Background Radiation

Background radiation is the radiation that is always present around us in the environment

Background radiation is the radiation that is present all around in the environment

Although most background radiation is natural, a small amount of it comes from artificial sources, such as medical procedures (including X-rays)
Levels of background radiation can vary significantly from place to place
- Radiation from Nuclear Power come to less than 0.1% of the total

Background radiation can come from natural sources on Earth or from space as well as man-made sources

Radon gas (in the air)
- Airborne radon comes from the ground
- This is from the natural decay of uranium in rocks and soil
- The gas is tasteless, colourless and oderless but it not generally a health issue

Rocks and Buildings
- Heavy radioactive elements, such as uranium and thorium, occur naturally in rocks in the ground
- Uranium decays into radon gas, which is an alpha emitter
- This is particularly dangerous if inhaled into the lungs in large quantities
- Natural radioactivity can be found in building materials, including decorative rocks, stone and brick
Cosmic rays from space
- The sun emits an enormous number of protons every second
- Some of these enter the Earth’s atmosphere at high speeds
- When they collide with molecules in the air, this leads to the production of gamma radiation
- Other sources of cosmic rays are supernovae and other high energy cosmic events
Carbon-14 in biological material
- All organic matter contains a tiny amount of carbon-14
- Living plants and animals constantly replace the supply of carbon in their systems hence the amount of carbon-14 in the system stays almost constant
Radioactive material in food and drink
- Naturally occurring radioactive elements can get into food and water since they are in contact with rocks and soil containing these elements
- Some foods contain higher amounts such as potassium-40 in bananas
- However, the amount of radioactive material is minuscule and is not a cause for concern

Medical sources
- In medicine, radiation is utilised all the time
- Uses include X-rays, CT scans, radioactive tracers, and radiation therapy
Nuclear waste
- While nuclear waste itself does not contribute much to background radiation, it can be dangerous for the people handling it
Nuclear fallout from nuclear weapons
- Fallout is the residue radioactive material that is thrown into the air after a nuclear explosion, such as the bomb that exploded at Hiroshima
- While the amount of fallout in the environment is presently very low, it would increase significantly in areas where nuclear weapons are tested
Nuclear accidents
- Accidents such as that in Chernobyl contributed a large dose of radiation into the environment
- While these accidents are now extremely rare, they can be catastrophic and render areas devastated for centuries

Background radiation must be accounted for when taking readings in a laboratory
This can be done by taking readings with no radioactive source present and then subtracting this from readings with the source present
- This is known as the corrected count rate

Sources of Background Radiation