NEXT
When the first minute is over.
Arrange water, medications, and a way to receive alerts within the shelter. Leave only for an immediate threat such as fire, collapse, or other life-threatening condition, or when officials direct a safe move.
03 / WATCH FOR
The exception that matters.
Fallout conditions vary by place and time. Do not treat a fixed distance or a clock as an all-clear; use the official instructions for your location. Potassium iodide is not a general radiation antidote and should be taken only when public-health officials advise it.
04 / VERIFY
Sources & context.
Osprey Zero wrote this guide from the references below. It is a general starting point, not a live alert. Check the issuing authority for your area; guidance and conditions can change.
Guide updated 02 October 2026. U.S.-based references unless noted; follow authorities where you are.