The basis for the MCG Radiation safety protection program is the ALARA philosophy. ALARA is the acronym for keeping radiation exposure As Low As Reasonably Achievable. We will be reviewing some general radiation safety topics in this training material and will discuss specific techniques that Public Safety personnel can use to keep their exposures ALARA.
Background radiation is natural and is a part of living on this planet. Below are some general categories that make up our natural background exposure. All figures are averages for the United States.
Radon: 200 mrem
Radon is a radioactive gas that is the decay product of naturally occurring isotopes in the earth's soil and rocks. Radon is the largest contributor to our natural background radioactive exposure.
Radionuclides in body: 40 mrem
All living things contain trace amounts of radioactive materials, including radioactive carbon and potassium. Certain foods that we eat also contain trace amounts of radioactive materials, including bananas and brazil nuts.
Terrestrial Sources: 30 mrem
In addition to radon, we also receive background exposure from the rocks in the earth's crust. Remember that most building materials, including bricks and concrete, are made from natural products. These materials contain small amounts of natural uranium and thorium.
Cosmic Radiation: 25 mrem
The sun and other stars emit radiation that reaches the earth's surface. People living at high altitudes and pilots who fly high altitude plane routes receive much more cosmic radiation exposure than we do in Augusta.
Man-made: 65 mrem
Man made sources of radiation that contribute to our background exposure include fallout form nuclear weapons testing, nuclear power plants, and medical uses of radiation.
The 65 mrem is an average for all US residents. This number reflects the fact that a very small percentage of the population receives large amounts of radiation as part of radiation therapy treatments. Also reflected in this category is the routine diagnostic x-ray procedures we may receive such as an annual bitewing x-ray at the dentist.
Not really. Here in Augusta the average background exposure is much lower than the natural average. Certain parts of the country have much higher levels than in Augusta. Some buildings and basements in the northeast US have radon ventilation systems installed to vent high radon levels. Radon gas is pretty much everywhere we are, so avoiding it is pretty difficult to do.
The sum of all these sources of background radiation is about 360 mrem per year, which is approximately 1 mrem per day.