The table in Chapter 3 shows the human body has a density of 0.4 relative to concrete. The shielding effect of human bodies can be used to provide extra protection. This protection would be of particular benefit to those people with the greatest sensitivity to radiation, namely, children and pregnant women.
If the estimated or projected radiation exposures look as if they may become high enough to cause radiation sickness and other ways to decrease or avoid radiation exposure are not possible, this shielding method could be used. It would be expected that this extreme measure of providing shielding would be used only during the first 24 hours after fallout arrives, when the radiation hazard is by far the most severe.
Ordinarily, people in most bomb shelters will be sitting or reclining on the floor most of the time. More gamma radiation will be blocked if the people are standing up, because their bodies will then absorb some of the gamma rays coming from the ceiling as well as those coming from the walls.
This shielding, provided by people who are standing, could provide an extra measure of protection for children, mothers with infants, and pregnant women. By forming a two-or three-person-deep circle around the more radiation-sensitive occupants of a bomb shelter, these individuals can possibly be spared high radiation exposures that would be especially detrimental to them. The survey meter should be used to find the arrangement of people that provides the best shielding.
Children and infants may be provided additional protection from overhead radiation by placing them underneath beds, desks, tables, or other suitable items. People with less radiation sensitivity may then sit or lie on top to provide additional shielding.
The RM may verify the shielding effect provided by people by reading the survey enter at different levels in the middle of a room full of people who are standing up. In basement bomb shelters, where no gamma radiation comes up through the floor, the survey meter reading at the floor might be as much as ten times lower than the reading at waist height at the wall. The radiation may even be undetectable at the floor. In high-rise bomb shelters where much of the gamma radiation comes in horizontally through the walls and some comes up at different angles through the floors, this effect won’t be as dramatic.