Page 15 - Curriculum Visions Dynamic Book

Radiation from the ground
Radioactive elements in rocks are found in groundwater and soils. They produce about half of the natural background radiation.
Radium, a natural element found in many rocks, especially those associated with granite and other volcanic materials, decays to release life-threatening radon gas.
radioactive decay: a change in a radioactive element due to loss of mass through radiation. For example uranium decays (changes) to lead.
X-rays: a form of very short wave radiation.  Medical X-rays are an important
contributor to man-made radiation.
Man-made radiation
Just under one-fifth of the radiation we receive is from many everyday sources,
such as having an X-ray in a hospital. Other factors contributing to low level background radiation include some radioactive gases and liquids released by nuclear power stations. Very occasionally there is an increase in this background radiation due to nuclear weapons testing in the atmosphere or an accident in a nuclear power station.
Natural background radiation from space (about 33%)
 Smoke detectors use a minute amount of radioactive material separated by a small air gap from a detector. When smoke particles enter the air gap, they reduce the count rate registered
by the detector, and the alarm is triggered. This provides a cheap and effective means of helping to prevent deaths by fire. Such detectors emit very low energy beta radiation, which is easily absorbed by the surrounding air and so does
not present a health hazard or contribute significantly to the normal background radiation.
Gamma radiation (19%)
Cosmic radiation (14%)
Fall-out (0.5%)
Miscellaneous (0.5%)
Nuclear discharges (0.1%)
Occupational (0.4%)
Sensing chamber containing radioactive source
Our radioactive bodies
Our own bodies have many atoms within them, some of which are naturally radioactive. The
most common of these is radioactive potassium, making up about one in ten thousand atoms of potassium. As these atoms decay, they release about a tenth of a microcurie, meaning that 3700 nuclear disintegrations take place inside your body every second. Thus about 17% of the background radiation we receive occurs inside ourselves!
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