What are common sources of background radiation in everyday life?

Common sources of background radiation include cosmic rays, radon gas, food and drink, and man-made sources.

Cosmic rays are a significant source of background radiation. These are high-energy particles from space that constantly bombard the Earth. When these particles interact with the Earth's atmosphere, they produce a shower of secondary particles that reach the surface and contribute to the background radiation we experience. The level of cosmic radiation varies depending on altitude and geographical location. For instance, people living at higher altitudes or near the poles are exposed to more cosmic radiation than those living at sea level or near the equator.

Radon gas is another major contributor to background radiation. It is a naturally occurring radioactive gas that is produced by the decay of uranium in rocks and soil. Radon gas can seep into homes and buildings through cracks in the foundation or gaps around service pipes. Once inside, it can become trapped and build up to high levels, increasing the risk of lung cancer. In fact, radon is the second leading cause of lung cancer after smoking.

Food and drink also contribute to background radiation. This is because they contain small amounts of naturally occurring radioactive materials, such as potassium-40 and carbon-14. For example, bananas are well-known for their relatively high levels of potassium-40. However, the radiation dose from eating a banana is extremely small and poses no health risk.

Lastly, man-made sources of radiation also contribute to the background level. These include medical procedures, such as X-rays and CT scans, as well as nuclear power plants and the fallout from nuclear weapons testing. While these sources contribute a relatively small fraction of the total background radiation, they can significantly increase an individual's radiation dose in certain situations. For example, a single CT scan can deliver a radiation dose equivalent to several years' worth of natural background radiation.