Background radiation is the low level of ionizing radiation that is always present in our environment, even without any man-made sources.
It comes from both natural and artificial sources:
Natural sources
- Cosmic rays: High-energy particles from space hitting the Earth’s atmosphere. Stronger at higher altitudes (e.g., in airplanes or mountains).
- Terrestrial radiation: Radioactive elements in the Earth’s crust, such as uranium, thorium, and radon gas (especially in basements).
- Internal radiation: Naturally occurring isotopes inside our bodies, like potassium-40 and carbon-14.
Artificial sources
- Fallout from past nuclear weapons testing.
- Radiation from medical procedures (X-rays, CT scans, radiotherapy).
- Small contributions from nuclear power plants or industrial use of radioactive materials.
Typical levels
- On average, people receive about 2–3 millisieverts (mSv) per year from background radiation (varies by location).
- This is generally harmless, as our bodies are adapted to it.
In short: background radiation is the “radiation noise” of the world — always there, unavoidable, and mostly natural.