Radiation Background Definition Sources Exposure Home Types Noniodizing Ionizing Decay Units Risks & Benefits Jobs Glossary/Quiz

Background Information
In our highly technical civilization, radiation has become a household word. Concern with radiation hazards increasingly fills our newspapers and causes anxiety among many members of the general public.

In various forms radiation is a normal part of the human environment. Background radiation has permeated the universe since time began and has been a normal part of the environment throughout the evolution of human beings. Everyone is bathed throughout life with low-level radiation.

Even with the widespread medical and other technological applications of radioactive sources, natural radiation, not produced by the activities of people, accounts for more than half of the radiation exposure a person typically receives. The natural background radiation is due to radiation from the sun and outer space and the natural radioactivity that is always present in the earth, the houses we live in, and the food and drink we consume. The largest contribution from man-made sources comes from radiation used for medical and dental purposes to diagnose and treat disease.

An example of an x-ray of a hand is shown below.

Radiation (Definition)
Radiation is the process of emitting energy in the form of waves or particles from certain kinds of atoms.

Matter is composed of microscopic particles called atoms. Radiation comes from atoms that are in the process of changing. This is true whether the atomic action is a naturally occurring process, or a human-made process.

The atom is the smallest unit that shows the chemical behavior characteristics of an element. The center of each atom has a nucleus that contains protons and neutrons. Protons are positively charged particles. Neutrons, which have no electrical charge, hold the protons together. Electrons are negatively charged particles. The electrons surround the nucleus and travel in orbits.

Sources of Radiation Exposure
Exposure to radiation varies widely from place to place, depending on how and where one lives. In the United States, about 20 % our radiation exposure is from man-made sources such as dental and medical use of radiation.

Natural and Man-Made Exposure to Radiation
Exposure to radiation results from medical and industrial applications of x-ray equipment and radioactive material. In addition, the series of steps involved in supplying fuel for nuclear power reactors expose both radiation workers and surrounding populations. Other sources of radiation exposure are background radiation, coal fired plants, and mining activities.

Types of Radiation

• Ionizing Radiation
  Ionizing radiation is the type of radiation that travels through matter and is capable of separating an electrically neutral atom or molecule into electrically charged components. The electrically charged components produced in this way are called ions. Hence, ionizing radiation is any wave or particulate radiation capable of producing ions.

• Alpha
  Radioactive alpha particles can be shielded by a sheet of paper or by human skin, but if these subatomic particles are inhaled, ingested, or if they enter your body through a cut in your skin, they can be very harmful. If you breathe alpha radiation, you may experience damage to your lungs.

• Beta
  Radioactive beta particles cannot be stopped by a sheet of paper. Some beta particles can be stopped by human skin, but some need a thicker shield (like wood) to stop them. Just like alpha particles, beta particles can also cause serious damage to your health if they enter your body. For example, if ingested, some radionuclides that emit beta particles might be absorbed into your bones and cause damage.

• Gamma
  Gamma rays are the most penetrating of the three types of radiation listed here. Gamma rays usually accompany beta, and some alpha rays. Gamma rays will penetrate paper, skin, wood, and other substances. To protect yourself from gamma rays, you need a shield at least as thick as a concrete wall. This type of radiation could causes severe damage to your internal organs. X-rays are similar to gamma rays.