How to decontaminate after fallout exposure

Of everything done after a nuclear detonation, the most effective measure is also the simplest and the most embarrassing: taking your clothes off. Fallout contamination is deposited dust, and dust stays almost entirely in the outer layer of what you are wearing.

Step 1: the clothing

Do it before entering the clean part of the house — ideally in the hallway, the garage or the landing — so you do not spread dust inside.

1. Take off the outer layer first: coat, jacket, trousers, shoes, hat and gloves.
2. Peel it outwards, like turning a sock inside out, so the dirty face ends up inside.
3. Do not pull clothing across your face. If it is a tight T-shirt, cut it off rather than pulling it over your head.
4. Put it in a plastic bag and seal it.
5. Leave the bag as far as possible from where you will be: a balcony, an unused room, outside. Not next to the living-room door.
6. Wash your hands before touching anything else.

Step 2: the shower

If there is running water:

• Warm water, neither cold nor very hot. Very hot water opens the pores and increases absorption.
• Ordinary soap and your hand. No rough sponges, brushes or exfoliants.
• No hard scrubbing. Irritating or grazing the skin makes it easier for particles to get in.
• Head to toe, paying particular attention to face, ears, neck, hands and nails.
• Mild shampoo for hair. Nothing else.

Step 3: if there is no water

This is the likely scenario if the network is down, and it still works well:

1. Remove the outer clothing, which is the part that contributes most and needs no water.
2. Clean exposed skin with wet wipes or a clean damp cloth: face, neck, ears, hands, wrists and any folds.
3. One pass per area, turning to a clean face of the cloth each time. Going over again with the same dirty face only redistributes.
4. Blow your nose with a tissue and keep it with the waste.
5. Do not use bottled water to wash while it is still needed for drinking. Hydration is the higher priority.

Step 4: dressing and closing up

• Clothes that were stored inside, not the ones that were in the hallway.
• Do not go back to where you left the bag of contaminated items, and mark it so nobody crosses it barefoot.
• Shoes are among the most contaminated items: they stay outside, always.
• Repeat the process for every person who comes in, and for animals that were outside: wipe them down before they settle anywhere.

What to do with the clothing afterwards

Do not wash it with the rest or put it in the ordinary bin. Keep it bagged and sealed until the authorities say how to dispose of it, which is usually part of the post-event instructions. If it has to stay in the house for several days, put it in the most distant, least-used spot you have.

What comes next — how long you have to stay inside and exactly where — is in where to shelter from fallout.