What are the sources of background radiation?

Background radiation comes from natural sources like cosmic rays, radon gas, and man-made sources like medical procedures.

Background radiation is the ionising radiation present in the environment that originates from a variety of natural and artificial sources. One of the primary natural sources is cosmic rays, which are high-energy particles from outer space that strike the Earth's atmosphere. When these particles collide with atoms in the atmosphere, they create secondary particles that reach the Earth's surface and contribute to background radiation.

Another significant natural source is radon gas, a radioactive gas that is produced from the decay of uranium found in rocks and soil. Radon can seep into buildings through cracks in the foundation and accumulate to higher concentrations indoors, especially in poorly ventilated areas. This makes radon a major contributor to the background radiation dose received by people.

Natural sources also include terrestrial radiation from radioactive materials in the Earth's crust, such as uranium, thorium, and potassium-40. These materials emit radiation as they decay, and this radiation can be found in varying amounts in different types of rocks and soils. Additionally, even the human body contains small amounts of naturally occurring radioactive isotopes, such as carbon-14 and potassium-40, which contribute to the background radiation dose.

Man-made sources of background radiation include medical procedures like X-rays, CT scans, and radiation therapy, which use ionising radiation to diagnose and treat medical conditions. Although these procedures are controlled and targeted, they still add to the overall background radiation exposure. Other man-made sources include nuclear power plants, which release small amounts of radioactive materials into the environment, and past nuclear weapons testing, which has left residual radioactive contamination in some areas.

Understanding the sources of background radiation helps us to appreciate the various ways we are exposed to ionising radiation in our daily lives and the importance of managing and minimising unnecessary exposure.