Background radiation is the ubiquitous ionizing radiation that the general population is exposed to, including natural and artificial sources.
Both natural and human-made background radiation varies by location.
| Radiation source | World | Range | USA | Japan | Remark |
|---|---|---|---|---|---|
| Inhalation of air | 1.26 | 0.2-10.0 | 2.28 | 0.40 | |
| Ingestion of food & water | 0.29 | 0.2-1.0 | 0.28 | 0.40 | |
| Terrestrial radiation from ground | 0.48 | 0.3-1.0 | 0.21 | 0.40 | |
| Cosmic radiation from space | 0.39 | 0.3-1.0 | 0.33 | 0.30 | |
| sub total (natural) | 2.40 | 1.0-13.0 | 3.10 | 1.50 | |
| Medical | 0.60 | 3.00 | 2.30 | ||
| Consumer items | - | 0.13 | |||
| Atmospheric nuclear testing | 0.005 | - | 0.01 | ||
| Occupational exposure | 0.005 | 0.005 | 0.01 | ||
| Chernobyl accident | 0.002 | - | 0.01 | ||
| Nuclear fuel cycle | 0.0002 | 0.001 | |||
| Other | - | 0.003 | |||
| sub total (man-made) | 0.6 | 0 to tens | 3.14 | 2.33 | |
| Total | 3.00 | 0 to tens | 6.2 | 3.83 | millisievert |
The natural background radiation of the human environment is a combination of:
- Sources in water and food that are incorporated into the body;
- Airborne radon gas released from the decay of uranium and thorium in the Earth's crust;
- Direct irradiation from radioactive materials in the ground;
- Direct sources from outer space, such as cosmic rays;
- Secondary radiation, produced by the bombardment of the atmosphere by cosmic rays.
Natural sources of background radiation account for most human exposure to ionizing radiation. Most artificial exposure is due to radiological imaging and radiation therapy. Other artificial sources of background radiation such as:
- building materials, cigarettes, and other products that incorporate radioactive sources from nature;
- Self-luminous dials and signs
- Global radioactive contamination consequent to nuclear weapons testing
- Nuclear power station and nuclear fuel reprocessing accidents
- Normal operation of nuclear power facilities and like scientific research
- Emissions from burning fossil fuels, such as those of coal-fueled power plants
Read more about Background Radiation: Natural Background Radiation, Human-caused Background Radiation, Other Usage
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