Background Radiation
Definition and meaning of Background Radiation in chemistry.
Background radiation is the constant, low-level ionizing radiation present in the environment from both natural and artificial sources that all living organisms continuously encounter. It represents a baseline radiation exposure that exists everywhere on Earth.
In more detail
Natural background radiation originates from cosmic rays entering the upper atmosphere, radioactive elements like uranium and thorium decaying in Earth's crust, and radon gas seeping from rocks and soil. Artificial contributions include residual fallout from historical nuclear weapons testing, emissions from nuclear power plants, and medical imaging procedures. The average annual exposure varies by geographic location but typically ranges from 2–3 millisieverts (mSv), with higher doses in areas with uranium-rich bedrock or at high altitudes where cosmic ray exposure is greater.
Key facts
| Typical annual exposure | 2–3 mSv (varies by location) |
|---|---|
| Primary natural source | Radon gas (approximately 50% of exposure) |
| Measurement units | Dose in millisieverts (mSv); radon activity in becquerels (Bq) |
| Field | Physical Chemistry |
A person living in a granite-rich region of Colorado receives significantly higher background radiation exposure than someone living at sea level on the Atlantic coast, due to greater concentrations of naturally radioactive uranium and thorium minerals in the granite bedrock combined with higher cosmic ray exposure at elevation.
Frequently asked questions
Is background radiation dangerous?
Natural background radiation at typical environmental levels is not considered acutely hazardous. However, long-term exposure at elevated levels or occupational exposures should be monitored and controlled.
Why does background radiation vary by location?
Geological composition (uranium and thorium concentrations), altitude, and proximity to radioactive mineral deposits determine local radiation levels. Radon accumulation in basements also increases indoor exposure.