How to survive a nuclear attack
To survive a nuclear attack, drop and take cover when you see the flash, get inside a solid building within about 10 minutes, and stay inside for at least 24 hours. Official guidance sums it up in three phrases: Get Inside. Stay Inside. Stay Tuned.
No guide can guarantee survival, and close to the detonation it is unlikely. But planners at FEMA and Lawrence Livermore National Laboratory consistently find that for most people in the wider affected area, what they do in the first minutes and hours makes a very large difference. This page is general information, not official advice; instructions from your local authorities always come first.
What to do in the first 60 seconds
The flash arrives instantly. The blast wave follows seconds later, or longer if you are far away.
- Drop immediately, face down, away from windows and behind anything solid.
- Cover your head and neck and any exposed skin. Keep your eyes closed.
- Stay down until the blast wave has passed. It can be followed by a strong wind blowing back the other way, so wait until things have been still for a short while.
- Don't go to a window to look. Where the blast damage is light, flying glass is the main cause of injury.
What to do in the first 10 minutes
Fallout is radioactive dust that can look like sand, grit or ash. Outside the blast area it usually takes 10 minutes or more to arrive.
- Check yourself and others for injuries. Stop serious bleeding first.
- Get into the best building you can reach. A basement, or the middle of a large brick or concrete building, is best. Any building is better than outdoors. A car is not a shelter.
- Go deep. Head for the basement or the centre of the building, away from outside walls, windows and the roof.
- Strip and wash if you were outside. Taking off your outer layer of clothing removes up to 90% of radioactive material. Bag it, then wash with soap and water.
- Seal up. Close windows, doors and fireplace dampers. Turn off fans, air conditioning and heating that draws in outside air.
- Turn on a radio and listen for official instructions.
Which building to choose is covered in the best place to shelter from nuclear fallout. If you are in a car or on foot, see what to do by where you are.
What to do in the first 24 hours
Fallout loses strength very quickly, so every hour inside makes the outside safer.
| Time after detonation | Radiation level compared with 1 hour after |
|---|---|
| 1 hour | 100% |
| 7 hours | about 10% |
| 2 days | about 1% |
| 2 weeks | about 0.1% |
- Stay at least 24 hours unless there is fire, a gas leak, building collapse, or officials tell you otherwise.
- Do not go out to collect family. Schools and workplaces have shelter plans, and going outside exposes you and them to the highest radiation levels.
- Text, don't call. Phone networks will be overloaded.
- Eat and drink what was inside. Food and water that were indoors are safe. Keep taking prescription medication as normal.
- Never run generators, barbecues or camping stoves indoors. Carbon monoxide is invisible and deadly.
- Do not take potassium iodide unless public health officials tell you to. See potassium iodide and other myths.
What to do in the days after
Leave only when officials say it is safe, or when they direct you to evacuate along a specific route. Some areas may be asked to shelter for longer than a day; see how long to stay inside after nuclear fallout.
- Water matters more than food. Plan on one gallon (about 4 litres) per person per day.
- Don't eat fresh garden produce or anything that was uncovered outside until authorities say it is safe.
- If told to evacuate, follow the official route even if it seems longer. Wear long sleeves, long trousers, a hat, gloves and a mask or cloth over your nose and mouth. Don't return until authorities say so.
- Watch for radiation sickness. It usually begins with nausea and vomiting within hours of a high dose. Tell medical staff as soon as care is available.
Power, water and shops may be disrupted for much longer than the shelter period, which is what a home kit and go-bag is for.
The book Fallout Ready works through each situation in full, with common mistakes, do-not lists and printable checklists.
Sources
- Ready.gov: Radiation Emergencies
- CDC: What to Do - Get Inside
- CDC: How to Self-Decontaminate after a Radiation Emergency
- FEMA: Planning Guidance for Response to a Nuclear Detonation, 3rd edition
- Lawrence Livermore National Laboratory: Key Response Planning Factors for the Aftermath of Nuclear Terrorism
- Glasstone and Dolan, The Effects of Nuclear Weapons, 3rd edition, 1977, chapter 9 (the 7:10 rule)
Questions
Can you survive a nuclear attack?
People close to the detonation are unlikely to survive, but most people in the wider affected area can. US federal planners find that getting inside a solid building quickly and staying there is the action that saves the most lives.
Is a car safe during nuclear fallout?
No. A car barely halves your radiation dose, and official guidance is to leave it and get into a building. Stay in a vehicle only as a last resort when no building can be reached.
How long should you stay inside after a nuclear attack?
Official guidance is to stay inside for at least 24 hours, unless there is fire, a gas leak or building collapse, or officials tell you otherwise. Radiation from fallout drops to about 10% of its one-hour level after 7 hours and about 1% after two days.
