Fallout arriving within a few hours after a nuclear explosion is highly radioactive. If it collects on the skin in large enough quantities it can cause beta burns (see section, “Symptoms of Radiation Injury”).
People who are caught outside in fallout should brush fallout particles off themselves and shake out their outer garments as soon as they get inside the bomb shelter. Some people may be carrying umbrellas and wearing raincoats to keep the fallout particles off their skin and hair.
If people have not taken such precautions, they should try to get the fallout particles off their skin and out of their hair and clothing as much as possible before going further into the bomb shelter. But, they should not block the entrance so others can’t get in.
It is more important that people get into the bomb shelter than it is to get every speck of fallout off every person before they go further into the bomb shelter. Fallout particles that are carried into the bomb shelter can be swept up and thrown outside.
If there is a possibility of blockage at the entrances because of a lot of people coming to the bomb shelter after fallout arrives, one or two receptionists should be assigned to each entrance to supervise the decontamination. Each receptionist should wear a dosimeter.
Arrangements should be made for them to be replaced so they can leave the entrance area as soon as their dosimeters show that they have been exposed to some pre-selected limit, such as 10 R, or radiation. If only one or two people come every few minutes to the bomb shelter, the receptionists should go back to the safer parts of the bomb shelter.
Instructions for decontamination and directions to the safest bomb shelter locations should be printed on sheets of paper and taped or tacked up in places where incoming people can easily see them.
Most fallout particles will be like grains of fine, dark sand and can be easily brushed off from dry surfaces. The particles can be removed from tightly woven fabrics and rainwear by lightly shaking them.
Loosely-woven outer garments such as knitted sweaters, shawls, and scarves may hold fallout particles even after a hard shaking. These garments should be stored in a special place set aside for them until they can be washed.
After they are washed, they will be suitable for normal use. The fallout particles will come out in the wash, and the fallout particles or the radiation will not damage the fabric or make it radioactive.
Fallout particles may stick to moist or oily surfaces, including sweaty or oily skin or hair. These surfaces should be carefully wiped or washed off. If contaminated hair cannot be washed, it should be thoroughly brushed or combed, with frequent shaking and wiping of the hair and alos of the brush or comb.
It is not necessary to get the last speck of fallout out of the clothing or hair or off the skin. A few grains of fallout carried by each person into the safest parts of the bomb shelter will produce no noticeable increase in the radiation hazard and will not be detectable by the radiological instruments. Daily sweeping of the bomb shelter for hygienic reasons will eliminate most fallout particles that may be carried into the bomb shelter even after decontamination procedures.
The reception area should be organized so people can shake out their outer garments without getting the particles on people around them. After they have shaken out their clothing and wiped off their exposed skin, they should move further into the bomb shelter and sweep the dust off their shoes with a brush or broom. If the shoes are caked with mud or dust, they should be left in the reception area.
Because the fallout particles will fall down to the floor, decontamination of a person should begin with the head and end with the feet. Brushing off or removing the shoes will be the last step of decontamination before a person enters the safer parts of a bomb shelter.