Module 2 Biological Effects
II. MODULE OUTLINE
Sources of Radiation
We live in a radioactive world and always have. In fact, the
majority of us will be exposed to more ionizing radiation
from natural background radiation than from our jobs.
1. Natural sources
There are several sources of radiation that occur naturally.
EO1 Identify the major
The radiation emitted from these sources is identical to
sources of natural
the radiation that results from manmade sources.
background and manmade
The four major sources of naturally occurring radiation
Sources in the earth's crust, also referred to as
Sources in the human body, also referred to as
Cosmic radiation (total average dose ~ 28 mrem/yr)
1) Cosmic radiation comes from the sun and outer space. It
consists of positively charged particles and gamma
2) At sea level, the average annual cosmic radiation dose is
about 26 mrem.
3) At higher elevations, the amount of atmosphere shielding
cosmic rays decreases; therefore, the dose increases.
b. Sources in earth's crust (terrestrial) (total average dose ~
There are natural sources of radiation in the ground (i.e.,
rocks and soil).