Define background radiation as ionising radiation that is always present in the environment.

Background radiation refers to the ionising radiation that is consistently present in our environment. It originates from both natural and artificial sources. Natural sources include cosmic rays from outer space, radiation from rocks and soil, radon gas released from the ground, and even radiation emitted by living organisms. Artificial sources can arise from medical procedures, nuclear power plants, and other human activities. Understanding background radiation is crucial for assessing exposure risks and ensuring safety in various applications, particularly in medicine and industry.