Facts of Radiation Part 2

Time
One should decrease the amount of time spent near the source of radiation. The amount of radiation exposure increases and decreases with the time people spend near the source of radiation. For example, exposures to radiation is expressed in terms of a committed dose. A committed dose is one that accounts for continuing exposures over long periods of time (such as 30, 50, or 70 years). It refers to the exposure received from radioactive material that enters and remains in the body for many years. In order to assess the potential for exposure in a situation, the amount of time a person is likely to spend in the area of contamination is considered. For example, in assessing the potential exposure from radon in a home, how much time people are likely to spend in the basement is estimated.

Distance
One should increase the distance from a radiation source. Distance is a prime concern when dealing with gamma rays, because they can travel long distances. Alpha and beta particles do not have enough energy to travel very far. As a rule, if one doubles the distance, one reduces the exposure by a factor of four. Halving the distance, increases the exposure by a factor of four.

Shielding
One should increase the shielding between one and the radiation source. Shielding is anything that creates a barrier between people and the radiation source. Depending on the type of radiation, the shielding can range from lead sheets, a plate of window glass or several feet of concrete. Being inside a building or a vehicle can provide shielding from some kinds of radiation. The greater the shielding around a radiation source, the smaller the exposure.

Alpha
A thin piece of light material, such as paper, or even the dead cells in the outer layer of human skin provides adequate shielding because alpha particles cannot penetrate it.

Beta
Additional covering, for example heavy clothing, is necessary to protect against beta-emitters. Some beta particles can penetrate and burn the skin.

Gamma
Thick, dense shielding, such as lead, is necessary to protect against gamma rays. The higher the energy of the gamma ray, the thicker the lead must be.